Zweikernige Komplexe des Molybdan(III): Die Kristallstruktur von μ-Bromo-μ-hydroxo-bis- [bromo(1,4,7-triazacyclononan)molybdan(III)]dibromid · Tetrahvdrat Dinuclear / Complexes of Molybdenum(III): The Crystal Structure of μ-Bromo-μ-hydroxo-bis- [bromo(1 ,4,7-triazacyclononane)molybdenum(III)]dibromide · tetrahydrate

Abstract

The syntheses of two binuclear complexes of molybdenum(III) is reported. The oxidation of LMo(CO)3 (L = 1,4,7-triazacyclononane, C6Hi5N3) with bromine in chloroform (0.75% ethanol) yields the monomeric complex [MovLOBr2](Br3) (μeff(298 K) = 1.61 μB). Reduction of this species in aqueous solution with Zn under an argon atmosphere at 25 °C affords - upon addition of NaBr - green crystals of [Mo2L2(μ-OH)(μ-Br)Br2]Br2 · 4H2O. The reduction at elevated temperatures yields green crystals of [Mo2L2(μ-OH)2Br2]Br2 ·2 H2O. Both complexes exhibit antiferromagnetic behaviour. The crystal structure of [Mo2L2(μ-OH)(μ-Br)Br2]Br2 · 4 H2O con­sists of dinuclcar cations, bromide ions and water of crystallization. It crystallizes in the triclinic space group P1 with cell constants a = 821.3(3). b = 837.7(2), c = 1008.1(3) pm, α = 103.63(2)°, β = 98.92(2)°, γ = 79.54(2)° and Z = 1. The two Mo(III)-centers are in a distorted octahedral environment of the tridentate amine, a terminal bromo-ligand and one hydroxo- and one bromide bridging ligand (edge sharing). The short Mo-Mo distance of 255.8(3) pm indicates strong metal- metal bonding.