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

Abstract

By interaction of SnCl 4 with condensation products of dihydrazides of oxalic, terephthalic, malonic acids and R-benzoic aldehydes (R = Н, 4-N(CH 3 ) 2 , 2-OH) in acetonitrile, the following complexes were synthesized: with oxaloyl- [SnCl 4 (H 2 Oxb)]∙CH 3 CN (R = Н, I ), [SnCl 4 (Oxdb∙2H)]·2CH 3 CN (R = 4-N(CH 3 ) 2 , II ), [SnCl 4 (H 4 Oxs)]∙CH 3 CN (R = 2-OH, III ), терефталоїл- [(SnCl 4 )2(μ-Tfdb·2H)]∙2CH 3 CN (R = 4-N(CH 3 ) 2 , IV ), [SnCl 4 (μ-H 2 Tfs)]∙CH 3 CN (R = 2-OH, V ), malonoyldihydrazones- [SnCl 4 (μ-Maldb·2H)]·2CH 3 CN (R = 4-N(CH 3 ) 2 , VI ), [SnCl 4 (μ-H 2 Mals)] ∙ CH 3 CN (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(CH 3 ) 2 ) – oxaloyl dihydrazones, regardless of the presence of functional groups (CН=N, OH) as part of these molecules, SnCl 4 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 – {SnCl 4 O 2 }, R = 4-N(CH 3 ) 2 – {SnCl 4 O 2 } 2- . In the presence of a spacer in dihydrazone molecules, regardless of their stereochemical rigidity (X = -C 6 H 4 -, -CH 2 -), only if R = 2-OH, 4-N(CH 3 ) 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(CH 3 ) 2 – {SnCl 4 ON} 2 - (tetra- in IV, VI ), R = 2-OH – {SnCl 3 O 2 N} (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 {SnCl 4 O 2 } 2- ( II ) and {SnCl 4 ON} 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.