Tungsten derivatives structural parameters

The metal-alkyne bonding parameters of molecules of the type CpML-(RC=CR)X are similar to those of other classes of four-electron donor alkynes in Table I. Both cationic and neutral derivatives with cyclopen-tadienyl (Cp = t75-C5H5) or indenyl (tj5-C9H7) illustrate the structural regularities of these molecules. The preponderance of molybdenum derivatives relative to tungsten reflects more extensive and diverse synthetic chemistry with molybdenum to date. 

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