Phosphine trans

Three different structural isomers are conceivable for these complexes [Ru(bdmpza)(Cl)(L)(PPh3)], which are (A) ligand L (L=C(OR )R, C=CHR, CO, C=C=CR2) trans to pyrazole and phosphine trans to pyrazole, (B) ligand L trans to carboxylate and phosphine trans to pyrazole and (C) ligand L trans to pyrazole and phosphine trans to carboxylate (Fig. 22). 

Anomalies in the 3H and 31P NMR spectra of complexes mer-[MoOX2(PMe2Ph)3] (X = Cl, Br) have been interpreted as being due to second order effects caused by the small difference in chemical shifts between the two trans phosphines and the unique phosphine trans to Cl.129... 

High n/b ratios (3.7-13) are obtained in the platinum-catalyzed hydrofbrmylation reaction n/b ratios as high as 99 have been obtained utilizing a chelating phosphine, trans-1,2-diphenylphosphinocyclo-butane.10... 

Pt(Me)(MeC=CMe)(PPhMe2)2]PF6 0.036 approximately square-planar if acetylene considered unidentate, phosphines trans-configuration i... 

E21.14 (a) [PRPRjIj] + 2C1". The first Cl ion substitution will produce the reaction intermediate [Pt(PR3)3CI]". This will be attacked by the second equivalent of Cl" ion. Since phosphines are higher in the trans effect series than chloride ion, a phosphine trans to another phosphine will be substituted, giving m-[PtCl2(PRj)2]. 

Iron powder reacts with two equivalents of PPhMe2Br2 in Et20 to form a white solid, which is acutely sensitive to dioxygen. At exposure to low O2-partial pressures (< 100 ppm) it is possible to isolate an intensely purple trigonal-bipyramidal complex [FeBr3(PPhMe2)2], with the phosphines trans to each other and in the apical positions. It might have been expected that exposure of the initial white material, presumably an iron(ii) species, would have yielded a jU-oxo complex. 

N4M0P4C4JHJ2, Molybdenum, bis(dinitro-gen)bis [ 1,2-ethanediylbis(diphenyl-phosphine)]-, trans-, 28 38... 

P4H,RC2C 22H(o, Rhenium(IV), octahydrido-tetrakis(triphenylphosphine)di-, 27 16 P4M0N4H4JH52, Molybdenum, bis(dinitro-gen)bis[l,2-ethanediylbis(diphenyl-phosphine)]-, trans-, 28 38 P4N2O,2PtRh4C H(0, Rhodate(2-),... 

We excluded from consideration the complexes with PH3 ligands located cis to o-bonded carbon atoms, since this type of Pt" derivatives (5, Table 2) showed very small effect of PH3 on reaction energetics. Previous Pt" /Pt" results (4 and 10, Table 2) suggest that phosphines trans to carbons should significantly facilitate the reductive elimination process. This trend seems to be rather general and applicable to Pd" complexes as well the corresponding Pd complex 13 with phosphines trans to carbons has a low activation barrier for C-C bond formation of only 7.3 kcal/mol. 

PjClPtCigHg, Platinum(IIX chloro(cis-l,2-diphenylethenyl)bis(triethyl-phosphine)-, trans-, 26 140... 

Takeuchi has shown that the stereoselectivity of alkyne hydrosilylation can be controlled by both the ligand and the solvent (Equation 16.31). addition of the Si-H bond across the alkyne has been observed for the hydrosilylation of hexyne by triethyl-silane in ethanol solvent in the presence of a catalyst generated from the combination of [Rh(COD),] " and PPhj. In contrast, trans addition occurs for the same reaction in the same medium with a neutral rhodium catalyst lacking added phosphine. Trans addition also occurs in the presence of Wilkinson s catalyst in toluene. (Equation 16.32). As discussed in Section 16.3.5.2.4 below, trans addition likely results from the isomerization of a vinyl intermediate. -... 

Metal-catalysed Isomerizations. The formation of 7r-allylchloropalladium(ii) complexes from a series of cyclopropenes proceeds with symmetrical complexation of the metal to the 7i-bond, and not a-bond cleavage, as the rate-determining step. With substituted cyclopropenes containing a phenyl group at C-3, the it-allyl complex rearranges to indenyl complex either spontaneously or on treatment with triphenyl-phosphine. trans-Chloropalladation of bicyclo[5,l,0]oct-3-ene has been described, and the complex decomposes not to cyclo-octadiene complex, but to a cyclo-octene n-allyl system. ... 

With ligands containing phosphorus With alkyl phosphines trans-[WCU P(C2H5)3 2] 293 2.09 Farad six-coordination suggested 72B39... 

Similar behavior was observed with [cw-(IMes)RhCl(P( -tolyl)3)2], which exchanged the phosphine trans to IMes an order of magnitude more slowly than in the homoleptic complex [RhCl(P(p-tolyl)3)3], resulting in poorer hydrogenation efficiency with the NHC complex. The dissociative mechanism suggested by these observations was further corroborated by catalytic results obtained using CuCl (an effective phosphine sponge) as an additive. 

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