N. Hu, Tsutomu Tokuno, K. Aoki
Nov 15, 1999
Citations
0
Influential Citations
19
Citations
Journal
Inorganica Chimica Acta
Abstract
Abstract Three salts of oxythiamine, (oxythiamineH)(picrolonate) 2 ·2H 2 O ( 1 ), (oxythiamineH)(PtCl 6 ) ( 2 ) and (oxythiamineH) 2 -(V 10 O 28 H 2 )·8H 2 O ( 3 ), and a metal complex Pt(oxythiamine)Cl 3 ·H 2 O ( 4 ) have been prepared and characterized by X-ray diffraction. In the salts 1 , 2 and 3 , the oxythiamine molecule exists as a divalent cation with both the N(1′) and the N(3′) sites protonated. In 1 , oxythiamine adopts a novel conformation termed as the V′ -form, with φ T =−63.1(6) and φ P =−54.7(6)°, where the oxo O(4′ α ) makes an electrostatic interaction with the thiazolium ring to stabilize the V′ -form. 2 and 3 are the first crystal structures in which oxythiamine assumes the F -conformation, with φ T and φ P being −5.3(9) and −84.8(7)°, respectively, for 2 , and 3.9(4) and 76.6(3)° for 3 . In 2 and 3 the anion-bridge of the type C(2)H⋯anion⋯pyrimidine ring stabilizes the F -form, where the anion is a PtCl 6 2− ion in 2 and a decavanadate ion in 3 . The water-bridge of the type O(4′α)⋯water⋯thiazolium ring and the anion-bridge of the C(6′)H⋯anion⋯thiazolium ring type are additional structural features which stabilize the F -form in 3 . The metal complex 4 provides the first X-ray example showing the direct metal bonding to oxythiamine. The N(1′)-metallated oxythiamine is in the usual V -conformation with φ T =104.0(9) and φ P =−72.6(8)°, which is stabilized by a close contact between O(4′α) and the thiazolium moiety.