Arsine, triphenyl metal complexes

Trialkyl and triphenyl substituted tertiary arsines and stibines are, like the phosphine analogues, suitable as ligands in transition metal complexes in several oxidation states, due to their low reduction potentials (cf Table 7 in Section III.A.l) and relatively high oxidation potentials (cf Table 14 in Section V.A). 

More limited investigations of the oxidation of triorganoarsines in the presence of transition metal complexes have been carried out but it appears that many of the same complexes which catalyze phosphine oxidation are also effective for arsines. The ruthenium complex, [Ru(NCSXN0XPPh3)2(02)], for example, has been found to be an efficient catalyst for the oxidation of triphenylarsine [79] the initial rate of oxidation being three to four times greater than the corresponding rate for triphenyl-phosphine oxidation under the same conditions. However, the rate of this oxidation was rapidly diminished by decomposition of the catalyst so that in a short time ca. 30 min) the catalyst was virtually ineffective. 

With the ligand dbp similar reactions yielded CoCl(dbp)3 and Co(dbp)4, but no Co(BH4)(dbp)3. Triphenyl-arsine and -stibine and CoCl2 were reduced to black products, probably cobalt metal. From NaBH3CN is afforded a Co(BH3CN)(Ph2-PCH2CH2PPh2) complex, but this does not subsequently yield a dinitrogen complex. 

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