Reactions of pentaphenylphosphorus with 2,6-dihydroxy­benzoic and succinic acid

Tetraphenylphosphonium carboxylates as solvates of [Ph4P]+[OC(O)C6H3(OH)2-2,6]-×PhH (1) and [Ph4P]2+[O2CCH2CH2CO2]2-×TolH (2) types were synthesized by the reactions of pentaphenylphosphorus with 2,6-dihydroxybenzoic and succinic acids at the mole ratio of 2:1 and 1:1, respectively. The reactions were accomplished by heating the benzene or toluene solutions of the mixture of compounds inside an evacuated glass ampoule at 60 °С for 0.5 hour. The structure of compounds was characterized by IR spectroscopy and single-crystal X-ray diffraction study. According to X-ray diffraction data, the crystals of tetraphenylphosphonium carboxylates 1 and 2 consist of the [Ph4P]+ tetrahedral cations (the СРС angles are 106.4(3)-113.5(3)° (1), 107.8(2)-111.5(2)° (2), and the P-C bond lengths are 1.771(6)-1.809(6) Å (1), 1.791(4)-1.804(4) Å (2)), single charged (1) or double charged (2) carboxylate anions and solvate arene molecules. Two types of crystallographically independent cations and anions ( a, b ) exist in crystals 1. Anions of the compound 2 are centrosymmetric. In the carboxylate anions the C-O bonds are aligned (1.263(9), 1.273(9) Å 1 а, 1.24(1), 1.257(9) Å 1 b, 1.254(6), 1.272(5) Å 2), and the OCO angles at the carboxyl carbon atom are close to the theoretical value of 120°. The anions 1 are characterized by the presence of intermolecular short contacts О-Н∙∙∙О-С between oxygen atoms of the carboxyl group and o -hydroxyl groups; the Н∙∙∙О and О∙∙∙О distances are 1.73-2.03 Å and 2.450(8)-2.484(8) Å, respectively. Structural organization in the crystals is caused by weak hydrogen bonds of the С-Н···О type between the carboxylate groups and oxygen atoms of the hydroxyl groups (in crystal 1). Short contacts between the carboxylate oxygen atoms and a hydrogen atom of the methyl group of the solvated toluene molecule are observed in complex 2.