Synthesis, crystal structure and properties of two new binuclear complexesbridged by end-to-end azido: [Ni-2(TLA)(2)(N-3)(3)](+) and [Mn-2(TLA)(2)(N-3)(3)](+) [TLA = tris(6-methyl-2-pyridylmethyl)amine]

Two new binuclear complexes bridged by end-to-end azido, [Ni-2(TLA)(2)(N-3) (3)].(ClO4) (1) and [Mn-2(TLA)(2)(N-3)(3)].(ClO4) (2), where TLA is tris(6- methyl-2-pyridylmethyl)amine, have been synthesized and characterized. The structures of the two complexes have been studied by X-ray diffraction anal ysis. The complex 1 cation is a dimeric structure consisting of two [(TLA)N i(N-3)](+) units linked by an end-to-end (mu-1,3-N-3(-)) bridging azide ani on. There is an inversion center at the center N(2) of the bridged azido gr oup. Each of the Ni-II atoms is in a distorted octahedral configuration. Th e crystal structure of 2 is very similar to that of 1, in which the Mn-II a toms by bridging the azide group are also in the distorted octahedral envir onment. The variable temperature magnetic susceptibilities of the title com plexes have been studied. For 1, the exchange integral is J = - 20.45 cm(-1 ) g = 2.23; for 2, J = 2.99 cm(-1). g = 2.04, indicating the existence of a n intramolecular antiferromagnetic interaction between the two metal ions i n both complexes. The spectral properties of the two complexes have been st udied further by UV-Vis techniques, and the results have been discussed in detail. (C) 2000 Elsevier Science Ltd. All rights reserved.