18399-63-8Relevant academic research and scientific papers
Reversible Silylium Transfer between P-H and Si-H Donors
Belli, Roman G.,Pantazis, Dimitrios A.,McDonald, Robert,Rosenberg, Lisa
supporting information, p. 2379 - 2384 (2020/12/07)
The Mo=PR2 π* orbital in a Mo phosphenium complex acts as acceptor in a new PIII-based Lewis superacid. This Lewis acid (LA) participates in electrophilic Si-H abstraction from E3SiH to give a Mo-bound secondary phosphine ligand, Mo-PR2H. The resulting Et3Si+ ion remains associated with the Mo complex, stabilized by η1-P-H donation, yet undergoes rapid exchange with an η1-Si-H adduct of free silane in solution. The equilibrium between these two adducts presents an opportunity to assess the role of this new LA in catalytic reactions of silanes: is the LA acting as a catalyst or as an initiator? Preliminary results suggest that a cycle including the Mo-bound phosphine-silylium adduct dominates in the catalytic hydrosilylation of acetophenone, relative to a putative cycle involving the silane-silylium adduct or “free” silylium.
Synthesis, spectroscopic and structural characterisation of chromium(0), molybdenum(0) and tungsten(0) complexes involving primary and secondary phosphines
Campbell, Tom,Gibson, Alexander M.,Hart, Richard,Orchard, Simon D.,Pope, Simon J.A.,Reid, Gillian
, p. 296 - 305 (2007/10/03)
[M(CO)6] (M=Mo or W) reacts with 4.5 molar equivalents of L (L=PPh2H or PPhH2) in excess ethanolic NaBH4 to yield the fac-trisubstituted species [M(CO)3(L)3] in good yield, with no evidence
Reactions Leading to Formation and Cleavage of Metal-Metal and Metal-μ-Phosphido Bonds in Binuclear Molybdenum and Tungsten Complexes. Structural Analyses of W2(CO)8(μ-PPh2)2 and Its Two-Electron Reduction Product, 2
Shyu, Shin-Guang,Calligaris, Mario,Nardin, Giorgio,Wojcicki, Andrew
, p. 3617 - 3625 (2007/10/02)
Reduction of M2(CO)8(μ-PPh2)2 (M= Mo (1-Mo) or W (1-W)) and reactions of various binuclear molybdenumand tungsten anionic products were found generally to proceed with a remarkably facile scission or formation of M-M and M-(μ-PPh2) bonds.Thus, complexes 1 are converted by M'BR3H (M'= Li, R= Et; M'= K, R= sec-Bu) or LiAlH4 in THF to the M-M bond cleaved 2- (2) or to (3) depending on the nature and, usually the amount of the reductant.Reactions of 1 with LiR (R= Me (a), N-B (b), Ph (c)) afford the acyl anions (4a-c), of which yield the carbene complexes (5a,c) when treated with Me3OBF4.The M-M bond of 3 is readily broken by CO and n-BuLi to give - (6) and 2, respectively.Treatment of 3 with CF3COOH leads to a fragmentation of the binuclear unit with the formation of cis-M(CO)4(PPh2H)2 and M(CO)5(PPh2H).The dianions 2 are converted to the M-M bonded 3 and 4a when reacted with 1 equiv of CF3COOH and MeI (in THF or DMF), respectively.Possible mechanisms of these reactions are discussed.The structures of 1-W and its 2-electron reduction product,Li(THF)3+>22-W, were determined by single-crystal X-ray diffraction analyses.Both crystals are monoclinic of space group P21/c, with a= 9.830 (2) Angstroem, b= 19.802 (4) Angstroem, c= 16.889 (5) Angstroem, β= 103.72 deg, and Z= 4 for 1-W and a= 11.265 (5) Angstroem, b= 19.546 (3) Angstroem, c= 16.446 (5) Angstroem, β= 122.07 (3) deg, and Z= 2 for +>22-W.The structure of 1-W was solved and refined to R= 0.030 and RW= 0.33 by using 5206 independent reflections, whereas the structure of +>22-W was solved and refined to R= 0.051 and RW= 0.062 by using 3987 independent reflections.Both structures possess a planar W2P2 core.The W-W distance of 3.0256 (4) Angstroem in 1-W increases to a nonbonding value of 4.1018 (4) Angstroem in 2-W, and the W-P-W bond angles of 75.14 deg (mean) in 1-W widen to 104.20 deg in 2-W.The Li+ ion in +>22-W possesses an almost regular tetrahedral oxygen environment, being attached to three THF molecules and an equatorial CO of 2-W.
Bimetallic Systems. Part 9. The Synthesis of and Nuclear Magnetic Resonance Studies on 10-Membered Ring Complexes of Type 1(μ-Ph2PCH2CH2PPh2)2M2(CO)4> (M1, M2 = Cr, Mo, or W)
Iggo, Jonathan A.,Shaw, Bernard L.
, p. 1009 - 1014 (2007/10/02)
The Ph2PCH2CH2PPh2(dppe) bridged, bimetallic 10-membered ring complexes 1(μ-dppe)2M2(CO)4> have been synthesised by treating a complex of type cis-1(CO)4(PPh2H)2> with one of type cis-2(CO)4(PPh2(CH=CH2))2> in the presence of potassium t-butoxide as catalyst.The new precursor complexes cis- were prepared by displacement of norbornadiene (nbd) from .The fluxional processes in the 10-membered M1(μ-dppe)2M2 rings have been studied by variable-temperature 31P-(1H) n.m.r. spectroscopy and are characterised by a change from a second-order AA'XX' system at 20 deg C to an essentially first-order AMPX system at -90 deg C.The spectra have been fully interpreted and values for 2J(cis-PMP) obtained.The 31P-(1H) n.m.r. spectra of the homonuclear M(μ-dppe)2M systems change from A4 at 20 deg C to AA'BB' at -90 deg C.The low-temperature (-100 deg C) 1H and 1H-(31P) spectra were not resolved.These binuclear complexes are remarkably inert towards disproportionation to mononuclear chelate species and to attack by HCl or halogens.
Reactions of M2(CO)8(μ-PPh2)2 (M = Mo or W) with BR3H- and LIR nucleophiles. Proton-induced cleavage of M-(μ-PPh2) bonds in binuclear anionic complexes
Shyu, Shin-Guang,Wojcicki, Andrew
, p. 809 - 812 (2008/10/08)
Reactions of M2(CO)8(μ-PPh2)2 (2, M = Mo or W) with 1 equiv of M′BR3H (M′ = Li or K; R = Et or sec-Bu) in THF proceed to [(CO)4M(μ-PPh2)M(CO)4-Scheme I (Chemical Equation Presented) (PPh2H)]- (3) and with 2 equiv of M′BR3H or LiAlH4, to [M2(CO)8(μ-PPh2)2]2- (4). Treatment of 4 with 1 equiv of CF3COOH in THF affords 3, whereas treatment of 3 with 1 equiv of CF3COOH yields cis -M(CO)4(PPh2H)2 and M-(CO)5(PPh2H) as major and minor products, respectively. Reactions of 2 with LiR (R = Me, n-Bu, and Ph) proceed regiospecifically to the equatorial isomers of [M2(CO)7-(COR)(μ-PPh2)2] -, which are alkylated by Me3O+BF4- to yield M2(CO)7[C(OMe)R] (μ-PPh2)2 (R = Me).
