The correlation of dative bond length and parameter n in adducts Me3N-AlMe3-nCln (n <= 3)

Complexes of the general formula Me3N-AlMe3-nCln (Me = CH3; n = 0, 1, 2, 3) 1-4 have been synthesized and structurally characterized by X-ray crystall ography and NMR spectroscopy. The shape of the molecules is trigonal-antipr ismatic with the nitrogen and aluminium atoms being tetrahedrally surrounde d. The length of the dative bond N-Al is correlated with the parameter n du e to inductive effects of the electronegative chlorine substituents, result ing in a difference in N-Al between 1 and 4 of 0.1 Angstrom (2.045, 2.010, 1.971, and 1.949 Angstrom). This shortening with increasing n, however, is not linear.