A NOVEL HOMOLEPTIC NICKEL THIOLATE WITH A PENTAGONAL-PRISMATIC SULFUR FRAMEWORK
Amir H. Mahmoudkhani and Vratislav Langer
Department of Inorganic Chemistry, Göteborg University and
Chalmers University of Technology, S-412 96 Göteborg, SWEDEN.
E-mail: amir@inoc.chalmers.se
Keywords: structure determination, nickel
thiolate, polynuclear complex.
Complexes of nickel(II) with thiolate ligands have been attracted attention due to their unusual structures and properties. Furthermore, identification of redox-active Ni complexes with S-donor ligands in biological systems such as hydrogenases has stimulated interest in the chemistry of nickel thiolate complexes [1]. So far, several polynuclear complexes of nickel thiolates have been synthesized, and characterized by diffraction techniques. In theses complexes, involving bridged thiolates and planar NiS4 units, there is a great tendency to form tetramers [3], pentamers [3, 4], hexamers [5 - 9, 10] and even higher polymers [11]. To our knowledge, there are only two examples of nickel thiolates with pentagonal-prismatic sulfur framework [3, 4]. It has been proposed that in these structures, axial-equatorial configuration of the thiolate ligands alternate to minimize steric interactions. It has been also suggested that steric effects have a relative importance in determining the degree of aggregation of nickel thiolates.
In our ongoing efforts to elucidate the factors determining
the formation of these complexes, we prepared pentakis[di-m-(diisopropylaminoethanethiolato)nickel] by
interaction of diisopropylaminoethanethiol with nickel(II)
chloride. Dark red-brown crystals of the complex were obtained
from its solution in acetone after few weeks. The crystal
structure of this novel homoleptic thiolate complex shows a
pentanuclear array of nickel atoms linked by sulfur bridging
ligands, without coordination of nitrogen atoms.