UBC Theses and Dissertations
Group 4 diene complexes stabilized by phosphine donors Haddad, Timothy S.
The synthesis of eight fluxional, diamagnetic group 4 complexes MR'(C₄H₆)[N(SiMe₂CH₂PR₂)₂] (M = Hf, Zr; R' = Ph, CH₂CMe₃; R = Me) and (M = Hf, Zr, R' = Cl; R = Me, CHMe₂ has been achieved. The X-ray crystallographic results of two of these complexes (M = Hf, Zr; R' = Ph; R = Me) indicate that the bonding of the diene unit has a significantly higher degree of ƞ⁴-π character than is present in Cp₂M(diene) (M = Hf, Zr) complexes, and therefore the M(II) resonance structure has more contribution to the overall bonding scheme. Consistent with all the NMR data available is that these complexes maintain a meridional coordination of the tridentate amide-phosphine ligand both in solution and in the solid state. The observed fluxional process is best described as diene rotation. Two of the diene complexes (M = Hf; R' = Cl; R = Me, CHMe₂ were found to react with allylmagnesium chloride and subsequently undergo a unique C-C bond forming reaction and rearrangement to generate two new non-fluxional diene complexes Hf [(ƞ⁴-CH₂CHCHCH)CH₂CH₂CH₂][N(SiMe₂CH₂PR₂)₂] (R = Me or CHMe₂). The latter of these two complexes has been crystallographically characterized.
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