Structure—activity correlation in iron nitrosyl complexes: crystal structures of [Fe(NO) 2(Cl)] 2(μ-dppe) and Fe(NO) 2(dppe)

Abstract

The nitrosyl dimer [Fe(NO) 2(Cl)] 2 in the presence of 1,2-bis(diphenylphosphino)ethane (dppe) yields complex 2, [Fe(NO) 2(Cl)] 2(μ-dppe); 2 is the first structurally characterized binuclear complex where dppe stands as the single bridge between two metallic centers without a metal—metal bond. Crystal data (at −10 °C): triclinic, space group P 1 , a = 9.047(3), b = 11.310(4), c = 8.663(3) Å, α = 92.3(1), β = 116.1(1), γ = 74.8(1)°, Z = 2, V = 765(1) Å 3, and R w, = 0.064 for 1393 reflections with I > 3.0σ( I). When allowed to react with dppe, 2 gives Fe(NO) 2 (dppe) ( 4). Crystal data (at room temperature): monoclinic, space group P2 1 /C, a = 12.551(4), b = 15.770(5), c = 15.158(5) Å, β = 123.9(1)°, Z = 4, V = 2488 Å 3 and R w = 0.035 for 1934 reflections with I > 3.0σ( I). Comparisons between the structures of 2 and 4 indicate a greater amount of NO − character in the chloro dinitrosyl complex, consistent with its easy oxygenation into a nitrate via electrophilic attack of dioxygen on coordinated NO.