ADDITION AND SUBSTITUTION-REACTIONS AND STRUCTURES OF HETEROBIMETALLIC PHOSPHIDO-BRIDGED FE-W COMPLEXES - ADJACENT METAL-ASSISTED SUBSTITUTION AND REACTION SITE SWITCHING VIA METAL-METAL BOND FORMATION

The metal-metal bond in CpFe(CO)(mu-PPh(2))(mu-CO)W(CO)(4) (1) was cleaved by Lewis bases L (L = PMe(3), PPh(2)H, CH3CN) to produce CpFe(CO)(2)(mu-PPh(2))W(CO)(4)L (3), in which L regioselectively and stereospecifically coordinates to W cis to the phosphido bridge. When L was PPh(3) or P(OMe)(3), both cis and trans isomers were obtained. When CpFe(CO)(2)(mu-PPh(2))W(CO)(5) (2) reacted with PMe(3), one CO ligand on Fe was replaced by PMe(3) to produce CpFe(CO)(PMe(3))(mu-PPh(2))W(CO)(5) (4). Structures of CpFe(CO)(2)(mu-PPh(2))W(CO)(4)(PMe(3)) (3b-cis), CpFe(CO)(2)(mu-PPh(2))W(CO)(4)(P(OMe)(3)) (3c-trans), and 4 were determined by single-crystal X-ray diffraction studies. Crystal data for 3b-cis: C26H15FeO6P2W, space group P2(1)/c, a = 9.832(4) Angstrom, b = 16.027(3) Angstrom, c = 18.264(4) Angstrom, beta = 103.87(2)degrees, V = 2794(1) Angstrom(3), and Z = 4. The structure was refined to R = 0.026 and R(w) = 0.031. Crystal data for 3C-trans: C26H24FeO9P2W, space group Pna2(1), a = 22.779(4) Angstrom, b = 11.669(2) Angstrom, c = 10.580(1) Angstrom, V = 2812.7(7) Angstrom(3), and Z = 4. The structure was refined to R = 0.023 and R(w) = 0.026. Crystal data for 4: C26H24FeO6P2W, space group P2(1)/n, a = 15.768(2) Angstrom, b = 10.7111(2) Angstrom, c = 17.784(2) Angstrom, beta = 114.10(1)degrees, V = 2741.8(7) Angstrom(3), and Z = 4. The structure was refined to R = 0.021 and R(w) = 0.024. UV irradiation of 3 removed one CO to form CpFe(CO)(mu-PPh(2))W(CO)(4)L (5). The structure of CpFe(CO)(mu-PPh(2))W(CO)(4)(PPh(3)) (5e-trans) was determined by a single-crystal X-ray diffraction study. Crystal data for 5e-trans: C40H30FeO5P2W, space group P2(1)/c, a = 18.6696(8) Angstrom, b = 12.6178(6) Angstrom, c = 18.195(1) Angstrom, beta = 118.220(5)degrees, V = 3777.5(3) Angstrom(3), and Z = 4. The structure was refined to R = 0.028 and R(w) = 0.030.