SYNTHESIS OF A DINUCLEAR YLID COMPLEX DERIVED FROM P(OPh)3: CRYSTAL STRUCTURES OF [Cp2Fe2(CO)2(μ-CO) (μ-CHP(OPh)3)+][BF4 −] AND [Cp2Fe2(CO)2 (μ-CO)(μ-CHPPh3)+][BF4 −

Abstract

[Cp2Fe2(CO)2(μ-CO)(μ-CHP(OPh)3)+][BF− 4] crystallizes in the centrosymmetric monoclinic space group P21/n with a = 12.553(7) Å, b = 16.572(11) Å, c = 15.112(8) Å, β = 100.00(4)°, V = 3096(3) Å3 and D(calcd.) = 1.579 g/cm3 for Z = 4. The structure was refined to R(F) = 5.83% for 1972 reflections above 4σ(F). The cation contains two CpFe(CO) fragments linked via an iron—iron bond (Fe(1)—Fe(2) = 2.544(3)Å), a bridging carbonyl ligand (Fe(1)—C(4) = 1.918(1) Å, Fe(2)—C(4) = 1.946(12)Å) and a bridging CHP(OPh)3 ligand (Fe(1)—C(1) = 1.980(9)Å, Fe(2)—C(1) = 1.989(8)Å). Distances within the μ-CHP(OPh)3 moiety include a rather short carbon—phosphorus bond [C(1)—P(1) = 1.680(10)Å] and P—O bond lengths of 1.550(7)–1.579(6)Å. The crystal is stabilized by a network of F…H—C interactions involving the BF− 4 anion. [Cp2Fe2(CO)2(μ-CO)(μ-CHPPh3)+][BF− 4], which differs from the previous compound only in having a μ-CHPPh3 (rather than μ-CHP(OPh)3) ligand, crystallizes in the centrosymmetric monoclinic space group P21/c with a = 11.248(5)Å, b = 13.855(5)Å, c = 18.920(7)Å, β = 96.25(3)°, V = 2931(2)Å3 and D(calcd.) = 1.559 g/cm3 for Z = 4. This structure was refined to R(F) = 4.66% for 1985 reflections above 4σ(F). Bond lengths within the dinuclear cation here include Fe(1)-Fe(2) = 2.529(2)Å, Fe(1)—C(3) = 1.904(9) Å and Fe(2)—C(3) = 1.911(8) Å (for the bridging CO ligand) and Fe(1)—C(1P) = 1.995(6) Å and Fe(2)—C(1P) = 1.981(7) Å (for the bridging CHPPh3 ligand). Distances within the μ-CHPPh3 ligand include a longer carbon—phosphorus bond [C(1P)—P(1) = 1.768(6)Å] and P(1)—C(phenyl) = 1.797(7)–1.815(8) Å.