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The synthesis, purification and characterisation of two coordination isomers of ruthenium() and osmium () complexes containing the ligand 3-(pyrazin-2Ј-yl)-5-(pyridin-2Љ-yl)-1,2,4-triazole (Hppt) are described. The X-ray and molecular structure of the complex [Ru(bipy) 2 (ppt)]PF 6 ؒCH 3 OH (1a) is reported, where the Ru(bipy) 2 -centre is bound to the ppt Ϫ ligand via the pyridine nitrogen and the N1 atom of the triazole ring. 1 H NMR spectroscopic measurements confirm that in the second isomer (1b) the Ru(bipy) 2 -moiety is bound via the N2 atom of the triazole ring and the pyrazine ring. Partially deuteriated metal complexes are utilised to facilitate interpretation of 1 H NMR spectra. The redox and electronic properties indicate that there are significant differences in the electronic properties of the two coordination isomers obtained. The acid-base properties of the compounds are also reported and show that the pK a of the 1,2,4-triazole ring varies systematically depending on the nature of the non-coordinating substituent. Analysis of these data indicates a significant electronic interaction between the pyridyl/pyrazyl rings and the 1,2,4-triazole ring in the coordinated ppt Ϫ ligand.

Assessment of intercomponent interaction in phenylene bridged dinuclear ruthenium(II) and osmium(II) polypyridyl complexes. Dalton Transactions, (23), 3943-3949.

Diphenylphosphinodithioic acid (6b) and its triethyl ammonium salt (6a) were prepared by two new synthetic pathways, each employing cheap and readily available starting materials. These facile one-pot reactions were conducted on a kilogram scale and produced the desired products in high yield and quality, thereby surpassing all previously known routes. The synthesis of triethyl ammonium salts of 6H-dibenzo[c,e][1,2]oxaphosphinine-6-thiolate 6-sulfide (3a) was also further improved.