Coordinational behavior of solvent-free diorganylzinc compounds: The remarkable X-ray structure of dimeric diphenylzinc

Article abstract of DOI:10.1021/om00158a022

The crystal structure of solvent-free diphenylzinc has been determined. Crystals of [Ph₂Zn]₂ are triclinic, space group P1, with unit cell dimensions a = 9.956 (1) ?, b = 10.024 (2) ?, c = 12.011 (2) ?, α = 113.74 (2)°, β = 108.79 (1)°, γ = 97.68 (2)°, and Z = 2. The structure refinement converged at R_F = 0.042. A remarkable PhZn(μ-Ph)₂ZnPh dimeric structure is found, in which the zinc atoms are tricoordinated. The structure confirms the ability of Zn to take part in multicenter bonding to carbon. It is unique not only in the sense that it is the first example of an arylzinc derivative but also because of the unsymmetrical orientation of the μ-phenyl groups: they retain the predominant bonding relation to one zinc atom, as the association of the two monomeric Ph₂Zn units only partially disturbs their original, linear geometry: the average Zn-C bond distances within one Ph₂Zn unit are 1.946 (5) ? (terminal) and 2.011 (5) ? (bridging), whereas the bridging Zn-C bond to the second Ph₂Zn unit is 2.403 (5) ?. In the crystal packing, two dimeric residues are weakly associated by interactions (3.0-3.7 ?) between the two zinc atoms of one dimer and one of the terminal phenyl groups of the other.