Synthesis and Coordination Behavior of Planar-Chiral Ferrocene Alkenylphosphines

A series of planar-chiral ferrocene alkenylphosphines, (Sp)-2-(diphenylphosphino)-1-vinylferrocene (2), (Sp)-2-(diphenylphosphino)-1-(prop-1-en-1-yl)ferrocene (3; as a mixture of Z and E isomers in ca. 5:1 ratio), and (E,Sp)-2-(diphenylphosphino)-1-(2-phenylethen-1-yl)ferrocene ((E)-4), was obtained by Wittig and Horner−Wadsworth−Emmons reactions from the common precursor, (Sp)-2-(diphenylphosphino)ferrocene-1-carboxaldehyde (1).
Coordination properties of these novel ferrocene donors were studied in their palladium(II) and tungsten(0)−carbonyl
complexes. The reaction between 2 and [{Pd(μ-Cl)(LNC)}2] (5, LNC = 2-{(dimethylamino)methyl-κN}phenyl-κC1)
gave the bridge-cleavage product [PdCl(LNC)(2-κP)] (6) while the reaction with [Pd(LNC)(MeCN)2]ClO4 (7) yielded
the cationic bis(chelate) [Pd(LNC)(2-η2:κP)]ClO4 (8). Chelate complexes of the type [W(CO)4(L-η2:κP)] (9 with L =
2; (Z/E)-10 with L = (Z/E)-3) were obtained by reacting [W(CO)4(cod)] (cod = η2:η2-cycloocta-1,5-diene) with the
appropriate phosphinoalkene in refluxing toluene while a similar reaction with (E)-4 yielded mixtures of [W(CO)5(4-κP)] ((E)-11) and [W(CO)4(4-η2:κP)] ((E)-12). All compounds were characterized by spectral methods (multinuclear
NMR, IR, MS, and CD), and the structures of 1, 2, 8, 9, (Z/E)-10, and (E)-11 were corroborated by X-ray diffraction
analysis. Ligands 2 and (E)-4 as well as their complexes 6, 8, 9, (E)-11, and (E)-12 were further studied by
electrochemical methods.