Reactions of ruthenium(II)-co-ordinated phenyl phosphines: synthesis and X-ray crystal structures of the orthometallated complexes [Ru(C6H4PR1R2)(CH2SiMe3)(η6-C6Me6)](R1= R2= Ph; R1= Ph, R2= Me; R1= R2= Me) and of [{Ru(CH2SiMe3)2(µ-σ,η6-PMe2Ph)}2] containing bridging dimethylphenylphosphine ligands

Abstract

The compounds [RuCl₂(η⁶-C₆Me₆)L][L = PPh₃, (1); PMePh₂, (2); or PMe₂Ph, (3)] react with an excess of Mg(CH₂SiMe₃)Cl to give the corresponding orthometallated complexes [[graphic omitted]R¹R²)(CH₂SiMe₃)(η⁶-C₆Me₆)][R¹= R²= Ph, (4); R¹= Ph, R²= Me, (5); R¹= R²= Me, (6)]. Both diastereomers of (5) have been isolated in a pure form. In the alkylation of (3) the dimeric dialkyl derivative [{Ru(CH₂SiMe₃)₂(µ-σ, η⁶-PMe₂Ph)}₂](7) and the chloroalkyl compound [RuCl(CH₂SiMe₃)(η⁶-C₆Me₆)(PMe₂Ph)](8) have also been isolated. The X-ray crystal structures of complexes (4)–(7) have been determined. Crystal data are: (4), a= 10.622(3), b= 15.851(10), c= 18.963(18)Å, β= 103.64(2)°, Z= 4, space group P2₁/c, R(2 202 reflections, 506 parameters)= 0.0599; (5a), a= 12.215(8), b= 17.920(10), c= 13.023(7)Å, β= 100.02(2)°, Z= 4, space group P2₁/a, R(4 505, 453)= 0.0528; (5b), a= 11.457(6), b= 11.452(5), c= 10.736(5)Å, α= 91.96(1), β= 96.39(1), γ= 87.92(1)°, Z= 2, space group P, R(5 855, 453)= 0.0435; (6), a= 14.633(4), b= 14.527(4), c= 11.936(3)Å, α= 94.03(1), β= 91.54(1), γ= 77.78(1)°, Z= 4, space group P, R(5 763, 244)= 0.0393; (7), a= 15.966(2), b= 13.165(1), c= 21.213(5)Å, β= 109.94(1), Z= 8, space group C2/c, R(2 899, 191)= 0.0593. The molecular structures of (4)–(6) are of the ‘three-legged piano-stool’ type, where the bulky C₆Me₆ ligand (effective cone angle 157–160°) produces widenings of the other co-ordination polyhedron angles. The orthometallated ring is planar and practically coplanar with the benzene ring that shows significant deformations in the angles at the carbon atoms involved in the cyclometallation. The molecular structure of complex (7) is binuclear with a centrosymmetric six-membered ring having a chair conformation. The formation of the orthometallated compounds is discussed.