The silver(I) coordination polymer [AgO2PPh2]n and unsupported Ag⋯Ag interactions derived from aminophosphinate and phosphinic acid

Abstract

The ligand N-tert-butyl-1,1-diphenylphosphinamine, Ph2P-N(H)CMe3, was prepared from tert-butylamine and diphenylchlorophosphine. The phosphine portion of the ligand became partially oxidized in air to form Ph2P(O)N(H)CMe3, L1, whilst further oxidation led to diphenylphosphinic acid, Ph2P(O)OH. X-ray analysis revealed that ligand L1 was isolated in the solid-state in a dimeric polymorphic form, different from the previously reported trimeric form. Ligand L1 was subsequently treated with solid AgSO3CF3 in THF which formed a rare silver(I) dinuclear complex of the type [Ag(CF3SO3){OPPh2N(H)CMe3}2{Ag(OPPh2N(H)CMe3)2}]SO3CF3, 1, and consists of ligand unsupported Ag⋯Ag interactions of 2.89Å coordinating through two O donor atoms from the two separate silver units (A and B) and with no coordination through the N atom. Further, silver unit A contains a 3-coordinate Ag(I) center, bent significantly from a linear geometry due to interaction from the triflate O donor atom, whilst unit B remained essentially 2-coordinate and linear. The diphenylphosphinate reacted with solid AgSO3CF3 in THF at room temperature and this led to an unusual Ag(I) coordination polymer, [Ag2{(μ-O)OPPh2}{O2PPh2}]n2, consisting of two different bonding modes of O-donor atoms in a 4-coordinate arrangement around the Ag(I) center. Compounds L1, 1 and 2 were all obtained in moderate to good yields, and analyzed by single crystal X-ray studies, solution 1H and 31P NMR, IR, and elemental analyses.