The crystal and molecular structures of the bispyridine and 1,10-phenanthroline adducts of Bis(ethyl 3-mercaptobut-2-enoato)nickel(II)

X-ray analyses of monoclinic crystals of the bispyridine and 1,10-phenanthroline adducts of the monothioacetylacetonate complex bis(ethyl 3-mercaptobut-2-enoato)nickel(n), Ni(eosm)2,* have defined their structures. Crystals of the bispyridine adduct Ni(eosm)2,py2, C22H28N2NiO4S2, belong to the space group P21/c with a 8.865(6), b 15.758(4), c 9.136(3)Ǻ, β 109.18(4)°, Z 2. Crystals of the 1,10-phenanthroline adduct Ni(eosm)2,phen, C24H26N2NiO4S2, belong to the space group P21c with a 12.451(2), b 16.949(1), c 15 5921(2) Ǻ, β 130.97(1)°, Z 4. The structures were refined with diffractometer data measured with Cu Ka radiation to R 0.047 (1962 terms) for the bispyridine adduct and R 0.061 (3115 terms) for the phenanthroline adduct. The geometry about the nickel in each complex is distorted octahedral. The molecule of the bispyridine adduct has exact rn symmetry with the two sulfur atoms cis-equatorial and the nitrogen atoms axial. In the phenan- throline adduct, pairs of sulfur, nitrogen and oxygen atoms are in cis configurations. In the bis-pyridine adduct, the Ni-N bond lengths, 2.153(3) and 2.182(4) Ǻ, are significantly longer than those in other bispyridine adducts of nickel(II) species. It is suggested that the long Ni-N distances reflect the relative instability of the bispyridine adduct, and thermodynamic data are presented to support this.