Facile Synthesis of Cyclometalated Ruthenium Complexes with Substituted Phenylpyridines

We have developed a new strategy that uses the Kröhnke synthesis for the preparation of various substituted phenylpyridines in excellent yields (up to 88 %). Starting with the appropriate commercially available acetophenone, a variety of phenylpyridines substituted by either electron‐donating (i.e. methyl, methoxy) or ‐withdrawing groups (i.e. bromide, nitro) on the phenyl ring are obtained in a two‐step synthesis. The corresponding functionalized cyclometalated ruthenium complexes can be prepared with unusually high yields by using methanol as reaction solvent. The electrochemical data of the complexes demonstrate the strong σ‐donating character of the anionic phenylpyridine ligand. X‐ray analyses of four complexes show a shortening of the Ru–C bond associated with the elongation of only one of the five Ru–N bonds (trans effect).(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)