Mo and Pt Complexes of an Azine Phosphine with a Ferrocene Moiety

Condensation of the phosphino hydrazone Z-PPh₂CH₂C(Bu^t)=NNH₂ II with ferrocene carboxaldehyde, CpFe(C₅H₄CHO) produced the azine monophosphine Z,E-PPh₂CH₂C(Bu^t)=N-N=CH(C₅H₄)FeCp (Z,E-LH). The reaction of Z,E-LH with the labile [Mo(CO)4(nbd)] (nbd = norbornadiene) at room temperature afforded the orange tetracarbonyl Mo(0) complex [Mo(CO)₄(Z,E-LH)] (3), Z,E-LH is a bidentate ligand. When (3) was heated in boiling toluene, isomerization around the -N=CH(C₅H₄)FeCp double bond occurred, and the resulting red complex [Mo(CO)₄(Z,Z-LH)] (4) was isolated in 78% yield. Treatment of [PtMe2(cod)] (cod = cycloocta-1,5-diene) with the ligand Z,E-LH at 20°C formed the dimethylplatinum(II) complex [PtMe₂(Z,E-LH)] (5) in which the H2-proton attached to the cyclopentadienyl group showed agostic interaction with the platinum(II) centre. When the complex (5) was heated in boiling toluene, the C-H(agostic) bond underwent an oxidative activation reaction followed by a loss of methane molecule to give the cyclometallated platinum(ll) complex [PtMe(Z,E-L)] (6), with the tridentate P^N^C ligand. The compounds were adequately characterized using IR, NMR, mass spectrometry, and elemental analysis.