Homonuclear and heteronuclear metal complexes with a cyclic tetracopper(II) unit. Syntheses, crystal structures, and magnetic properties of [CuII4(dmap)3(OH)(O2CCH3)2(HO2CCH3)(H2O)][PF6]2, [CuII4(dmap)2(O2CCH3)4][PF6]2, [CuII4(dmap)2(O2CCH3)2(OH)2][HgII(O2CCH3)Cl2]2[HgIICl2], and [CuII4(dmap)2(O2CCH3)3(OH)2(H2O)][PF6] (dmap = 1,3-bis(dimethylamino)-2-propanolato)

Tetranuclear copper(ii) cubane complexes derived from self-assembled 1,3-dimethyl-5-(o-phenolate-azo)-6-aminouracil: structures, non-covalent interactions and magnetic property

A new doubly opened 4 + 2 Cu₄O₄ cubane cluster exhibits strong antiferromagnetic exchange coupling with J₁ = −110.1 cm⁻¹, and J₂ = −27.1 cm⁻¹.

Defective dicubane-like tetranuclear nickel(II) cyanate and azide nanoscale magnets

Four tetrameric nickel(II) pseudohalide complexes have been synthesized and structurally, spectroscopically, and magnetically characterized. Compounds 1-3 are isostructural and exhibit the general formula [Ni(2)(dpk·OH)(dpk·CH(3)O)(L)(H(2)O)](2)A(2)·2H(2)O, where dpk = di-2-pyridylketone; L = N(3)(-), and A = ClO(4)(-) for 1, L = NCO(-) and A = ClO(4)(-) for 2, and L = NCO(-) and A = NO(3)(-) for 3. The formula for 4 is [Ni(4)(dpk·OH)(3) (dpk·CH(3)O)(2)(NCO)](BF(4))(2)·3H(2)O. The ligands dpk·OH(-) and dpk·CH(3)O(-) result from solvolysis and ulterior deprotonation of dpk in water and methanol, respectively. The four tetramers exhibit a dicubane-like core with two missing vertexes where the Ni(II) ions are connected through end-on pseudohalide and oxo bridges. Magnetic measurements showed that compounds 1-4 are ferromagnetic. The values of the exchange constants were determined by means of a theoretical model based on three different types of coupling. Thus, the calculated J values (J(1) = J(2), J(3), and D) were 5.6, 11.8, and 5.6 cm(-1) for 1, 5.5, 12.0, and 5.6 cm(-1) for 2, 6.3, 4.9, and 6.2 cm(-1) for 3, and (J(1), J(2), J(3), and D) 6.9, 7.0, 15.2, and 4.8 cm(-1) for 4.

Interaction of 2-(2′-pyridyl)benzimidazolyl derivative ligands with group 12 metal ions: coordination, structures and luminescence

The coordination chemistry of the group 12 metal ions with two 2-(2'-pyridyl)benzimidazolyl derivative ligands 1,3,5-tris[2-(2'-pyridyl)benzimidazolyl]benzene (tmb) and 2-(2'-pyridyl)benzimidazolylbenzene (mb) has been investigated. The crystal structures of two coordination compounds (HgCl(2))(2)(tmb) and [Zn(mb)(2)(H(2)O)][ClO(4)](2) have been determined by single-crystal X-ray diffraction analysis which established the chelate bonding mode by the group 12 metal ions to the tmb or mb ligand. The luminescent response of tmb and mb toward group 12 metal ions, Zn(II), Cd(II) and Hg(II) has been examined by fluorescent titration experiments which established that the three group 12 metal ions have distinct luminescent response toward the tmb or mb ligand. The addition of the Hg(II) ion resulted in fluorescence quenching. In contrast, the addition of Zn(II) or Cd(II) led to a red shift and dramatic intensity increase of the emission spectrum of the ligand.

Complementarity and countercomplementarity in polynuclear copper(ii) complexes with R2NCH2CH(OH)CH2NR2 (R = H, CH3): crystal structures and magnetic study

The syntheses, structural characterization and magnetic behavior of five new copper(II) polynuclear compounds with formulae [Cu4(mu2-CH3COO)2(mu-bdmap)2(micro(1,5)-dca)2(dca)2(H2O)2] 1, [Cu2(mu2-CH3COO)(mu-bdap)(mu(1,1,5)-dca)(mu(1,3)-dca)]n 2, [Cu4(mu2-CH3COO)2(mu-bdmap)2(mu(1,1)-NCS)2(NCS)2] 3, [Cu2(mu2-CH3COO)(mu-bdap)(NCS)2] 4 and [Cu2(mu(1,3)-N3)(mu-bdmap)(N3)2]n 5 in which bdmapH is 1,3-bis(dimethylamino)-2-propanol, bdapH is 1,3-bis(amino)-2-propanol and dca is the anionic dicyanamide ligand, are reported herein. Tetranuclear complex 1 crystallizes in the monoclinic system, space group P2(1)/n, with unit cell parameters a = 8.284(8), b = 21.52(1), c = 11.432(3) A, beta = 105.19(2) degrees , Z = 2. Bi-dimensional complex 2 crystallizes in the triclinic system, space group P1, with unit cell parameters a = 8.184(5), b = 8.792(2), c = 10.887(2) A, alpha = 75.65(2), beta = 76.55(3), gamma = 74.36(3) degrees , Z = 2. Tetranuclear complex 3 crystallizes in the triclinic system, space group P1, with unit cell parameters a = 8.455(4), b = 9.114(9), c = 12.744(8) A, alpha = 104.62(8), beta = 99.86(6), gamma = 106.10(8) degrees, Z = 1. Dinuclear complex 4 crystallizes in the triclinic system, space group P1, with unit cell parameters a = 8.15(1), b = 8.18(2), c = 11.44(1) A, alpha = 69.39(2), beta = 80.36(2), gamma = 80.37(2) degrees , Z = 2. One-dimensional complex 5 crystallizes in the orthorhombic system, space group P2(1)2(1)2(1), with unit cell parameters a = 20.45(4), b = 11.36(3), c = 6.43(1) A, Z = 4. The magnetic behavior of all the complexes has been checked giving a bulk antiferromagnetic coupling in all the cases with |J| values in the range 109-144 cm(-1) for 1-4. Compound 5 is diamagnetic in the 2-300 K range of temperatures. The found J values 1-5 for can be justified from the structural data taking into account the orbital countercomplementarity for 1-4 and the orbital complementarity for 5.

Syntheses and Magneto−Structural Study of Several Polynuclear Copper(II) Complexes Derived from 1,3-Bis(dimethylamino)-2-propanolato

The syntheses, structural characterization, and magnetic behavior of the three new polynuclear copper(II) complexes with formulas [Cu(4)(eta(2):mu-CH(3)COO)(2)(mu-OH)(2)(mu-OH(2))(mu-bdmap)(2)](ClO(4))(2).H(2)O (1), [Cu(8)(NCO)(2)(eta(1):mu-NCO)(4)(mu-OH)(2)(mu(3)-OH)(2)(mu-OH(2))(3)(mu-bdmap)(4)](ClO(4))(2)x2H(2)O (2), and [Cu(9)(eta(1):mu-NCO)(8)(mu(3)-OH)(4)(OH(2))(2)(mu-bdmap)(4)](ClO(4))(2).4H(2)O (3), in which bdmapH is 1,3-bis(dimethylamino)-2-propanol, are reported. Tetranuclear complex 1 crystallizes in the triclinic system, space group P, with unit cell parameters a = 12.160(1) A, b = 13.051(1) A, c = 13.235(1) A, alpha = 110.745(1) degrees , beta = 109.683(1) degrees , gamma = 97.014(1), and Z = 2. Octanuclear complex 2 crystallizes in the monoclinic system, space group C2/c, with unit cell parameters a = 26.609(1) A, b = 14.496(1) A, c = 16.652(1) A, beta = 97.814(1) degrees , and Z = 4, and nonanuclear complex 3 crystallizes in the monoclinic system, space group C2/c, with unit cell parameters a = 24.104(1) A, b = 13.542(1) A, c = 24.355(1) A, beta = 109.98(1) degrees , and Z = 4. The magnetic behavior of the three complexes has been checked showing strong antiferromagnetic coupling in all the cases.