Synthesis and some reactions of a terminal carbyne complex of osmium. Crystal structures of Os(CR)Cl(CO)(PPh3)2 and Os(C[AgCl]R)Cl(CO)(PPh3)2

Abstract The reaction of two equivalents of LiR (R = p -tolyl) with the dichlorocarbene complex OsCl 2 (CCl 2 )(CO)(PPh 3 ) 2 gives the carbyne complex Os(CR)Cl(CO) (PPh 3 ) 2 (I) in good yield. X-ray crystal structure determination shows that I is mononuclear with an OsC distance of 1.78(2) A. The OsC bond reacts with electrophiles rather than nucleophiles. Thus, HCl adds to give the alkylidene complex OsCl 2 (CHR)(CO)(PPh 3 ) 2 , Cl 2 forms OsCl 2 (CClR)(CO)(PPh 3 ) 2 and sulphur, selenium and tellurium react to yield to corresponding dihapto -chalcoacyls Os(η 2 -C[X]R)Cl(CO)(PPh 3 ) 2 (X = S, Se, Te). Group Ib metal halides also add to the OsC bond to form the adducts Os(C[M X]R)Cl(CO)(PPh 3 ) 2 (MX = CuI, AgCl, AuCl). The X-ray crystal structure determination of Os(C[A gCl]R)Cl(CO)(PPh 3 ) 2 (II) suggests that this complex can be considered as a dimetallacyclopropene derivative. Crystals of I are monoclinic, space group P 2 1 / n , a 17.030(2), b 12.774(1), c 18.315(3) A, β 107.96 (1)°, V 3793.2 A 3 , Z = 4, D m 1.53(1), D c 1.54. Crystals of II are monoclinic, space group P 2 1 / n , a 13.021(2), b 23.714(2), c 12.999(2) A, β 90.556(2)°, V 4013.7 A 3 , Z = 4, D m 1.705(5), D c 1.695. The structures were solved by conventional heavy-atom methods, and refined by full-matrix least-squares employing anisotropic thermal parameters for all non-hydrogen atoms except for the carbon atoms of the phenyl rings. Phenyl hydrogen atoms were included in calculated positions. Final residuals R were 0.040 and 0.037, respectively.