Organometallic compounds bent sandwich structures

M(II) organometallic compounds are found with cyclopentadienyl. Sn(C5H5)2 has a bent sandwich structure 2, where the stereochemical influence of the lone-pair is apparent. M(IV) organometallic compounds with M C s bonding are extremely varied and include simple tetraalkyls MR4 and compounds with Sn Sn bonds similar to those of Si and... 

The only well-defined examples of lead(II)organometallic compounds are bis(cyclopenta-dienyl)lead(n) and its ring methyl derivative s. In the gas phased this has a bent sandwich structure as shown in Fig. 1 (a). Such a structure is also proposedso to account for the solution spectra of (CsHs)2Pb, where the two rings are believed bonded to two sp lead hybrid orbitals, and a further sp orbital contains a non-bonding pair of electrons. Such a bonding situation is in accord with the crystal structure of the orthorhombic form shown in Fig. 1 (b). 

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