Metal trifluorophosphines

In some cases H2 can interact directly with binary metal-trifluorophosphine complexes under mild conditions with or without addition of PF3 or UV irradiation (method B), and group IV hydrides have also been utilized (method C). 

Ionization Potentials (eV) of Transition Metal Trifluorophosphine and Hydridotrifluorophosphine Complexes. Data for... 

Dinuclear Transition Metal Trifluorophosphine Complexes Containing PF2-Bridging Ligands... 

Several other tetranuclear complexes containing different metals have been obtained from the reaction between metal carbonyl and metal trifluorophosphine complexes (method E) or by intermolecular ligand-exchange reactions (method F) between tetranuclear complexes. The following structures have been proposed on the basis of 19F NMR and mass spectroscopic studies. 

The first reported arene-transition metal trifluorophosphine complex [Cr(i/6-C6H6)(PF3)3] was obtained by UV irradiation of [Cr(i/6-C6H6)(C0)3] with PF3 (method A), whereas the corresponding thermal reaction afforded instead the mixed carbonyl trifluorophos-... 

A rather unusual synthetic route to an 6-arene-metal-trifluorophosphine complex has been described in which displacement... 

Other routes involve treatment of a metal-trifluorophosphine halide with either sodium or lithium cyclopentadienide (method D), or direct reaction between a metal-PF3 complex and cyclopentadiene (method E). 

Relatively few examples of metal trifluorophosphine complexes of formula [MRx(PF3)y are known (see Table XVI). 

Since fluorophosphines form part of a general review of phosphorus fluorides (282), and there is an excellent account of transition metal-trifluorophosphine complexes (152), the present article is not intended to be comprehensive, but rather to highlight some of the more recent developments in this expanding area of inorganic chemistry. 

A general method of preparation of the zero valent metal trifluorophosphines is by ligand replacement. Under high PF3 pressure, for example, the chromium or molybdenum compound can be prepared from the dibenzene derivatives (8.175). Carbon dioxide is also displaced under high pressure (8.176), although the reaction is reversible. Under some conditions, partial replacement can be effected to produce complexes of type M(CO) j (PFslx-... 

Trifluorophosphine complexes of transition metals. J. F. Nixon, Adv. Inorg, Chem. Radiochem., 1985,29,1 (368). 

Platinum produced by the decomposition of platinum hexafluoro-2,4-pentadionate, Pt(CF3COCHCOCp3)2 by an argon laser has been reported.The metal can also be obtained from the decomposition oftetrakis-trifluorophosphine, Pt(Pp3)4 at200-300°C in an atmosphere of hydrogen,... 

Direct condensation of metal vapors with trifluorophosphine at -196°C provides a convenient alternative to the high-pressure route to metal-PF3 complexes. The reactions of Mo, Cr, Co, Ni, and Pd vapors with PF3 yield only one volatile product in each case, namely Mo(PF3)6 (132), Cr(PF3)6, Co2(PF3)g, Ni(PF3)4, and Pd(PF3)4 (128), respectively. The yields are good, 40-100% depending on the metal vapor used. Some defluorination of the PF3 accompanies the formation of Cr(PF3)6. No complex could be isolated from the manganese vapor-PF3 reaction, although some defluorination seems to have occurred. The reaction of iron and PF3 is complex,... 

Trifluorophosphine is a very convenient ligand in metal atom chemistry to use along with other ligands, e.g., in the stabilization of metal arene complexes (Section III,B). Reaction of a mixture of PF3 and PH3 with nickel vapor yields Ni(PF3)3PH3 and Ni(PF3)2(PH3)2 but no Ni(PH3)4. Attempts to make Ni(PH3)4 lead to hydrogen evolution from the ligand during or after condensation with the nickel vapor (128). 

Phosphorus trifluoride is a ligand that is used extensively in coordination chemistry. It substitutes readily into various metal carbonyl complexes using either thermal or photochemical techniques. As a ligand, it is unique in its similarity to carbon monoxide in lower-valent organometallic compounds. In its role as a model for CO, a number of studies are possible that cannot be done on the carbonyls themselves.1 The name normally used for PF3 in complexes is trifluorophosphine. 

There are many similarities in the behavior of PF3 and CO as ligands. This is manifested by the existence of a large number of PF3 complexes of the transition metals (197, 226). Several UPS studies of such complexes have now appeared in the literature (20, 152, 169, 182, 221, 227). As pointed out in Section II, it is difficult to arrive at a completely unequivocal set of assignments for these compounds other than for the predominantly metal MOs. It is seen below, however, that one of the advantages of studying the UPS of the PF3 complexes is that many more ionizations pertinent to bonding discussions are discernible. Furthermore, trifluorophosphine complexes tend to be more thermally stable than their carbonyl counterparts. 

Structural and/or spectroscopic investigations have shown that the local symmetries around the metal atoms in the M(PF3)4 (189,215), M(PF3)5(2), and M(PF3)6 compounds are Td, D3h, and Oh, respectively. Unfortunately theoretical studies on trifluorophosphine complexes are confined to CNDO/2 calculations on Ni(PF3)4, Fe(PF3)5, and Cr(PF3)6 (251). In view of the discussion of relaxation effects and basis set dependences presented in Section II the CNDO/2 results (Table XXVI) should be used only as a qualitative guide to spectral assignment. 

The pentacoordinate trifluorophosphine complexes behave similarly. Thus the difference in energy between the 2E and 2E" states, Ae e"> increases markedly in going from Fe(PF3)s to Ru(PF3)s. This increase is caused by the change in energy of the 2E state, which, in turn, results from changing from a 3d to a 4d metal orbital. 

Trifluorophosphine Complexes of Transition Metals John F. Nixon... 

Transition metal carbonyl chemistry originated with the discovery of [Ni(C0)4] in 1890. Although the first trifluorophosphine coordination complex was prepared the following year by Moissan (263) by treating... 

Dinuclear complexes have been made by photolysis of the related hydrido complex (vide infra) (method K) or by interaction of halogeno PF3-metal derivatives with the trifluorophosphine metallate salt (method L). 

An interesting feature of hydrido transition metal-PF3 complexes is that apart from a few dinuclear systems (Section VI) only mononuclear systems are so far known and there is as yet no corresponding chemistry analogous to that of polynuclear carbonyl hydrido compounds. The trifluorophosphine metal hydrido compounds are usually highly acidic and can readily form metallate ions such as [M(PF3)m]x and [MH(PF3) r. 

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