Insertion reactions of the 16-electron complexes MHCl(CO)[P(CHMe2)3]2 (M = Ru, Os) with alkynes. The x-ray crystal structure of [(E)-PhCH:CHOs(Cl)(CO)[P(CHMe2)3]2

Abstract

The carbonyl hydrido complexes MHCl(CO)(P-i-Pr3)2 (M = Ru, Os) react with alkynes HC=CR (R = Ph, H) by insertion to give the five-coordinate vinylmetal compounds M(CH=CHR)Cl(CO)(P-t-Pr3)2 (3-6) in nearly quantitative yields. Addition of CO or displacement of the chloride ligand in 3-6 by acetate or acetylacetonate produces the six-coordinate complexes M(CH=CHR)Cl(CO)2(P-t-Pr3)2 (R = Ph; 7, 8),
\nM(CH=CHR)(i;-02CMe)(C0)(P-t-Pr3)2 (R = Ph; 9,10) and M(CH=CHR)(772-acac)(CO)(P-¿-Pr3)2 (R = H, Ph; 11-14), respectively. Treatment of RuHCl(CO)(P-t-Pr3)2 with HC=CPh and KOH in methanol leads to a mixture of Ru(C=€Ph)2(CO)(P-i-Pr3)2 (15) and Ru(C=CPh)(CH=CHPh)(CO)(P-i-Pr3)2 (16), the latter of which reacts with CO to form the octahedral compound Ru(C^CPh) (CH=CHPh) (CO)2(P-i-Pr3)2 (17). The molecular structure of Os(CH=CHPh)Cl(CO)(P-i-Pr3)2 (4) has been determined by X-ray
\ninvestigation. 4 crystallizes in the space group P2xjn with o = 16.437 (5) A,b = 10.980 (4) A, c = 17.086 (4) A, and ß = 105.56 (2)°. The osmium atom has a nearly perfect square-pyramidal coordination with the vinyl ligand in the apical position and the two phosphines trans to each other in the base of the pyramid. With regard to the stereochemistry at the vinyl C=C bond, only the E isomer is formed. A stereo ORTEP diagram illustrates that the metal atom, although coordinatively unsaturated, nevertheless is well shielded at the sixth position of the (uncompleted) octahedron by four of the 12 methyl groups of the phosphine ligands. IR as well as 1H, 13C, and 31P NMR data of the complexes 3-17 are reported.