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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.

The stability of silver(I) complexes with pyridine ligands is affected by solvation. Pyridine exhibits differential affinity for silver(I) ion in water and dmso.

A detailed analysis of the interactions of the hydroxo complexes cis-([L.sub.2]Pt(mu-OH)].sub.2].sup.2) (L = P[Me.sub.2]Ph and P[Ph.sub.3]), with 1-methylcytosine (1-MeCy) showing that the cytosinate anion forms trinuclear adducts when L is P[Me.sub.2]Ph is presented. The thermodynamically stable product is found to be the cyclic species cis[(P[Me.sub.2]Ph.sub.2])Pt{1-MeCy(-H),(N.sup.3)(N.sup.4)}.sub].sup.3}, characterized by a single-crystal X-ray analysis structurally similar to that of the P[Me.sub.3] complex.

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.

The 2+2 neutral metallacycles made of porphyrins and octahedral ruthenium coordination compounds of formula [trans,cis,cis-RuCl2(dmso-S)2(4'-cis-DPyP)]2, [trans,cis,cis-RuCl2(CO)2(4'-cis-DPyP]2, and [trans,cis,cis-RuCl2(dmso-S)(CO)(4'-cis-DPyP)]2 is formed after the treatment of the octahedral Ru(II)-dimethyl sulfoxide trans-RuCl2(dmso-S)4, trans-RuCl2(dmso-O)2(CO)2, and trans-RuCl2(dmso)3(CO) with a stochiometric amount of 5,10-bis(4'-pyridyl)-15,20-diphenylporphyrin (4'-cis-DPyP).

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 conformers of cis,cis,cis-RuCl2(Me2SO)2(3,5-lut)(1,2-Me2Im) (3,5-lut = 3,5-lutidine, 1,2-Me2Im = 1,2-dimethylimidazole) in fluxional equilibrium in solution were observed to be trapped and almost unaltered in the solid state. These presented a rare example in which the solid state closely reflects the solution state, both in the structure of species involved in a conformational equilibrium and in the position of that equilibrium.

X-ray crystallographic determination of the molecular structure of trans-(NH3)2Pt(mu-1-MeC-)2Pd(NH3)Pd(NH3)4 0.5(NO3)3*3H2O shows that this compound crystallizes in the triclinic space group and has a square planar coordination of Pd and a square pyramidal coordination of Pt with Pd in the apical position. Extended studies have led to the formation of d8-d10 Pt(II)-Hg(II)13. The effect and correlation of the M-M' bond in d8-d8 dimers are discussed.

The sizes of the Me3Bzm ligand and py are compared to reveal the largeness of the ligand, though both have equal effective bulk. The two sides the lopsided ligand reveal more and less bulkiness compared to py. Stimulatory influences on shifts are presumed due to the stimulatory influences of Co on 13C shifts in cobaloximes. The process reveals the stimulatory abilities of simple metal ions on shifts over the potential of the proton. The ligand-responsive electronic characteristics of the metal core are calculated by epsilon.

Mixed-metal Pt-Hg complexes of the nucleobases 1-methylcytosine and 1,5-dimethylcytosine were described. It was shown that the heteronuclear compounds contain two bridging cytosyl ligands, binding Pt through N3 and Hg via deprotonated exocyclic amino groups of the nucleobases. 1H nuclear magnetic resonance spectra of the various Pt-Hg compounds show 195Pt and 199Hg coupling. Moreover, the mixed-metal Pt-Hg species, when reacted with a large variety of N and S donor ligands X, tend to decompose with formation of trans-(a2PtL2)2+ and HgX2.

The reaction of trans-(a2Pt(1-MeC-N3)2)(NO3)2 (a = NH3, CH3NH2; 1-MeC = 1- methylcytosine), K2PdCl4 and trans-(NH32Pd(H2O)2)(NO3)2 yielded trans-a2Pt((1-MeC- -N3,N4)PdCl)+,PtPdCl and trans-(a2Pt(1-MeC- -N3)), N42Pd(NH3)2+,PtPd(NH3). The PdPtY (Y = nucleobase) complexes consisted of large cations, nitrate anions and water molecules. Steric factors prevented the formation of trans-(a2Pt(1-MeC-)2PdY2)n+ (n = 2 or 0)-type compounds.

The reaction between H(AuCl4) and gly-L-his resulted in the formation of the binary complex, (Au gly-L-his Cl)Cl.3H2O. The complex contained a dipeptide structure attached to an Au(III) molecule which exhibited a strong polarizing activity. This property allowed the formation of the cyclic tetramer (Au gly-L-his3-)4.10H2O at pH six to seven. This identified Au(III) from Cu(II), Ni(II) and Pd(II) which required basic solutions to prepare cyclic tetramers.

The synthesis and characterization of a series of dinuclear copper(II) complexes were performed to study their applicability as potential structure and function models for the active site of catechol oxidase enzyme. All the complexes exhibited high catecholase activity in methanol medium and were found to be most suitable structure-functional models to mimic the active site of catechol oxidase.

The synthesis and characterization of the complexes cis-[[([PPh.sub.3]).sub.2]Pt(nucleobase)(ON[O.sub.2])]N[O.sub.3] and cis-[[([PPh.sub.3]).sub.2]Pt[(nucleobase).sub.2]][(N[O.sub.3]).sub.2], containing the neutral nucleobases 1-MeCy and 9-methylguanine (9-MeGu) acting as monodentate ligands, is described. The high stability of the monoadducts cis-[[[L.sub.2]Pt(nucleobase)].sup.2+] (L = [PPh.sub.3]) ligands is accounted for by the presence in both complexes of a strong intramolecular [pi]-[pi] interaction occurring between a phenyl group and the pyrimydinic ring, leading the P-Pt-N3/7 angle to assume a value near to ideality.

The derivatives of Ru(II)-DMSO anticancer complexes with potentially chelating dicarboxylates (dicarb) are prepared in order to assess the effect of anionic ligands on the biological activity of these species. The analysis has provided insights into the preferential binding modes of these ligands on octahedral metal centers and has stressed the importance of steric hindrance and hydrogen bonding in determining the nature and geometry of the products.

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.

The single-crystal X-ray was used to synthesize and characterize lanthanide-organic coordination polymeric networks of [[Ln.sup.III.sub.2][(succinate).sub.3][(H2O).sub.2]].0.5H2O [Ln = Pr, Nd, Sm, Eu, Gd, and Dy]. The complexes were found to possess a 3D architecture with Ln ion in a nine-coordination geometry attained by eight oxygen atoms from succinate and one oxygen atom from an aqua ligand.

Metal-mediated couplings of acetonitrile with the exocyclic nitrogen of 9-methyladenine and 1-methylcytosine afford the class of azametallacycles. In chlorinated solvents, the adenine derivatives release reversibly the inserted CH3CN molecule to give the cyclic trimer cis-[L2Pt{9-MeAd(-H)}]3(super 3+) (L = PMePh20), with metals bridged by the adenine N(1), N(6) donors or the mononuclear complex cis-[L2Pt{9-MeAd(-H)}](super +) (L = PPh3).

The preparation and structural characterization of the 2+2 neutral porphyrin metallacycle in solution and in solid state is discussed. External Ru(II) metal fragments with an interplanar distance of 4.18 A and a lateral offset of 9.82 A hold the two porphyrins in a rigid slipped cofacial geometry.

Research has been conducted on dinuclear hydroxo complex cis-[L (sub)2 Pt(ONO (sub)2){9-MeAd(-H)}PtL (sub)2](NO (sub)3) (sub)2, where L is PMePh (sub)2. The authors have demonstrated that this complex deprotonates NH (sub)2 group of 9-methyladenine in solution to produce cis-[L (sub)2 Pt{9-MeAd(-H)}] (sub)3 (NO (sub)3) (sub)3.

Research has been conducted on metal-organic polymeric complexes. The authors describe the synthesis and characterization of these complexes carried out via low-temperature magnetic measurements and single-crystal X-ray diffraction studies.

Research has been conducted on organic-inorganic hybrid 3D networks of nickel(II) and manganese(II). The authors decsribe the synthesis and characterization of these networks carried out via the use of single-crystal X-ray diffraction studies and loe-temperature magnetic measurements.