MOLECULAR DIHYDROGEN AND HYDRIDO DERIVATIVES OF RUTHENIUM(II) COMPLEXES CONTAINING CHELATING FERROCENYL-BASED TERTIARY PHOSPHINE AMINE LIGANDS AND OR MONODENTATE TERTIARY PHOSPHINE-LIGANDS

Reactions of complexes of the type RuCl2(PPh3)(P-N) with H2 are reported, where P-N represents the chelating ferrocene-based ligands (eta-C5H5)Fe(etaC5H3(CHMeNMe2)PR2-1,2) with R = i-Pr (the isoPFA ligand) or Ph (the PPFA ligand). Depending on the solvent(s) used, and absence or presence of added base, RuCl2(PPh3)(isoPFA) (2b) generates the dinuclear eta2-H2 complexes L2(eta2-H2)Ru(eta-Cl)2(eta-H)Ru(H)(PPh3)2 where L2 = isoPFA (complex 3) or L2 = (PPh3)2 (complex 4). n-Butanol solutions of RuCl2(PPh3)(PPFA) (2a) under H-2 also yield 4, as well as Ru(H)Cl2(PPh3)(PPFA.H)(BuOH), a zwitterionic species containing a protonated amine moiety stabilized by coordinated n-BuOH, which is a likely intermediate in heterolytic cleavage of the H-2: the complex RuH(Cl)-PPh3)(isoPFA) (5), together with a hydrido carbonyl species, is isolated from methanol solutions of 2b. Complexes 2b, 3, 4, and 5 are characterized by X-ray crystallography; the mononuclear complexes 2b and 5 are orthorhombic with space groups F2dd and P2(2)2(1)2(1), respectively. For 2b, a = 10.4316 (3) angstrom, b = 31.4693 (10) angstrom, c = 43.2963 (18) angstrom, v = 14213.1 (8) angstrom3, and Z = 16; the structure refined to R = 0.054 and R(w) = 0.046 for 1783 reflections with I > 2sigma(I). Corresponding crystallographic data for 5 are a = 9.915 (2) angstrom, b = 16.511 (4) angstrom, c = 21.781 (5) angstrom, V = 3566 (1) angstrom3, Z = 4, R = 0.077, and R(w) = 0.079 for 2691 reflections. The essential crystallographic data for the dinuclear complex 3 have been published [Hampton, C.; et al. J. Am. Chem. Soc. 1988, 110, 6918]. The related complex 4 crystallizes in the monoclinic system, space group P2(1)/c, with a = 15.866 (5) angstrom, b = 18.931 (5) angstrom, c = 24.472 (7) angstrom, beta = 108.69 (2)-degrees, V = 6963 (3) angstrom3, Z = 4, R = 0.078, and R(w) = 0.0792 for 4507 reflections. Variable-temperature H-1- and P-31-NMR data for 3 reveal fast exchange between the eta2-H-2 and the eta-H at 20-degrees-C and a slower exchange of this system with the terminal hydride; corresponding data for 4 and its P(p-tolyl)3 analogue 7 show a faster exchange involving all the hydrogens. Activation parameters are determined for the exchange processes.