Halogenophosphine complexes

The dimeric complexes (65 L = PPr3 or PBU3) are reported to undergo 

Halogenophosphine complexes. Follow a preliminary communication details have appeared of the preparation of the bridged dinuclear cations (78) and (79). Structures were assigned from i.r., B n.m.r., P n.m.r., and conduct- 

Similar bridge-splitting processes have been independently used to prepare the new cationic series trans-[PtX(CO)L2]BF4 (X = anions L = PEt3, PPhj, or PMe Ph), and cis-[PtClYLj (Y = SCN, NO3, or NOj). The geometries were suggested from their n.m.r. spectra. A detailed study was made of the effect of the trans influence of X on the reactivity of the trans-[PtX(CO)L2]BF4 complexes. 

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Tetra- and pentachloro- and tetrabromo-complexes of Tc(IV) containing different phosphines were prepared by reaction of technetium tetrahalogenide with the pertinent phosphine [356] or by refluxing TcOj with the phosphine in ethanol in the presence of hydro-halogenic acid [386]. Halogenophosphine complexes are summarized in Table 12.12. A. 

A comprehensive review of the preparation, reactions, and n.m.r. spectra of phosphorus-fluorine compounds has appeared. This year s literature has been notable for the first detailed applications of ab initio SCF-MO calculations to the problems of bonding in halogenophosphines and their derivatives. - Comparison of the results of such theoretical calculations with experimental data obtained from photoelectron spectra shows a good correlation in the case of phosphorus trichloride and phosphoryl chloride, and of phosphorus trifluoride and its borane complex. ... 

Two papers have appeared on the reactions of halogenophosphines with tervalent phosphorus compounds. In a detailed study of the reactions at 20 °C of a range of tertiary phosphines with phosphorus trichloride, dichlorophenylphosphine, and chlorodiphenylphosphine, it has been shown that, in general, 1 1 adducts are formed, provided that the tertiary phosphine is a good nucleophile. With diphenylchlorophosphine, for example, an adduct (18) is formed with dimethylphenylphosphine, but not with diphenylmethylphosphine, although the relative importance of steric and electronic factors remains to be established. The related reactions of phosphorus trichloride and of dichlorophenylphosphine are much more complex, and the initial crystalline products are not amenable to analysis. The reactions at 280 °C of a similar system have been shown to lead to halogen exchange, e.g. the conversion of (19) to (20). 

The basicity of halogenophosphines has attracted some attention this year. A careful study of the protonation of several halogenophosphines (6) has led to the characterization by 31P n.m.r. of phosphonium species, such as (7).12 These salts show 31P shifts to relatively high fields, and large Vph values e.g., (7) has 1190 Hz.12 Attempts have been made to correlate phosphine basicity with Vpb values in borane complexes,13 and, in turn, to correlate Vpb with electrostatic interactions in the phosphorus-boron bond.13 From such correlations, the authors deduce that this bond is dominated by electrostatic contributions, and not by other factors, such as -bonding. 

The bidentate halogenophosphines were dehalogenated by Fe2(CO)9 to give complexes of diphos-phiranes (Equation (13)) <90JOM(399)C4>. 

Reactions.—Electrophilic Attack by Phosphorus. This year has seen a resurgence in Friedel-Crafts and related chemistry of the halogenophosphines, with the general objective of establishing mechanisms. For example, the conversion of phosphorus trichloride into complexes of either dichlorophenylphosphine (28) or chlorodiphenylphosphine (29) has been studied in order to establish the... 

Fluorophosphines are tervalent phosphorus compounds containing phosphorus-fluorine bonds and they often show markedly different chemical behavior compared with other halogenophosphines. This article is mainly concerned with recent advances in the chemistry of derivatives of PF 3 of the type PF3 X , with particular reference to (a) synthesis of new structural types, (6) the role of fluorophosphines as ligands, particularly in transition metal complexes, and (c) nuclear magnetic resonance (NMR) studies. 

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