MAGNETOSTRUCTURAL CORRELATIONS IN MU(2)-1,1-N-3 BRIDGED, DINUCLEAR COPPER(II) COMPLEXES .1. FERROMAGNETIC AND ANTIFERROMAGNETIC COUPLING ASSOCIATED WITH THE AZIDE BRIDGE - X-RAY CRYSTAL-STRUCTURES OF [CU-2(DMPTD)(MU(2)-N-3)(MU(2)-CL)CL-2]CENTER-DOT-CH3CN, [CU-2(DMPTD)(MU(2)-N-3)(2)(N-3)(2)], [CU-2(DIP)(MU(2)-N3)(MU(2)-CL)CL-2]CENTER-DOT-0.5CH3OH, [CU-2(PAP46ME-H)(MU(2)-N-3)(N-3)(2)]CENTER-DOT-0.33H2O, [CU-2(PAP)(MU(2)-N-3)CL-3]CENTER-DOT-CH2CL2, [CU-2(PAP)(MU(2)-N-3)(N-3)(NO3)(CH3OH)](NO3)CENTER-DOT-CH3OH, [CU-2(PPD3ME)(MU(2)-N-3)CL-3(H2O)(1.5)], AND [CU-2(PPD)(MU(2)-N-3)(NO3)(3)(H2O)(1.6)]

A series of dinuclear, mu(2)-1,1-azide bridged copper(II) complexes of seven tetradentate (N-4) diazine ligands has been prepared and characterized through spectroscopic, magnetochemical, and, in some cases, single-crystal X-ray diffraction studies: [Cu-2(DMPTD)(mu(2)-N-3)(mu(2)-X)X(2)]-CH3CN (X = Cl (1), Br (2)), [Cu-2(DMPTD)(mu(2)-N-3)(2)(N-3)(2)] (3), [Cu-2(DBITD)(mu(2)-N-3)(2)Cl-2].H2O (4), [Cu-2(DIP)(mu(2)-N-3)(mu(2)-X)X(2)].0.5CH(3)OH (X = Cl (5), X = Br (6)), [Cu-2(PAP46Me-H)(mu(2)-N-3)(N-3)(2)].0.33H(2)O (7), [Cu-2(PAP)(mu(2)-N-3)Cl-3].CH2Cl2 (8), [Cu-2(PAP)(mu(2)-N-3)(N-3)(NO3)(CH3OH)](NO3).CH3OH (9), [Cu-2(PPD3Me)(mu(2)-N-3)Cl-3(H2O)(1.5)] (10), [Cu-2(PPD3Me)(mu(2)-N-3)Br-3].0.5CH(3)CN (11), [Cu-2(PPD3Me)(mu(2)-N-3)(NO3)(3)].0.5CH(3)OH (12), and [Cu-2(PPD)(mu(2)-N-3)(NO3)(3)(H2O)(1.6)] (13) (DMPTD = 2,5-bis-((pyridylmethyl)thio) thiadiazole, DBITD = 2,5-bis(benzimidazolylmethyl)thio)thiadiazole, DIP = 3,6-bis(2'-imidazolyl-1'-methyl)thio)pyridazine, PAP46Me = 1,4-bis((4',6'-dimethyl-2'-pyridyl)amino PAP = 1,4-bis(2'-pyridylamino)phthalazine, PPD3Me = 3,6-bis(3'-methyl-1'-pyrazolyl)pyridazine), PPD = 3,6-bis(1,-pyrazolyl)pyridazine). Compound 1 crystallized in the monoclinic system, space group P2(1)/n, with a = 8.390(3) Angstrom, b = 24.857(2) Angstrom, 11.698(2) Angstrom, beta = 93.38(2)degrees, and Z = 4 (R = 0.030 and R(w) = 0.026). Compound 3 crystallized in the triclinic system, space group P $($) over bar$$ 1, with a = 11.448(6) Angstrom, b = 11.541(5) Angstrom, c = 9.635(3) Angstrom, alpha = 106.99(3)degrees, beta = 90.99(4)degrees, gamma = 71.41(3)degrees, and Z = 2 (R = 0.073, R(w) = 0.060). Compound 5 crystallized in the orthorhombic system, space group Pnma, with a = 11.711(5) Angstrom, b = 21.713(8) Angstrom, c = 7.926(6) Angstrom, and Z = 4 (R = 0.113, R(w) = 0.104). Compound 7 crystallized in the monoclinic system, space group P2(1) with a = 7.163(8) Angstrom, b = 16.074(7) Angstrom, c = 22.51(1) Angstrom, beta = 93.4(1)degrees, and Z = 4 (R = 0.137, R(w) = 0.135). Compound 8 crystallized in the monoclinic system, space group P2(1)/c (No. 14), with a = 13.382(2) Angstrom, b = 11.513(7) Angstrom, c = 16.424(2) Angstrom, beta = 106.65(1)degrees, and Z = 4 (R = 0.029, R(w) = 0.027). Compound 9 crystallized in the triclinic system, space group P $($) over bar$$ 1, with a = 13.466(6) Angstrom, b = 14.833(5) Angstrom, c = 8.087(1) Angstrom, alpha = 99.76(2)degrees, beta = 107.35(2)degrees, gamma = 63.16(3)degrees, and Z = 2 (R = 0.049, R(w) = 0.038). Compound 10 crystallized in the monoclinic system, space group P2(1)/n (No. 14), with a = 10.909(2) Angstrom, b = 12.524(2) Angstrom, c = 14.744(2) Angstrom, beta = 101.63(1)degrees, and Z = 4 (R = 0.046, R(w) = 0.038). Compound 13 crystallized in the monoclinic system, space group P2(1)/m, with a = 6.9617(9) Angstrom, b = 20.898(4) Angstrom, c = 7.568(1) Angstrom, beta = 114.32(1)degrees, and Z = 2 (R = 0.062, R(w) = 0.055). In 1 and 2 the two square-pyramidal copper centers are bridged simultaneously by end-on mu(2)-1,l-azido, halogen, and diazole groups, with one terminally bound halogen per square-pyramidal copper center. In 3 two essentially square-planar copper centers are bridged simultaneously by two equatorial mu(2)-1,l-azides, with one terminal azide per metal. In 5 two distorted square-pyramidal copper centers are bridged equatorially by both the pyridazine (N-2) and mu(2)-1,l-azide, and axially by a chlorine atom. In 7 each copper center has a distorted four-coordinate structure with one mu(2)-1,l-azide and the phthalazine (N-2) bridging the two metals. In 8 one square-pyramidal copper center and one square-planar copper center are bridged equatorially by just two groups, the pyridazine (N-2) and mu(2)-1,l-azide. In 9 a square-pyramidal and square-planar copper are bridged equatorially by a phthalazine (N-2) and mu(2)-1,1-azide. In 10 two essentially square-planar copper centers are bridged equatorially by the pyridazine (N-2) and the mu(2)-1,l-azide, while in 13 two square-pyramidal copper centers are bridged similarly. mu(2)-l,l-azide bridge angles fall in the range 98.3-124.1 degrees, which is unprecedented for azide-bridged dicopper(II) complexes. For 1-6 room temperature magnetic moments fall in the range 1.85-2.26 mu(B)/Cu, while for 7-13 the moments fall below the spin only value (0.35-1.62 mu(B)). Variable temperature magnetic studies (4-300 K) confirm the presence of moderate to strong net ferromagnetic interactions within each dinuclear unit for 1-6 (2J = 60-170 cm(-1)), while for 7-13 net antiferromagnetic exchange prevails with -2J falling in the range 40-1100 cm(-1), a most unusual feature of mu(2)-1,l-azide bridged dicopper(II) complexes. A magnetostructural analysis of the complexes with equatorial diazine/mu(2)-1,l-azide bridge combinations indicates that, contrary to the prevailing view, the mu(2)-1,l-azide bridge can propagate antiferromagnetic coupling between two copper(II) centers if the bridge angle is large enough, and the critical angle for accidental orthogonality for the azide bridge is approximate to 108.5 degrees.