Structure and Reactivity of [Ru-Al] and [Ru-Sn] Heterobimetallic PPh-Based Complexes.

Treatment of [Ru(PPh)(CHPPh)H][Li(THF)] with AlMeCl and SnMeCl leads to elimination of LiCl and CH and formation of the heterobimetallic complexes [Ru(CHPPh){PPhCHAlMe(THF)}H] and [Ru(PPh)(CHPPh)(PPhCHSnMe)] , respectively. The pathways to and have been probed by variable temperature NMR studies, together with input from DFT calculations. Complete reaction of H occurs with at 60 °C and with at room temperature to yield the spectroscopically characterized trihydride complexes [Ru(PPh){PPhCHAlMe}H] and [Ru(PPh){PPhCHSnMe}H] .

[Ni(NHC) ] as a Scaffold for Structurally Characterized trans [H-Ni-PR ] and trans [R P-Ni-PR ] Complexes.

The addition of PPh H, PPhMeH, PPhH , P(para-Tol)H , PMesH and PH to the two-coordinate Ni N-heterocyclic carbene species [Ni(NHC) ] (NHC=IiPr , IMe , IEt Me ) affords a series of mononuclear, terminal phosphido nickel complexes. Structural characterisation of nine of these compounds shows that they have unusual trans [H-Ni-PR ] or novel trans [R P-Ni-PR ] geometries. The bis-phosphido complexes are more accessible when smaller NHCs (IMe >IEt Me >IiPr ) and phosphines are employed.

Impact of the Novel Z-Acceptor Ligand Bis{(-diphenylphosphino)phenyl}zinc (ZnPhos) on the Formation and Reactivity of Low-Coordinate Ru(0) Centers.

The preparation and reactivity with H of two Ru complexes of the novel ZnPhos ligand (ZnPhos = Zn(-CHPPh)) are described. Ru(ZnPhos)(CO) () and Ru(ZnPhos)(IMe) (; IMe = 1,3,4,5-tetramethylimidazol-2-ylidene) are formed directly from the reaction of Ru(PPh)(CHPPh)(ZnMe) () or Ru(PPh)HCl/LiCHTMS/ZnMe with CO and IMe, respectively. Structural and electronic structure analyses characterize both and as Ru(0) species in which Ru donates to the Z-type Zn center of the ZnPhos ligand; in , Ru adopts an octahedral coordination, while displays square-pyramidal coordination with Zn in the axial position.

Reductive Elimination at Carbon under Steric Control.

It has been previously demonstrated that stable singlet electrophilic carbenes can behave as metal surrogates in the activation of strong E-H bonds (E = H, B, N, Si, P), but it was believed that these activations only proceed through an irreversible activation barrier. Herein we show that, as is the case with transition metals, the steric environment can be used to promote reductive elimination at carbon centers.