The chemistry of sterically crowded aryloxide ligands-VII. Synthesis, structure and spectroscopic properties of some group 4 and group 5 metal derivatives of 2,6-diphenylphenoxide

A series of early transition metal organometallic derivatives containing the ancillary ligand 2,6-diphenylphenoxide (OAr-2,6Ph2) have been synthesized. Compounds of stoichiometry Ti(OAr-2,6Ph2)2(R)2 (R = CH3, CH2SiMe3, CH2Ph and Ph) and Ti(OAr-2,6Ph)3(R) (R = CH3, CH2SiMe3) are obtained by treating the corresponding homoleptic alkyl, TiR4, with the required amount of phenol, HOAr-2,6Ph2. For the Group 5 metals Nb and Ta, the methyl derivatives M(OAr-2,6Ph2)2(CH3)3 and M(OAr-2,6Ph2)3(CH3)2 are obtained via methylation of the corresponding chloro-aryloxides. Besides routine spectroscopic characterization the diphenyl Ti(OAr-2,6Ph2)2(Ph)2 and mono-alkyl Ti(OAr-2,6Ph2)3(CH2SiMe3) have been structurally characterized by X-ray diffraction techniques. Both molecules contain a pseudo-tetrahedral environment about the titanium atom with short 1.794(3)-1.806(2) Å, TiO distances and large, 153-179°, TiOAr angles. The TiC distances appear normal for these types of compounds.