Conformations and coordination properties of trialkyltrithiophosphites in copper(I) complexes

A series of complexes (RS)(3)P . CuBr with R = Et, Pr, Bu, i-Pr as well as the complex of (PrS)(3)P . CuSCN were studied by X-ray single-crystal diffr action. Coordination properties of thiophosphites were found to be essentia lly different from their oxygen and nitrogen analogues and depend on the na ture of the metal center, substituents at sulfur atoms, the conditions of r eactions and of the crystal growth. All trithiophosphites in the studied co pper(I) complexes except the isopropyl derivative exhibit bidentate coordin ation with both phosphorus and sulfur participating in coordination bonds w ith copper. Trithiophosphites increase their conformational multiformity upon complexat ion regardless of the coordination mode, propyl and butyl derivatives being conformationally inhomogeneous in crystals. Unusual cis-conformations abou t the P-S bond, which are not observed for "free" trialkyltrithiophosphites or their phosphoryl and thiophosphoryl analogues, are realized in the comp lexes. The complexation results in the significant high-frequency shift of the sym metric and asymmetric PS3 stretching vibrations in the Raman spectra of com plexes regardless of the coordination mode and in minor changes of the C-S stretching vibrations in comparison with the spectra of the "free" ligands. (C) 2000 Elsevier Science B.V. All rights reserved.