Molybdenum complexes sulfur dioxide

On the other hand, the cyclopentadienyl derivatives of iron(II), Fe(rj -CsH5)R(CO)2, molybdenum(II), Mo(r -C5H5)R(CO)3, and MR(CO)5, M = Mn, Re, react with sulfur dioxide giving initially the 0-sulfinato complexes, which then rearrange to the S-bonded linkage isomers . ... 

Sulfur dioxide is known to behave as an S—O bidentate to metal ions in low oxidation states, resulting in the formation of three-membered chelate rings. The structures of three such complexes of molybdenum have been described by Kubas and Ryan,including an unusual dinuclear complex in which the SO2 ligands bridge two Mo atoms. A closely related complex of Ru also has been characterized. This bonding form was discussed in relation to these structimes. 

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