Variable co-ordination numbers in 1:1 adducts of silver(I) tetrakis(pyrazolyl)borates with tertiary phosphines

Silver(I) derivatives containing tertiary phosphines and anionic tetrakis(pyrazol-1-yl)borates were prepared from AgO3SCF3, PR3 (R = phenyl, benzyl, cyclohexyl, 2,4,6-Me3C6H2, o-, m- or p-tolyl) or PPh2R' (R' = methyl or ethyl) and K[B(pz)(4)] or K[B(mpz)(4)] (Hpz = pyrazole, Hmpz = 3-methylpyrazole) and characterized through analytical and spectral (IR, H-1, C-13 and P-31 NMR) measurements. These compounds are stable, soluble in chlorinated solvents, and non-electrolytes in CH2Cl2 and acetone. Room-temperature single-crystal structural characterizations were made for several of them. The pyrazolyl ligand is potentially maximally tridentate, and the maximally four-co-ordinate array about the silver potentially of threefold symmetry (excepting the fourth pz moiety) where the symmetry of the phosphine permits. The variation in the silver(I) co-ordination number and environment in various combinations of various degrees of steric interaction among the above entities has been explored. The reactivity of [{AgB(pz)(4)} {P(C6H4Me-m)(3)}] and [{AgB(pz)(4)} {P(C6H4Me-o)(3)}] towards unidentate N-, S- and P-donors was also investigated.