The novel bis(acesulfamato-O)tetraaquanickel(II) and bis(acesulfamato-N)tetraaquacobalt(II) complexes have been synthesized and characterized by elemental analyses, magnetic measurements, u.v.-vis and FT-IR spectra. The thermal behavior of the complexes was also studied by simultaneous TG, DTG and DTA methods in a static air atmosphere. The crystal structure of bis(acesulfamato-O)tetraaquanickel(II) complex has been identified by singlecrystal X-ray diffraction analyses. The acesulfamate ligand (acs) acts as an O-donor through the carbonyl oxygen as a monodentate ligand in the Ni(II) complex. The Ni(II) ion structure resides on a two-fold axis and is coordinated by four aqua ligands defining the basal plane, and by two monodentate acesulfamate ligands occupying the axial positions. The chromotropism of both complexes has been studied using thermal and spectral analysis. The bis(acesulfamato-N)tetraaquacobalt(II)complex is found to be very soluble in water and organic solvents and exhibits a reversible thermochromism from pink to violet depending on deaquation, which occurs in two steps, in the solid state. The bis(acesulfamato-O)tetraaquanickel(II) complex has shown two thermochromic properties one of which is a reversible and changes the color from green to yellow by an endothermic effect, whereas the other one is irreversible and changes from yellow to brown depending on deaquation, in the solid state. The bis(acesulfamato-N)tetraaquacobalt(II) complex exhibits solvatochromism in solvents with different donor number and ionochromism in the presence of various cations in solution.

In the crystal structure of the title compound {systematic name: bis[6-methyl-1,2,3-oxathiazin-4(3H)-one 2,2-dioxide(1-)-kappa2N3,O4]bis(3-methylpyridine)copper(II)}, [Cu(C4H4NO4S)2(C6H7N)2], the CuII centre resides on a centre of symmetry and has an octahedral geometry that is distorted both by the presence of four-membered chelate rings and because of the Jahn-Teller effect. The equatorial plane is formed by the N atoms of two methylpyridine ligands and by the more basic O atoms of the acesulfamate ligands, while the weakly basic N atoms of these ligands are in elongated axial positions with a misdirected valence. The crystal is stabilized by two intermolecular C-H...O interactions involving the methyl and CH groups, and the sulfonyl O atoms of the acesulfamate group.

In the crystal structure of the title compound [systematic name: diaquabis(6-methyl-2,2-dioxo-1,2,3-oxathiazin-4-olato-kappaO4)bis(3-methylpyridine-kappaN)nickel(II)], [Ni(C4H4NO4S)2(C6H7N)2(H2O)2], the Ni(II) centre resides on a centre of symmetry and has a distorted octahedral geometry. The basal plane is formed by two carbonyl O atoms of two monodentate trans-oriented acesulfamate ligands and two trans aqua ligands. The axial positions in the octahedron are occupied by two N atoms of two trans pyridine ligands. Molecules are stacked in columns running along the a axis. There are pi-pi stacking interactions between the molecules in each column, with a distance of 3.623 (2) A between the centroids of the pyridine rings. There are also O-H...O interactions between the columns.

The novel ½M(acs) 2 ð3-picÞ 2 ðH 2 OÞ 2 [M: Mn II , Co II , and Ni II ] and ½Cu(acs) 2 ð3-pic) 2 complexes (acs: acesulfamate; 3-pic: 3-methylpyridine) have been synthesized and characterized using elemental analyses, magnetic moments, UV-Vis and FT-IR spectra. The thermal behaviour of the complexes was also studied by simultaneous TG, DTG and DTA methods in static air atmosphere. The chromotropic properties of all complexes have been studied using thermal and spectral analysis. While the complexes of Co II and Ni II show reversible continuous thermochromism, an irreversible discontinuous thermochromism is observed in the Mn II and Cu II ) complexes in the solid state. The observed thermochromism in the Mn II , Co II and Ni II complexes is due to the different ligand field strength associated with the deaquation reaction. The solvatochromic behaviour of the complexes is also studied and all ½M(acs) 2 ð3-picÞ 2 anhydrous complexes (except Mn II ) exhibit solvatochromic properties depending on the donor number of the solvent.

FA4-MS05-P33 Experimental and Theoretical Investigation of the Molecular and Electronic Structure of N-Cyclohexyl-2-[5-(4-pyridyl)-4-(p-tolyl)-4H-1,2,4-tria-zol-3-ylsulfanyl]acetamide Dihydrate.