78362-94-4Relevant academic research and scientific papers
A convenient general route to a series of diphosphine-bridged heterobinuclear complexes that contain rhodium and structures of the mixed-valent complexes [RhM(CO)4(Ph2PCH2PPh2)2] (M = Mn, Re)
Antonelli, David M.,Cowie, Martin
, p. 1818 - 1826 (2008/10/08)
A convenient route to a series of dppm-bridged complexes has been developed in which the chloride anion in [RhCl(dppm)2] is displaced by a metal carbonylate anion. This metathesis reaction is accompanied by unwinding of one or both of the chelating dppm groups to adopt a bridging arrangement and by loss of one carbonyl group. In the compounds [RhCo(CO)3(dppm)2], [RhMH(CO)3(dppm)2] (M = Fe, Ru, Os), [RhM(CO)4(dppm)2] (M = Mn, Re), and [RhMH(CO)4(dppm)2] (M = Cr, W), both diphosphines adopt a bridging arrangement, whereas in [RhFeCp(CO)(dppm)2] and [RhMoCp(CO)2(dppm)2] only one dppm group bridges the metals while one remains chelating on rhodium. The structures of [RhM(CO)4(dppm)2] (M = Mn (5), Re (6)) have been determined by X-ray methods. The coordination geometries at Mn and Re are not octahedral, but instead (ignoring the Rh atoms), the [M(CO)3L2] (L = one end of dppm unit) moieties have trigonal-bipyramidal geometries, suggesting that a M(-I) formulation is appropriate. This [M(CO)3L2]- fragment then functions as a pseudohalide, forming a dative M→Rh bond and giving the Rh center a square-planar arrangement consistent with a Rh(+I) formulation. The resulting M-Rh bond lengths are 2.8428 (8) ? (M = Mn) and 2.7919 (6) ? (M = Re). Compound 5 crystallizes in the triclinic space group P1 with a = 10.897 (2) ?, b = 11.046 (2) ?, c = 11.700 (2) ?, α = 68.14 (1)°, β = 67.48 (1)°, γ = 87.69 (1)°, V = 1198.7 (4) ?3, and Z = 1 and was refined to R = 0.054 and Rw = 0.082. Compound 6 crystallizes together with one THF molecule in the monoclinic space group P21/c with a = 12.963 (4) ?, b = 19.883 (3) ?, c = 11.277 (2) ?, β = 99.12 (2)°, V = 2870 (2) ?3, and Z = 2 and was refined to R = 0.053 and Rw = 0.088. Both compounds occupy a crystallographic inversion center so the metal carbonyl fragments are disordered, although this disorder, in reality, is readily handled crystallographically, with only two carbonyl carbons having two sets of half-occupancy positions and each metal position being composed of one half-occupancy rhodium atom and one half-occupancy manganese or rhenium atom.
Comparitive Reactivities of Two Isoelectronic Transition-Metal Hydrides with Transition-Metal Carbonyls and Alkyls
Jones, William D.,Huggins, John M.,Bergman, Robert G.
, p. 4415 - 4423 (2007/10/02)
The two isoelectronic hydrides PPN+CpV(CO)3H- (1) and -CpMo(CO)3H (2) react with a variety of metal carbonyls and alkyls.Treatment of Fe(CO)5, Cr(CO)6, (CH3C5H4)V(CO)4, CH3Re(CO)5, and (CH3CO)Re(CO)5 with 1 produces HFe(CO)4-, HCr(CO)5-, (CH3C5H4)V(CO)3H-,(H)(CH3)Re(CO)4-, and (H)(CH3CO)Re(CO)4-, respectively, and CpV(CO)4 (3). 1 also catalyzes ligand substitution reactions in 3 and CpFe(CO)(PPh3)(COCH3).In comparison 2 reacts only with CH3Mn(CO)5 and CpMo(CO)3R (R=CH3, C2H5, CH2C6H5) producing aldehydes and the dimers 2 (4a) and 2 (5a).Reaction of 2 with ethylene produces ethane and diethyl ketone. 1 is proposed to react by an electron-transfer mechanism, whereas 2 is proposed to react by hydrogen transfer to a vacant coordination site.The relationship of the molybdenum hydride/alkyl reaction to the final step in hydroformylation (oxo process) is discussed.
