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Synthesis and crystal structure of (pipzH2)2Mo2Cl8·4H2O (pipz = piperazine)

1984; Elsevier BV; Volume: 85; Issue: 2 Linguagem: Inglês

10.1016/s0020-1693(00)80998-6

1873-3255

I. Leban, P. Šegedin,

Asymmetric Hydrogenation and Catalysis

Abstract The title compound (pipzH2)2Mo2Cl8·4H2O (pipz = piperazine),was isolated from the solution of (morphH)2Mo2Cl6(H2O)2 in HCl 1:1 by addition of (pipzH2)Cl2. This reaction indicates the reversibility of the substitution of chloride ions in Mo2Cl84− by water molecules. (pipzH2)2Mo2Cl8·4H2O crystallizes in the Pbca space group, with a = 15.154(2), b = 13.170(2), c = 12.208(2) A and Z = 4. The structure was solved by the Patterson method and refined to the unweighted and weighted residuals of 0.050 and 0.048. The crystal structure is built form Mo2Cl84−, (pipzH2)2+ and H2O. The MoMo distance of 2.129(3) A is the shortest one found in all structurally-characterised Mo2X84− (X = Cl, Br) anions. Four independent MoCl distances are 2.456(3), 2.445(3), 2.463(4) and 2.455(4) A. The (pipzH22+ exists in a usual chair conformation. There is a network of hydrogen bonds of the type NH⋯Cl, NH⋯O, OH⋯Cl and OH⋯O between the ions and water molecules.