Structural and magnetic properties of dicopper(II) complexes of polydentate diazine ligands

A series of dinuclear copper(II) complexes of three polydentate diazine ligands (PAHAP, PHMAP, and PAHOX) is reported. The PAHAP and PHMAP complexes involve tetradentate ligand coordination with an N-N bridge between the metal centers. For PAHOX,one case involves oxime (N-O) bridges, while, in another, mu(2)-SO4 bridges are present. Free rotation of the copper magnetic planes around the N-N band occurs for the PAHAP complexes and is influenced by secondary ligand steric effects (cis), but for PHMAP, additional coordination fixes the complex in;a trans configuration. Preliminary structures are reported for [Cu-2(PAHAP)(NCS)(4)-(DMF)(2)]. 2DMF (1) and [Cu-2(PAHAP)(bipy)(2)(NO3)(2)](NO3)(2). 4H(2)O (2), and full structures are reported for [Cu-2(PAHAP)(aln)(2)(H2O)(2)](NO3)(2). 3H(2)O (3), [Cu-2(PAHAP)(gly)(2)(NO3)(H2O)](NO3). 3H(2)O (4), [Cu-2(PHMAP-H)(NO3)(3)(H2O)(MeOH)] (6), [Cu-2(PAHOX-H)(2)](ClO4)(2) (7), and [Cu(PAHOX)(SO4)](2). 2H(2)O (8). Complex 3 crystallized in the triclinic system, space group P (1) over bar (No. 2), with a = 17.503(4) Angstrom, b = 18.378(4) Angstrom, c = 10.742(4) Angstrom, alpha = 93.44(3)degrees, beta = 93.19(3)degrees, gamma = 62.98(2)degrees, and Z = 4. Complex 4 crystallized in the triclinic system, space group P (1) over bar with a = 11.506(12) Angstrom, b = 12.525(18) Angstrom, c = 10.319(4) Angstrom, alpha = 94.47(7)degrees, beta = 106.58(5)degrees, gamma = 114.55(9)degrees, and Z = 2. Complex 6 crystallized in the triclinic system, space group P (1) over bar, with a = 7.4754(1)Angstrom, b = 8.7430(1) Angstrom, c = 17.9942(2) Angstrom, alpha = 84.690(1)degrees, beta = 83.190(1)degrees, gamma = 6.885(1)degrees, and Z = 2. Complex 7 crystallized in the monoclinic system, space group C2/c, with a = 33.5849(6) Angstrom, b = 7.6016(1) Angstrom, c = 22.6654(3) Angstrom, beta = 106.949(1)degrees, and Z = 8. Complex 8 crystallized in the monoclinic system, space group P2(1)/n, with a = 9.866(2) Angstrom, b = 10.128(2) Angstrom, c = 15.418(1) Angstrom, beta = 108.051(8)degrees, and Z = 4. Antiferromagnetic exchange for 1, 3, 4, and 6 (-2J = 51.1, 45.6, 1.5,- and 208 cm(-1), respectively) is consistent with the angle of rotation (alpha) of the copper magnetic planes about the N-N bond. A Linear relationship is found between alpha and 2J for a combined series of nine related complexes over an angle range of 105 degrees. An estimate of the inherent ferromagnetism in the system is obtained from magnetic measurements close to the calculated angle of accidental orthogonafity (2J = 27 cm(-1)).