0000000000174017
AUTHOR
William Levason
Synthesis and structural characterisation of germanium(II) halide complexes with neutral N-donor ligands.
The Ge(II) complexes [GeX(2)(L-L)] (L-L = 1,10-phen (X = Cl, Br); L-L = Me(2)N(CH(2))(2)NMe(2), 2,2'-bipy (X = Cl)), [GeX(L-L)][GeX(3)] (L-L = 2,2'-bipy (X = Br); L-L = pmdta (MeN(CH(2)CH(2)NMe(2))(2)) (X = Cl, Br)) have been prepared and their crystal structures determined. The crystal structure of [GeCl(2){Me(2)N(CH(2))(2)NMe(2)}] shows a weakly associated centrosymmetric dimer based upon distorted square-pyramidal coordination at Ge(II) and containing asymmetrically chelating diamine ligands. The structure of [GeCl(2)(2,2'-bipy)] contains a chelating 2,2'-bipy ligand and forms a zig-zag chain polymer via long-range intermolecular Ge...Cl bridging interactions, leading to a very distorted…
Synthesis, Structures and DFT Calculations on Alkaline-Earth Metal Azide-Crown Ether Complexes
The first examples of azide complexes of calcium, strontium or barium with crown ethers have been prepared and fully characterised, notably [Ba([18]crown-6)(N3)2(MeOH)], [Sr([15]crown-5)(N3)2(H2O)], [Ca([15]crown-5)(N3)2(H2O)] and [Sr([15]crown-5)(N3(NO3)]. Crystal structures reveal the presence of a variety of coordination modes for the azide groups including kappa 1-, mu-1,3- and linkages via H-bonded water molecules, in addition to azide ions. The [Ba([18]crown-6)(N3)2(MeOH)].1/3 MeOH contains dinuclear cations with three mu-1,3-NNN bridges, the first example of this type in main group chemistry. The structures obtained have been compared with molecular structures computed by density fun…
Unexpected Structural Diversity in Alkali Metal Azide-Crown Ether Complexes: Syntheses, X-ray Structures, and Quantum-Chemical Calculations
A series of alkali metal azide-crown ether complexes, [Li([12]crown-4)(N-3)], [Na([15]crown-5)(N-3)], [Na([15]crown-5)(H2O)(2)]N-3, [K([18]crown-6)(N-3)(H2O)], [Rb([18]crown-6)(N-3)(H2O)], [Cs([18]crown-6)(N-3)](2), and [Cs([18]crown-6)(N-3)(H2O)(MeOH)], has been synthesised. In most cases, single crystals were obtained, which allowed X-ray crystal structures to be derived. The structures obtained have been compared with molecular structures computed by density functional theory (DFT) calculations. This has allowed the effects of the crystal lattice on the structures to be investigated. Also, a study of the M-N-terminal metalazide bond length and charge densities on the metal (M) and termin…
The characterization of molecular alkaly metal azides
Matrix isolation infrared (IR) studies have been carried out on the vaporisation of the alkali-metal azides MN(3) (M = Na, K, Rb and Cs). The results show that under high vacuum conditions, molecular KN(3), RbN(3) and CsN(3) are present as stable high-temperature vapour species, together with variable amounts of nitrogen gas and the corresponding metal atoms. The characterisation of these molecular azides is supported by ab initio molecular orbital calculations and density functional theory (DFT) calculations, and for CsN(3) in particular, by the detection of the isotopomers CS((14)N(15)N(14)N) and Cs((15)N(14)N(14)N). The IR spectra are assigned to a "side-on" (C(2v)) structure by comparis…
ChemInform Abstract: Synthesis, Structures and DFT Calculations on Alkaline-Earth Metal Azide-Crown Ether Complexes.
The first examples of azide complexes of calcium, strontium or barium with crown ethers have been prepared and fully characterised, notably [Ba([18]crown-6)(N3)2(MeOH)], [Sr([15]crown-5)(N3)2(H2O)], [Ca([15]crown-5)(N3)2(H2O)] and [Sr([15]crown-5)(N3)(NO3)]. Crystal structures reveal the presence of a variety of coordination modes for the azide groups including 1-, -1,3- and linkages via H-bonded water molecules, in addition to azide ions. The [Ba([18]crown-6)(N3)2(MeOH)]1/3 MeOH contains dinuclear cations with three -1,3-NNN bridges, the first example of this type in main group chemistry. The structures obtained have been compared with molecular structures computed by density functional th…