SYNTHESIS, STRUCTURE OF MONO- AND BINUCLEAR COMPLEXES OF Sn(IV) WITH DIHYDRAZONES OF AROMATIC ALDEHYDES

Abstract

By interaction of SnCl4 with condensation products of dihydrazides of oxalic, terephthalic, malonic acids and R-benzoic aldehydes (R = Н, 4-N(CH3)2, 2-OH) in acetonitrile, the following complexes were synthesized: with oxaloyl- [SnCl4(H2Oxb)]∙CH3CN (R = Н, I), [SnCl4(Oxdb∙2H)]·2CH3CN (R = 4-N(CH3)2, II), [SnCl4(H4Oxs)]∙CH3CN (R = 2-OH, III), терефталоїл- [(SnCl4)2(μ-Tfdb·2H)]∙2CH3CN (R = 4-N(CH3)2, IV), [SnCl4(μ-H2Tfs)]∙CH3CN (R = 2-OH, V), malonoyldihydrazones- [SnCl4(μ-Maldb·2H)]·2CH3CN (R = 4-N(CH3)2, VI), [SnCl4(μ-H2Mals)] ∙ CH3CN (R = 2-OH, VII). Their composition and structure are established by the methods of elemental analysis, conductometry, thermogravimetry, and IR spectroscopy. It was established that in the absence of a spacer (X = 0) in the dihydrazone molecules of R-benzoic aldehydes (R = H, 2-OH, 4-N(CH3)2) – oxaloyl dihydrazones, regardless of the presence of functional groups (CН=N, OH) as part of these molecules, SnCl4 forms only mononuclear complexes I-III with the same O,O- coordination and composition of the coordination node, the charge of which is determined by a substituent (R) in the aldehyde fragment: R = H, 2-OH – {SnCl4O2}, R = 4-N(CH3)2 – {SnCl4O2}2-. In the presence of a spacer in dihydrazone molecules, regardless of their stereochemical rigidity (X = -C6H4-, -CH2-), only if R = 2-OH, 4-N(CH3)2, binuclear Sn(IV) complexes are formed with spatially separated coordination nodes, the composition of the nodes and the dihydrazone denatism is been determined by the substituent (R): R = 4-N(CH3)2 – {SnCl4ON}2- (tetra- in IV, VI), R = 2-OH – {SnCl3O2N} (hexacoordinated ligand in V, VII). Coordination of dihydrazones in a enol form, both in mono- (II) and in binuclear complexes (IV, VI), is a consequence of the presence of vacant nitrogen atoms in the aldehyde fragments of their molecules (R = 4-N(CH3)2); due to their protonation, a negative charge is compensated, which is localized in this case at the coordination sites of the zwitterionic complexes {SnCl4O2}2- (II) and {SnCl4ON}2- (IV, VI). The patterns of the formation of each spatially separated coordination node and the tautomeric form of the ligands in IV-VII are the same as in mononuclear tin(IV) complexes.

Keywords

• станум(iv)
• дигідразид
• дигідразони ароматичних альдегідів
• моно- і біядерні комплекси