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The complex [(triphos)(CO)2Re(OTf)] (1) reacts with disubstituted propargyl alcohols HC⋮CCR(R‘)OH in CH2Cl2 at room temperature (R = R‘ = Ph, Me; R = Ph, R‘ = Me), to give either allenylidene derivatives [(triphos)(CO)2Re{CCC(R)Ph}]OTf (R = Ph, 2; R = Me, 3) or the dinuclear vinylidene−carbene complex [{(triphos)(CO)2Re}2{μ-(C10H12)}](OTf)2 (5) (R = R‘ = Me) (triphos = MeC(CH2PPh2)3; OTf = CF3SO3 -). The secondary propargyl alcohol HC⋮CCH(Me)OH reacts with 1 in the presence of methanol to give the methoxyalkenyl Fischer-type carbene [(triphos)(CO)2Re{C(OMe)-CHCHMe}]OTf (11). Compound 11 has been authenticated by an X-ray diffraction analysis. The structure of this complex shows the metal center to be surrounded by a fac triphos ligand, by two mutually cis carbonyl groups, and by the organyl ligand in a slightly distorted octahedral geometry. The reaction with HC⋮CCH2OH results in the double addition of methanol to give the carbene complex [(triphos)(CO)2Re{C(OMe)(CH2CH2OMe)}]OTf (9). When the reaction between 1 and propargyl alcohol is carried out in the dichloromethane dinuclear vinylidene−carbene complex, [{(triphos)(CO)2Re}2{μ-(C6H6O)}](OTf)2 (10) is obtained.

After displacement of the η 2 -H 2 ligand from [(triphos)Re(CO) 2 (η 2 -H 2 )]BF 4 (2), ethyne and various 1-alkynes, HC≡CR, are tautomerized at the Re(I) center to vinylidene ligands (R ) H, Ph, p-tolyl, COOEt, n-C 6 H 13 , SiMe 3 ). A kinetic π-alkyne adduct is intercepted at low temperature during the reaction between 2 and ethyne. The primary vinylidene complex [(triphos)Re(CO) 2 (CdCH 2 )]BF 4 (7-BF 4 ) can also be obtained by reaction of the (trimethylsilyl)vinylidene complex [(triphos)Re(CO) 2 {CdC(H)SiMe 3 }]BF 4 with stoichiometric water. Unprecedented examples of addition of either water or alcohols to Re-vinylidene moieties to give hydroxycarbene or alkoxycarbene complexes are presented. In particular, an excess of water transforms 7-BF 4 into the secondary hydroxycarbene complex [(triphos)Re(CO) 2 {C(OH)-CH 3 }]BF 4 (11), which can be isolated in the solid state. Upon thermolysis in refluxing tetrahydrofuran, 11 selectively converts to the tricarbonyl complex [(triphos)Re(CO) 3 ]BF 4 and methane. Deprotonation of 11 by mild bases gives the acetyl derivative (triphos)Re-(CO) 2 (COCH 3 ), which regenerates the hydroxycarbene precursor by protonation with strong acids. The ethoxycarbene complexes [(triphos)Re(CO) 2 {C(OEt)CH 2 R}]BPh 4 (R ) H, COOEt) are prepared by nucleophilic addition of ethanol across the CdC double bond of the corresponding vinylidene derivatives. Neutral σ-alkynyl complexes of the general formula (triphos)Re(CO) 2 (C≡CR) (R ) Ph, p-tolyl, COOEt, n-C 6 H 13 , H) are obtained by reaction of the vinylidene derivatives with strong bases. The reaction of the σ-alkynyl complexes with various methylating agents affords disubstituted vinylidene derivatives, herein exemplified by [(triphos)Re(CO) 2 {CdC(Me)Ph}](OSO 2 CF 3 ). The structural identities in the solid state of the phenylvinylidene complex [(triphos)Re(CO) 2 {CdC(H)Ph}]BF 4 and of the ethoxycarbene complex [(triphos)Re(CO) 2 {C(OEt)CH 3 }]BPh 4 have been determined by X-ray diffraction analyses. In both complexes the metal center is octahedrally coordinated by a fac triphos ligand, by two mutually cis terminal carbonyls, and by the organyl ligand.

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Reaction of the rhenium(I) allenylidene complex [Re{CCCPh2}(CO)2(triphos)]OTf (1; triphos = MeC(CH2PPh2)3, OTf = -OSO2CF3) with thiophenol, 2-thionaphthol, or allyl mercaptan gave selectively the α,β-unsaturated thiocarbene complexes [Re{C(SR)CHCPh2}(CO)2(triphos)]OTf (R = Ph (2), α-naphthyl (3), CH2CHCH2 (4)). A reversible reaction was observed for PhSH in DMSO at 80 °C. Compounds 2 and 3 have been found to react with sodium alkoxides, yielding the kinetic thioallenyl products [Re{C(SR)CCPh2}(CO)2(triphos)] (R = Ph (6a), α-naphthyl (7a)). These equilibrated in room-temperature solution with the thermodynamic thioalkynyl products [Re{C⋮CC(SR)Ph2}(CO)2(triphos)] (R = Ph (6b), α-naphthyl (7b)) to give stationary states (6a/6b, 40/60; 7a/7b, 20/80). Deprotonation of the thioallyl complex 4 gave the stable allenyl derivative [Re{C(SCH2CHCH2)CCPh2}(CO)2(triphos)] (8). Ammonia, aniline, and propargylamine each reacted with 1 to give the azoniabutadienyl compounds [Re{C(NHR)CHCPh2}(CO)2(triphos)]OTf (R = H (9), Ph (10), CH2C⋮CH (11)) via N−H bond addition across the CαCβ double bond. NMR spectroscopy showed the γ-alkynylammonium complex [Re{C⋮CCPh2(NH3)}(CO)2(triphos)]OTf (12) to be a transient intermediate along the reaction of 1 with ammonia. Treatment of 10 or 11 with sodium methoxide resulted in the selective deprotonation of the nitrogen atom to give the azabutadienyl compounds [Re{C(NR)CHCPh2}(CO)2(triphos)] (R = Ph (13), CH2C⋮CH (14)). The molecular structure of the azoniabutadienyl complex 11 was determined by a single-crystal X-ray analysis. The geometry around the rhenium center conforms to a slightly distorted octahedron, with the polyphosphine sitting on a face of the coordination polyhedron. In keeping with the azoniabutadienyl structure, the Re−Cα bond length is 2.151(7) Å, and the Cα−N distance is 1.300(9) Å.