Catalytic hydrogenolysis of biphenylene with platinum, palladium, and nickel phosphine complexes

Journal Article · Mon Oct 26 04:00:00 EST 1998 · Organometallics

DOI:https://doi.org/10.1021/om9805281· OSTI ID:315972

Edelbach, B L; Vicic, D A; Lachicotte, R J; Jones, W D ^[1]

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1. Univ. of Rochester, NY (United States). Dept. of Chemistry

The catalytic hydrogenolysis of biphenylene was carried out using Pt, Pd, and Ni phosphine complexes under an atmosphere of H{sub 2} between 56 and 120 C. The Pt species Pt(PEt{sub 3}){sub 3}, (PEt{sub 3}){sub 2}Pt(2,2{prime}-biphenyl), 1, trans-(PEt{sub 3}){sub 2}PtH{sub 2}, and trans-(PEt{sub 3}){sub 2}Pt({alpha}-biphenyl)H, 4, were all viable catalysts. The resting state species in each case was complex 4. At 80 C under an atmosphere of H{sub 2}, 4 reductively eliminates biphenyl and forms trans-(PEt{sub 3}){sub 2}PtH{sub 2}. Free PEt{sub 3} inhibits the rate of reductive elimination from 4 and the overall rate of hydrogenolysis. The novel Pt(IV) dihydride trans,cis-(PEt{sub 3}){sub 2}Pt(2,2{prime}-biphenyl)H{sub 2} was synthesized and characterized by X-ray analysis. trans-cis-(PEt{sub 3}){sub 2}Pt(2,2{prime}-biphenyl)H{sub 2} undergoes unimolecular reductive elimination to give 2. On the basis of these results a catalytic cycle is proposed. A mixture of [(dippe)PtH]{sub 2} and (dippe)PtH{sub 2} (dippe = bis(diisopropylphosphino)ethane) was also capable of catalyzing the hydrogenolysis of biphenylene under an atmosphere of H{sub 2} at 120 C. The rate of hydrogenolysis increases as the concentration of biphenylene, H{sub 2}, and (dippe)PtH{sub 2} increases. These observations are consistent with the C-C bond activation of biphenylene occurring via (dippe)PtH{sub 2}, not [(dippe)Pt{sup 0}]. The rate of catalytic hydrogenolysis was not affected by the length of the chelating phosphine bridge. The Ni complex [(dippe)NiH]{sub 2} was the most efficient catalyst for the hydrogenolysis of bisphenylene (16 turnovers/day at 56 C). The resting state species was (dippe)Ni(2,2{prime}-biphenyl).

• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: FG02-86ER13569
• OSTI ID: 315972
• Journal Information: Organometallics, Journal Name: Organometallics Journal Issue: 22 Vol. 17; ISSN 0276-7333; ISSN ORGND7
• Country of Publication: United States
• Language: English

Related Subjects

40 CHEMISTRY
AROMATICS
CATALYSIS
HYDROGEN
HYDROGENATION
NICKEL COMPLEXES
PALLADIUM COMPLEXES
PHENYLENE RADICALS
PHOSPHINES
PLATINUM COMPLEXES