Phosphine substituted, complexes

Phosphine-substituted complexes have shown promise for cluster catalysis, especially in the case of chelating ligands, because of the added stability that might help avoid cluster fragmentation. Bergounhou et al. reported a detailed study of the hy-... 

For (CO) CoMR3 complexes, substitution of a carbonyl residue requires very drastic conditions and optically active phosphine-substituted complexes could not be obtained in this manner. In Section 2.2.2 we have described an alternative synthesis of L(CO)3CoGeMePh 1-Np [L = PPh3, P(OPh)3]. 

M-C bond lengths testify to efficient backbonding resulting in a bond order of between 2 and 3. This back-donation is stronger with phosphine-substituted complexes. 

Homogeneous Catalytic Oxidation with Phosphine-Substituted Complexes of Rhodium Carbonyl Clusters... 

Related phosphine-substituted complexes [Mo(CO)2(PR3)Tp] have also been described. 

The c /.s-bis(phosphine)-substituted complexes 68 were found in our laboratory to isomerize to the trans derivatives under irradiation with visible light [Eq. (57)] (97). The isomerization reaction was postulated to involve a stereochemically nonrigid pentacoordinate intermediate which is generated by photochemical carbyne-carbonyl coupling. (The evidence for the ligand coupling step as well as other photoinduced coupling reactions are discussed in Section IV,F.)... 

Phosphine-substituted complexes [CsEL CEyjn TiC (n= 1, 2) (Scheme 702 Section 4.05.6) have been synthesized by the reaction of the potassium salt K[C5H4(GH2) PPh2] with TiCl3 followed by oxidation with HC1.1100... 

This transformation could not be accomplished with bis- or tris-phosphine substituted complexes. In a special case, namely when inserting a phenyl (naphtyl)imine, an equilibrium was observed. 

The phosphine-substituted complex Ru3(CO)9(PPh3>3 was also surveyed as a shift reaction catalyst. The catalyst activities were also relatively insensitive to the H2SO4 and H2O concentrations of the system. Changes in the sulphuric acid and water concentrations over the respective ranges 0.25-1.5 and 4-12 M have small effects on the catalysis rates. However, the activity of the system was found to be... 

Triruthenium complexes bridged by l,r-bis(diphenylphosphino)ferrocene, thus formally containing Ru-P-C bonds, have been reported. " Examples are complexes Ru3(CO)i2-2 L ( =1, 2). Phosphine-substituted complexes, such as Ru3(CO)9(PTA)3 (PTA= l,3,5-triaza-7-phospha-adamantane), are soluble in water. Finally, triruthenium complexes, substituted with quinolines, react with dppm, forming clusters with Ru-C-P bonds due to the orthometallation of the dppm phenyls. " ... 

Cobalt. - Crystal structures are reported for the phosphine substituted complex [Co2(C0)g(PMe3)2] and for the alkynyliron bridged species [Co2((t-PhCsCFp) (CO)g].240 studies of the radical anion [CO2(C0)2 (PF2)2NMe>3r indicate that the unpaired electron is in an intermetallic a molecular orbital mainly composed of cobalt orbitals.241 The coupling of alkylIdene with CO in complexes [Co2 /t-CHR)(jx-L)( -dppm)(CO)4] to yield ketenes has been studied under CO or S02. ... 

Phosphine substituted complexes also undergo a facile intramolecular rearrangement at low temperatures. Two distinct carbonyl signals are seen in the NMR spectrum, which interconvert even at 0°C via a process believed to involve a capped trigonal-prismatic intermediate (1073). Related phosphine... 

---