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 (DMPTD)(MU(2)-N-3)(MU(2)-CL)CL-2]CENTER-DOT-CH3CN, [CU-2(DMPTD)(MU(2)-N-3)(2)(N-3)(2)], (DIP)(MU(2)-N3)(MU(2)-CL)CL-2]CENTER-DOT-0.5CH3OH, (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,

A series of dinuclear, mu(2)-1,1-azide bridged copper(II) complexes of seven tetradentate (N-4) diazine ligands has been prepared and charac terized through spectroscopic, magnetochemical, and, in some cases, si ngle-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-((pyridylme thyl)thio) thiadiazole, DBITD = 2,5-bis(benzimidazolylmethyl)thio)thia diazole, DIP = 3,6-bis(2'-imidazolyl-1'-methyl)thio)pyridazine, PAP46M e = 1,4-bis((4',6'-dimethyl-2'-pyridyl)amino PAP = 1,4-bis(2'-pyridyla mino)phthalazine, PPD3Me = 3,6-bis(3'-methyl-1'-pyrazolyl)pyridazine), PPD = 3,6-bis(1,-pyrazolyl)pyridazine). Compound 1 crystallized in th e 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, an d Z = 4 (R = 0.030 and R(w) = 0.026). Compound 3 crystallized in the t riclinic system, space group P $($) over bar$$ 1, with a = 11.448(6) A ngstrom, b = 11.541(5) Angstrom, c = 9.635(3) Angstrom, alpha = 106.99 (3)degrees, beta = 90.99(4)degrees, gamma = 71.41(3)degrees, and Z = 2 (R = 0.073, R(w) = 0.060). Compound 5 crystallized in the orthorhombi c system, space group Pnma, with a = 11.711(5) Angstrom, b = 21.713(8) Angstrom, c = 7.926(6) Angstrom, and Z = 4 (R = 0.113, R(w) = 0.104). Compound 7 crystallized in the monoclinic system, space group P2(1) w ith a = 7.163(8) Angstrom, b = 16.074(7) Angstrom, c = 22.51(1) Angstr om, beta = 93.4(1)degrees, and Z = 4 (R = 0.137, R(w) = 0.135). Compou nd 8 crystallized in the monoclinic system, space group P2(1)/c (No. 1 4), with a = 13.382(2) Angstrom, b = 11.513(7) Angstrom, c = 16.424(2) Angstrom, beta = 106.65(1)degrees, and Z = 4 (R = 0.029, R(w) = 0.027 ). Compound 9 crystallized in the triclinic system, space group P $($) over bar$$ 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). Compoun d 10 crystallized in the monoclinic system, space group P2(1)/n (No. 1 4), 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 simu ltaneously by end-on mu(2)-1,l-azido, halogen, and diazole groups, wit h one terminally bound halogen per square-pyramidal copper center. In 3 two essentially square-planar copper centers are bridged simultaneou sly by two equatorial mu(2)-1,l-azides, with one terminal azide per me tal. In 5 two distorted square-pyramidal copper centers are bridged eq uatorially by both the pyridazine (N-2) and mu(2)-1,l-azide, and axial ly by a chlorine atom. In 7 each copper center has a distorted four-co ordinate 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 o ne square-planar copper center are bridged equatorially by just two gr oups, the pyridazine (N-2) and mu(2)-1,l-azide. In 9 a square-pyramida l 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 c enters 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) comple xes. 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 val ue (0.35-1.62 mu(B)). Variable temperature magnetic studies (4-300 K) confirm the presence of moderate to strong net ferromagnetic interacti ons 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 bridge d dicopper(II) complexes. A magnetostructural analysis of the complexe s with equatorial diazine/mu(2)-1,l-azide bridge combinations indicate s that, contrary to the prevailing view, the mu(2)-1,l-azide bridge ca n propagate antiferromagnetic coupling between two copper(II) centers if the bridge angle is large enough, and the critical angle for accide ntal orthogonality for the azide bridge is approximate to 108.5 degree s.