Anionic Metal Hydride Catalysts. 1. Synthesis of Potassium Hydrido(phosphine)ruthenate Complexes

Article abstract of DOI:10.1021/ja00415a021

The potassium hydrido(phosphine)ruthenate complexes (1) and K2⁺<(Ph3P)3(Ph2P)Ru2H4>^2-*2C6H14O3 (2) were prepared for study as possible homogeneous catalysts for the catalytic hydrogenation of polar organic substrates.Complex 1 was prepared by reaction of (Ph3P)3RuHCl*C6H5CH3 (1 mol) with potassium naphthalene (2 mol) at -80 to -111 deg C in tetrahydrofuran (THF).It was isolated as a yellow crystalline solid from solutions in diethyl ether and in the presence of excess naphthalene (C10H8).The complex was characterized by a combination of chemical and spectral techniques and single-crystal X-ray crystallography.The complex crystallizes in space group P<*> with a = 15.603 (6) Angstroem, b = 15.974 (4) Angstroem, c = 23.774 (8) Angstroem, α = 90.69 (2) grad, β = 102.96 (3) grad, γ = 106.51 (3) grad, and contains four formula units of 1 in the unit cell.In the asymmetric unit there are two different molecules of 1: consisting of two , ruthenate anions, associated potassium (counterions), and also diethyl ether and naphthalene as molecules of crystallization.In the ruthenate anions there is a distorted octahedral arrangement of two triphenylphosphine and one ortho-metalated triphenylphosphine ligands around ruthenium.Two hydride atoms (not located by the crystallography) are assumed to occupy the remaining pseudooctahedral positions.The presence of the hydride atoms was shown by infrared spectra (ν_Ru-H = 1735, 1825 cm^-1), ¹H NMR spectra (δ_(CH3)4Si = -7, -11), and the reactions of 1 with HCl and CH3I to give respectively H2 (2.0 mol/mol of 1) and CH4 (2.4 mol/mol of 1)).The second hydrido(phosphine)ruthenate complex 2 was prepared by the analogous potassium naphthalene reduction of <(Ph3P)2RuHCl>2*2toluene.The composition of 2 as obtained by crystallization from toluene/diglyme (C6H14O3) was established from ¹H and ³¹P NMR spectra and its chemical reactivity with HCl to yield H2 (ca. 2 mol/mol of Ru) and a tris(triphenylphosphine)(diphenylphosphine)diruthenium chloride complex.