Syntheses and structures of diruthenium triple-decker complexes with bridging 1,2,4-triphospholyl and 1-arsa-3,4-diphospholyl anions

Article abstract of DOI:10.1021/om00009a048

Yellow-brown oils, characterized spectroscopically as [Cp*Ru(η⁵-C₂-t-Bu₂P₃)], 11, and [Cp*Ru(η⁵-C₂-t-Bu₂AsP₂)], 12, were isolated from the reaction of [Cp*Ru(CH₃CN)₃][PF₆], 6, with [Li(C₂-t-Bu₂P₃)], 2, or [Li(C₂-t-Bu₂AsP₂)], 4, respectively. Both 11 and 12 reacted further with 6 to give the triple-decker complexes [Cp*Ru(μ-η⁵:η⁵-C₂-t-Bu ₂P₃)RuCp*][PF₆], 7, and [Cp*Ru(μ-η⁵:η⁵-C₂-t-Bu ₂AsP₃)RuCp*][PF₆], 8, in which the triphospholyl or arsadiphospholyl anions bridge two ruthenium centers. Both 7 and 8 have been characterized by single-crystal X-ray crystal structure determinations. Crystal data for C₃₀H₄₈F₆P₄Ru₂, 7: M = 848.7, P2₁2₁2₁, a = 12.642(9) A?, b = 15.151(10 A?, c = 18.176(10) A?, V = 3481.4 A?³, D_calcd = 1.62 g cm^-3 (Z = 4) μ = 10.8 cm^-1 for Mo Kα radiation (λ = 0.7107 A?), final R = 0.055, R_w = 0.057, from 2716 observed reflections (3437 measured). Data for C₃₀H₄₈AsF₆P₃Ru₂, 8: M = 892.7, P2₁2₁2₁, a = 12.650(9) A?, b = 15.147(8) A?, c = 18.111(10) A?, V = 3470.1 A?³, D_calcd = 1.71 g cm^-3 (Z = 4) μ = 19.9 cm^-1 for Mo Kα radiation (λ = 0.7107 A?), final R = 0.049, R_w = 0.053, from 2760 observed reflections (3430 measured). Attempts to prepare mixed-metal triple-decker complexes by reacting [Fe(η⁵-C₅R₅)(η⁵-C ₂-t-Bu₂P₃)] (R = H, 14a; R = Me, 14b] or [Fe(η⁵-C₅R₅)(η⁴5-C ₂-t-Bu₂AsP₂)] (R = H, 15a; R = Me, 15b) with 6 were unsuccessful. Likewise when either 14a or 15a is treated with 6 the intermediate complexes [Fe(η⁵-C₅H₅)(η⁵-C ₂-t-Bu₂P₃)RuCp*(CH₃CN) ₂][PF₆], 17, or [Fe(η⁵-C₅H₅)(η⁵-C ₂-t-Bu₂AsP₂)RuCp*(CH₃-CN) ₂][PF₆], 18, were isolated and spectroscopically characterized. When these were heated in nitromethane, a ring transfer occurred and the triple-decker species 7 or 8 was observed. Similar reactions involving 14b or 15b led directly to 7 or 8 without detection of any intermediate complexes.