16925-29-4Relevant articles and documents
Transformations of group 7 carbonyl complexes: Possible intermediates in a homogeneous syngas conversion scheme
Elowe, Paul R.,West, Nathan M.,Labinger, Jay A.,Bercaw, John E.
, p. 6218 - 6227 (2010/01/29)
A variety of C-H and C-C bond forming reactions of group 7 carbonyl complexes have been studied as potential steps in a homogeneously catalyzed conversion of syngas to C2+ compounds. The metal formyl complexes M(CO)3(PPh3)2(CHO) (M = Mn, Re) are substantially stabilized by coordination of boranes BX3 (X = F, C6F5) in the form of novel boroxycarbene complexes M(CO)3- (PPh3)2(CHOBX3), but these boron-stabilized carbenes do not react with hydride sources to undergo further reduction to metal alkyls. The related manganese methoxycarbene cations [Mn(CO)5-x(PPh3)x(CHOMe)]+ (x = 1 or 2), obtained by methylation of the formyls, do react with hydrides to form methoxymethyl complexes, which undergo further migratory insertion under an atmosphere of CO. The resulting acyls, cis- and trans-Mn(PPh3)(CO) 4(C(O)CH2OMe), can be alkylated to form the cationic carbene complex [Mn(PPh3)(CO)4(C(OR)CH2OMe)] +, which undergoes a 1,2 hydride shift to form 1,2-dialkoxyethylene, which is displaced from the metal, releasing triflate or diethyl ether adducts of [Mn(PPh3)(CO)4]+. The acyl can also be protonated with HOTf to form a hydroxycarbene complex, which rearranges to Mn(PPh3)(CO)4(CH2COOMe) and is protonolyzed to yield methyl acetate and [Mn(PPh3)(CO)4]+; addition of L (L = PPh3, CO) to the manganese cation regenerates [Mn(PPh3)(CO)4(L)]+. Since the original formyl complex can be obtained by the reaction of [Mn(PPh3)(CO) 5]+ with [PtH(dmpe)2]+, which in turn can be generated from H2, this set of transformations amounts to a stoichiometric cycle for selectively converting H2 and CO into a C2 compound under mild conditions.
Formation of μ-silylene μ-hydrido manganese-platinum heterobimetallics via oxidative addition of (OC)5MnSiR2H to zerovalent platinum compounds and the structure of (OC)4Mn(μ-PPh2)(μ-H)PtPh(PPh3), a product of a solvolysis of a silylene bridge
Powell, John,Sawyer, Jeffery F.,Shiralian, Mahmoud
, p. 577 - 583 (2008/10/08)
The complexes (OC)5MnSiR2H (R = Me, Ph, Cl) react with Pt(C2H4)(PPh3)2 or Pt(PPh3)4 via oxidative addition of the Si-H bond across Pt to give the μ-silylene μ-hydrido complexes (OC)4Mn(μ-SiR2)(μ-H)-Pt(PPh3) 2. These complexes react with PEt3 to give (OC)4Mn(μ-SiR2)(μ-H)Pt(PEt3)2, react reversibly with CO to give (OC)4Mn(μ-SiR2)(μ-H)Pt(PPh3)(CO), and react with MeOH or H2O to give (OC)4Mn(μ-PPh2)(μ-H)PtPh(PPh3) (8) (a product of P-Ph bond cleavage). The structure of 8 has been determined by single-crystal X-ray diffraction. Complex 8 is monoclinic, space group P21/c, with a = 12.929 (2) A?, b = 26.382 (5) A?, c = 11.245 (2) A?, β = 110.52 (1)°, V = 3592 A?3, and Dcalcd = 1.63 g cm-3 for 7 = 4. The structure was refined to R = 0.0348 and wR = 0.0460 for the 4763 reflections with I > 3σ(I). The structure of 8 consists of distorted pseudo-square-planar Pt and pseudooctahedral Mn centers with trans phenyl and hydride ligands on Pt. The Mn and Pt atoms are separated by 2.864 (1) A? and bridged by μ-PPh2 and μ-H ligands. The position of the μ-H was located and refined. Associated bond lengths are Pt-H = 1.64 (8) A? and Mn-H = 1.80 (8) A?; 〈PtHMn = 113 (4)°.
A Radical-Chain Mechanism for Dinuclear C-H Bond Formation
Edidin, Robin T.,Norton, Jack R.
, p. 948 - 953 (2007/10/02)
Both the formation of (Ph3PAu)2Os(CO)4 from Ph3PAuCH3 and H2Os(CO)4 and the formation of (Ph3PAu)Mn(CO)5 from Ph3PAuCH3 and HMn(CO)5 occur by radical-chain mechanisms.The chain carriers are .Mn(CO)5 and .Os(H)(CO)4, respectively, arising from hydrogen atom abstraction from the initial hydrides.Photolysis of a small amount of the appropriate dimer (Mn2(CO)10 or H2Os2(CO)8) generates the chain carrier and thus initiates the reaction.No such reaction occurs between Ph3PAuCH3 and HRe(CO)5, even in the presence of substantial amounts of .Re(CO)5.The formation of H2Os(CO)3PPh3 from Ph3P and H2Os(CO)4 also occurs by a radical-chain mechanism with .Os(H)(CO)4 as the chain carrier, and the reactions of Ph3PAuCH3 and Ph3P with H2Os(CO)4 can be simultaneously initiated.
