Reactions of Hydride Complexes of Ruthenium and Osmium with Propargylic Alcohols: Preparation of Chelate Vinyl ­Derivatives

Allenylidene and Higher Cumulenylidene Complexes

“…, which results from the protonation of the alkynyl-isocyanide com- 118 The preparation of a unique example of a bisallenylidene complex 40 and its reduced one-electron radical has also been reported (Scheme 7). 52 Along with the previously reported dinuclear allenylidene complex [Ru 2 (µ-Cl) 3 (dCdCdCPh 2 ) 2 (PPh 3 ) 4 ][PF 6 ], 85,119 new derivatives containing (µ-X) 2 halide systems have also been reported (Chart 9).…”

“…Besides the use of coordinatively unsaturated 16-electron precursors [ML 4 X] + and [ML 3 X 2 ], alternative synthetic methodologies of allenylidenes based on different starting materials have also been used for the preparation of (i) [RuCl 2 (CCCPh 2 )(CO)(Sb i Pr 3 ) 2 ] obtained from [RuHCl(CO)(Sb i Pr 3 ) 3 ] and 1,1-diphenyl 2-propyn-1-ol; (ii) [Ru(κ 1 -O 2 CMe)(CCCPh 2 )(CN t Bu) 2 (PPh 3 ) 2 ], which results from the protonation of the alkynyl−isocyanide complex [Ru(κ 1 -O 2 CMe){CCC(OH)Ph 2 }(CN t Bu) 2 (PPh 3 ) 2 ]; (iii) [Ru(acac) 2 (CCCPh 2 )(P i Pr 3 )] generated from [Ru(acac) 2 (P i Pr 3 ) 2 ]; (iv) [RuCl 2 (CCCPh 2 )(PPh 3 ) 2 (L)] (L = H 2 O, MeOH, EtOH, 4-( N , N -dimethylamino)pyridine) obtained by reaction of the five-coordinate complex [RuCl 2 (CCCPh 2 )(PPh 3 ) 2 ] (prepared by treatment of carbyne [RuCl 2 {CC(H)CPh 2 }(PPh 3 ) 2 ] + with base) with the ligands L; (v) cationic complexes [RuCl{CCC(NMe 2 )(CH 2 Fc)}(dppm) 2 ] +110 and [RuCl{CCC(ER n )Me}(dppm) 2 ] + , with a broad range of heteroatom substituents, ,− which are prepared from the transient butatrienylidene complex [RuCl(CCCCH 2 )(dppm) 2 ] + (see reactivity studies); (vi) the cationic osmium derivative [Os{κ 2 ( C , O )-C(CO 2 Me)CH 2 }(CCCPh 2 )(CO)(P i Pr 3 ) 2 ][BF 4 ] obtained by the displacement of the acetone ligand in [Os{κ 2 ( C , O )-C(CO 2 Me)CH 2 }(OCMe 2. )(CO)(P i Pr 3 ) 2 ][BF 4 ] by 1,1-diphenyl-2-propyn-1-ol; (vii) complex trans−cis- [OsH(CCCPh 2 )(NCMe) 2 (P i Pr 3 ) 2 ][BF 4 ], which results from the deprotonation of the carbyne complex [OsH{CC(H)CPh 2 }(NCMe) 2 (P i Pr 3 ) 2 ][BF 4 ]; and (viii) [Os(CCCPh 2 ){P(OEt) 3 } 5 ][BPh 4 ] 2 , which results from the reaction of [Os{κ 2 ( O , O )-OTf} 2 {P(OEt) 3 } 4 ] with HCCC(OH)Ph 2 and P(OEt) 3 in the presence of NaBPh 4 . The preparation of a unique example of a bisallenylidene complex 40 and its reduced one-electron radical has also been reported (Scheme ) …”

The Coupling of N-Heterocyclic Carbenes to Terminal Alkynes at Half Sandwich Cobalt NHC Complexes

“…The complex [(η 5 -C 5 H 5 )­Co­(C­{R}C­{H}­{Dipp 2 Im})] ( 7 ) is the product of NHC migration to the alkyne C–H carbon atom, and the crystal structure of 7 reveals nicely that the carbene carbon atom C15 is now bound to the alkyne α carbon C14. The former β alkyne carbon atom (C13) coordinates at the cobalt atom at a distance Co–C13 of 1.8992(35) Å, which is at the lower end of the region typically observed for Co–C single bonds in vinyl type ligands (1.95–2.0 Å). − This indicates minor contributions from a resonance structure with a CoC double bond as indicated in Scheme . The distance C13–C14 of 1.3813(45) Å is within double bond range as is the bond length C14–C15 of 1.3983(40) Å and also accounts for delocalization in the Co–C13–C14–C15 chain (and also within the NHC ring), which should be responsible for the deep violet color of the complex 7 .…”