Insertion von Rhodizonsäure in die Gallium‐Gallium‐ bzw. Indium‐Indium‐Bindungen von Digallan(4)‐ bzw. Diindan(4)‐Verbindungen

Insertion of Rhodizonic Acid into the Gallium‐Gallium and Indium‐Indium Bonds of Digallane(4) and Diindane(4) Compounds Rhodizonic acid (C₆O₆H₂, 5, 6‐dihydroxy‐5‐cyclohexene‐1, 2, 3, 4‐tetraone) did not react with tetrakis[bis(trimethylsilyl)methyl] digallane(4) ( 1 ) and the corresponding diindium compound ( 2 ) by the transfer of protons. Instead the acid was completely inserted into the element‐element bonds of the starting compounds and the gallium or indium atoms were oxidized from the oxidation state of +II to +III. In contrast to the free acid, the OH groups of the products are not attached to neighbouring carbon atoms, but occupy the 1, 4‐positions of the central six‐membered rings. Both dialkylgallium and dialkylindium groups of the products ( 3 (Ga) and 4 (In)) are coordinated by two oxygen atoms. They adopt opposite positions at the C₆O₆ molecular core.     

Synthese und Charakterisierung von InIII–SnII‐Halogenido‐Alkoxiden und von Indiumtri‐tert‐butoxid

Synthesis and Characterization of In^III–Sn^II‐Halogenido‐Alkoxides and of Indiumtri‐ tert ‐butoxide Through sodium halide elimination between Indium(III) halides and sodium‐tri‐tert‐butoxistannate(II) or sodium‐tri‐tert‐butoxigermanate(II) the three new heterometallic and heteroleptic alkoxo compounds THF · Cl₂In(OtBu)₃Sn ( 1 ), THF · Br₂In(OtBu)₃Sn ( 2 ), and THF · Cl₂In‐ (OtBu)₃Ge ( 3 ), have been synthesized. The molecular structures of 1 and 2 in the solid state follow from single crystal X‐ray structure determinations while structural changes in solution may be derived from temperature dependant NMR spectroscopy. The crystal structures of compounds 1 and 2 are despite different halide atoms isostructural. Both crystallize in the ortho‐rhombic crystal system in space group Pbca with eight molecules per unit cell. The heavy atoms occupy the apical positions of empty trigonal bipyramids of almost point symmetry C_s(m) and are connected through oxygen atoms occupying the equatorial positions. The indium atoms in both compounds are in the centers of distorted octahedra from 4 oxygen and 2 halogen atoms whereas the tin atoms are coordinated by three oxygen atoms in a trigonal pyramidal fashion. Although the coordinative bonding of THF to indium leads to an asymmetry of the molecule the NMR spectra in solution are simple showing a more complex pattern at lower temperatures. Tri(tert‐butoxi)indium [In(OtBu)₃]₂ ( 4 ), is obtained through alcoholysis of In(N(Si(CH₃)₃)₂)₃ using tert‐butanol in toluene and is crystallized from hexane. The X‐ray structure determination of 4 seems to be the first one of a homoleptic and homometallic indiumalkoxide. Compound 4 crystallizes in the monoclinic crystal system in a dimeric form with eight molecules in the unit cell of space group C2/c. The dimeric units have C₂ symmetry and an almost planar In₂O₂ ring which originates from oxygen bridging of the monomers. Through this mutual Lewis acid base interaction the indium atoms get four oxygen ligands in a distorted tetrahedral environment.     

Zur Hydrolyse von 2,3‐Dihydro‐1,3‐di‐tert‐butyl‐4,5‐dimethylimidazol‐2‐yliden. Die Kristallstruktur von 1,3‐Di‐tert‐butyl‐4,5‐dimethylimidazoliumhydrogencarbonat

On the Hydrolysis of 2,3‐Dihydro‐1,3‐di‐tert‐butyl‐4,5‐dimethylimidazol‐2‐ylidene. The Crystal Structure of 1,3‐Di‐tert‐butyl‐4,5‐dimethylimidazolium Bicarbonate 1,3‐Di‐tert‐butyl‐4,5‐dimethylimidazolium bicarbonate ( 7 ), formed on the exposure of 2,3‐dihydro‐1,3‐di‐tert‐butyl‐4,5‐dimethylimidazol‐2‐ylidene ( 6 ) towards air, is prepared on the reaction of 6 with ammonium bicarbonate; its crystal structure analysis reveals the presence of dimeric bicarbonate anions linked to each other and to the imidazolium ions with hydrogen bonds.