DSpace at VNU: Syntheses and Structures of New Trinuclear M(II)LnM(II) (M = Ni, Co; Ln Gd, Ce) Complexes with 2, 6-Bis(acetobenzoyl)pyridine

Journal of Inorganic and General Chemistry ARTICLE www.zaac.wiley-vch.de Zeitschrift für anorganische und allgemeine Chemie DOI: 10.1002/zaac.201500016 Syntheses and Structures of New Trinuclear MIILnMII (M = Ni, Co; Ln = Gd, Ce) Complexes with 2,6-Bis(acetobenzoyl)pyridine Thi Nguyet Trieu,*[a] Minh Hai Nguyen,[a] Ulrich Abram,[b] and Hung Huy Nguyen*[a] Keywords: Lanthanide complexes; Trinuclear complexes; d-f Mixed metal complexes; β-Diketonate; X-ray structure Abstract One-pot reactions of 2,6-bis(acetobenzoyl)pyridine (H2L) with a mixture of LnCl3 (Ln = Ce, Gd) and Ni(CH3COO)2 (ratio 2:1:2) in CH2Cl2/MeOH in the presence of a supporting base like Et3N give trinuclear complexes with the general composition [Ni2Ln(L)2(CH3COO)3(MeOH)2/3] (1) in high yields Trinuclear [Ni2Ln(L)2(PhCOO)3(MeOH)2] (2) complexes are formed when similar reactions are performed starting from NiCl2, and benzoic acid (PhCOOH) is added subsequently Under the same conditions, reactions with the corresponding cobalt(II) salts result in the formation of a neutral [Co8(μ3-O)2(L)6] complex, which has a bis(triple-helical) structure The cobalt(II) analogues to compounds and 2, however, can be synthesized by a pre-treatment of the lanthanide salts with H2L and subsequent addition of the cobalt salts, and benzoic acid (in the case of 2) Introduction Heteronuclear complexes comprising 3d-4f metal ions have attracted great interests due to their intriguing physicochemical properties such as magnetism[1] or photoluminescence.[2] Rational synthesis of such complexes is commonly done by using ligand systems containing coordination sites with different donor atoms and chelating abilities Among these systems, 2,6bis(acetoacetyl)pyridines (H2LR) are the most frequently used ligands They have three metal binding sites, one central 2,6diacylpyridine site suitable for lanthanide binding and two terminal 1,3-diketonate sites favorable for transition metal binding.[3,4] Some series of discrete trinuclear 3d-4f [MIILnIIIMII] mixed-metal complexes, where MII is NiII,[5] CoII,[6] CuII,[7] or ZnII [8] have been prepared In all of the reported complexes, the three metal ions are chelated by two dinegative pyridine2,6-bis(β-diketonato) ligands, which give the thermodynamically stable [MIILnIIIMII(LR)2]3+ framework The isolated complexes are commonly of the type [MIILnIIIMII(LR)2(NO3)n](NO3)3–n where nitrates can act as counterions and also as auxiliary ligands.[4–8] * Prof Dr H H Nguyen Fax: +84-4382-41140 E-Mail: nguyenhunghuy@hus.edu.vn * Prof Dr T N Trieu E-Mail: trieuthinguyet@yahoo.com.vn [a] Department of Chemistry Hanoi University of Science Le Thanh Tong str.19 Hanoi, Vietnam [b] Institute of Chemistry and Biochemistry Freie Universität Berlin Fabeckstrasse 34–36 14195 Berlin, Germany Z Anorg Allg Chem 2015, 641, (5), 863–870 The [MIILnIIIMII(LR)2]3+ skeletons are expected to be versatile building blocks for supramolecules or coordination polymers due to (i) their high thermodynamic stability, which gives access to rational syntheses of the supramolecules by connecting these blocks with bi-functional linkers, (ii) their planar structure which allows convenient assembling, and (iii) the large variety of coordination sites, which are available with LnIII and MII ions Surprisingly, there are hitherto only a few papers dealing with such compounds.[6,8,9] In the presented work, we report the syntheses and structures of some neutral, trinuclear {NiIILnIIINiII} and {CoIILnIIICoII}complexes with 2,6-bis(acetobenzoyl)pyridine (H2L, Scheme 1) using acetate and benzoate as co-ligands The obtained complexes provide examples other than their nitrate congeners for studies of their physicochemical properties and represent trinuclear prototype compounds for tailored supramolecules with bridging bis-carboxylato ligands, the synthesis, of which is planned for the future Scheme The ligand H2L used in this work 863 © 2015 WILEY-VCH Verlag GmbH & Co KGaA, Weinheim Journal of Inorganic and General Chemistry www.zaac.wiley-vch.de ARTICLE Zeitschrift für anorganische und allgemeine Chemie Scheme Reactions of H2L with Ni(CH3COO)2 and LnCl3 Results and Discussion H2L readily reacts with a mixture of Ni(CH3COO)2 and LnCl3 in MeOH/CH2Cl2 at ambient temperature Yellow, crystalline solids of trinuclear complexes with the composition [Ni2Gd(L)2(CH3COO)3(MeOH)2] (1a) and [Ni2Ce(L)2(CH3COO)3(MeOH)3] (1b) were isolated in high yields (Scheme 2) Addition of a supporting base such as Et3N accelerates the formation of the products The resulting complexes are well soluble in DMSO or DMF, but only slightly soluble in CH2Cl2 or CHCl3 and almost insoluble in alcohols The ESI+ mass spectra of complexes 1a and 1b show main peaks at m/z = 1130.09 and 1112.13, respectively, corresponding to [Ni2Ln(L)2(CH3COO)2]+ fragments A less intense peak (about % of the base peak) in the spectrum of the cerium compound at m/z = 1172.02 can be assigned to [Ni2Ce(L)2(CH3COO)3 + H]+ The fact that no signals of species with coordinated methanol can be detected refers to the only weak coordination of the solvent ligands The IR spectra of the nickel complexes were taken from carefully vacuumdried samples They exhibit no absorption bands of OH stretches, what reflects the deprotonation of the ligands Additionally, the shift of the ν(C=O) bands from 1620 cm–1 in H2L to the region below 1600 cm–1 indicates the formation of β-diketonato chelate rings Two different absorptions of ν(C=O) stretches observed around 1610 cm–1 and 1590 cm–1 were previously reported for the trinuclear [Ni2Ln(LMe)2(NO3)3] complexes, where H2LMe is 2,6bis(acetoacetyl)pyridine.[5] In the IR spectra of 1, the two absorptions are slightly bathochromically shifted compared to those of [Ni2Ln(LMe)2(NO3)3] While one is a sharp strong absorption around 1600 cm–1, the other is observed as a shoulder at about 1580 cm–1 The C=O stretching bands of the acetato ligands appear as broad absorptions with very high intensity at 1570 cm–1 Consequently, they overlap with the second absorption bands of the ν(C=O) vibrations of β-diketonato rings The relatively low frequencies of ν(C=O) absorptions of the acetato ligands indicate that both of their oxygen atoms are coordinated.[10] Crystals of the complexes were obtained by slow evaporation of the reaction mixtures They are stable in the mother solutions, but quickly turn to yellow powders by losing solvents when they run dry An ellipsoid representation of the molecular structure of 1a is shown in Figure Selected bond lengths and angles are given in Table The quality of the single crystals of the cerium complex 1b was not fully satisfactory, so that the corresponding structure determination [space Z Anorg Allg Chem 2015, 863–870 group P21, a = 10.174(1) Å, b = 23.865(2) Å, c = 11.286(1) Å, β = 111.12(1)°, V = 2556.1(4) Å3] could only be refined with isotropic thermal parameters and converged at an R1 value of 12 % Thus, a detailed discussion of the bond lengths and angles of this compound shall not be done here Nevertheless, its composition as a trinuclear Ni/Ce/Ni complex can be derived from the available data unambiguously Figure depicts the molecular structure of the product, which shows some remarkable differences in contrast to the gadolinium compound 1a Figure Ellipsoid representation of the molecular structure of 1a Hydrogen atoms are omitted for clarity Thermal ellipsoids represent 50 percent probability Hydrogen bonds were found: H bond / d(D– H) / d(H···A) / d(D···A) /Å: O7–H7···O6 / 0.87 / 1.77 / 2.58(1); O8–H8···O1#1 / 0.87 / 1.96 / 2.794(7) Symmetry equivalent #1 : –1+x,+y,+z Figure Molecular structure of 1b Hydrogen atoms are omitted for clarity Both 1a and 1b reveal trinuclear {NiLnNi(L)2}3+ cores, which are similar to the series of trinuclear complexes {MIILnMII) with 2,6-bis(acetoacetyl)pyridine ligands.[5–8] Two L2– ligands bind each two NiII ions through the 1,3-diketonato sites and the LnIII ions through the 2,6-diacetylpyridine sites This results in nearly planar {Ni2Ln(L)2}3+ skeletons, which 864 © 2015 WILEY-VCH Verlag GmbH & Co KGaA, Weinheim Journal of Inorganic and General Chemistry ARTICLE www.zaac.wiley-vch.de Zeitschrift für anorganische und allgemeine Chemie Table Selected bond lengths /Å and angles /° in [Ni2Gd(L)2(CH3COO)3(MeOH)2] (1a), [Ni2Gd(L)2(PhCOO)3(MeOH)2] (2a), [Ni2Ce(L)2(CH3COO)3(MeOH)(H2O)] (2b) and [Co2Ce(L)2(PhCOO)3(MeOH)(H2O)] (5b) The same atomic labeling schemes were used for all molecules Bond lengths M1–O11 M1–O13 M1–O21 M1–O23 M1–O1 M1–O7 M2–O14 M2–O16 M2–O24 M2–O26 M2–O3 M2–O8 Ln–N1 Ln–N2 Ln–O13 Ln–O14 Ln–O23 Ln–O24 Ln–O2 Ln–O4 Ln–O5 Ln–O6 Angles O11–M1–O23 O13– M1–O21 O14– M2–O26 O16–M2–O24 O13– M1–O23 O14– M2–O24 N1–Ln–N2 O13–Ln–O24 O23–Ln–O14 1a 2a 2b 5b 1.991(5) 2.009(5) 1.999(6) 2.010(5) 2.067(7) 2.084(7) 1.988(6) 1.977(6) 2.020(6) 1.995(6) 2.060(6) 2.116(6) 2.655(7) 2.708(7) 2.445(5) 2.533(5) 2.532(5) 2.469(6) 2.383(6) 2.358(6) 2.291(7) – 2.006(2) 2.023(2) 2.024(2) 2.012(2) 2.050(2) 2.163(2) 2.008(2) 1.980(2) 2.007(2) 1.991(2) 2.041(2) 2.179(2) 2.735(2) 2.690(2) 2.567(2) 2.508(2) 2.455(2) 2.583(2) 2.361(2) 2.322(2) 2.571(2) 2.472(2) 2.003(2) 2.014(2) 1.978(2) 2.019(2) 2.074(2) 2.153(2) 2.016(2) 2.005(2) 2.034(2) 1.992(2) 2.068(2) 2.136(2) 2.787(2) 2.774(2) 2.639(2) 2.535(2) 2.556(2) 2.644(2) 2.463(2) 2.422(2) 2.570(2) 2.672(2) 2.026(3) 2.049(2) 2.022(2) 2.037(2) 2.067(3) 2.174(3) 2.050(2) 2.040(2) 2.067(2) 2.049(2) 2.093(2) 2.133(2) 2.772(3) 2.804(3) 2.607(2) 2.554(2) 2.587(2) 2.630(2) 2.524(2) 2.435(2) 2.631(2) 2.582(2) 175.6(2) 171.2(3) 172.3(2 171.9(3) 84.2(2) 81.4(2) 160.0(2) 168.6(2) 149.8(2) 172.42(7) 174.84(6) 173.83(7) 174.85(7) 84.17(6) 86.39(6) 170.19(6) 152.62(5) 165.52(5) 179.59(6) 172.60(7) 175.62(7) 178.34(6) 88.24(6) 86.90(6) 170.41(5) 158.16(5) 172.16(5) 174.6(1) 174.9(1) 174.4(1) 173.4(1) 87.0(1) 86.6(1) 169.9(1) 155.4(1) 171.8(1) consist of N2O4 hexagonal bases for the LnIII ions and O4 square-planar bases for the NiII ions There are three additional acetato ligands bonded to central metal atoms, including two bidentate ligands and one unidentate ligand In the molecular structure of 1a (Figure 1), two acetates act as bridges between the gadolinium and the nickel ions, while the third one is unidentate bonded to GdIII Also in the molecular structure of 1b (Figure 2), the two bidentate acetates are located above the {Ni2Ln(L)2}3+ plane, but only one of them is a bridging ligand between CeIII and one of the NiII ions, whereas the second one exclusively binds to the central CeIII ion The unidentate acetate ligands are coordinated to the lanthanides below the {Ni2Ln(L)2}3+ plane, which is defined by the chelating ligands Thus, CeIII and GdIII show coordination numbers of 10 and 9, respectively The higher coordination number of CeIII is consistent with the larger radius of this cation compared to that of GdIII The coordination spheres of the six-coordinate NiII ions are completed by axial methanol molecules The slightly different radii of the Gd3+ and Ce3+ ions obviously have also influence on the coordination modes of the central lanthanide ions Since the size of the central cavity is mainly determined by the coordination of the two peripheral nickel ions, the coordination positions of the Gd3+ and Ce3+ ions are controlled by their size The relatively small gadolin- Z Anorg Allg Chem 2015, 863–870 ium ion is well accommodated in the central hexagonal plane formed by the bis(acetylpyridine) fragments The two organic ligands are slightly twisted to accommodate the GdIII ions in an optimal way This is consistent with the O13–Gd1–O14, O13–Gd1–O24, N1–Gd1–N2 trans angles being in the range of 150–169°, which largely deviate from 180° The O13–Ni1– O23 and O14–Ni2–O24 angles of 81.4(2)° and 84.2(2)°, respectively, are also significantly lower than expected for an ideal octahedral arrangement The C–O bond lengths in the bridging acetato ligands are almost equal reflecting the delocalization of electron density In contrast, the two negative charges of L2– are not equally delocalized over three metal cores The highest charge density is localized in the chelate rings of the nickel atoms This is consistent with the fact that the corresponding Ni–O bond lengths are nearly equal to the Ni–O(acetate) bond lengths, while the Gd–O(acetate) bonds are significantly shorter than those to oxygen atoms of the chelating ligands Nevertheless, all M–O and M–N bonds in 1a are in the same ranges of the corresponding bond lengths in the previously reported trinuclear [NiLnNi] complexes.[5] In the structure of 1b, the larger Ce3+ ion seems to be too big for the cavity formed between the two nickel β-diketonato ligands and, thus, it is positioned above the planar N2O4 hexagonal base toward the two bidentate acetates 865 © 2015 WILEY-VCH Verlag GmbH & Co KGaA, Weinheim Journal of Inorganic and General Chemistry www.zaac.wiley-vch.de ARTICLE Zeitschrift für anorganische und allgemeine Chemie Reactions of two equivalents of H2L with a mixture of NiCl2 (2 equiv.) and LnCl3 (1 equiv.) in dichloromethane/methanol (1:1, v:v) yield deep yellow-green solutions Although no pure crystalline products could be isolated from such solutions, there is mass spectrometric evidence for the formation of trinuclear compounds such as [Ni2Ln(L)2Cl2]+, [Ni2Ln(L)2(OH)Cl]+, [Ni2Ln(L)2Cl]2+ The addition of acetic acid to such solutions results in the formation of complexes 1, but with slightly lower yields compared to the synthesis starting directly from the transition metal acetates Nevertheless, this route represents a synthetic approach to compounds with other auxiliary carboxylato ligands than acetate Accordingly, trinuclear complexes with the composition [Ni2Ln(L)2(PhCOO)3(solvent)2] (2) can be isolated from such reactions with benzoic acid in high yields (see Scheme 3) Figure Molecular structure of 2a Hydrogen atoms are omitted for clarity Thermal ellipsoids represent 50 percent probability Hydrogen bonds were found, H bond / d(D–H) / d(H···A) / d(D···A) /Å: O7– H7···O5 / 0.86(3) / 1.88(3) / 2.728(2); O8–H8···O6 / 0.87 / 2.00 / 2.828(2) Scheme Reactions of H2L with MIICl2, LnCl3, and benzoic acid The IR spectra of are almost identical to those described for Two absorptions corresponding to the ν(C=O) stretches of L2– are sharp, strong bands at 1600 cm–1 and 1570 cm–1 The absorptions of ν(C=O) stretches of carboxylato ligands appear at about 1550 cm–1 and are well separated from the ν(C=O) stretches belonging to L2– The mass spectra of not show the molecular ions but intense fragment ions with m/z = 1254.04 for the gadolinium complex 2a and m/z = 1236.12 for the cerium compound 2b due to ions of the composition [Ni2Ln(L)2(PhCOO)2]+ The complexes are moderately soluble in CH2Cl2 and CHCl3 Single crystals of [Ni2Gd(L)2(PhCOO)3(MeOH)(H2O)] (2a) and [Ni2Ce(L)2(CH3COO)3(MeOH)2] (2b) were obtained by slow evaporation of the reaction mixtures Figure and Figure illustrate the molecular structures of these compounds Selected bond lengths and angles of the complexes are summarized in Table The cores of compounds reveal trinuclear {NiLnNi(L)2}3+ arrangements similar to those described for 1a and 1b The three positive charges of the skeletons are compensated by each three benzoate anions to form neutral complexes All benzoates serve as bidentate ligands Two of them act as bridges between NiII and LnIII and one binds exclusively to the LnIII ion Thus, in both complexes, the LnIII atoms possess coordination number 10 with a nearly planar hexagonal base formed by N1, N2, O13, O14, O23, and O24 atoms of two 2,6-diacetylpyridine sites and each two oxygen donors from acetates above and below this base The two nickel atoms are six-coordinate with a distorted octahedral environment, where Z Anorg Allg Chem 2015, 863–870 Figure Molecular structure of 2b Hydrogen atoms are omitted for clarity Thermal ellipsoids represent 50 percent probability Hydrogen bonds were found, H bond / d(D–H) / d(H···A) / d(D···A) /Å: O7– H7···O5 / 0.832(10) / 2.001(12) / 2.818(2); O8–H8···O6 / 0.80(3) / 1.97(3) / 2.760(2) the donor atoms of the diketonato units of two L2– ligands occupy the equatorial positions The axial positions are completed by only weakly bonded methanol or aqua ligands The Gd–O and Gd–N bonds in 2a are slightly shorter than the corresponding Ce–O, Ce–N bonds in 2b, what can be explained by the smaller ionic radius of Gd3+ Similar to the situation in 1a, the smaller size of GdIII also results in a marked distortion of the main {Ni2Ln(L)2}3+ framework, which is indicated by small N–Ln–N, O–Ln–O, O–Ni–O trans angles In order to obtain analogous trinuclear complexes of CoII, the reactions of H2L with mixtures of Co(CH3COO)2 and LnCl3 or CoCl2, LnCl3, and benzoic acid were carried out under the same conditions applied for the syntheses of and All such reactions, however, resulted in a mixture of products, from which dark-red hexagonal plates of compound were isolated as the main product The IR spectrum of shows two absorptions corresponding to ν(C=O) stretches of L2– at 1609 cm–1 and 1572 cm–1 The second band is well resolved 866 © 2015 WILEY-VCH Verlag GmbH & Co KGaA, Weinheim Journal of Inorganic and General Chemistry ARTICLE www.zaac.wiley-vch.de Zeitschrift für anorganische und allgemeine Chemie and much less intense compared to that of and This suggests the absence of acetate in the ligand sphere of The ESI+ MS spectrum of shows a very intense peak at m/z = 1360.01 corresponding to the cation [Co4(L)3(OH)]+ Dark red hexagonal plates of 3, suitable for crystal structure analysis, were obtained by a slow evaporation of its MeOH/CH2Cl2 solution The compound is a neutral, octanuclear bis(triple-helical) chelate complex of the composition [Co8(μ3-O)2(L)6] (3) A structural sketch of the compound is given in Figure 5a Figure 5b represents an ellipsoid representation of the asymmetric unit of 3, from which the complete molecule is derived by a threefold axis Table Selected bond lengths /Å in compound Co1–O11 Co1–O13 Co2–O21 Co2–O23 Co3–O13 Co3–N1 Co3–O14 Co3–O24 2.062(4) 2.076(4) 2.069(3) 2.078(3) 2.200(3) 2.094(4) 2.488(5) 2.062(3) Co3–O26 Co3–O3 Co4–O23 Co4–N2 Co4–O24 Co4–O14 Co4–O16 Co4–O4 2.051(3) 1.936(1) 2.181(3) 2.128(4) 2.238(3) 2.087(3) 2.106(3) 2.020(1) Mixed cobalt(II)/lanthanide(III) complexes with the core structures [Co2Ln(L)2(CH3COO)3] (4) and [Co2Ln(L)2(PhCOO)3] (5), however, can be rationally synthesized in high yields via a three-step reaction: (1) H2L is first fixed on the LnIII ion by the reaction with LnCl3 solutions, (2) CoII and a supporting base like Et3N are added in order to form the main skeleton [Co2Ln(L)2]3+, and (3) the [Co2Ln(L)2]3+ cores are stabilized by the coordination of bridging acetate (in the case of 4) or by the addition of benzoic acid (in the case of 5) IR and MS spectra of and are almost identical to those discussed for and 2, which strongly suggest analogous structures Compounds and are better soluble in chlorinated solvents like CH2Cl2 or CHCl3 than the corresponding nickel complexes While no single crystals of reasonable quality could be obtained for compounds 4, single crystals of [Co2Ce(L)2(Benz)3](MeOH)(H2O)] (5b) were formed easily by slow evaporation of the corresponding reaction mixture The molecular structure of 5b is shown in Figure Selected bond lengths and angles of the complexes are compared with the values in the analogous nickel compounds in Table The bonding situation in 5b is virtually the same to that of compounds The CeIII ion has the coordination number 10 and two CoII have the coordination number Similar to the situation of 2b, one CoII in 5b has a coordinated methanol and the other has a water ligand in its octahedral ligand sphere All Figure (a) Structure of (b) Ellipsoid representation of the asymmetric cell Hydrogen atoms are omitted for clarity Thermal ellipsoids represent 50 per cent probability Like analogous octanuclear cobalt complexes,[11] complex consists of eight Co2+ ions forming a twofold capped, twisted trigonal prism with a μ3-O2– ion centered in each of the two inner faces All six doubly negatively charged L2– ligands act as pentadentate ligands and bind to three cobalt atoms: to two by the two β-diketonate moieties and to the remaining ones by the 2,6-diacetylpyridine site The two antipodal cobalt atoms and two μ3-O2– ligands are placed on the threefold rotational axis The other six central cobalt atoms are divided into three pairs, which are symmetrically equivalent Finally, all eight Co atoms are six-coordinate, from which the two antipodal atoms show an octahedral tris(β-diketonato) ligand sphere and the remaining six Co atoms reveal a slightly distorted trigonalprismatic arrangement, bonded to one bidentate β-diketonate, one tridentate 2,6-diacetylpyridine site, and one μ3-O2– ligand Selected bond lengths and angles are summarized in Table Z Anorg Allg Chem 2015, 863–870 Figure Molecular structure of 5b Hydrogen atoms are omitted for clarity Thermal ellipsoids represent 50 percent probability Hydrogen bonds were found, H bond / d(D–H) / d(H···A) / d(D···A) /Å: O7– H7···O6 / 0.88(1) / 1.99(2) / 2.72(1); O8–H8B···O16#1 / 0.87 / 2.59 / 3.22(1); O8-H8A···O26#1 / 0.87 / 1.99 / 2.76(1) Symmetry equivalent #1 : –x,–y,1-z 867 © 2015 WILEY-VCH Verlag GmbH & Co KGaA, Weinheim Journal of Inorganic and General Chemistry ARTICLE www.zaac.wiley-vch.de Zeitschrift für anorganische und allgemeine Chemie Co–O bonds in 5b are slightly longer than the equivalent Ni–O bonds in 2b (w), 939 (w), 766 (m), 721 (w), 651 (w), 534 (w) cm–1 +ESI-MS: 1172.02 (5 % base peak, [M + H]+), 1112.13 (100 % base peak, [M-CH3COO] +) Conclusions [Ni2Ln(L)2(PhCOO)3] (2Ј): A methanol solution (5 mL) of NiCl2·6 H2O (47.5 mg, 0.2 mmol) and LnCl3·xH2O (0.1 mmol) was added to a solution of H2L (74.2 mg, 0.2 mmol) in CH2Cl2 (10 mL) After stirring for at room temperature, solid benzoic acid (36.6 mg, 0.3 mmol) and then triethylamine (80.8 mg, 0.8 mmol) were added to obtain deep yellow-green solutions The isolation of products (2 and 2Ј) was done essentially the same as described for [Ni2Ln(L)3](CH3COO)3] The ready combination of thermodynamically stable trinuclear [MIILnMII(L)2]3+ cores (MII = Ni, Co; Ln = Gd, Ce) with carboxylic acids recommends the use of bifunctional carboxylic linkers to build supramolecules from [MIILnMII(L)2]3+ building blocks Ongoing studies about such coordination polymers with the use of dicarboxylic acids are presently underway in our laboratories Experimental Section Materials: All chemicals used in this study were reagent grade and used without further purification Solvents were freshly distilled unless otherwise stated Physical Measurements: Infrared spectra were measured as KBr pellets with a Shimadzu IRAffinity - 1S FTIR spectrometer between 400 and 4000 cm–1 Positive ESI mass spectra were measured with an Agilent 6210 ESI-TOF (Agilent Technology) mass spectrometer All MS results are given in the form: m/z, assignment Elemental analysis of carbon, hydrogen, and nitrogen were determined with a Heraeus vario EL elemental analyzer Synthesis of the Ligand: H2L was prepared by a standard procedure.[12] The product was obtained as a yellow crystalline solid Yield 65 % C23H17NO4: calcd C 74.38; H 4.61; N 3.77 %; found: C 75.26; H 4.49; N 3.54 % IR (KBr): ν˜ = 3130 (w), 3074 (w), 1620 (vs), 1570 (vs), 1489 (m), 1261 (m), 1228 (m), 1070 (s), 997 (m), 923 (m), 773 (vs), 702 (s), 684 (s), 617 (s) cm–1 +ESI-MS: 372.12 (100 % base peak, [M + H] +, 394.10 (20 % base peak, [M + Na] +) Syntheses of the NiII Complexes [Ni2Ln(L)2(CH3COO)3] (1Ј): A solution of Ni(CH3COO)2·4H2O (49.8 mg, 0.2 mmol) and LnCl3·xH2O (0.1 mmol) in MeOH (5 mL) was added to a solution of H2L (74.2 mg, 0.2 mmol) in CH2Cl2 (10 mL) The mixture was stirred for at room temperature and then triethylamine (50.5 mg, 0.5 mmol) was added Upon the addition of Et3N, the color of the solution turned from light green to deep yellow-green The resulting solution was allowed to evaporate at room temperature for several days to give single crystals of 1, which were suitable for X-ray structure analysis The crystals of collected by suction filtration and dried in vacuo to obtain pure powders 1Ј, which were used for the physical measurements This drying operation obviously also removed coordinated solvent molecules as is strongly suggested by the analytical data (1aЈ): Yield 84.9 % (109.3 mg) [Ni2Gd(L)2(CH3COO)3] C52H39N2O14Co2Gd: calcd C 52.46; H 3.30; N, 2.35 %; found: C 52.32; H 3.21; N 2.22 % IR (KBr): ν˜ = 3065 (w), 1605 (vs), 1568 (vs), 1520 (vs), 1460 (s), 1435 (s), 1283 (m), 1244 (w), 1159 (w) 1074 (w), 939 (w), 763 (m), 723 (w), 650 (w), 534 (w) cm–1 +ESI-MS: 1130.09 (100 % base peak, [M-CH3COO] +) [Ni2Ce(L)2(CH3COO)3] (1bЈ): Yield 82.0 % (96.0 mg) C52H39N2O14Co2Ce: calcd C 53.23; H 3.35; N 2.39 %; found: C 53.12; H 3.23; N 2.25 % IR (KBr): ν˜ = 3064 (w), 1600 (vs), 1566 (vs), 1519 (vs), 1457 (s), 1435 (s), 1280 (m), 1242 (w), 1157 (w) 1026 Z Anorg Allg Chem 2015, 863–870 (2aЈ): Yield 73 % (100.3 mg) [Ni2Gd(L)2(PhCOO)3] C67H45O14N2Ni2Gd: calcd C 58.45; H 3.29; N 2.03 %; found: C 58.50; H 3.21; N 2.15 % IR (KBr): ν˜ = 3061 (w), 1599 (vs), 1571 (s), 1551 (vs), 1520 (vs), 1460 (vs), 1434 (s), 1281 (m), 1242 (w), 1157 (w) 1066 (w), 937 (w), 766 (m), 721 (m), 652 (w), 538 (w) cm–1 +ESIMS: 1254.04 (100 % base peak, [M-PhCOO] +) (2bЈ): Yield 70 % (95.0 mg) [Ni2Ce(L)2(PhCOO)3] C67H45O14N2Ni2Ce: calcd C 59.19; H 3.34; N 2.06 % ; found: C 58.90; H 3.22; N 2.11 % IR (KBr): ν˜ = 3063 (w), 1599 (vs), 1570 (s), 1551 (vs), 1517 (vs), 1458 (vs), 1435 (s), 1278 (m), 1240 (w), 1157 (w) 1070 (w), 956 (w), 765 (m), 721 (m), 650 (w), 536 (w) cm–1 +ESI-MS: 1236.12 (100 % base peak, [M-PhCOO] +) Syntheses of the CoII Complexes [Co8(L)6(O)2] (3): Compound was isolated as main product from reactions mixtures, which were described for the syntheses of and 2, but with Co(CH3COO)2·4H2O or CoCl6·6H2O instead of the corresponding nickel salts as starting materials Typical yield: 50 % (34.0 mg) C138H90N6O26Co4: calcd C 60.94; H 3.34; N 3.09 %; found: C 60.12; H 3.25; N 2.97 % IR (KBr): ν˜ = 3059 (w), 1609 (vs), 1572 (s), 1516 (vs), 1454 (vs), 1417 (s), 1269 (m), 1240 (w), 1159 (w) 1068 (w), 938 (w), 760 (m), 721 (m), 636 (w), 527 (w) cm–1 +ESIMS: 1360.01 (100 % base peak, [Co4L3(OH)] +) [Co2Ln(L)2(CH3COO)3] (4Ј): LnCl3·xH2O (0.1 mmol) was dissolved in methanol (3 mL) and added to a solution of H2L (74.2 mg, 0.2 mmol) in CH2Cl2 (10 mL) The mixture was stirred for 15 at room temperature Subsequently, a methanol solution (3 mL) of Co(CH3COO)2·H2O (49.8 mg, 0.2 mmol) and triethylamine (50.5 mg, 0.5 mmol) were added to the obtained solution, Upon the addition of Et3N, the color of the solution turned to deep red The resulting solution was stirred for additional 30 and then allowed to evaporate at room temperature Red single crystals of 4, which were suitable for X-ray structure analysis, were obtained after a few days They were collected by suction filtration and used for the X-ray analyses Drying in vacuo gave red powders of solvent-free 4Ј [Co2Gd(L)2(CH3COO)3] (4aЈ): Yield 83.7 % (997 mg) C52H39N2O14Co2Gd: calcd C 52.44; H, 3.30; N, 2.35 % Found: C, 52.31; H, 3.29; N, 2.27 % IR (KBr): ν˜ = 3063 (w), 1593 (vs), 1564 (vs), 1524 (vs), 1456 (s), 1420 (s), 1282 (m), 1246 (w), 1159 (w) 1026 (w), 937 (w), 769 (m), 721 (w), 671 (w), 534 (w) cm–1 +ESI-MS: 1132.21 (100 % base peak, [M-CH3COO] +) (4bЈ): Yield 88.0 % (0.103 g) [Co2Ce(L)2(CH3COO)3] C52H39N2O14Co2Ce: calcd C 53.21; H 3.35; N 2.39 %; found: C 53.29; H 3.30; N 2.29 % IR (KBr): ν˜ = 3064 (w), 1599 (vs), 1564 (vs), 1520 (vs), 1458 (vs), 1429 (s), 1279 (m), 1242 (w), 1156 (w) 1024 (w), 937 (w), 766 (m), 720 (w), 671 (w), 532 (w) cm–1 +ESIMS: 1114.06 (100 % base peak, [M-CH3COO] +) 868 © 2015 WILEY-VCH Verlag GmbH & Co KGaA, Weinheim Journal of Inorganic and General Chemistry ARTICLE www.zaac.wiley-vch.de Zeitschrift für anorganische und allgemeine Chemie Table Crystal data and refinement results Formula Mw Crystal system a /Å b /Å c /Å α /° β /° γ /° V/Å3 Space group Z Dcalcd /g·cm–3 μ /mm–1 No of reflections No of indept (Rint) No parameters R1 / wR2 GOF 1a·2.5H2O·2.5MeOH 2a·2CH2Cl2 2b·MeOH 5b·CH2Cl2 C56.5H57GdN2Ni2O21 1374.71 triclinic 11.0803(13) 13.2615(16) 21.639(3) 98.040(3) 95.021(3) 95.802(4) 3115.5(6) P1¯ 1.4650 1.723 10963 10963(0.0365) 732 0.0635 / 0.1486 1.117 C71H57Cl4GdN2Ni2O16 1610.65 triclinic 12.5078(11) 13.5926(12) 20.3783(18) 98.603(3) 93.464(3) 101.086(3) 3347.5(5) P1¯ 1.5979 1.766 215024 15955 (0.0357) 901 0.0291 / 0.0656 1.077 C69H55CeN2Ni2O17 1441.69 triclinic 13.3081(6) 15.8525(7) 16.6939(7) 69.0000(14) 85.1110(16) 68.0360(14) 3044.4(2) P1¯ 1.5726 1.423 78731 15135 (0.0543) 828 0.0333 / 0.0622 1.022 C138H90Co8N6O26 2719.59 trigonal 19.9840(15) 19.9840(15) 21.6684(17) 90 90 120 7494.1(13) P3¯ 1.2052 0.926 138914 8967 (0.0618) 535 0.0732 / 0.2125 1.096 C69H53CeCl2Co2N2O16 1495.01 triclinic 12.5444(6) 15.9674(8) 17.7448(8) 65.8700(10) 86.217(2) 82.684(2) 3216.9(3) P1¯ 1.5434 1.359 100256 14736 (0.0428) 834 0.0411 / 0.0993 1.046 [Co2Ln(L)2(PhCOO)3 (5): The synthesis of was done essentially similar to that described for except that CoCl2·6H2O was used instead of Co(CH3COO)2·4H2O After the addition of CoCl2·6 H2O to the yellow mixture of LnCl3 (0.1 mmol) and H2L (0.2 mmol), solid benzoic acid (36.6 mg, 0.3 mmol) was added and the mixture was stirred for The addition of triethylamine (80.8 mg, 0.8 mmol) immediately gave red solutions The isolation of and 5Ј was the same as that of and 4Ј (5aЈ): Yield 76.3 % (0.105 g) [Co2Gd(L)2](PhCOO)3] C67H45N2O14Co2Gd: calcd C 58.43; H 3.29; N 2.03 %; found: C 58.28; H 3.20; N 2.275 % IR (KBr): ν˜ = 3065 (w), 1595 (vs), 1564 (vs), 1525 (vs), 1455 (s), 1420 (s), 1281 (m), 1247 (w), 1162 (w) 1025 (w), 933 (w), 765 (m), 721 (w), 668 (w), 534 (w) cm–1 +ESI-MS: 1256.03 (100 % base peak, [M–PhCOO] +) [Co2Ce(L)2](PhCOO)3] (5bЈ): Yield 81.3 % (0.113 g) C67H45N2O14Co2Ce: calcd C 59.17; H 3.33; N 2.06;%; found: C 59.03; H 3.25; N 2.11 % IR (KBr): ν˜ = 3063 (w), 1593 (vs), 1564 (vs), 1524 (vs), 1456 (s), 1420 (s), 1282 (m), 1246 (w), 1159 (w) 1026 (w), 937 (w), 769 (m), 721 (w), 671 (w), 534 (w) cm–1 +ESI-MS: 1238.02 (100 % base peak, [M–PhCOO] +) X-ray Crystallography: The intensities for the X-ray determinations were collected with a Bruker D8 Quest instrument with Mo-Kα radiation (λ = 0.71073 Å) Standard procedures were applied for data reduction and absorption correction Structure solution and refinement were performed with SHELXS97 and SHELXL97.[13] More details on data collections and structure calculations are listed in Table The single crystal used for the structure determination of compound 1a was found to be a non-merohedral twin with two components The integration using Apex2, resulted in a total of 31027 reflections 3784 reflections (1385 unique) involved component only (mean I/σ = 69.4), 3657 reflections (1315 unique) involved component only (mean I/σ = 32.2), and 23527 reflections (10509 unique) involved both components (mean I/σ = 32.5) The data were corrected for absorption using Twinabs[14] and the structure was solved by direct methods with only the non-overlapping reflections of component The structure was refined using the HKLF routine resulting in a BASF value of 0.225(1) In an asymmetric cell of 1a, non-coordinated solvents including 2.5 molecules of H2O and 2.5 molecules of MeOH are disordered Z Anorg Allg Chem 2015, 863–870 and were refined isotropically Hydrogen atoms of water molecules cannot be located unambiguously and thus, they were excluded To finish the structure calculations of 3, highly disordered solvent was treated by the SQUEEZE option in PLATON[15] identified a remarkably large potential solvent volume of 2422 Å3 for the unit cell volume The use of PLATON/SQUEEZE resulted in an improvement of the R1 values of about % Crystallographic data (excluding structure factors) for the structures in this paper have been deposited with the Cambridge Crystallographic Data Centre, CCDC, 12 Union Road, Cambridge CB21EZ, UK Copies of the data can be obtained free of charge on quoting the depository numbers CCDC-1041205 (1a·2.5H2O·2.5MeOH), CCDC-1041207 (2a·2CH2Cl2), CCDC-1041206 (2b·MeOH), CCDC-1041208 (3), and CCDC-1041209 (5b·CH2Cl2) (Fax: +44-1223-336-033; E-Mail: deposit@ccdc.cam.ac.uk, http://www.ccdc.cam.ac.uk) Acknowledgements We thank Vietnam’s National Foundation for Science and Technology Development for financial support through Project 104.02–2011.31 References [1] a) L B L Escobar, G P Guedes, S Soriano, N L Speziali, A K Jordao, A C Cunha, V F Ferreira, C Maxim, M A Novak, M Andruh, M G F Vaz, Inorg Chem 2014, 53, 7508; b) Q.-W Xie, S.-Q Wu, W.-B Shi, C.-M Liu, A.-L Cui, H.-Z Kou, Dalton Trans 2014, 43, 11309; c) X.-C Huang, C Zhou, H.-Y Wei, X.-Y Wang, Inorg Chem 2013, 52, 7314; d) L Ungur, M Thewissen, J.-P Costes, W Wernsdorfer, L F Chibotaru, Inorg Chem 2013, 52, 6328 [2] a) M Sarwar, A M Madalan, C Tiseanu, G Novitchi, C Maxim, G Marinescu, D Luneau, M Andruh, New J Chem 2013, 37, 2280; b) T Gao, L.-L Xu, Q Zhang, G.-M Li, P.-F Yan, Inorg Chem Commun 2012, 26, 60 [3] a) R W Saalfrank, A Scheurer, R Puchta, F Hampel, H Maid, F W Heinemann, Angew Chem Int Ed 2007, 46, 265; b) R Puchta, B Roling, A Scheurer, V Weiskopf, F Hampel, N J R van Eikema Hommes, H.-U Hummel, Solid State Ionics 2008, 179, 489 869 © 2015 WILEY-VCH Verlag GmbH & Co KGaA, Weinheim Journal of Inorganic and General Chemistry www.zaac.wiley-vch.de ARTICLE Zeitschrift für anorganische und allgemeine Chemie [4] T Shiga, T Nakanishi, M Ohba, H Okawa, Polyhedron 2005, 24, 2732 [5] T Shiga, N Ito, A Hidaka, H Okawa, S Kitagawa, M Ohba, Inorg Chem 2007, 46, 3492 [6] T Shiga, H Okawa, S Kitagawa, M Ohba, J Am Chem Soc 2006, 128, 16426 [7] a) T Shimada, A Okazawa, N Kojima, S Yoshii, H Nojiri, T Ishida, Inorg Chem 2011, 50, 10555; b) T Shiga, M Ohba, H Okawa, Inorg Chem 2004, 43, 4435 [8] A E Ion, S Nica, A M Madalan, C Maxim, M Julve, F Lloret, M Andruh, CrystEngComm 2014, 16, 319 [9] a) X.-J Song, Z.-C Zhang, Y.-L Xu, J Wang, H.-B Zhou, Y Song, Dalton Trans 2013, 42, 9505; b) T Shiga, A Mishima, K Sugimoto, H Okawa, H Oshio, M Ohba, Eur J Inorg Chem 2012, 16, 2784 Z Anorg Allg Chem 2015, 863–870 [10] K Nakamoto, Infrared and Raman Spectra of Inorganic and Coordination Compounds, Part B, Applications in Coordination, Organometallic, and Bioinorganic Chemistry, 6th ed., John Wiley & Sons, Inc., New York, 2009, p 63–67 [11] R W Saalfrank, V Seitz, F W Heinemann, C Gobel, R HerbstIrmer, J Chem Soc., Dalton Trans 2001, 599 [12] J Pons, A Chadghan, J García-Antón, J Ros, Lett Org Chem 2010, 7, 178 [13] G M Sheldrick, SHELXL-97, Program for the Refinement of Crystal Structures, University of Göttingen, Göttingen, Germany, 1997 [14] G M Sheldrick, TWINABS - Bruker AXS Scaling for Twinned Crystals - Version 2012/1 [15] A L Spek, Acta Crystallogr., Sect D 2009, 65, 148 Received: January 11, 2015 Published Online: February 25, 2015 870 © 2015 WILEY-VCH Verlag GmbH & Co KGaA, Weinheim ... absorption bands of the ν(C=O) vibrations of β-diketonato rings The relatively low frequencies of ν(C=O) absorptions of the acetato ligands indicate that both of their oxygen atoms are coordinated.[10]... indicated by small N Ln N, O Ln O, O–Ni–O trans angles In order to obtain analogous trinuclear complexes of CoII, the reactions of H2L with mixtures of Co(CH3COO)2 and LnCl3 or CoCl2, LnCl3, and. .. M2–O26 M2–O3 M2–O8 Ln N1 Ln N2 Ln O13 Ln O14 Ln O23 Ln O24 Ln O2 Ln O4 Ln O5 Ln O6 Angles O11–M1–O23 O13– M1–O21 O14– M2–O26 O16–M2–O24 O13– M1–O23 O14– M2–O24 N1 Ln N2 O13 Ln O24 O23 Ln O14 1a 2a