Four Different Coordination Modes of 1,1′-Bis(diphenylphosphino)ferrocene: Synthesis, X-Ray Crystal Structure, and Iron-57 Mössbauer Spectroscopy of Four Metal Carbonyl Complexes with 1,1′-Bis(diphenylphosphino)ferrocene (dppfe)

Four kinds of methal carbonyl complexes with 1,1′-bis(diphenylphosphino)ferrocene (dppfe) are synthesized and their molecular structures are determined by single-crystal X-ray analyses. Crystal data for (η5-CH3C5H4)Mn(CO)2dppfe (1), (η5-CH3C5H4)Mn(CO)dppfe (2), [ClMn(CO)4]2(μ-dppfe) (3), and CH3CCo3(CO)7dppfe (4) are as follows: 1, Pbca, a = 20.551(3), b = 28.951(5), c = 11.786(1) Å, V = 7012(2) Å3, Z = 8; 2, P21/n, a = 18.682(5), b = 20.495(4), c = 9.750(2) Å, β = 91.24(2)°, V = 3732(1) Å3, Z = 4; 3, A2/a(C2/c), a = 18.978(5), b = 15.293(4), c = 16.513(5) Å, β = 112.62(2)°, V = 4423.9(2) Å3, Z = 4; 4, , a = 13.031(2), b = 15.338(2), c = 11.583(2) Å, α = 99.13(2)°, β = 98.35(2)°, γ = 99.64(2)°, V = 2218.1(7) Å3, Z = 2; Mo Kα radiation; R = 0.075, 0.084, 0.074, and 0.056 for 2639, 4219, 2575, and 6098 reflections, respectively. Dppfe functions as a monodentate ligand in 1 with the rotational angle 128.0° for two cyclopentadienyl rings, as a bidentate chelating ligand in 2 with the rotational angles 3.1°, as a bidentate bridging ligand (no metal–metal bond) in 3 with the rotational angle 180°, and as a bridging ligand (over metal-metal bond) in 4 with the rotational angle 69.6°, respectively; Mn–P = 2.242(4) Å (1), Mn–P = 2.215(2) and 2.216(3) Å (2), Mn–P = 2.364(4) Å (3), and Co–P = 2.297(2) and 2.314(2) Å (4). The two cyclopentadienyl rings of dppfe are slightly tilted (2.3–5.7° for tilt angles in 1, 2, and 4) and are parallel in 3. The coordinated P atoms are significantly displaced from the cyclopentadienyl ring planes. From the comparison of these geometrical parameters, it is concluded that the rotation of the two cyclopentadienyl rings is a predominant factor to determine various coordination modes of dppfe rather than the tilt of the two rings and/or the deviation of the P atoms from the ring plane. The 57Fe Mössbauer spectra of this series of compounds show doublets with parameters (IS = 0.50–0.52 mm s−1 relative to Fe, QS = 2.22–2.35 mm s−1). Although isomer shifts are essentially constant, the quadrupole splittings have a tendency to increase with the increase of the rotational angle of the two cyclopentadienyl rings. 1H and 31P NMR spectra are measured for all of these compounds.