Germund Glatz

Copper-containing SiCN precursor ceramics (Cu@SiCN) as selective hydrocarbon oxidation catalysts using air as an oxidant.

A molecular approach to metal-containing ceramics and their application as selective heterogeneous oxidation catalysts is presented. The aminopyridinato copper complex [Cu(2)(Ap(TMS))(2)] (Ap(TMS)H=(4-methylpyridin-2-yl)trimethylsilanylamine) reacts with poly(organosilazanes) via aminopyridine elimination, as shown for the commercially available ceramic precursor HTT 1800. The reaction was studied by (1)H and (13)C NMR spectroscopy. The liberation of the free, protonated ligand Ap(TMS)H is indicative of the copper polycarbosilazane binding. Crosslinking of the copper-modified poly(organosilazane) and subsequent pyrolysis lead to the copper-containing ceramics. The copper is reduced to copper metal during the pyrolysis step up to 1000 degrees C, as observed by solid-state (65)Cu NMR spectroscopy, SEM images, and energy-dispersive spectroscopy (EDS). Powder diffraction experiments verified the presence of crystalline copper. All Cu@SiCN ceramics show catalytic activity towards the oxidation of cycloalkanes using air as oxidant. The selectivity of the reaction increases with increasing copper content. The catalysts are recyclable. This study proves the feasibility of this molecular approach to metal-containing SiCN precursor ceramics by using silylaminopyridinato complexes. Furthermore, the catalytic results confirm the applicability of this new class of metal-containing ceramics as catalysts.

Single and Double CCl-Activation of Methylene Chloride by P,N-ligand Coordinated Rhodium Complexes

Two in one: The simultaneous formation of bimetallic mu-methylene bridged Rh(III) complexes as well as dimeric Rh(III) complexes with terminal chloromethyl groups is observed for P,N-ligand stabilized Rh(I) complexes by C-Cl bond activation of methylene chloride. A mechanistic proposal for the formation of both activation products is also discussed. The synthesis of Rh(I) complexes with P-functionalized aminopyridine ligands is reported as well as the first simultaneous observation of a single and double activation of C-Cl bonds of methylene chloride affording both a dimeric Rh(III) complex bearing terminal CH(2)Cl groups in addition to a binuclear Rh(III) complex with a bridging mu-CH(2) group. The structures of the oxidative addition products were obtained by X-ray diffraction studies and NMR experiments were performed to elucidate some aspects of the reaction pathway.

Crystal structure of bis(2-(2,6-diisopropyl-phenylamino)-6-(2,4,6-triisopropylphenyl)-pyridinium) hexachloro-titanate(IV) toluene solvate, (C32H45N2)2[TiCl6] · C7H8

C71H98Cl6N4Ti, monoclinic, P121/c1 (no. 14), a = 14.273(3) Å, b = 14.778(3) Å, c = 16.970(3) Å, 3 = 103.21(3)°, V = 3484.7 Å, Z = 2, Rgt(F) = 0.055, wRref(F) = 0.151, T = 193 K. Source of material TiCl3(thf)3 (0.798 g, 2.146 mmol), KAp* (1.062 g, 2.146 mmol) (Ap* = deprotonated (2,6-diisopropyl-phenyl)-(6-(2,4,6-triisopropyl-phenyl)-pyridin-2-yl)-amine) [1] and THF (30 mL) were added to a Schlenk flask, and the mixture was stirred for 14 h at room temperature.After removing of the solvent, the residue was extracted with 20 mL of toluene. The filtrate was layered with hexane and upon standing at –78 °C for seven days, green crystals of the title complex were formed. Experimental details TheH atoms attached toN atomswere included in the refinement process due to their importancewith regard to theH-bond pattern. Discussion The title compound is amononuclear titanium(IV) complex. The titanium center is octahedrally coordinated by six chloro ligands. In both protonated aminopyridines, the Npyridine atoms are protonated and intermolecular hydrogen bonds are formed. The HNpyridine bridged the Cl2 and Cl3 atoms (d(NpyridineH···Cl2) = 2.826 Å and d(NpyridineH···Cl3) = 2.544 Å) with a Cl2–N2–Cl3 angle of 60.10°. The H(Namino) atom coordinates to the Cl1 (d(NaminoH···Cl1) = 2.650 Å). These intermolecular hydrogen bonding interactions leads in a transoid arrangement of the 2(2,6-diisopropyl-phenylamino)-6-(2,4,6-triisopropyl-phenyl)pyridinium ligands. An uncoordinated toluene molecule is also found in the crystal structure. 284 Z. Kristallogr. NCS 222 (2007) 284-286 / DOI 10.1524/ncrs.2007.0120