Charge Density Analysis of the (C−C)→Ti Agostic Interactions in a Titanacyclobutane Complex

The experimental electron density study of Ti(C5H4Me)2[(CH2)2CMe2] provides direct evidence for the presence of (C−C)→Ti agostic interactions. In accord with the model of Scherer and McGrady, the Cα−Cβ bond densities no longer show cylindrical symmetry in the vicinity of the Ti atom and differ markedly from those of the other C−C bonds. At the points along the Cα−Cβ bond where the deviation is maximal the electron density is elongated toward the metal center. The distortion is supported by parallel theoretical calculations. A calculation on an Mo complex in which the agostic interaction is absent supports the Scherer and McGrady criterion for agostic interactions. Despite the formal d0 electron configuration for this Ti(IV) species, a significant nonzero population is observed for the d orbitals, the d orbital population is largest for the dxy orbital, the lobes of which point toward the two Cα atoms. Of the three different basis sets for the Ti atom used in theoretical calculations with the B3LYP functio...