TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preparation (Claimed): Preparation of (I) comprises reacting the free ligand with a corresponding metal salt. Preferred Definitions:    M = transition metal or its ion (preferably Mo, W, Ru, Os, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au or Zn) or main group metal or its ion (preferably alkali metals, alkaline earth metals, Al, Ga or In), when X that is coordinated to the metal, is N, Z is N, R2 is a non-binding electron pair and M is Pt or when X, which is coordinated to the metal, is C, then M is Pt;    Cy = (hetero)aryl or cyclic carbene with 5-16 ring atoms, preferably phenyl, naphthyl, anthracyl, phenanthryl, biphenyl, pyridyl, 1,3-diazolyl, 1,3-diazocyclopentyl or benzo-1,3-diazolyl (all optionally substituted by R1);    Ar1 = phenyl, naphthyl, anthracyl, phenanthryl or pyridyl (all optionally substituted by R1); either    L = CO, NO, SH, OH, carbene, isonitrile, amine, phosphine, phosphite, arsine, stibine, N containing heterocycle, hydride, deuteride, F, Cl , Br, I, alkylacetylidene, arylacetylidene, heteroarylacetylidene, cyanide, cyanate, isocyanate, thiocyanate, isothiocyanate, aliphatic or aromatic (thio)alcoholate, amide, carboxylate, anionic N containing heterocycles and anionic aryl; or    R1L = -CH2CH2PMe2, -CH2CH2PPh2, -CH2CH2O-, -CH2CH2S-, -CH2COO-, -CH2COS-, -CH2-pyridine, -CH2-quinoline, -CH2-phenyl, -CH2-isoquinoline, imidazolidinyl group of formula (a), 2,3-dihydro-1H-imidazolyl group of formula (b) or 2,3-dihydro-1H-benzoimidazolyl group of formula (c).    SPECIFIC COMPOUNDS - 10 Compounds (I) are disclosed e.g. platinum complexes of formulae (Ia)-(Ie). 12 Compounds (IA) are disclosed e.g. nitrogen containing macrocyclic ligand of formulae (IAA)-(IAE).    EXAMPLE - A suspension of ligand (IAB) (3.9 g), dipotassium tetrachloroplatinate (II) (4.2 g) and lithium acetate (3.3 g) in glacial acetic acid (50 ml) was heated for 60 hours under reflux. After cooling, the acetic acid was removed under vacuum and the residue was dissolved in dichloromethane and chromatographed on silica gel with dichloromethane. The resulting solid was then recrystallized from dichloromethane/hexane and then in vacuum to give platinum complex (Ia) (675 mg).