The unusual solid state structures of pentasubstituted bis(cyclopentadienyl)zinc compounds: Bis(pentamethylcyclopentadienyl)zinc and Bis(tetramethylphenyl- cyclo-pentadienyl)zinc

The replacement of all hydrogen atoms of Zn(C5H5)2 by methyl groups causes a major change in the solid state structure. Whereas Zn(C5H5)2 is polymeric in the solid state, an X-ray diffraction study of Zn(C5Me5)2 has shown it to be a monomer, with one 5- and one 1-bonded ring. The crystals are monoclinic, space group P21/n with unit cell a 8.70(4), b 7.88(5), c 14.64(8) Å, 102.1(2)°, Z = 2. The structure is disordered. The crystal structure of Zn(C5Me4Ph)2 has been studied in more detail. The compound crystallizes in the monoclinic space group P21/a, with unit cell a 8.086(1), b 17.640(2), c 8.823(1) Å, 93.70(2)°, Z = 2. Anisotropic full-matrix least-squares refinement with 1693 observed reflections and 158 parameters converged at RF = 0.0621. This compound is also monomeric. The zinc atom is disordered between two equivalent sites. In each site it is 1-bonded to one ring and 5 to the other