Thomas Kratz

Heterocycles as ligands 211. Stable titanium carbene complexes

The titanium carbene complexes 2 are obtained by the reaction of the imidazol-2-ylidenes 1 with TiCl4 in good yields. Careful hydrolysis of 2c gives the dinuclear complex 3c in which two complex fragments of pentacoordinated titanium are connected by a near linear oxygen bridge.

Heterozyklen als Liganden. XX: Spektroskopische und strukturelle Charakterisierung von Pentacarbonylmetall-Komplexen der Imidazol-2-ylidene

The imidazol-2-ylidene complexes I–III are obtained from M(CO)6 (M  Cr, Mo, W) and the corresponding imidazol-2-ylidenes in good yields. 13C-NMR data and the X-ray structure of II confirm the carbenes to be strong donor ligands, no evidence for significant π-interaction between the carbene carbon atom and the metal centre being detected.

2-Selenoimidazoline / 2-Selenoimidazolines

The 2-selenoimidazolines 5 are obtained from the reaction of the imidazol-2-ylidenes 4 with selenium in very good yields. The ylidic nature of the carbon selenium bond (2) is revealed both by NMR and by X-ray analysis. On comparison with the corresponding tellurium compounds 3, reduction of the carbon chalcogen bond order in 5 is suggested.

ZUR OXIDATION VON 2-SELENOIMIDAZOLINEN MIT IOD1

Abstract The stepwise oxidation of 2-selenoimidazolines 1 (ImSe; Im = 1,3-dihydro-1,3,4,5-tetraalkyl-2H-imi-dazol-2-ylidene) leads to a series of carbene stabilised selenium iodine compounds whose composition depend from the stoichiometry and the substituents at the nitrogen atoms. No diselenides or selenium(IV) compounds have been detected. The X-ray structures of the compounds [ImSeSelm]2+ (3c), (ImSel2)2I2 (5c) and (ImSel)I3 (6b) are reported.

HETEROCYCLEN ALS LIGANDEN XXII. 2-CHALKOGENOIMIDAZOLINE ALS LIGANDEN IN PENTACARBONYLMETALL-KOMPLEXEN

Abstract The chalcogenoimidazoline complexes N—CMe—CMe—NR—C=X·M(CO)3 (VIII-XI; R = Me, iso-Pr; X = S, Se, Te; M = Cr, Mo, W) are obtained from the metal hexacarbonyls (M = Cr, Mo, W) and the chalcogenoimidazolines IV-VII. In these complexes the chalcogeno ligands exhibit strong donor properties according to the sequence Te > Se > S which is demonstrated by n. m. r. and i. r. data. The X-ray structures of N(iso-Pr)—CMe—CMe—N(iso-Pr)—C=X·Cr(CO)3 (X = S; Se; VIIIa, IXa) are reported.

2-Seleno- and 2-Telluroimidazolines: Syntheses, Structures and Properties

2,3-dihydro-2-selenoimidazoles and their tellurium analogues (2) are formed through the reaction of the corresponding 2,3-dihydro-imidazol-2-ylidenes (1) with the chalcogenes. 2 exhibit nucleophilic properties demonstrated by the formation and properties of their iodine derivatives 3 – 7 and their pentacarbonyl metal complexes 8.

A stable carbene iodine adduct: secondary bonding in 1,3-diethyl-2-iodo-4,5-dimethylimidazolium iodide

The stable carbene iodine adduct 2 is formed by the reaction of the imidazol-2-ylidene 1 with iodine; the X-ray structure of 2 is reported.