Synthesis and Crystal and Molecular Structure of cyclo-Tetrakis[bis(μ-N-methylpiperidine-4-thiolato)nickel(II)]

The reaction of nickel chloride with 4-mercapto-iV-methylpiperidine in a basic solution gives the title complex. Crystals of the compound are monoclinic, space group P2/n, with a = 24.345 (3) Å, b = 10.638 (2) Å, c = 12.323 (2) Å, and β = 92.34 (2)⁰. With Z = 2 the calculated density is 1.32 g cm-3(measured density 1.33 g cm-3). Solution of the structure by direct methods led to a final weighted R factor of 0.077 for 2433 independent reflections. The crystal structure of the complex consists of a cyclic tetranuclear array of nickel atoms, bridged by eight sulfur atoms. The approximate square-planar NiS4 units form the faces of a skew parallelogram with the sulfur atoms located at the comers. Axial and equatorial ligandsalternate around the ring. The Ni-Ni distances average 2.665 (5) Å, and the closest S-S distances average 2.868 (6) Å. The Ni-S-Ni angles are 74.3 (1)⁰. The steric bulk of the piperidine rings provides a reasonable rationalization for the tetrameric structure. © 1984, American Chemical Society. All rights reserved.