Hans G. Schmidt

DIMETHYL TELLURIUM(IV) DERIVATIVES : SYNTHESIS, SPECTROSCOPIC CHARACTERISATION AND STRUCTURES OF ME2TEBR2 AND ME2TE(OCOC6H5)2

The comparative solution 1H-NMR spectra and solid state crystal structures of dimethyltellurium dihalides, Me2TeX2 (X=CI, Br, I) are described. The dimethyltellurium dicarboxylates, Me2TeX′2 (X′=OCOC6H5, OCOCH3, OCO) were obtained from the reactions of Me2TeI2 with silver carboxylates. They were characterised by IR, 1H- and 13C-NMR spectroscopy. The structures of Me2TeBr2 and Me2Te(OCOC6H5)2 were established by single crystal X-ray diffraction studies. Both possess immediate distorted trigonal bipyramidal geometries with a stereochemically active electron lone pair and the latter contains weak intermolecular C–H⋯O interactions.

Diboraethenverbindungen als liganden in metallkomplexen ☆: IX. Synthese und komplexierung von derivaten des Δ4-1,2-diaza-3,6-diborins. Strukturen des 4,5-diethyl-3,6-dimethyl-1,2-diaza-3,6-diborins und des entsprechenden tricarbonylchrom-komplexes

Reactions of 3,4-diethyl-2,5-dimethyl-1,2,5-thiadiborolene (I) with hydrazines lead to 1,2-diaza-3,6-diborin (IIa) and its methyl (IIb) and dimethyl (IIc) derivatives. Their constitution follows from spectroscopic data. The X-ray structure analysis of IIa proves the planar arrangement of the ring atoms with the distances NN 139.1, BN 138.7, BC 156.1 and CC 137.1 pm. The compound crystallizes in space group Pnma with a 917(1), b 1680(3), c 668(1) pm and four molecules in the unit cell. Diazadiborins (II), which are isoelectronic and isosteric with benzene and borazine, react with (CH3CN)3Cr(CO)3 yielding red tricarbonylchromium complexes (III). As in hexaethylborazinetricarbonylchromium the metal—ring atom distances in IIIa are different: CrN 214.5(10), CrC 230(1), CrB 236(1) pm. The NN and CC distances are slightly changed, for BC a shortening to 1.52(1) and for BN a lengthening to 143(2) pm is found. IIIa crystallizes in space group Pbca with Z = 8 and a 1312.4(7), b 1617.7(9) and c 1421.4(8) pm.

Benzo-1,2,3,6-diazadiborine als liganden in d6-(CO)3M-metallkomplexen

Benzo-1,2,3,6-diazadiborines (III) react with hexacarbonyls of chromium, molybdenum and tungsten to yield the corresponding tricarbonyl-(benzo[d]-1,2,3,6-diazadiborine)metal complexes. From 1H, 11B and 13C NMR results it is concluded that complexation of the (CO)3M-group occurs at the benzo ring. The ligands IIIa–IIIc exhibit better π donor properties than benzene.

1,3-bis(silyl)indole-Synthese und Kristallstruktur

Abstract 1-(Di-tert-butylfluorosilyl)indole ( 1 ) is prepared by the reaction of lithiated indole with (di-tert-butyldifluoro)silane. Compound 1 reacts with tert-butyllithium to give a lithio derivative, in which the lithium has replaced the hydrogen on the C(3)-atom, as indicated by the formation of 1,3-bis(silyl)indoles 2–4 in the reactions with fluorosilanes. In order to prove the conclusions, drawn from the NMR spectra of 2–4 , the crystal structure of 1-(di-tert-butylfluorosilyl)-3-(trimethylsilyl)indole ( 2 ) was determined. 1-(Di-tert-butylfluorsilyl) indol ( 1 ) entsteht in der Reaktion des lithiierten Indol mit Di-tert-butyldifluorsilan. 1 reagiert mit tert-Butyllithium zum Lithioderivat. Die Bildung der 1,3-Bis(silyl)indole 2–4 in der Reaktion mit fluorsilanen deutet die Substitution des Wasserstoffs durch Lithium am C(3)-Atom an. Zum Beweis der Schlusfolgerungen aus den NMR-Spektren von 2–4 wurde eine Kristallstrukturuntersuchung des 1-(Di-tert-butyltfluorsily l)-3-(trimethylsilyl)indols durchgefuhrt.

Notizen: The Crystal Structure of [Et4N]22+[TeI6]2-, a Tetraalkyl Ammonium Salt Containing a Discrete Octahedral [TeI6]2- Anion

The structure of [Et4N]22+[TeI6]2-, the first tetraalkyl ammonium salt to contain the almost regular octahedron of a discrete [TeI6]2- anion, has been determined by single crystal X-ray diffraction studies. It crystallizes in the monoclinic space group C2/c with a = 18.757(3), b = 11.578(2), c = 15.447(2) Å, β = 109.380(10)°. The [TeI6]2- anion has Te - I bond distances in the range of 2.845 to 2.948 Å and I - Te - I bond angles in the range of 89(1) to 90.1(1)°.

Reactions of tetrasulphur tetranitride with titanium and vanadium tetrachlorides; crystal structure of VCl2(S2N3)

Tetrasulphur tetranitride reacts with excess of VCl4 in CH2Cl2to form a mixture of VCl2(S2N3)(2) and S2N2·VCl4(3), whereas with excess of TiCl4 only S4N4·TiCl4(1) is formed. Crystals of (2) are triclinic, space group P, with a= 571.3(2), b= 695.7(3), c= 772.9(3) pm, α= 95.38(3), β= 99.62(3), γ= 97.58(3)°, and Z= 2. The structure was refined to R= 0.053 for 1 601 unique observed diffractometer data. It consists of chlorine-bridged dimers, linked by additional weak V–N interactions to form polymeric chains. The six-membered VNSNSN ring is effectively planar.

Tetrakis(tetrasulphur tetranitrogen dioxide)silver hexafluoroarsenate(V)

A complex of silver(I) containing tetrasulphur tetranitrogen dioxide ligands has been prepared. The crystals of [Ag(S4N4O2)4]+[AsF6]– are triclinic, space group P, with unit-cell dimensions a= 1 142.6(6), b= 1 194.9(5), c= 1 254.8(6) pm, α= 66.44(4), β= 96.71(4), γ= 91.30(4)°, and Z= 2, final R= 0.039 for 4 968 unique diffractometer data with F > 3σ(F). The Ag atom lies 53 pm below a square of four nitrogen atoms (mean Ag–N 256 pm). Bisdisphenoidal (triangulated dodecahedral) co-ordination of Ag is completed by two intramolecular Ag–O contacts (mean 307 pm), and intermolecular Ag–N and Ag–O interactions (both 273 pm). These intermolecular interactions give rise to a centrosymmetric cationic dimer. The S4N4O2 ligands are approximately planar except for the SO2 units; only nitrogen and oxygen atoms attached to SVI interact with Ag, thereby causing the least disruption of delocalised bonding in the rest of the ring.

Darstellung und Ligandeneigenschaften eines 1.2.5-Azadiborolen-Derivates [1] / Synthesis and Ligand Properties of an 1,2,5-Azadiborolene Derivative [1]

3,4-Diethyl-1,2,5-trimethyl-1,2,5-azadiborolene (3) is obtained from 3,4-diethyl-2,5-dimethyl-1,2,5-thiadiborolene (1) and heptamethyldistannazan. The Lewis-acidic π4 ligand (3) forms the transition metal complexes 5, 6, 7 and 8, when reacted with Fe2(CO)9, (C5H5)CO(CO)2, Ni(CO)4 and Co2(CO)8, respectively. The properties of 5-8 are compared with those of the corresponding thiadiborolene complexes. In contrast to 1 the azadiborolene ligand does not favor the formation of tripledecker complexes