Double bonds, formulation rotation about

Acetic acid treatment of the transition metal Ge(IV) hydride salt Kb/5-C5H5Mn(CO)2GeH3] yields a red product, b/5-C5H5Mn (CO)2]2Ge, which contains a linear Mn-Ge-Mn system in which the germanium atom occupies a special position with equal Ge-Mn distances of 2.204 A. Solution infrared spectra show four v(CO) stretching absorptions instead of the two expected from the cen-trosymmetric structure in the solid state, implying free rotation about the Ge-Mn bonds. Simple application of the rare-gas rule would favor a double-bonded formulation containing Ge(IV), but a molecular-orbital... 

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