Provided are complexes of the formula: ##STR00001## wherein: M is selected from Ti, Zr, Hf, Nb, Re, Sn, and Ge, R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6, R.sup.7, and R.sup.8 are each independently F, Cl, CF.sub.3, diarylamine, carbazolyl, alkoxy, cyano, alkyl or aryl; and a, b, c, d, e, f, g, and h are each 0, 1, 2, or 3; provided that at least one of R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6, R.sup.7, and R.sup.8 is diarylamine or carbazolyl; or R.sup.1, R.sup.4, R.sup.5, and R.sup.7 are not all the same; or R.sup.2, R.sup.3, R.sup.6, and R.sup.8 are not all the same.