Alkyne transformations at RhMn centres. Facile conversion between parallel and perpendicular alkyne binding modes and conversions to vinyl groups
- 1 July 1995
- journal article
- Published by Canadian Science Publishing in Canadian Journal of Chemistry
- Vol. 73 (7) , 1058-1071
- https://doi.org/10.1139/v95-131
Abstract
The heterobinuclear complex [RhMn(CO)4(dppm)2] (1) (dppm = Ph2PCH2PPh2) reacts with alkynes (RC≡CR; R = CO2Me (DMAD), CF3 (HFB)) to yield the alkyne-bridged products [RhMn(CO)4(μ-RC2R)(dppm)2] (3a, 3b), in which the alkyne binds parallel to the metals. These species lose one carbonyl to yield two isomers in which the bridging alkyne group is either parallel or perpendicular to the Rh–Mn vector (4 or 5). Unusually facile interconversion between these two alkyne binding modes occurs. Protonation of the different alkyne-bridged species appears to occur at the metals with subsequent transfer to the alkyne ligand, yielding a series of vinyl complexes. These vinyl complexes are also obtained from the reaction of the hydride-bridged complex [RhMn(CO)4(μ-H)(dppm)2][BF4] (2) with alkynes. A related vinyl species [RhMn((CH3)C=CH2)(CO)4(dppm)2][BF4] (9a) is obtained in the reaction of 2 with allene. Also obtained in the allene reaction is the isomeric η1-allyl complex [RhMn(η1-CH2C(H)=CH2)(CO)4(dppm)2][BF4] (9b), which converts to 9a upon refluxing. The methyl analogues [RhMnCH3(CO)4(dppm)2][X] (X = SO3CF3, I) have been characterized and their structural formulations offer support for those of the vinyl species. Keywords: heterobinuclear, alkyne complexes, vinyl complexes.Keywords
This publication has 35 references indexed in Scilit:
- Bridging Vinylidene Complexes of RhMn and Evidence for Migratory Insertions To Give Terminal Vinyl GroupsOrganometallics, 1995
- Heterobinuclear Hydrido, Alkyl, and Related Complexes of Rh/Os. Site-Specific Reductive Elimination of Methane from a Rh/Os Core and the Structures of [RhOs(CH2CN)(CO)3(dppm)2] and [RhOs(CH3)(CO)3(dppm)2]Journal of the American Chemical Society, 1995
- Alkyne-to-vinylidene tautomerism mediated by two adjacent metal centers. Structures of iridium complexes [Ir2I2(CO)2(.mu.-CCHR)(Ph2PCH2PPh2)2] (R = H, Ph)Organometallics, 1993
- Novel binuclear bis(dimethylphosphino)methane-bridged complexes of rhodium containing two and three alkyne moleculesOrganometallics, 1992
- Unusual low-valent dirhodium complexes bridged by bis(dimethylphosphino)methane ligandsOrganometallics, 1992
- Binding of .pi.-acid ligands in diiridium and rhodium-iridium iodo complexes, including rare examples of ethylene coordination in a "a-frame" compounds. Structure of [Ir2I2(CO)(.mu.-CO)(Ph2PCH2PPh2)2].cntdot.CH2Cl2Organometallics, 1991
- Low-valent, heterobinuclear complexes of rhodium and osmium. Influence of the coordinatively unsaturated rhodium center on the reactivityOrganometallics, 1991
- Models for multicenter catalysts. 4. Reactions of binuclear hydrides with alkynes and the structure of [Ir2(H)2Cl(CH3O2CC = C(H)CO2CH3)2(CO)2(Ph2PCH2PPh2)2]-[BF4].cntdot.3THF, a model hydrogenation intermediate containing mutually adjacent alkenyl and hydrido ligandsOrganometallics, 1990
- Binuclear diiridium and mixed-metal rhodium-iridium complexes containing terminal .eta.2-alkynes: the structure of [Ir2(CO)(.eta.2-F3CC CF3)(.mu.-S)(.mu.-CO)(Ph2PCH2PPh2)2].cntdot.CH2Cl2Organometallics, 1989
- Perpendicular and parallel acetylene complexesJournal of the American Chemical Society, 1982