TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preparation (Disclosed): Preparation of (I) comprises reacting substituted aryl compounds of formula (II) with potassium tetrachloroplatinate and tetrabutylammonium bromide in presence of acetic acid at room temperature and then at 108-115 degrees C under nitrogen or argon to give metal complexes (III) (representative of (I)). Preferred Definitions:    At least one of V1b-V4b=N;    at least two of L1a-L4a=at least one phenyl or at least one pyridine; and    M1a=Pt or Pd.    SPECIFIC COMPOUNDS - 274 Compounds of (I) are specifically claimed e.g. (3-pyridin-2-yl-5-(3-pyridin-2-yl-phenyl)-5H-dibenzo(b,f)azepine)-platinum complex of formula (Ia), (5-(3-(4-methyl-pyridin-2-yl)-phenyl)-3-pyridin-2-yl-5H-dibenzo(b,f)azepine)-platinum complex, (3-(4-methyl-pyridin-2-yl)-5-(3-pyridin-2-yl-phenyl)-5H-dibenzo(b,f)azepine)-platinum complex, (5-(3-(4-tert-butyl-pyridin-2-yl)-phenyl)-3-pyridin-2-yl-5H-dibenzo(b,f)azepine)-platinum complex, and (3-(4-tert-butyl-pyridin-2-yl)-5-(3-pyridin-2-yl-phenyl)-5H-dibenzo(b,f)azepine)-platinum complex.    EXAMPLE - To an oven dried pressure vessel equipped with a magnetic stir bar, 1.33 g of 3-(pyridin-2-yl)-5H-dibenzo(b,f) azepane, 180 mg of tris(dibenzylideneacetone)dipalladium(0), 118 mg of 2-(dicyclohexylphosphino)biphenyl and 756 mg of potassium tert-butoxide were added. The vessel was evacuated and backfilled with nitrogen. The evacuation and backfill procedure was repeated four additional times. Then a degassed solution of 1728 mg of 2-(3-bromophenyl)pyridine in 20 ml of toluene was added under the atmosphere of nitrogen. The sealed vessel was then placed in a preheated oil bath at 95-105 degrees C. The reaction was stirred and monitored by TLC and after 4 days the reaction was completed, and cooled down to ambient temperature. The solvent was removed under reduced pressure using a rotary evaporator and the residue was purified through column chromatography on silica gel using hexane and ethyl acetate (5:1-3:1) as eluent to obtain ligand 3-(pyridin-2-yl)-5-(3-(pyridin-2-yl)phenyl)-5H-dibenzo(b,f)azepane. To an oven dried pressure vessel equipped with a magnetic stir bar, 84.7 mg of ligand 3-(pyridin-2-yl)-5-(3-(pyridin-2-yl)phenyl)-5H-dibenzo(b,f)azepane, 87.2 mg of potassium tetrachloroplatinate and 5.5 mg of tetrabutylammonium chloride were added. The vessel was taken into a glove box. Then 12 ml of acetic acid was added. The reaction mixture was bubbled with nitrogen for 30 minutes. Then the vessel was sealed and taken out of the glove box and stirred at ambient temperature for 18 hours. After that the reaction mixture was heated in an oil bath at 110 degrees C for another 18 hours, and cooled down to ambient temperature, followed by addition of 24 ml of water. The precipitate was collected through filter and washed with water for three times. The precipitate was dried in air and purified through column chromatography on silica gel using dichloromethane as eluent to obtain a crude product which was further purified by recrystallization in dichloromethane and ether at refrigerator to obtain 5.9 mg of (3-pyridin-2-yl-5-(3-pyridin-2-yl-phenyl)-5H-dibenzo(b,f)azepine)-platinum complex.