Russian Chemical Bulletin, International Edition, Vol. 52, No. 11, pp. 2419—2423, November, 2003 2419 1066-5285/03/5211-2419 $25.00 © 2003 Plenum Publishing Corporation Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2289—2292, November, 2003. Transformation of white phosphorus in the coordination sphere of nickel complexes with σ-donating ligands Yu. H. Budnikova,  A. G. Kafiyatullina, A. S. Balueva, R. M. Kuznetsov, V. I. Morozov, and O. G. Sinyashin A. E. Arbuzov Institute of Organic and Physical Chemistry, Kazan Research Center of the Russian Academy of Sciences, 8 ul. Akad. Arbuzova, 420088 Kazan, Russian Federation. Fax: +7 (843 2) 75 2253. E-mail: yulia@iopc.knc.ru Oxidation of white phosphorus in the coordination sphere of the nickel(II) complex with 1,1,1-tris(diphenylphosphinomethyl)ethane and 1,1´,5,5´-bis[methylenedi(p-phe- nylene)]di(3,7-diphenyl-1,5-diaza-3,7-diphosphacyclooctane) was shown to be possible and accompanied by the transformation of P 4 into the σ-P 3 ligand. The change in the nickel state was monitored by cyclic voltammetry, 31 P NMR spectroscopy, ESR, and IR spectroscopy. Key words: white phosphorus, nickel complexes, 1,1,1-tris(diphenylphosphino- methyl)ethane, cyclic voltammetry. Coordinatively unsaturated organometallic com- pounds are intermediates in both stoichiometric and cata- lytic reactions. 1,2 At the first step of catalytic transforma- tion, substrates can act as ligands and thus form a com- plex with the central metal atom of the metallocomplex. These substrates are, in particular, olefins 3 and white phos- phorus. 4 The latter can act as a σ-donating ligand because it contains free unshared electron pairs. Spectrophotometry and NMR spectroscopy are most widely used for studying such systems. These methods cannot be employed in several cases, for example, when chromophoric or resonant nuclei are absent, the time scale of the spectroscopic method does not coincide with the time scale of the equilibrium reaction, or paramag- netic species present in the system. The broad time scale characteristic of electrochemical methods can be useful for the description of interactions associated with elec- tron transfer processes. In particular, voltammetric meth- ods can provide an information on the dynamics of the systems, which are "frozen" in the time scales of NMR or other spectroscopic methods. In addition, minor amounts of species can be determined and labile organometallic complexes can be studied more reliably using electro- chemical methods. It seems of special interest to study the possibility and mechanism of white phosphorus activation by the nickel complexes, because the latter are catalysts of some reac- tions of phosphorus functionalization, for example, arylation 5,6 and alkoxylation. 7 It is very important to know the factors determining the routes of transformation of white phosphorus into polyphosphorus cycles. The metal and its ligand environment act as a matrix on which white phosphorus is transformed and the polyphosphorus struc- tures formed are stabilized. Several stable nickel complexes with polyphosphorus cycles are known. 8—11 White phosphorus is coordinated to Ni 0 in a complex with a ligand of the NP 3 type, retain- ing its molecular structure 8 (Scheme 1). Scheme 1 The known η 1 -P 4 metal complexes in solutions are mainly characterized using 31 Р{ 1 H} NMR spectroscopy, which is a reliable method for determining the type of coordination of the Р 4 molecule. 4 In the coordination sphere of the Ni II complex with 1,1,1-tris(diphenyl- phosphinomethyl)ethane (triphos), P 4 is transformed, as a rule, into cyclo-Р 3 to form the [LNi(P 3 )NiL](BF 4 ) 2 bi- nuclear three-deck complex (L = triphos), 9,10 whose stabilization is caused by steric hindrances, namely, the presence of three bulky screening PPh 2 groups. The complex with the Р 3 ligand is fairly stable and its structure is confirmed by X-ray diffraction method, al- though other physicochemical characteristics have been insufficiently studied. 4,9,10