Chemistry of (η6-C6Me6)Ru(Cl)2(P(OMe)3) with AgOTf in different solvents, the high affinity for traces of water and structural characterization of mono-, di- and trinuclear derivatives

Abstract

An extensive study of the reactions of (η6-C6Me6)Ru(Cl)2(P(OMe)3) (1) with AgOTf in three different deuterated and non-deuterated solvents: chloroform, acetone and nitromethane is described. A series of compounds with the moiety (η6-C6Me6)Ru(P(OMe)3) is isolated and characterized, along with their crystalline structures. A simple associative step assisted by coordination of the silver cation to two molecules of 1 through the Cl-Ru-Cl bonds affords [{(η6-C6Me6)Ru(Cl)2(P(OMe)3)}2(μ-Ag)](OTf) (2), loss of AgCl from 2 gives 1 and (η6-C6Me6)RuCl(OTf)(P(OMe)3) (3), meanwhile 3 dimerizes to [(η6-C6Me6)Ru(μ-Cl)(P(OMe)3)]2(OTf)2 (4) which in presence of P(OMe)3 gives [(η6-C6Me6)RuCl(P(OMe)3)2](OTf) (11OTf). A comparative study of the influence of the counterions OTf− and BF4− was carried out with the analogue [(η6-C6Me6)RuCl(P(OMe)3)2](BF4) (11BF4), as well as the corresponding demethylation of the coordinated trimethylphosphite ligands by the classical Michaelis-Arbuzov reactions. The resulting “quasi-chelate” (η6-C6Me6)RuCl(P(O)(OMe)2)(P(OH)(OMe)2) (17) where a bridging proton in the phosphinito-phosphinous acid ligands is replaced by BF2 affords (η6-C6Me6)RuCl({P(OMe)2(O)}2BF2) (18) which contains the chelating structure [Me2POBF2OPMe2]. The chemistry in solution at room temperature of 1 with AgOTf shows non-selective reactions, as can be determined by multinuclear NMR spectroscopy (1H, 13C{1H}, 31P, 19F). The mixture of products shows a great preference to coordinate water, even when it is in traces, as observed for the formation of [(η6-C6Me6)RuCl(H2O)(P(OMe)3)](OTf) (5), [(η6-C6Me6)Ru(H2O)(OTf)(P(OMe)3)]OTf (6) and [(η6-C6Me6)Ru(H2O)2(P(OMe)3)](OTf)2 (7), being the latter 7 the “sink” product. Also, in presence of anhydrous AgOTf compound 1 can be transformed into the highly hygroscopic (η6-C6Me6)Ru(OTf)2(P(OMe)3) (8) which readily replaces triflate ligands by trace water. Structural characterization by single crystal X-ray diffraction of trinuclear compound 2, dinuclear 4 and mononuclear 7, 11X (X = OTf, BF4), 18 and nitrile derivatives [(η6-C6Me6)Ru(NCR)2(P(OMe)3)](OTf)2 (R = Et, 9; Me,10) is discussed.