111405-65-3Relevant articles and documents
A-frame complexes of dirhodium bridged by dicarbene and diphosphine ligands
Wells, Kyle D.,Ferguson, Michael J.,McDonald, Robert,Cowie, Martin
, p. 691 - 703 (2008)
The complexes [RhBr(COD)]2(μ-di-NHC), in which di-NHC represents the di-N-heterocyclic carbenes MeCCmeth (1,1′-methylene-3,3′-dimethyldiimidazol-2,2′-diylidene), tBuCCmeth (1,1′-methylene-3,3′-di-tert- butyldiimidazol-2,2′-diylidene), and MeCCeth (1,2-ethylene-3,3′-dimethyldiimidazol-2,2′-diylidene), have been prepared from the reactions of the corresponding diimidazolium bromide salts with the acetate-bridged complex [Rh(μ-OAc)(COD)]2. The analogous complex containing the tBuCCeth group (1,2-ethylene-3, 3′-di-tert-butyldiimidazol-2,2′-diylidene) could not be prepared by this route, but the related chloro complex [RhCl(COD)]2(μ- tBuCCeth) was prepared by prior double deprotonation of the corresponding diimidazolium salt and reaction of the resulting dicarbene with [RhCl(COD)]2. Reaction of the above MeCC eth and tBuCCeth complexes with CO yields the corresponding dicarbene-bridged carbonyl products [RhX(CO)2] 2(μ-di-NHC) (X = Cl, Br), while reaction of the MeCCmeth and tBuCCmeth complexes with CO instead yielded the products [Rh(CO)2(η1: η1-di-NHC)]+, containing chelating dicarbenes. The X-ray structure determinations of several of the above dicarbene-bridged species have been carried out and show metal-metal separations of greater than 6.6 A in all cases. Reaction of all of the above COD complexes with dppm (Ph2PCH2PPh2) followed by CO yields the dicarbene- and dppm-bridged A-frame species [Rh2(CO) 2(μ-X)(μ-di-NHC)(dppm)]+ (X = Cl, Br), in which the larger bite of the dicarbenes, compared to that of dppm, induces strain within the complexes. Introduction of the bridging dppm and bromide groups lowers the Rh-Rh separation to about 3.3 A. Replacement of the bridging bromide by hydroxide in the MeCCeth complex yields [Rh 2(CO)2(μ-OH)(μ-MeCCeth)-(dppm) ]+, in which the bridging hydroxide can be used to deprotonate a monoimidazolium iodide to give [Rh2Br(CO)2(IMe)(μ- MeCCeth)(dppm)][I] (IMe = 1,3-dimethylimidazol-2-ylidene). In this species the bromide is on one metal while the monocarbene occupies the other, opening up the dicarbene bite to 5.18 A and the metal-metal separation to 4.07 A. Attempts to better match the larger bite of the dicarbenes by substituting dppm with dppe (Ph2PCH2CH 2PPh2) did not give a dppe-bridged product and, instead, yielded [(Rh(CO)(dppe))2(μ-MeCCeth)][CF 3SO3]2 in which the dppe groups are chelating.
Thermodynamic studies of [H2Rh(diphosphine)2] + and [HRh(diphosphine)2(CH3CN)]2+ complexes in acetonitrile
Wilson, Aaron D.,Miller, Alexander J. M.,Dubois, Daniel L.,Labinger, Jay A.,Bercaw, John E.
, p. 3918 - 3926 (2010/06/19)
Thermodynamic studies of a series of [H2Rh(PP)2] + and [HRh(PP)2(CH3CN)]2+ complexes have been carried out in acetonitrile. Seven different diphosphine (PP) ligands were selected to allow v
