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The [2+2] compartmental macrocyclic complexes [Ln(H2-L)- (NO3)], where H2-L is the cyclic Schiff base, derived from the condensation of 2,6-diformyl-4-chlorophenol (H-LA) or 2,6- diformyl-4-methylphenol (H-LB) and N,N-bis(2-aminoethyl)- 2-hydroxybenzylamine·3HCl (HA'·3HCl), contains a free N3O3 coordination chamber and can act as a ligand toward an identical or a different lanthanide(III) ion and a d transition metal(II) ion to give the related f,f homodinuclear [Ln2(L)- (X)2] and f,f' heterodinuclear [LnLn'(L)(X)2] or d,f heterodinuclear [LnM(L)(X)] complexes. They have been characterized by ESEM-EDS, ESI-MS, and IR and 1H and 13C NMR spectroscopy. The X-ray single-crystal analysis of the [2+1] acyclic complex [Lu2(L')2], derived from partial hydrolysis of the related [2+2] homodinuclear complex [Lu2(L)(Cl)2], followed by the loss of one lutetium(III) ion with the free formyl groups turning into diacetal ones, is also reported.

The challenge to realize polymetallic assemblies of unambiguous structure and stereochemistry, in which the nature of the intervalence transition (IT) is rationalized, has been faced by investigating the syn and anti isomers of ·6-Cr(CO)3{·5-[(2-ferrocenyl)indenyl]Rh(CO)2} and their mixed-valence cations. Crystallographic studies and DFT calculations provide a detailed description of the structural and electronic features of these complexes, evidencing a significant difference in geometrical distortions and frontier MO composition between syn and anti isomers. Mixed-valence cations are generated and monitored by low-temperature spectroelectrochemistry in the visible, IR, and near-IR regions. The IT bands in the near-IR spectra are rationalized in the framework of Marcus-Hush theory and at quantum chemistry level by density functional theory. Noteworthy, the results reported provide rare experimental evidence that the presence of a third metal center (Rh) increases the metal-metal (Fe-Cr) interaction with respect to the structurally correlated binuclear system.

A series of heterobimetallic n6-((ferrocenyl)indene]-Cr(CO)3 complexes differing for the position of the ferrocenyl group, 1-(ferrocenyl)indene and 2-(ferrocenyl)indene, and the degree of indene methylation (tetramethyl- and hexamethyl-) have been prepared and studied with the aim to stabilise the monoand dications generated by chemical and electrochemical oxidation, and at same time to tune the metal–metal electronic coupling in the mixed-valence cations. The magnitude of electronic delocalisation and spin density in the cations have been monitored by means of optical techniques (UV–Vis, near-IR, mid-IR) and EPR spectroscopy. The results have been rationalised in the framework of Marcus-Hush theory and at quantum chemistry level by DFT and TD-DFT methods, establishing that a metal-to-metal electronic coupling occurs the magnitude of which depends on the degree of indene methylation.

The new sodium bis(1-methyl-1H-imidazol-2-ylthio)acetate, Na((S-tim)2CHCO2), has been prepared in ethanol solution using 2-mercapto- 1-methylimidazole, dibromoacetic acid and NaOH. New di- and tri-organotin(IV) derivatives have been synthesized from reaction betweenSnRnCl4-n (R = Ph, Cy and nBu, n= 2–3) acceptors and Na((S-tim)2CHCO2). Complexes of the type ((K1O-(S-tim)2CH-CO2)SnR3) and related decarboxylated species((K2N,N-(S-tim)2CH2)SnR2Cl2) have been obtained and characterized by elemental analyses, FT-IR, ESIMS and multinuclear (1H, 13C and 119Sn) NMR spectral data. The adduct ((K1O-(S-tim)2CH-CO2)Sn(H2O)(C4H9)3) was characterized by single crystal X-ray studies. The dichloromethane reaction solution of (K1O-((S-tim)2CHCO2)Sn(C6H5)3) was re-crystallized and the decarboxylated species(((S-tim)2CH2)SnCl(H2O)(C6H5)3) was obtained as a crystalline solid and characterized by X-ray crystallography.

New silver(I) complexes have been synthesised from the reaction of AgNO3, monodentate PR3 (PR3 = P(o-tolyl)3, P(m-tolyl)3, P(ptolyl) 3, P(p-C6H4F), SeP(C6H5)3) or bidentate tertiary (dppe = bis(diphenylphosphane)ethane, dppf = 1,10-bis(diphenylphosphane)ferrocene) phosphanes and potassium dihydrobis(3-nitro-1,2,4-triazolyl)borate, K[H2B(tzNO2)2]. These compounds have been characterized by elemental analyses, FT-IR, ESI-MS and multinuclear (1H and 31P) NMR spectral data. The adduct {[H2B(tzNO2)2]Ag[P(m-tolyl)3]2} has been characterized by single crystal X-ray studies. In the former, the H2B(tzNO2)2 acts as a monodentate ligand utilizing the coordinating capability of only one of the additional (exo-) ring nitrogens to complete the coordination array about the silver atom.

The new sodium bis(2-pyridylthio)acetate ligand has been prepared in ethanol solution using 2-mercaptopyridine, dibromoacetic acid and NaOH. New mono- and di-organotin(IV) derivatives containing the anionic bis(2-pyridylthio)acetate have been synthesized and characterized by elemental analyses, FT-IR, ESI-MS, multinuclear (1H and 119Sn) NMR spectral data and X-ray crystallography. ESI-MS spectra of methanol solution of the complexes show the existence of hydrolysed species. Attempts to crystallize the dimethyltin(IV) derivative (3), from acetonitrile solution yield the dimeric dicarboxylatotetramethyldistannoxane (8), which was characterized by single crystal diffraction analysis.

Novel palladium(II) complexes with oxazolin-2-ylidene ligands have been synthesized via direct reaction of palladium acetate and oxazolium salts, prepared in turn by alkylation of oxazole with methyl iodide or benzylic bromides. The resulting complexes have been characterized and used as catalysts in Heck coupling reactions of aryl bromides, where they exhibit remarkable catalytic activity, higher than that of the closely related bis-imidazolin- 2-ylidene and bis-benzothiazolin-2-ylidene complexes.

Among the synthesized (CH3)2AlOR compounds (R=CH2CH2OCH3 (1), CH(CH3)CH2OCH3 (2), CH2CH2OCH(CH3)2 (3), CH(CH3)CH2OC(CH3)3 (4)), 2 and 4 have been characterized by 1H and 27Al NMR spectroscopy and X-ray diffraction, while 1, 2 and 3 have been analysed by mass spectrometric measurements with a mass spectrometer equipped with a special designed input system imitating a CVD reactor. While in the solid state it is unequivocally clear that the compounds are present in the form of an oxygen-bridged dimer with a five-coordinated aluminum center, in solution an equilibrium exists between two fluxional species containing tetra and penta coordinated Al atoms respectively.

The silicon compounds SiMe2(NRR')(2) [NRR' = NMe2 (1), NEt2 (2), NC4H8 (3), NHEt (4), (NHPr)-Pr-i (5), (NHBu)-Bu-t (6), NMeBu (7)] have been synthesised via aminolysis of the dichloro species SiMe2Cl2 and their ligating ability has been investigated towards zirconium(IV). The dimer zirconium compound {Zr[((NPr)-Pr-i)(2)SiMe2](2)}(2) (8) has been synthesised by reacting ZrCl4 with the lithium salt Li-2[((NPr)-Pr-i)(2)SiMe2] and its molecular structure has been determined in the solid state by X-ray diffraction analysis. The reaction of ZrCl4 with SiMe2(NRR')(2) yields the Lewis adducts ZrCl4[(NRR')(2)SiMe2] [NRR' = NMe2 (10), NC4H8 (11), NHEt (12), (NHPr)-Pr-i (13), (NHBu)-Bu-t (14), NMeBu (15)]. On the other hand, the mixed amido derivative Zr(NMe2)(3)(NHMe)[((NBu)-Bu-t) SiMe2((NHBu)-Bu-t)] (9) has been obtained from the reaction of Zr(NMe2)(4) with SiMe2((NHBu)-Bu-t)(2). The solution molecular structure and dynamics of the zirconium derivatives have been elucidated by 1D and 2D multinuclear NMR spectroscopy.

An improved synthesis of platinum acetate is reported in detail. This tetrameric complex reacts with PPh3 or P–n-Bu3 at room temperature to give the thermodynamically unstable bis-substituted trans-[Pt(OAc)2L2] complexes, which are not easily accessible via other routes. The structure of the new compound trans-[Pt(OAc)2(PPh3)2] has been determined by X-ray analysis.

The synthesis and the X-ray structure of the two pseudotetrahedral Zn(II) zwitterionic complexes: trichloro(1-methylpiperazin-1-ium-N4)zinc(II). [ZnCl3(H,Meppz)], and trichloro(1,4-dimethylpiperazin-1-ium-N4)zinc (II). [ZnCl3(HMe2ppz)], are described [(H2Meppz)+ = 1-methylpiperazin-1- ium monocation and (HMe2ppz)+ 1,4-dimethylpiperazin-1-ium monocation], [ZnCl3(H2Meppz)] and [ZnCl3(HMe2ppz)] complexes ave isomorphous and isostructural, respectively, to the [CoCl3(H2Meppz)] and [C0Cl3(HMe2ppz)] complexes. already reported in Iiterature by us. Both complexes present a very uncommon and distorted tetrahedral aminotrichlorozinc(II), NZnCl3, group, where N is a nitrogen atom of an aliphatic amine. So far this group has been found only in the (1,3,5,7-tetraazaadamantane)trichloro-zincate (II) anion [{(CH2)6N4}ZnCI3]. The bulky ZnCI3 group present in [ZnCl3 (HMe2ppz)], is coordinated to the axial position of the piperazine ring instead of the less hindered equatorial position, as found in the analogous [C0Cl3(HMe2ppz)] complex. An extended hydrogen bond network is present in the crystals of both the complexes but, while the [ZnCl3 (H2Meppz)] complex shows nearly Iinear N+...Cl intermolecular hydrogen bonds, the [ZnCl3(HMe2ppz)] complex shows a perfectly symmetrical (imposed by space group symmetry) ZnNCl three-centre intermolecular hydrogen bond. The solid state infrared spectra of both the compounds are discussed in agreement with the hydrogen bond network present in the crystals.

Lanthanide(III) complexes of six-nitrogen-donor macrocyclic ligands carrying a benzyl-type group, -CH2-C6H4-X (X = -H, -OH, or -NH2), at each di-imine side-chain were synthesized by the Schiff-base condensation of 2,6-diacetylpyridine with substituted S- and R,S-1,2-diaminopropanes. The complexes were obtained as mixtures of constitutional isomers and stereoisomers, which were identified by 1H NMR spectra and separated by fractional crystallization. The molecular structure of the 11-coordinate complex [La(NO3)2(H2O)(C36H38N6)](NO3)(H2O) was established by X-ray crystallography.

The reaction of the oxocumulene ylide ketenylidenetriphenylphosphorane, Ph3PC=C=O, 1, with an excess of water in THF yielded a white microcrystalline solid that was recognized as methyltriphenylphosphonium hydrogencarbonate, containing one molecule of crystallization water, [Ph3MeP]CO3H·H2O, 2. Compound 2 was characterized by IR, multinuclear NMR and ESI mass spectra. The chemical constitution was confirmed by an X-ray crystal analysis. On heating, compound 2 decomposes giving CO2, H2O, C6H6 and Ph2MePO.

The reactions of cis-[PtCl2(NCMe)2] with a 5-fold excess of the primary aliphatic amines RNH2 (R = Me, Et, Pri, But) in CH2Cl2 at 10 °C afford in high yield the bis-amidine complexes cis-[PtCl2{Z-N(H)=C(NHR)Me} 2], where both the amidine ligands assume the Z configuration. The corresponding reactions of trans-[PtCl2(NCMe)2] with RNH2 (R = Me, Et, But) give a mixture of the bis-amidine trans-[PtCl2{Z-N(H)=C(NHR)Me}2] and the mono-amidine trans-[PtCl2(NCMe){Z-N(H)=C(NHR)Me}] derivatives, which could be isolated as pure products operating with a platinum nitrile complex:amine molar ratio of 1:50 or 1:1, respectively. The reaction of trans-[PtCl2(NCMe)2] with a 50-molar excess of PriNH2 affords the bis- amidine bis-amine dicationic complex trans-[Pt(H2NPri)2{Z-N(H)=C(NHPri)Me} 2]Cl2, which has been characterized also by X-ray diffraction analysis. The reactions of cis- and trans-[PtCl2(NCMe)2] with the secondary aliphatic amines R'R NH yield the bis-amidine complexes cis- and trans- [PtCl2{E-N(H)=C(NR'R)Me}2] (R', R = Et) and/or cis- and trans-[PtCl(NCMe) {E-N(H)=C(NR'R)Me}2] (R', R = Et; R' = Me, R = But), where the amidine ligands have the E configuration. The compound trans-[PtCl2(NCMe){E-N(H)=C (NMeBut)Me}] has been characterized by single crystal X-ray diffraction. All the complexes have been characterized by IR, 1H and 13C NMR spectroscopies. The Z or E configuration of the amidine ligand can be readily deduced by 1H NMR data.

In this paper a theoretical study, concerning molecular mechanics optimised structures, obtained by quantum mechanics as well as molecular mechanics calculations was carried out with the aim of correlating the theoretical model of the interactions between azapsoralens and DNA with the data experimentally obtained. The theoretical model suggests that both furan-side and pyrone-side double bonds may be involved in the cycloaddition with pyrimidines (although the cycloaddition at the level of furan is preferred), and is in line with the capacity of these compounds to form inter-strand cross-links. Moreover, concerning the theoretical intercalation model calculations on 3,4,4',5'-tetramethylazapsoralen intercalated inside a polynucleotide, they suggest a cis-syn arrangement between furan-side of the intercalated ligand and the above situated thymine, with which, under light activation, a cycloadduct may take place, having a cis-syn steric arrangement. Also this datum is in agreement with the cis-syn regio and stereochemistry of the isolated 4,4',5'-trimethylazapsoralen-thymine cycloadduct. Finally, from theoretical data, the role of nitrogen seems not important: in fact only small differences were found with the corresponding methylpsoralens so that the small differences observed may be mainly attributed to steric rather than to electronic effects. In general a good correlation between the theoretical model and the experimental data was observed.