ABSTRACT
The S 1s X-ray absorption near edge structure (XANES) and X-ray photoelectron spectra (XPS) of the neutral complexes [SbL(dmit)] (L = Br or I; dmit =1,3-dithiole-2-thione-4,5-dithiolate) have been measured using tunable synchrotron radiation. The valence shell electronic excitation by ultraviolet-visible (UV-vis) spectroscopy and the infrared vibrational spectra are presented and analyzed. The UV-vis results lead to an assignment of bands at 400 nm as π(Sm) â π*(CâS), where S(m) is the thiolate sulfur. The corresponding S 1s â π*(CâS) transition was identified at 2468.3 eV. Ab initio calculations, within the improved virtual orbital (IVO) method, carried out with the GSCF3 program, were applied to establish a complete and accurate spectral assignment. It has been the first attempt to apply such methodology for dmit coordination compounds, and very consistent results were obtained.
ABSTRACT
The structure of the title compound, [Ni(C13H9FNO)2(C5H5N)2], consists of an Ni(II) atom on a crystallographic center of symmetry, octa-hedrally bonded through both the N and O atoms to two 2-[(2-fluoro-phen-yl)imino-meth-yl]phenolate (L) ligands, as well as two pyridine ligands. The F atoms of L are disordered over two positions related by a 180° rotation of the fluoro-phenyl group around its external C-N bond.
ABSTRACT
The Sn atom in the title compound, [Sn(C(6)H(5))(2)(C(3)S(5))(C(2)H(6)OS)], exists within a distorted trigonal-bipyramidal geometry defined by two S atoms of the 1,2-dithiole-3-thione-4,5-dithiol-ate dianion, two ipso-C atoms from the phenyl groups, and the O atom of the dimethyl sulfoxide mol-ecule. In this description, one of the S atoms and the O occupy axial positions. In the crystal, centrosymmetrically related mol-ecules associate via pairs of C-Hâ¯S contacts, forming dimeric aggregates.
ABSTRACT
Metal complexes of dmit and related ligands, such as dmio, have been studied extensively over the last few decades: [dmit](2-) = bis(1,3-dithiole-2-thione-4,5-dithiolato); [dmio](2-) = bis(1,3-dithiole-2-one-4,5-dithiolato). While much effort has been placed on determining structural properties, very few vigorous spectroscopic studies of these metal complexes have been undertaken. The spectroscopic features of the infrared, Raman and UV-vis spectra, previously reported, have largely been used to characterize compounds. In particular, many details of the electronic structure are still to be revealed. We now report a detailed analysis of the UV-vis spectra of the [M(dmit)](-1) and [M(dmio)](-1) anions, where M = Sb(III) or Bi(III). Experimental spectra were deconvoluted and analysed by several theoretical methodologies, including ab initio CI, TD and CISD calculations. The results led to the assignments of several MLCT/LMCT bands, occurring between 390 and 300 nm, and the confirmation of metal orbital contributions to the HOMO-LUMO boundary.
Subject(s)
Tetraethylammonium/chemistry , Acetonitriles/chemistry , Antimony/chemistry , Bismuth/chemistry , Carbon/chemistry , Electronics , Ions , Ligands , Metals/chemistry , Models, Theoretical , Molecular Conformation , Oxygen/chemistry , Spectrophotometry/methods , Spectrophotometry, Ultraviolet/methods , Sulfur/chemistryABSTRACT
As shown previously by X-ray structure determinations, [tris(1,3-dithiole-2-thione-4,5-dithiolato)stannate(IV)](2-) salts, [Q](2)[Sn(dmit)(3)], contain isolated cations and dianions. While the tin centres generally having octahedral geometries, the overall shapes of the dianions of these complexes in the solid state can differ with conformations varying from T, Y to asymmetrical arrangements. We now report, as a follow up to our earlier study on the Y-shaped complex, [NEt(4)](2)[Sn(dmit)(3)], an experimental and theoretical study of the vibrational spectra of solid solvated {[AsPh(4)](2)[Sn(dmit)(3)] x Me(2)CO}, in which the dianion has a T-shaped conformation. The infrared and Raman spectra, recorded from 4000 to 150 cm(-1), have been analysed by different ab initio calculations based on restricted Hartree-Fock (RHF) and density functional theory (DFT-Beck3LYP). The calculations were carried out on isolated dianions and cations with the 6-31G and 6-31G(d) basis sets and effective core potentials of Steven, Bash and Krauss (SBK). Fundamentals, overtones and combinations have been assigned. Generally, the Y- and T-shaped dianions exhibit similar infrared/Raman spectra, apart from differences in the C=C and the symmetrical M-S stretching frequencies: such differences can be used diagnostically to distinguish the overall shape of the tris(chelated)metallate dianion.
Subject(s)
Organotin Compounds/chemistry , Sulfhydryl Compounds/chemistry , Thiones/chemistry , Models, Molecular , Molecular Conformation , Spectrophotometry, Infrared , Spectrum Analysis, Raman , Vibration , X-Ray Diffraction/methodsABSTRACT
The title compounds, (C16H36N)2[Sn(C3OS4)3], (I), and (C24H20P)2[Sn(C3OS4)3], (II), are examples of complex salts of the general form [Q]2[Sn(dmio)3], where Q is nBu4N+ or Ph4P+ and dmio is the 2-oxo-1,3-dithiole-4,5-dithiolate dianion. Features of both structures are the slightly distorted octahedral coordination of tin in the propeller-shaped dianions and the absence of any significant inter-anion contacts. The structure of (I) is particularly notable because all of the dianions in the sample crystal have the same propeller configuration, which is very unusual in this type of structure.
ABSTRACT
The title compounds are salts of the general form (Q(+))(2)[Zn(dmit)(2)](2-), where dmit corresponds to the ligand (C(3)S(5))(-) present in both and Q(+) to the counter-cations ((n)Bu(4)N)(+) [or C(16)H(36)N(+)] and (Ph(4)As)(+) [or C(24)H(20)As(+)], respectively. In the first case, Zn is in the 4e special positions of space group C2/c and hence the [Zn(dmit)(2)](2-) dianion possesses twofold axial crystallographic symmetry. Including these, there are now 11 known examples of [Zn(dmit)(2)](2-) or its analogues, with O replacing the exocyclic thione S, and [Zn(dmio)(2)](2-) dianions in nine structures with various Q. Comparison of these reveals a remarkable variation in details of the conformation which the dianion may adopt in terms of Zn coordination, equivalence of the Zn-S bond lengths, displacement of Zn from the plane of the ligand and overall dianion shape.
