Organometallic acetylene chemistry IV. Disubstituted acetylenes of the type PhP(CCMR3)2 and P(CCMR3)3

Trialkynylphosphines substituted with bulky triarylsilyl groups at the alkyne termini were synthesized. The new phosphines P(C[triple chemical bond]CSiAr(3))(3) (Ar=3,5-tBu(2)-4-MeOC(6)H(2), 3,5-(Me(3)Si)(2)C(6)H(3)) are uncrowded near the phosphorus atom but bulky in the distal region. As a result, they contain a large cavity, at the bottom of which the phosphine lone-pair electrons are located. The compounds are stable to oxidation by air and hydrolysis. DFT calculations suggested that the triethynylphosphines are good pi-acceptor ligands, comparable with P(OAr)(3). The trialkynylphosphines reacted with [{RhCl(cod)}(2)] (P/Rh=1.1:1) to give selectively the monophosphine-rhodium complex [RhCl(cod)P(C[triple chemical bond]CSiAr(3))(3)]. X-ray crystal-structure analysis revealed that the {RhCl(cod)} fragment is fully accommodated by the cavity of the phosphine ligand. Compared to the effect of analogues with smaller end caps and PPh(3), the trialkynylphosphines accelerated markedly the rhodium-catalyzed hydrosilylation of ketones with a triorganosilane. It is proposed that the higher catalytic activity observed with the holey phosphines is a result of the preferential formation of a monophosphine-rhodium species.

show abstract

Zum Koordinationsverhalten von Alkinylphosphanen R_nP(CC–R')_3–n

Lang

Zsolnai

1991

Chem. Ber.

View full text Add to dashboard Cite

Coordination Ability of Alkynylphosphines RnP(CC – R')3 – n Alkynylphosphines RP(CC–R')2 (2) react with one equivalent of octacarbonyldicobalt to yield selectively the η2‐μ side‐on‐coordinated alkyne complexes (R)(R' – CC)P[(η2‐CC–R')Co2(CO)6] (6); with another equivalent of Co2(CO)8 the dicoordinated compounds (R)P[(η2‐CC–R')Co2(CO)6]2 (7) are obtained. 7 may also be synthesized directly by the reaction of 2 with two equivalents of Co2(CO)8. However, P(CC–Ph)3 yields with two equivalents of Co2(CO)8 the cyclic Co2P2C2 system {(Ph–CC)(R')P[(η2‐CC–Ph)Co2(CO)5]} 2 (4) [R' = (η2‐CC–Ph)Co2(CO)6]. Decarbonylation of 6a gives the six‐membered cyclic compound {(Ph)(Ph – C  C)P[(η2‐C  C – Ph)Co2(CO)5]}2 (8), while 6b yields the cluster Co3(CO)9(μ3‐PtBu) (9). The structure of (tBu)P[(η2‐C  C – H)Co2)CO)6]2 (7b) is elucidated by an X‐ray analysis.

show abstract

Organometallic acetylene chemistry IV. Disubstituted acetylenes of the type PhP(CCMR3)2 and P(CCMR3)3

Cited by 13 publications

References 3 publications

From Tin Halides (Di‐ and Tetravalent)

From Tin Halides (Di‐ and Tetravalent)

Phosphorus Ligands with a Large Cavity: Synthesis of Triethynylphosphines with Bulky End Caps and Application to the Rhodium‐Catalyzed Hydrosilylation of Ketones

Zum Koordinationsverhalten von Alkinylphosphanen R_nP(CC–R')_3–n

Contact Info

Product

Resources

About

Organometallic acetylene chemistry IV. Disubstituted acetylenes of the type PhP(CCMR3)2 and P(CCMR3)3

Cited by 13 publications

References 3 publications

From Tin Halides (Di‐ and Tetravalent)

From Tin Halides (Di‐ and Tetravalent)

Phosphorus Ligands with a Large Cavity: Synthesis of Triethynylphosphines with Bulky End Caps and Application to the Rhodium‐Catalyzed Hydrosilylation of Ketones

Zum Koordinationsverhalten von Alkinylphosphanen RnP(CC–R')3–n

Contact Info

Product

Resources

About

Zum Koordinationsverhalten von Alkinylphosphanen R_nP(CC–R')_3–n