INTERMOLECULAR FERROMAGNETIC AND ANTIFERROMAGNETIC INTERACTIONS IN HALOGEN-BRIDGED COPPER(I) IMINO NITROXIDES - CRYSTAL-STRUCTURES AND MAGNETIC-PROPERTIES OF [CU-I(MU-X)(IMINO NITROXIDE)](2) (X=I OR BR)

Reaction of CuI or CuBr with some imino nitroxides in methanol gave th e halogen bridged dinuclear Cu(I) complexes [Cu(mu-I)(impy)](2) (1), [ Cu(mu-I)immepy)](2) (2), [Cu(mu-Br)(immepy)](2) (3), and [Cu(mu-Br)(im ph-No-2)](2) (4), respectively (impy = ,5,5-tetramethyl-4,5-dihydro-1H -imidazolyl-1-oxyl, immepy = ,5,5-tetramethyl-4,5-dihydro-1H-imidazoly l-1-oxyl, imph-NO2 = 5,5-tetramethyl-4,6-dihydro-1H-imidazolyl-1-oxyl) . Crystal structures and magnetic properties have been studied. Comple xes 1-4 have dimeric structures where two copper ions are doubly bridg ed by halide ions in a mu 2 fashion. In 1-3, each copper ion is tetrah edral with a bidentate imino nitroxide and two halide ions, and the tw o copper ions are separated by 2.592(2), 2.6869(8), and 2.7357(6) Angs trom, respectively, In 4, triangular coordination sites of the copper ions are completed with a nitrogen atom from the imino nitroxide and t wo bromide ions bridging the two copper ions with a separation of 3.07 4(2) Angstrom. Ligand imino nitroxides in 1-4 form one-dimensional rad ical chains, and the chains are linked with halocuprate dimer units. S tructural and magnetic susceptibility data support that radicals in 1 and 4 are ferromagnetically stacked, while radicals in 2 and 3 form an antiferromagnetic chain. The magnetic behaviors are discussed in conn ection with the stacking modes of the radicals and bridging conformati ons. Crystal data (mo K alpha, lambda = 0.71069 Angstrom): 1, orthorho mbic, space group P2(1)2(1)2(1), a = 17.807(2) Angstrom, b = 8.595(2) Angstrom, c = 19.336(6)Angstrom, and Z = 4; 2, monoclinic, space group P2(1)/c, a = 9.941(2) Angstrom, b = 18.482(2) Angstrom, c = 8.337(2) Angstrom, beta = 96.41(2)degrees, and Z = 2; 3, monoclinic, space grou p P2(1)/c, a = 9.964(6) Angstrom, b = 18.167(4) Angstrom, c = 8.009(7) Angstrom, beta = 95.81(6)degrees, and Z = 2; 4, monoclinic, space gro up P2(1)/c, a = 11.998(7) Angstrom, b = 17.998(8) Angstrom, c = 7.215( 6) Angstrom, beta = 104.07(6)degrees, and Z = 2.