Fluorophosphines coordination

In a systematic survey of fluorophosphine coordination compounds the following points can be made. 

Fluorophosphates, 16 183 Fluorophosphine complexes with borane, 13 439-444 coordination, 13 41CM14 bonding, in, 13 410-414 with nontransition metal halides, 13 445-447... 

Organic derivatives of phosphorus trichloride—i.e., chlorophosphines of the types RPC12 or R2PC1—had never been fluorinated. We assumed the hitherto unknown fluorophosphines to be possibly interesting ligands in coordination chemistry. Such expectations were supported by earlier observations of Chatt (5, 6) and Wilkinson (32), who found that the parent compound phosphorus trifluoride as a ligand in certain coordination compounds with platinum or nickel behaved very much like carbon monoxide. 

Knowing all these facts, especially the difficult access to fluorophosphines and the poor donating abilities of phosphorus trifluoride (5, 6), we decided to use another approach, which readily led to a number of coordination compounds with fluorophosphine ligands—namely, the fluorination of chlorophosphines already coordinated to the transition metal, where the 3s electrons of phosphorus are blocked by the complex formation. There was no reaction between elemental nickel and phosphorus trifluoride, even under extreme conditions, whereas the exchange of carbon monoxide in nickel carbonyl upon interaction with phosphorus trifluoride proceeded very slowly and even after 100 hours interaction did not lead to a well defined product (5,6). 

In our study of the fluorination of coordinated chlorophosphine ligands (23), we started out with tetrakis(trichlorophosphine)nickel-(0), which could previously be converted into tetrakis(trifluorophosphine)nickel-(0) by displacement of the coordinated phosphorus trichloride with excess phosphorus trifluoride in a sealed tube (32). The limitations of this method, requiring the use of phosphorus trifluoride, a low boiling gas, under pressure, and involving the mechanical separation of the fluorophosphine complex from phosphorus trichloride, are obvious, and the yield was low. A straightforward method for the synthesis of this interesting compound was found in the fluorination of the coordinated phosphorus trichloride with potassium fluorosulfinate ... 

A theoretical study of the intermediates involved in the formation of phospha-propyne from pyrolysis of vinylphosphirane has led to a new route to phospha-alkynes. Thus, pyrolysis of trimethylsilyl(l-phosphiranyl)diazomethane has yielded MeaSiC = P, via an intermediate 1-phosphiranylmethylene . Regioselec-tivity in the [3 + 2] cycloaddition reaction between phosphaethyne and diazomethane has been studied by theoretical techniques , and further examples of reactions of this type described . Cycloaddition of phospha-alkynes with silylenes has also been reported. The primary phosphine 324 has been isolated from the addition of diethylphosphite to t-butylphosphaethyne. The chemistry of phospha-alkyne cyclotetramer systems has been reviewed and the first examples of platinum(II) complexes of such cage systems described. Aspects of the reactivity of coordinated phospha-alkynes have received further study, and a remarkable metal-mediated double reduction of t-butylphosphaethyne to the complexed fluorophosphine 325 described Phosphorus-carbon-aluminium cage structures have been isolated from the reactions of kinetically stable phospha-alkynes with trialkylaluminium compounds and new phosphaborane systems have been obtained from the reactions of phospha-alkynes with polyhedral boranes . Further studies of wo-phospha-alkyne coordination chemistry have appeared . The reactivity of the ion 326 has been explored. ... 

The ease of substitution of metal-fluorophosphine complexes has also been related to the a-donor and 7r-acceptor characteristics of the substituting ligand (152), since only ligands of high 7T-acceptor ability (e.g., CO, phosphites) can completely displace the coordinated fluorophos-phines, whereas tertiary amines, phosphines, arsines, and stibines usually form partially substituted products (see Section IX, 6). 

On heating with PCI3, the fluorine is replaced by chlorine and a mixed trihalide is produced. A mixed trihalide also results when a hydrogen halide is used. If dimethylamino difluorophosphine is treated with chlorine or bromine at low temperatures, a pentaphosphorane is produced, which will in turn react with sulphur dioxide to give dimethylamino fluorophosphine oxide. A 6-coordinated phosphoride anion is obtained in a reaction with KHF2 (7.107). 

Observations have been made which support coordination of the dialkyl-amino fluorophosphine ligands to the transition metal through phosphorus, rather than through nitrogen, whereas in the reaction of (CH )2NPp2 with some boron acceptor molecules coordination both through phosphorus or nitrogen was observed (1). 

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