Synthesis, redox properties, and reactivity of a novel family of electron-rich vinylidene and vinylphosphonium complexes of rhodium(I)

Journal Article · Mon Jan 01 00:00:00 EST 1990 · Organometallics; (USA)

DOI:https://doi.org/10.1021/om00115a036· OSTI ID:6620691

Bianchini, C; Meli, A; Peruzzini, M; Zanobini, F ^[1]; Zanello, P ^[2]

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1. CNR, Firenze (Italy)
2. Universita di Siena (Italy)

The trigonal-bipyramidal Rh(I) vinylidene complexes ((NP{sub 3})Rh=C=C(H)(R)){sup +} have been prepared by treatment of the neutral {sigma}-acetylides ((NP{sub 3})Rh(C{triple bond}CR)) with strong protic acids and isolated as BPh{sub 4}{sup {minus}} or PF{sub 6}{sup {minus}} salts (NP{sub 3} = N(CH{sub 2}CH{sub 2}PPh{sub 2}){sub 3}; R = Ph, CO{sub 2}Et). Reaction of the vinylidene complexes with nucleophiles such as NEt{sub 3}, MeLi, and PhLi leads to deprotonation to restore the parent {sigma}-acetylide compounds. When the vinylidene complexes are treated with NaBH{sub 4} or LiHBEt{sub 3}, the acid-base reaction competes with the nucleophilic addition of H{sup {minus}} to the vinylidene C{sub {alpha}} atom to form the alkenyl derivatives ((E)-(NP{sub 3})Rh(CH=C(H)R)). Two-electron oxidation of the vinylidene complexes by controlled-potential electrolysis results in the deprotonation of the vinylidene ligand. When O{sub 2} is bubbled into CH{sub 2}Cl{sub 2} solutions of the vinylidene complexes, the Rh(III) hydroxide acetylide compounds ((NP{sub 3})Rh(OH)(C{triple bond}CR))BPh{sub 4} are obtained in ca. 60% yield because of extensive decomposition of the starting compounds. For R = Ph, an appreciable amount of phenol is found. Thermal decomposition of the vinylidene complexes in refluxing THF produces H{sub 2} and the paramagnetic Rh(II) derivatives ((NP{sub 3})Rh(C{triple bond}CR)){sup +}. Unlike the NP{sub 3} {sigma}-acetylides, the PP{sub 3} analogues (PP{sub 3} = P(CH{sub 2}CH{sub 2}PPh{sub 2}){sub 3}) react with strong acids in THF or CH{sub 2}CL{sub 2} to form unusual examples of vinylphosphonium compounds of formula (((Ph{sub 2}PCH{sub 2}CH{sub 2}){sub 2}P(CH{sub 2}CH{sub 2}PPh{sub 2}))Rh(C=C(H)C(O)R))BPh{sub 4}.

• OSTI ID: 6620691
• Journal Information: Organometallics; (USA), Vol. 9:1; ISSN 0276-7333
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
RHODIUM COMPLEXES
REDOX REACTIONS
SYNTHESIS
CHEMICAL REACTIONS
DATA ANALYSIS
EXPERIMENTAL DATA
MEASURING INSTRUMENTS
MEASURING METHODS
PHOSPHORUS
SPECTRA
COMPLEXES
DATA
ELEMENTS
INFORMATION
NONMETALS
NUMERICAL DATA
TRANSITION ELEMENT COMPLEXES
400200* - Inorganic
Organic
& Physical Chemistry