Synthesis and Structural Characterization of Novel Oxorhenium(V) Complexes Containing N‐Heterocyclic Carbenes

Rhenium and technetium complexes with N-heterocyclic carbenes – A review

“…They were prepared by the addition of LiCH 3 or LiC 6 H 5 to [Tc 2 (CO) 10 ] or [Re 2 (CO) 10 ] and subsequent methylation. The products have the general formula [(CO) 9 M 2 C(OCH 3 )R] (1) (M = Re, Tc; R = CH 3 , C 6 H 5 ) [5], and this synthetic route has successfully been applied for further examples containing additional {Cp*} À (2) or PPh 3 ligands (3) [6,7].…”

“…The first crystallographically characterised representatives were not published until 2003 [1,2]. This lack of knowledge is unexpected considering the extensive coordination chemistry of such ligand systems with almost all transition metals [3] and the wide range of applications that representatives of this group of compounds have found in various fields [4].…”

Dioxomolybdenum(VI) complexes containing N-heterocyclic carbenes

“…This is in agreement with the results recently published by Abram and co-workers, who observed that the number of NHCs introduced in a series of oxorhenium complexes depends on the electron-donating nature of the carbene, the more electron-donating the carbene, the higher the number of ligands [13]. In this sense, 4,5-dimethyl substituted NHCs always provide complexes with general formula [ReOCl-(NHC) 4 ] 2+ [4,15] (complexes with less than four carbenes could not be obtained), while non-substituted and triazolylidene NHCs provide ReOCl 3 (NHC) 2 [5] and [ReO(OMe)-Cl 2 (NHC)(PPh 3 )], respectively.…”

“…Although most of the NHC-metal complexes reported to date refer to late transition metals in low oxidation states, a few examples concerning the coordination of these ligands to high oxidation state species have been reported [3][4][5]. Regarding the studies of N-heterocyclic carbene complexes of molybdenum, these are scarce, and most of them concern carbonyl molybdenum (0) complexes [6].…”

The Role of NHC Ligands in Oxidation Catalysis

“…for rhenium [71,72] and uranium [73], but no oxygen transfer using those complexes has been reported yet.…”