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metal-organic compounds
The molecular structure of the chloro-bridged tetraosmium cluster, dodecacarbonyl-1κ3C,2κ3C,3κ3C,4κ3C-μ-chloro-3:4κ2Cl-tris-μ-hydrido-1:2κ2H;1:3κ2H;2:4κ2H-tetraosmium(5Os—Os), [Os4(μ-Cl)(μ-H)3(CO)12], consists of a `butterfly' arrangement of Os atoms, just as in the iodo analogue. The chloro bridge in the tetraosmium cluster is symmetric, whereas in the pentaosmium cluster, tetradecacarbonyl-1κ3C, 2κ2C,3κ3C,4κ3C,5κ3–μ-chloro-2:5κ2Cl-tris-μ-hydrido-1:2κ2H;2:3κ2H;2:4κ2H-pentaosmium(8 Os—Os), [Os5(μ-Cl)(μ-H)3(CO)14], it is distinctly asymmetric. This asymmetry is attributed to the trans influence of a carbonyl ligand, which lengthens the trans-Os—Cl bond.
