In dichloromethane the complexes [[(η6-arene)RuCl(μ—Cl)]2] (arene- = benzene or p-cymene) and [[(η5-C5Me5)RhCl(μ-Cl)]2] react with the triazines 4-amino-6-methyl-5-oxo-3-thioxo-2,3,4,5-tetrahydro-1,2,4-triazine (3-S-ATAZ), 4-amino-6-methyl-5-oxo-3-phenylamino-4,5-dihydro-1,2,4-triazine (3-PhNH-ATAZ) and 4-amino-6-methyl-5-oxo-3-amino-4,5-dihydro-1,2,4-triazine (3-NH2-ATAZ) to form the corresponding complexes [(η6-arene)RuCl(triazine)]Cl and [(η5-C5Me5)RhCl(triazine)]Cl. The new compounds have been characterized by conductance measurements and spectroscopic (IR, 1H, 13C) methods. In every case the triazine acts as a chelating bidentate ligand, which has been confirmed by a single-crystal diffraction study carried out with [(η5-C5Me5)RhCl(3-PhNH-ATAZ)]PF6·H2O.

Reactions of [(η6-arene)RuCl(μ-Cl)2] [arene = benzene or p-cymene (p-isopropyltoluene)] have been carried out with 4-cyano-pyridine (4-CNpy), o-aminophenol (oap), o-phenylenediamine (opda), p-phenylenediamine (ppda) and 2,6-dimethyl-5-oxo-3-thioxo-2,3,4,5-tetrahydro-1,2,4-triazine (taz). The isolated complexes are of the types [(η6-C6H6)RuCl2L] [L = 4-CNpy (Ia) or oap (IIa)], [(η6-C6H6)RuClL2]Cl [L = oap (IIIa); L2 (bidentate) = opda (IVa) or taz (VIa)] or [(η6C6H6)Cl2Ru2(μ-ppda)] (VIIIa). Complexes IVa and VIa undergo anion exchange with KPF6 to give the corresponding hexafluorophosphates (Va and VIIa). The p- cymene analogues (Ib–VIIIb) have been obtained. Conductance measurements, thermogravimetry and spectroscopic (IR and 1H and 13C NMR) methods have been used to study the new compounds. The structure of VIIb was determined by X-ray diffraction methods. The ruthenium atom of the cation of VIIB is coordinated by the 4-amino (RuN = 2.140(2) Å) and 3-thioxo (RuS = 2.354(1) Å) groups of the triazine and a chloride ligand (RuCl = 2.394(1) Å). The η6-p-cymene ring completes the hexacoordination.

The TG, DTG and DSC study of pentamethylcyclopentadienylrhodium(III) derivatives [Cp*RhCl2L] (Cp* = η5-C5Me5; L = o-aminophenol, pyridine, 4-cyanopyridine, 4-methylpyridine, 4-chloropyridine, or 4-bromopyridine), [Cp*RhCl2(μ-ppda)Cl2RhCp*] (ppda = p-phenylenediamine) and [Cp*RhClL2]Cl (L2 (chelating bidentate) = ethylenediamine, tetramethylethylenediamine, or o-phenylenediamine) was carried out under a dynamic nitrogen atmosphere. From the DSC curves the heat of decomposition was calculated. The values of kinetic parameters such as activation energy E, frequency factor A and reaction order have been obtained using the Coats—Redfern and Horowitz—Metzger equations.

The complex [{Cp * RhCl(μ-Cl)} 2 ] (Cp *  η 5 -C 5 Me 5 ) reacts in dichloromethane with the relevant neutral ligands to give the complexes [Cp * RhCl 2 L] [L (monodentate)  o -aminophenol (oap), o -aminothiophenol (oatp), 4-cyanopyridine (4-CNpy)], or 4-amino-2,6-dimethyl-5-oxo-3-thioxo-1,2,3,4-tetrahydro-1,2,4-triazine (taz)], [{Cp * RhCl 2 } 2 (μ-ppda)] (ppda = p -phenylenediamine), and [Cp * RhCl(LL)]Cl [LL (chelating bidentate)  o -phenylenediamine (opda), ethylenediamine (en), or tetramethylethylenediamine (tmen)]. Anion exchange occurs when the opda complex is treated with KPF 6 , giving [Cp * RhCl(opda)]PF 6 . The new complexes have been characterized by elemental analysis, thermogravimetry, conductance measurements, and spectroscopic (IR and 1 H- and 13 C-NMR) methods.