Synthesis and molecular structure of six-coordinate dichlorodihydridoruthenium(IV) and five-coordinate vinylideneruthenium(II) complexes

The dichlorodihydridoruthenium(IV) compound [RuH2Cl2-(PiPr(3))(2)] (4) was prepared from [RuCl2(C8H12)](n) (3), PiPr(3), and H-2 in 2-butanol via the chlorohydridoruthenium (II) derivative [RuHCl(H-2)(PiPr(3))(2)] (5) as an intermediate. The synthesis of 5 was achieved under similar conditions from 3, PiPr3, H-2, and 2-butanol in the presence of NEt3. Compound 4, which was characterized by X-ray crystal structure analysis, reacts with excess phenylacetylene to give the phenylvinylidene complex [RuCl2(=C=CHPh) (PiPr(3))(2)] (7) and with propargylic alcohols or derivatives thereof to afford the vinylcarbene complexes [RuCl2(=CHCH=CR2) (PiPr(3))(2)] (9, 10), respectively. From 5 and terminal alkynes RC=CH the chlorohydridovinylidene compounds [RuHCl(=C=CHR)(PiPr(3))(2)] (11, 12) were obtained. The phenylvinylidene complex [RuCl2(=C= CHPh)(PCy3)(2)] (15) was prepared from phenylacetylene and either [RuH2Cl2(PCy3)(2)] (14) or one of the carbene derivatives [RuCl2(=CHR)(PCy3)(2)] (16, 17) as starting materials. The X-ray crystal structure analysis of 15 confirms a distorted square-pyramidal geometry with the vinylidene ligand in the apical position. The interconversion of 4 to 5 and of the tricyclohexylphosphane counterparts 14 to 13 was achieved by hydrogen transfer from 2-propanol in the presence of PR3. The reverse reaction occurs upon treatment of 5 or 13 with the corresponding phosphonium salt [HPR3]Cl or HCl, respectively.