Susanne L. Huth

Square-pyramidal bonding of I2 molecules at the I− nodes of a polyiodide infinite pseudo-cubic 3D-network

The reaction of di-[2]-pyridyl-disulfide (L) with diiodine in molar ratios ranging between 1 : 0.5 and 1 : 5 afforded [(HL+)(I−)·5/2I2] as the only product, containing the first example of a self-assembled infinite polyiodide pseudo-cubic 3D-network featuring distorted square pyramidal I−·5I2 moieties at the nodes.

Synthesis and Characterization of Novel Gold(III) Complexes of Asymmetrically Aryl-Substituted 1,2-Dithiolene Ligands Featuring Potential-Controlled Spectroscopic Properties

The tetrabutylammonium (TBA(+)) salts of square-planar monoanionic gold complexes of the unsymmetrically substituted Ar,H-edt(2-) 1,2-dithiolene ligands (Ar,H-edt(2-)=arylethylene-1,2-dithiolato; Ar=phenyl (1(-)), 2-naphthyl (2(-)), and 1-pyrenyl (3(-))) were synthesized and characterized by spectroscopic and electrochemical methods and the corresponding neutral species (1, 2, and 3, respectively) were obtained in CH(2)Cl(2) solution at room temperature by diiodine oxidation. The single-crystal X-ray diffraction structural data collected for (TBA(+))(2(-)), supported by DFT theoretical calculations, are consistent with the ene-1,2-dithiolate form of the ligand and the Au(III) oxidation state. All complexes feature intense near-IR absorptions (at about 1.5 microm) in their neutral states and Vis-emitting properties in the 400-550 nm range, the energy of which is controlled by the charge of the complex in the case of the 3(-)/3 couple. The spectroscopic and electrochemical features of 1(x-) and 2(x-) (x=0, 1), both in their cis and trans conformations, were investigated by means of DFT and time-dependent (TD) DFT calculations.

Investigation on the reactivity of dithiophosphonato/dithiophosphato NiII complexes towards 2,4,6-tris-2-pyridyl-1,3,5-triazine: developments and new perspectives

The reactions between tptz and differently substituted dithiophosphonato [Ni(ROpdt)2] [ROpdt = (RO)(4-MeOC6H4)PS2-; R = Et (2); Pr (3); i-Pr (4); Bu (5)] and dithiophosphato [Ni((EtO)2PS2)2] (6) Ni(II) complexes have been investigated, and the characterisation of the resulting neutral mixed complexes (2.tptz)-(6.tptz) is reported. In all these complexes, tptz forces one of the two dithiophosphonato/dithiophosphato ligands to behave as a monodentate ligand, a coordination mode rarely found in analogous Ni(II) phosphorodithioato complexes. A comparison has been performed between the Ni-S bond distances of the new complexes and those of isologous dithiophosphonato, dithiophosphato and dithiophosphito Ni(II) square-planar complexes, and of their penta- and hexa-coordinated adducts. The results, also supported by DFT calculations, are discussed and explained in terms of the structural trans-effect (STE). The reactivity of 2.tptz towards AgNO3 and CuSO4 to yield the complex [Ni(EtOpdt)(tptz)(H2O)]NO3 (7), and the dimer [(Ni(tptz)(mu-SO4)(H2O)]2.6H2O (8), respectively, is consistent with the proposed bonding models.

Investigation into the reactivity of the coordinatively unsaturated phosphonodithioato [Ni(MeOpdt)2] towards 2,4,6-tris(2-pyridyl)-1,3,5-triazine: goals and achievements

The reaction between the coordinatively unsaturated phosphonodithioato complex [Ni(MeOpdt)2] (1) [MeOpdt = (MeO)(4-MeOC(6)H(4))PS2-] and tptz [2,4,6-tris(2-pyridyl)-1,3,5-triazine] has been investigated. Spectrophotometric and conductometric titrations showed the formation of a neutral and an ionic species, i.e. [Ni(MeOdtp)2(tptz)] (2) and [Ni(tptz)2](MeOdtp)2 (3), in correspondence to 1 : 1 and 2 : 1 tptz : ratios, respectively. XRD studies confirmed the formation of both complexes isolated in the compounds 2.MeOH and 3.4H(2)O. In the neutral complex 2 the central Ni(II) ion features a distorted octahedral coordination, achieved through three N-atoms of tptz and three S-atoms belonging to two MeOpdt anions, one of which unexpectedly acts as a monodentate S-donor. In 3.4H(2)O, the two phosphonodithioato anions are non-coordinating and counterbalance the charge of the [Ni(tptz)2](2+) distorted octahedral complex. From the reaction 2 of with I2 and Br2, crystals of [Ni(tptz)2](I3)2 (5) and [Ni(tptz)Br(micro-Br)]2 (6) have been obtained. The dinuclear complex 6 features a structure showing tubular canals with openings of about 6 x 6 A.

Characterisation of temperature-dependent phase transitions in 2,2-trimethylenedioxy- 4,4,6,6-tetrachlorocyclotriphosphazene, N3P3Cl4[O(CH2)3O]

BackgroundThe crystal structure of 2,2-trimethylenedioxy-4,4,6,6-tetrachlorocyclo triphosphazene has been determined at 120, 274 and 293 K. The result at 293 K confirms the room temperature Cmc21 structure, but at the lower temperatures the space group is Pna21. Nevertheless the basic structure remains the same, with only small displacements of the atoms, amounting to an average of 25 pm between 120 and 293 K.ResultsX-ray diffraction and DSC results indicate that the phase transition takes place in two steps between 274 – 293 K and provides an understanding of previous NQR results. In the intermediate temperature range the molecules are displaced from their room temperature positions in such a way as to give an average structure with Cmc21 symmetry.ConclusionThe overall phase transition is consistent with the occurrence of a soft lattice mode at room temperature in which a large displacement of the molecule in the x-direction is coupled with a flexing motion about an axis defined by the nitrogen atoms in the N1 and N3 positions.