Reactions of trifluoromethyl-phosphine and -arsine with a ruthenium carbonyl cluster: Synthesis, characterization and reactivity of cluster derivatives capped by trifluoromethyl-phosphinidene and -arsinidene moieties

Abstract

Reactions of CF3EH2 (E = P or As) with [Ru3(CO)12] under various conditions resulted in the elimination of two hydrogen atoms to afford new trifluoromethyl-phosphinidene and -arsinidene capped ruthenium carbonyl clusters: [Ru3(CO)9(μ-H)2(μ3-PCF 3)] 1, [Ru4(CO)13(μ-H)2(μ4-PCF 3)] 2, [Ru4(CO)12(μ-H)2(μ3-PCF 3)2] 3, [Ru5(CO)15(μ-H)2-(μ3-PCF 3)3] 4, [Ru5(CO)15(μ4-PCF3)] 5, [Ru4(CO)12(μ-H)2(μ3-AsCF 3)2] 6, [Ru4(CO)13(μ-H)2(μ4-AsCF 3)] 7, [Ru4(CO)13-(μ3-AsCF3) 2] 8 and [Ru5(CO)15(μ-H)2(μ3-AsCF 3)3] 9. The structures 2 and 7 contain spiked ruthenium frameworks with a phosphinidene or arsinidene group co-ordinated to all four metal atoms. The molecular structures of 4 and 9 have been shown to contain two-metal and three-metal fragments joined together by three μ3-phosphinidene (or arsinidene) units. The hydrides in 2 and 7 display similar fluxional behaviour yielding the same values of ΔG‡ (= 49 kJ mol-1). The transformation from 1 to 5, probably via intermediate 2, occurs with increase in nuclearity by the treatment of 1 with [Ru3(CO)12]. Pathways for the formation of cluster 3 from 2, 9 from [Ru4(CO)12(μ-H)2(μ3-AsCF 3)2(μ-AsCF3)] 10, and also 6 from 8 by hydrogenation are discussed.