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A series of organotin (IV) compounds of the type [R3SnL]2, R is Me (1), Bu (2), [R2SnL]2, R is Ph (3), Me (4), Bu (5), L is pyruvic acid thiophene-2-carboxylic hydrazone, and R2SnL, R is Me (6), Bu (7), Ph (8), L is salicylaldehyde thiophene-2-carboxylic hydrazone have been synthesized in 1:1 molar ratio. All compounds were characterized by elemental analysis, IR, 1H NMR, 13C NMR and 119Sn NMR spectra. The crystal structure of compounds 1, 3, 4, 8 have been determined by X-ray single crystal diffraction analyses, study found that the compounds 1 and 3 are rendered one-dimensional chain structure and the tin atoms are five-coordinated in a distorted trigonal-bipyramidal geometry. The compound 4 has a dimeric structure and the central tin atom is rendered seven-coordinate in a distorted pentagonal-bipyramid configuration. While the compound 8 is a monomer in which the tin atom adopts five-coordinated in distorted trigonal-bipyramidal geometry.

A series of diorganotin(IV) and triorganotin(IV) compounds of the type [R2Sn(pca)2ClSnR3]2 (R PhCH2 1, 2-ClC6H4CH2 2, 2-FC6H4CH2 3, 4-FC6H4CH2 4, 4-CNC6H4CH2 5, 4-ClC6H4CH2 6, 2,4-Cl2C6H3CH2 7; Hpca 2-methylpyrazine-5-acid), [(nBu)3Sn(pca)]∞ 8, [(CH3)2Cl2Sn(pca)Sn(CH3)2(pca)]∞ 9, {[(nBu)2Sn(pca)]2O}2 10 and {[Ph2Sn(pca)]3O2[Ph2Sn(OCH3)]} 11 have been obtained by reactions of 2-methylpyrazine-5-acid with triorganotin(IV) chloride, diorganotin(IV) dichloride, and diorganotin(IV) oxide. All compounds were characterized by elemental, IR, and NMR spectra analyses. The crystal structure of compounds 1, 8–11 were determined by X-ray single crystal diffraction, which revealed that compound 1 was tetranuclear macrocyclic structures with seven-coordinate and five-coordinate tin atoms, compounds 8 and 9 were polymeric chain structures with five-coordinate and seven-coordinate tin atoms, compounds 10 and 11 were monomeric structures with six-coordinate and five-coordinate tin atoms.

The two solid-state coordination reactions (1) CuAc 2 · H 2 O ( s )+2 Ala ( s )→trans- Cu ( Ala ) 2 ( s )+2 HAc ( l )+ H 2 O ( l ) (2) CuAc 2 · H 2 O ( s )+2 Gly ( s )→trans- Cu ( Gly ) 2 · H 2 O ( s )+2 HAc ( l ) have been studied by solution calorimetry. The molar dissolution enthalpies of the reactants and the products in some solvents (such as 2 mol l−1 HCl or its solutions) of these solid–solid coordination reactions have been measured by an isoperibol solution calorimeter. The standard molar formation enthalpies of [trans-Cu(Ala)2(s), 298.15 K] and [trans-Cu(Gly)2(s), 298.15 K] have been determined to be −1015.42 ± 0.06 and 1252.36 ± 0.05 kJ mol−1, respectively, from the results of the molar dissolution enthalpies and other auxiliary thermodynamic data.

The solid-state coordination reactions: 2 HQ ( s )+ Co ( Ac ) 2 ·4 H 2 O ( s )→ Co ( HQ ) 2 ·2 H 2 O ( s )+2 HAc ( l )+2 H 2 O ( l ) 2 HQ ( s )+ Zn ( Ac ) 2 ·2 H 2 O ( s )→ Zn ( HQ ) 2 · H 2 O ( s )+2 HAc ( l )+ H 2 O ( l ) have been studied by solution calorimetry. The molar dissolution enthalpies of the reactants and the products in a certain solvent, 4 mol l −1 HCl, of this solid–solid coordination reaction have been measured using an isoperibol calorimeter. From the results and other auxiliary quantities, the standard molar formation enthalpies of [Co(HQ) 2 ·2H 2 O(s), 298.15 K], [Zn(HQ) 2 ·H 2 O(s), 298.15 K] and have been determined to be Δ f H m Θ (Co(HQ) 2 ·2H 2 O(s), 298.15 K)=−766.9±3.0 kJ mol −1 , Δ f H m Θ (Zn(HQ) 2 ·H 2 O(s), 298.15 K)=−580.7±3.0 kJ mol −1 .