Crystal structures of Tetrakis(p-ethylphenyl)tin(IV) and Tetrakis (p-t-butylphenyl)tin(IV)

Single-crystal X-ray studies of (p-C2H5C6H4)(4)Sn (A) and [p-(CH3)(3)CC6H4] (4)Sn (B) have been undertaken to determine the effect of increasing para-s ubstituent size on the structures of tetra-aryltins. Molecules of(A) are al most tetrahedral at tin but have 2-fold symmetry. The p-C2H5 groups are per pendicular to the phenyl ring planes having the all exo-conformation in one -half of the molecule but equally disordered (exo/endo) in the other half. In contrast (B) crystallises in the unusual tetragonal space group P42/n, w ith molecules having -4 symmetry. Four t-butyl groups from four adjacent Ar 4Sn molecules form a tetrahedral array around parallel 42 axes resulting in strongly directional intermolecular forces and a highly ordered and robust diamantoid network structure for (B).