Tripodal phosphines

The complex 17a underwent a reversible one-electron oxidation, which was assumed by the authors to be ligand-centered, producing Co(ll) species ([L3Co(7 -H2)SnPh3] (L3 = the phosphine tripod ligand). Unfortunately, this species has not been isolated (Figure 7). 

Reactions involving transition metal ions and tripodal phosphines and arsines. F. Mani and L. Sac-coni, Comments Inorg. Chem., 1983, 2, 157-186 (73). 

Besides such intermolecular stabilized compounds, intramolecular stabilized compounds have also been reported. Rettig et al. described the synthesis of phosphine-stabilized Al—N monomers by using a tripodal ligand [101]. More recently, Raston et al. reported on the synthesis of compounds of the type [H2A1E(H)R]2, containing only weak Al—H bridges [102]. 

Casares, J.A., Espinet, P., Hernando, R., Iturbe, G., Villafane, F., Ellis, D.D. and Orpen, A.G. (1997) Poly(2-pyridyl) phosphines, PPynPh3 (n = 2, 3), and Their P-Substituted Derivatives as Tripodal Ligands in Molybdenum(O) Carbonyl Complexes. Inorganic Chemistry, 36(1), 44-49. 

A related procedure to that discussed for the tris-dmgH system has been employed to cap one end of Fe(n), Co(n), Ni(n) and Zn(n) complexes of the tripod ligand, tris(2-aldoxime-6-pyridyl)phosphine... 

Examination of the backbones of the neopentane-based, carbon-anchored TIME and bulky TIME tripodal ligands reveals possible reasons for the lack of 1 1 complex formation with metal centers. A hypothetical complex of TIME would contain three eight-membered rings (Fig. 9, I) with much lower stability than the more commonly observed five, six, or seven-membered rings formed, for instance, by poly(p5irazolyl)borate or poly(phosphine) ligands. In order... 

The structures of the bis-ligand iron(II) complexes of the tripodal ligands tiis(pyiidin-2-yl)methane and tris(pyridin-2-yl)phosphine oxide have been determined." " The tetradentate tripodal ligand... 

Most of the nickel(l) complexes are four-coordinate, either tetrahedral (phosphine and arsine complexes) or square planar (macrocyclic and dithiolene complexes), but five-coordinate complexes are also easily formed in the presence of tetradentate tripodal ligands. 

Selected nickel(I) complexes with phosphines and arsines, together with relevant properties and synthetic routes, are reported in Table 21. In general, these nickel(I) complexes are air-unstable, especially when dissolved in solution consequently their preparation and handling require the exclusion of oxygen and, often, of moisture. The synthetic routes which afford nickel(I) complexes are strictly dependent on the nature of the phosphines and arsines and are not of general application, except in the case of some tripodal ligands. Most of the nickel(I)... 

The greater stability of these organometallic complexes, as compared with that of analogous complexes with monodentate phosphines, is attributed to the steric effects of the tripodal ligands which surround the metal atom with their phenyl groups on the basal donor atoms, thus imparting a degree of kinetic inertness to the compounds. 

Structural and Magnetic Investigation on Transition Metal Complexes with Tripodal Polytertiary Phosphines... 

Tripodal tritertiary phosphines as 1,1,1-tris(diphenyl--phosphinomethy1)ethane, triphos, and tris(2-diphenylphosphino--ethyl)amine, np3 are capable a) to act as tridentate or tetradentate ligands b) to promote several reactions with formation of several types of metal complexes which are presented. 

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