The nature of aryloxide and arylsulfide ligand bonding in dimethyltitanium complexes containing cyclopentadienyl ligation

A series of dimethyltitanium compounds [CpTi(EAr)Me2] (E = O, S) ligated by one cyclopentadienyl (Cp) and one aryloxide (OAr) or arylsulfide (SAr) have been structurally characterized in order to gain a better understanding of aryloxide and arylsulfide bonding in these systems. Experimental structures were compared to those predicted by density functional theory (DFT). Bonding in the arylsulfide systems was found to be significantly different from bonding in the aryloxide systems. The aryloxide ligands exhibited wide Ti–O–Ar angles (≥150°) with the Ar group oriented proximal to the Cp group. DFT computations revealed two conformers for the arylsulfide systems. Arylsulfides with the Ar group proximal to the Cp group had a predicted Ti–S–Ar angle of ∼120° while those with the Ar group distal to the Cp group had a measured and predicted Ti–S–Ar angle of ∼100°. Molecular and natural bond orbital (NBO) analyses were employed to explain the nature of ligand bonding in these systems.