Structural characterization of heterodimetallic Zr/Pd and Zr/Rh catalyst precursors containing the C5H4PPh2 ligand

(Cp-PPh2)(2)ZrCl2 (5) reacts with (PhCN)(2)PdCl2 to yield the early-late heterodimetallic complex [(Cp-PPh2)(2)ZrCl2/PdCl2], 7, which was characterized by an X-ray crystal structure analysis. The phosphine-substituted bent metallocene moiety in 7 serves as a conformationally flexible chelate phosphine ligand (angle P-Pd-P: 96.46(3)degrees). Complex 7 is an active catalyst for the cross-coupling of sec-butylmagnesium bromide with bromobenzene, leading to excellent regioselectivity and moderate reactivity. Complex 5 reacts with dicarbonyl-rhodium chloride dimer (0.5 equiv) to yield the triply bridged complex 12, [ClZr(mu-Cp-PPh2)(2)-(mu-Cl)Rh(CO)Cl], which was also characterized by X-ray diffraction (the angle P-Rh-P is 158 degrees at the distorted square-pyramidal pentacoordinated rhodium center). (Cp-PPh2)(2)Zr-(CH3)(2) (13) reacts with [H(CO)Rh(PPh3)(3)] (14) with loss of two PPh3 ligands and instantaneous liberation of methane to form complex 15, [CH3Zr(mu-Cp-PPh2)(2)Rh(CO)PPh3](Zr-Rh), which probably contains a metal-metal bond between the early and late transition metal. Complex 15 is a very active l-hexene hydroformylation catalyst (TOF > 600, n/iso approximate to 3 at 80 degrees C).