Stabilization of the tautomers HP(OH)_2 and P(OH)_3 of hypophosphorous and phosphorous acids as ligands

摘要

Treatment of [CpRu(PPh_3)_2Cl] 1 with the stoichiometric amount of H_3PO_2 or H_3PO_3 in the presence of chloride scavengers (AgCF_3SO_3 or T1PF_6) yields compounds of formula [CpRu(PPh_3)_2(HP(OH)_2)]Y (Y = CF_3SO_3 2a or PF_6 2b) and [CpRu(PPh_3)_2(P(OH)_3)]Y (Y = CF_3SO_3 3a or PF_6 3b) which contain,respectively,the HP(OH)_2 and P(OH)_3 tautomers of hypophosphorous and phosphorous acids bound to ruthenium through the phosphorus atom.The triflate derivatives 2a and 3a react further with hypophosphorous or phosphorous acids to yield,respectively,the complexes [CpRu(PPh_3)(HP(OH)_2)_2]-CF_3SO_3 4 and [CpRu(PPh_3)(P(OH)_3)_2]CF_3S0_3 5 which are formed by substitution of one molecule of the acid for a coordinated triphenylphosphine molecule.The compounds 2 and 3 are quite stable in the solid state and in solutions of common organic solvents,but the hexafluorophosphate derivatives undergo easy transformations in CH_2C1_2:the hypophosphorous acid complex 2b yields the compound [CpRu(PPh_3)_2(HP(OH)_2)]PF_2O_2 6,whose difluorophosphate anion originates from hydrolysis of PF_6~-;the phosphorous acid complex 3b yields the compound [CpRu(PPh_3)_2(PF(OH)_2)]PF_2O_2 7,which is produced by hydrolysis of hexafluorophosphate and substitution of a fluorine for an OH group of the coordinated acid molecule.All the compounds have been characterized by elemental analyses and NMR measurements.The crystal structures of 2a,3a and 7 have been determined by X-ray diffraction methods.