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Equimolar (1:1:1) mixed-ligand Cu(II) complexes with iminodiacetato (IDA) or N-methyl-IDA (MIDA) and N-methyl-imidazole (1MeImH) or ImH, respectively, have been prepared and characterized by thermal, spectral, magnetic and X-ray diffraction methods. [Cu(MIDA) (ImH)] (I) crystallizes in the monoclinic system P21/n (a = 12.465(3), b = 5.999(1), c = 14.733(3) A, β = 111.91(1)°, Z = 4, R = 0.043, Rw = 0.047). The Cu(II) atom exhibits a flattened square base byramidal coordination (type 4 + 1). The N and two O atoms of the tridentate MIDA and one N of ImH form the square base; one longer CuO bond with the next MIDA ligand in the chain complex completes the Cu(II) five-coordination. [Cu(IDA) (1MeImH) (H2O)2]·H2O (II) crystallizes in the orthorhombic system Pna21 (a = 14.733(2), b = 7.721(1), c = 11.288(1) A, Z = 4, R = 0.041, Rw = 0.043). The N and two O atoms from IDA and one N from 1 MeImH define a square coordination; two longer CuOH2 bonds complete the unsymmetrical elongated octahedral coordnation of Cu(II) (type 4 + 1 + 1). The polar NH bonds of ImH in I and of IDA in II as well as the OH bonds of the water molecules of the latter compound are involved in hydrogen bonds. The stepwise water loss in II is explained on the basis of its structural role in the Cu(II) coordination and/or in the crystal packing.

Crystalline samples of CuH3L · 3.5H2O (L = anion of N,N,N′,N′-tetrakis(carboxymethyl)-2,4-diamino-butyric acid; H5TDB = H5L) have been characterized by X-ray diffraction and other methods. The compound crystallizes in the monoclinic system, space group P21/n (a = 6.260(2), b = 18.505(5) c = 15.659(3) A, β = 91.78(3)° and Z = 4). Final R = 0.049 and Rw = 0.054 for 1400 independent observed reflections. The structure consists of one-dimensional chains of CuH3L complex units and non-coordinated water molecules linked together in a network of hydrogen bonds. Only two [H(062) and H(N2)] of the three “acid” hydrogen atoms of the ligand (H3L2−) have been located in the structure. Each H3L2− anion acts as a tetradentate chelating agent for a Cu(II) ion by means of the C-substituted hydrogen nitrilotriacetato (NTA) group (Cu-N(1) 2.026(9), Cu-O(11) 1.971(8), Cu-O(81) 2.003(8) and Cu-O(61) 2.186(6)A. The O(11) and O(61) atoms are part of carboxylato and carboxylic groups, respectively. The distorted five c...

Diaqua(iminodiacetato)copper(II), [Cu(IDA)(H2O)2] (I), reacts with 2-methylimidazole to yield [Cu(IDA)(2MeImH)]·nH2O (n = 3, 1/2) or [Cu(IDA)(2MeImH)2]2·4H2O. However, the reaction of I with 4MeImH (even in excess) only gives the 1:1:1 ternary complex in the form of the ‘remote’ tautomer derivative [Cu(IDA)(5MeImH)]·H2O. This compound crystallizes in the monoclinic system, space group P21/n (a = 13.875(1), b = 5.748(1), c = 14.739(3) A, β = 106.32(1)°, Z = 4; final R = 0.059 and Rw = 0.060 for 1169 independent reflections). The crystal consists of H2O molecules non-bonded to the metal and zigzag chains of the complex. The Cu(II) atom shows a flattened square base pyramidal coordination (type 4+1). One N of 5MeImH and one N and two O of the same IDA ligand are at the coordination square base. One longer CuO bond with the next adjacent IDA ligand of the chain complex accomplishes the Cu(II) distorted five-coordination. The new mixed-ligand copper(II) complexes were characterized by thermal, spectral and magnetic methods. The results are discussed in connection with the reported data for analogous compounds with an unsubstituted imidazole ligand.

Homonuclear compounds [M(H 2 O) 6 [M 2 L 2 (H 2 O) 2 ]·4H 2 O (M(II)Co(II) or Zn(II), L 3− =anion of N , N -bis(carboxymethyl)-β-alanine or ((2-carboxyethyl)imino)diacetic acid) have been synthesized and characterized by chemical analysis, magnetic susceptibility data and/or IR spectra, thermal analysis and X-ray diffraction method. They are isostructural and crystallize in the triclinic system, space group P 1 with Z =1. The crystal structure was determined for the cobalt(II) compound ( a =8.732(7)- b =9.751(6), c =9.918(5) A, α=99.96(4), β=110.88(5), γ=103.79(5), V =734.6A 3 , D meas =1.80 g cm −3 , D exp =1.80 g cm −3 ,μ=1.767 mm − (MoKα)). Final R =0.034 and R w =0.043 for 3145 independent observed reflections. This compound consists of both centrosymmetric hexaaquocobalt(II) cations (Co(1)-OW(1)=2.046(2), (Co(1)-OW(2)=2.077(2), Co(1)-OW(3)=2.119(2) A) and anions [Co 2 L 2 (H 2 O ) 2 ] 2− , and non-coordinated water molecules. In the homodinuclear chelate anions, each cobalt(II) atom is bonded to one water molecule (Co( 2 )-OW(4)=2.098(2) A) and one tetradentate chelating ligand L 3− (Co(2)−N=2.134(2), Co(2)−O(5)=2.113(2), Co(2)−O(13)=2.081 (2), Co(2)-O(23)=2.101(2) A). The dimer has an imposed C i symmetry. One carboxylate oxygen atom from the β-alanine arm acts as a bridge between the two cobalt atoms so completing the octahedral coordination of cobalt. The values of the distances Co(2)−Co(2 i ) and the angle at the oxygen atom Co(2)−O(5)−Co(2 i ) are 3.2934(7) A and 103.5(1) o respectively.

μ-(N,N,N′,N′-Tetrakis(carboxymethyl)cystaminato (4−))-bis(imidazole)diaquodicopper dihydrate, [Cu2- (TCC)(ImH)2(H2O)2]·2H2O (I) (where TCC = (O2- CCH2)2NC2H4SSC2H4N(CH2CO2)24−), has been obtained in good yield by reaction of [Cu2 (TCC)(H2O)2]·4H2O (II) with excess of imidazole (ImH) in water. The new product I has been characterized by chemical analysis, TG-DTA diagram, infrared, reflectance and ESR spectra and the single- crystal X-ray diffraction method. The compound crystallizes in the monoclinic system, space group P21/n (a = 20.800(2), b = 10.191(2), c = 13.419(2) A, β = 92.41(1)°). Final R = 0.036 and Rw, = 0.035 for 2784 independent observed reflections. Instead of the polynuclear layered crystal structure of II, the crystal of I consists of hydrogen bonded water molecules and discrete dinuclear units [Cu2(TCC)- (ImH)2(H2O)2] linked together in a tridimensional hydrogen bonding network. Both crystallographic independent copper atoms of the mixed dinuclear unit show analogous distorted elongated octahedral coordination (of the type 4 + 1 + 1). The two CuN(ImH) bonds are shorter than the homologous bond in a variety of copper(II)imidazole derivatives, lying in the lowest limit of the corresponding bond lengths in Cu(II)(ImH)aminoacidato (or peptide) complexes (1.95–1.98 A). However, the ImH ligands do not play any π acceptor role (the CuN(ImH) bonds are tilted with respect to the ImH planes, which are twisted with respect to the mean equatorial coordination planes of the copper(II) atoms). By reacting ImH with II to give I, the copper coordinated water molecule in the equatorial position in II is replaced by an ImH molecule in I and moves to an apical position; this results in the lengthening of the CuS(disulfide) bonds, from 2.721(3) A in II to 2.959(2) A, average in I.