Preparation and structural comparison of the ruthenium(0) derivatives Ru(DMPE)2L (L = PMe3, CO; DMPE = 1,2-bis(dimethylphosphino)ethane)

Abstract

The thermal reaction of Ru(DMPE)/sub 2/(nap)H (DMPE = 1.2-bis(dimethylphosphino)ethane; nap = naphthyl) with PMe/sub 3/ results in the formation of the new zerovalent derivative Ru(DMPE)/sub 2/(PMe/sub 3/). The molecule crystallizes in orthorhombic space group Pnam with Z = 4 (d/sub calcd/ = 1.38 g/cm/sup 3/) and lattice parameters a = 16.3540 (18) A, b = 9.3240 (30) A, and c = 16.0210 (23) A. The structure displays a square-pyramidal geometry in which the PMe/sub 3/ occupies the apical position. Separate modeling of two disorders due to 4-fold rotation of the DMPE ligands about the apical Ru-P vector and 2-fold rotation of the PMe/sub 3/ ligand gives refinement to R/sub 1/ = 0.042, R/sub 2/ = 0.066. Some reactions of the low-valent derivative are reported. Displacement of PMe/sub 3/ by CO occurs at 25/sup 0/C, producing Ru(DMPE)/sub 2/(CO). Similarly, P(CD/sub 3/)/sub 3/ exchanges with coordinated PMe/sub 3/ more slowly. Neopentyl isocyanide slowly displaces PMe/sub 3/ at higher temperatures to give the isocyanide derivative. The CO adduct crystallizes in orthorhombic space group Pbca with Z = 16 and lattice parameters a = 19.110 (9) A, b = 23.116 (6) A, and c = 18.780 (6) A, the non-hydrogen atoms being refined tomore » R/sub 1/ = 0.048, R/sub 2/ = 0.066. A trigonal-bipyramidal geometry is observed in which the CO occupies an equatorial site. The mechanism of substitution indicates both associative and dissociative pathways.« less