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The treatment of the 90 degree angular precursor trans-[Ru[Cl.sub.2][(dmso-S).sub.4]] with an equivalent amount of the linear and rigid pyrazine (pyz) linker has produced the molecular triangle [[{trans,cis-Ru[Cl.sub.2][(dmso-S).sub.2]([mu]-pyz)}.sub.3]] instead of the molecular squares. The results have shown that the entropically favored molecular triangles are preferred over the expected molecular squares with metal corner fragments that have favored [N.sub.pyz]-M-[N.sub.pyz] angles narrower than 90 degrees due to the presence of ancillary ligands.

Research has been conducted on the ruthenium(II)- and ruthenium(III)-chloride-dimethyl sulfoxide precursors and the antimetasatic drug [ImH][trans-RuCl (sub)4 (dmso-S)] (Im= imidazole, dmso= dimethyl sulfoxide). The reactivity of these compounds toward nitric oxide has been studied and the details are reported.

Research has been conducted on the pyridylporphyrins and ruthenium complexes. The adducts between these complexes have been investigated and the results indicate that the porphyrin singlet is quenched in all the adducts.

Research has been conducted on the factors that influence the dynamic motion of planar N-donor heterocyclic ligands. The use of X-rays and NMR in investigating mixed-ligand mu-oxorhenium dimers is discussed.

The X-ray structure of (Ru(TTP)(CO)(3'MPyP)) (1) showed that, in the solid state, the two mean porphyrin planes in 1 are canted at an angle of ca. 43 degrees. Diffraction data permitted the refinement of the atomic positional parameters of 1 with the lowest calculated errors among those determined for similar porphyrin adducts. Based on NMR measurements, the solution structure of 1 was found to be very similar to that observed in the solid state though more symmetrical because of the presence of a pseudomirror plane perpendicular to 3'MPyP and going through the 3'N(py) ring.

The synthetic strategies that can be used for the construction of multiporphyrin assemblies and the X-ray structural features of the supramolecular assemblies are described. The collection of solid-state structures has demonstrated that the flexibility of the porphyrins and the metal junctions, combined with the conformational freedom of the coordination bonds, might lead to assemblies with hardly predictable architectures.

Unsymmetrical arrays containing porphyrins and coordination compounds may be assembled by stepwise coordination of mesao-4'-pyridyl porphyrins (4'-PyPs) to different metal centers. The results indicate that the pyridyl units react independently of the presence or absence of a subsituent on the other py rings.