No abstract

The rNHC complexes (5-butyl-1,2-dimethylpyridin-4(1H)-ylidene)Cr(CO) 5 (1), as well as the novel compounds (1,2-dimethyl-5-phenylpyridin-4(1H)-ylidene)M(CO) 5 (2, M = Cr; 3, M = W) and (1-methylpyridin-4(1H)-ylidene)Cr(CO) 5 (7) were prepared from Fischer carbene complexes. Reaction of 1 with [Rh 2 (µ-Cl) 2 (CO) 4 ] then afforded the first rNHC Rh I complex, 4. Transfer of the ligand in 2 to Ph 3 PAu + afforded the cationic rNHC gold complex, 5 and reaction of 3 and 7

Readily prepared 2-, 4-and 5-bromo-3-methyl thiazolium triflates react by oxidative substitution with M(PPh 3 ) 4 (M = Ni or Pd) to furnish five of the expected normal and abnormal cationic thiazolylidene complexes (1a, 1b, 2a, 2b, and 3b). Carbene complex formation is accompanied by a ca. 40 ppm downfield shift of the a-N carbene carbons in Pd complexes 1 and 2 in their 13 C NMR spectra but the chemical shift of C(carbene) in the abnormal 3b (d 135.7) is particularly low. Crystal and molecular structures of complexes 1a, 2b, and 3b all indicate a square planar arrangement of the ligands around the central metal atoms. The new complexes catalyse Suzuki-Miyaura aryl coupling.

No abstract

Dedicated to Professor Wolfgang Beck on the occasion of his 80 th birthday in recognition of his many contributions to inorganic and organometallic chemistryTransmetallation and oxidative substitution were utilized to prepare examples of group 14, group 6 and group 10 complexes from lithiated or chlorinated 4,4-dimethyl-2-(2-thienyl) oxazoline or its N-alkylated analogs. Two of the product types (2 and 5) can be classified as α-thio or remote carbene complexes, depending on the position (3-or 5-) of attachment to the substituted thiophene ring. Spectroscopic measurements as well as crystal and molecular structure determinations clarified the bonding within the new compounds.