Preparation and Structural Comparison of the Ruthenium(0) Derivatives Ru(DMPE)2L (L = PMe3, CO; DMPE = 1, 2-Bis(dimethylphosphino)ethane)

The thermal reaction of Ru(DMPE)2(nap)H (DMPE = 1, 2-bis(dimethylphosphino)ethane; nap = naphthyl) with PMe3 results in the formation of the new zerovalent derivative Ru(DMPE)2(PMe3). The molecule crystallizes in orthorhombic space group Pnam with Z = 4 (dcalcd=1.38 g/cm3) and lattice parameters a = 16.3540 (18) Å, b = 9.3240 (30)Å, and c = 16.0210 (23) Å. The structure displays a square-pyramidal geometry in which the PMe3 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 PMe3 ligand gives refinement to R1 = 0.042, R2= 0.066. Some reactions of the low-valent derivative are reported. Displacement of PMe3 by CO occurs at 25 °C, producing Ru(DMPE)2(CO). Similarly, P(CD3)3 exchanges with coordinated PMe3 more slowly. Neopentyl isocyanide slowly displaces PMe3 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) Å, b = 23.116 (6) A, and c = 18.780 (6) A, the non-hydrogen atoms being refined to R1= 0.048, R2= 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. © 1986, American Chemical Society. All rights reserved.