부산대학교 도서관

The previously described phosphino-alcohol α,α-dimethyl-2-(diphenylphosphino)benzenemethanol 2and hydridophosphorane 6(derived from the reaction of 2-lithio(diphenylphosphino)benzene with (−)-fenchone) are shown by 31P{1H} NMR saturation transfer experiments to be in equilibrium with the alternative closed chain P(V) tautomer σ5-P 2and open-chain P(III) tautomer σ3-P 6, respectively. Using standard basis sets, the density function theory (DFT)-calculated equilibrium constant for σ3-P 6⇌ σ5-P 6is shown to vary by several orders of magnitude; this was found to be largely dependent on the polarization functions on phosphorus and the mobile hydrogen, with the requirements for accurate modeling examined. The phosphino-alcohol 2and the deprotonated species from treatment with BuLi react with [RuCl(μ-Cl)(η6-p-cymene)]2to form unstable κ2(P,O)-complexes 9and 12, respectively. These complexes subsequently rearrange to form a common complex (RP*,SRu*)-10, where a phenyl substituent on phosphorus has been displaced by oxygen to generate a κP-1,3-dihydro-3,3-dimethyl-1-phenyl-2,1-benzoxaphosphole ligand coordinated to (η6-p-cymene)RuClPh. In the case of complex 9, the HCl liberated on the formation of (RP*,SRu*)-10subsequently leads to a proto-demetalation reaction to generate the corresponding dichloride complex 11and benzene. Kinetic measurements, DFT modeling, and quantum chemical topology analysis indicate that the rearrangement of complex 12takes place in a fully concerted single step, while in the case of complex 9, a two-step process occurs via a metallophosphorane intermediate 18featuring a κP-[(1,2-η)-phenyl]phosphine bonding mode. In the reaction of hydridophosphorane 6with [RuCl(μ-Cl)(η6-p-cymene)]2, hydridic behavior is observed, with the formation of known complex [RuCl(η6-p-cymene)]2(μ-Cl)(μ-H) 13, together with an alkoxyphosphonium chloride species 14. However, deprotonation of 6with BuLi followed by reaction with [RuCl(μ-Cl)(η6-p-cymene)]2follows a similar course to deprotonated 2, affording a mixture of complexes where a κP-1,3-dihydro-3,3-disubstituted-1-phenyl-2,1-benzoxaphosphole ligand is coordinated to (η6-p-cymene)RuClPh: (SP,RRu)-16and (RP,RRu)-16. Chromatographic purification, followed by reaction with HCl, converts complex (SP,RRu)-16to the stereochemically pure chiral-at-phosphorus ruthenium dichloride complex (SP)-17.