Zur Frage eines Wolfram‐Carbonyl‐Carben‐Komplexes

Coordinated Isonitriles

“…So it is even possible to stabilize isonitriles as ligands of complexes which do not exist in the free state. For example, the parent compound of all isonitriles "hydrogen isocyanide" XXXV cannot be isolated and exists only in equilibrium (13) with hydrogen cyanide XXXVa.…”

Fischer mono- and biscarbene complexes of tungsten with mono- and dimeric heteroaromatic substituents

“…The following dimeric heteroarene precursors were synthesized according to known literature methods: 2,2'-Thienylfuran (A) [13] and 4 N-methyl-2-(2'-thienyl)pyrrole (B) [13]. For the carbene complexes, well-known Fischer synthetic methodology was used [1] [20].…”

“…0.5 V less negative potential than the first reduction of the related monocarbene complex 1, see Figure 10. From a quantum chemistry point of view, the LUMO energy of (7), (10) and (11) is much lower than that of complex (1), making the reduction of (7), (10) and (11) easier than that of (1). The added electron during the reduction of (10) and (11) can be distributed over two thienyl units, making the reduced complex relative more stable to such an extent that a re-oxidation peak of the reduction process is observed, with E  0.115 V in CH 3 CN, making the reduction process 15 For the dimeric complex (7) with a direct thienyl ring as linker, two reduction peaks, associated with the reduction of the two carbene carbons, are observed, while dimeric complexes (11) and (12) 16 with two thienyl rings as linker, produce only one reduction peak; proposed to be the simultaneous reduction of the two carbene carbons.…”

“…Although the first Fischer carbene complex had been synthesized in 1964 already [1], the redox properties and activity of the generated radical species have only been considered more recently.…”

Synthesis and structural characterization of (pyrazolyl)alkenyl Fischer carbene complexes of chromium and tungsten

“…Fischer carbene complexes were first synthesized by Fischer and Maasbö l in 1964 [1,2] and have been paid much attention in the last two decades because they can be rather readily prepared and manipulated to demonstrate diverse reactivity in organic synthesis [3]. Transformations from alkynyl carbene to alkenyl carbene complexes have been extensively investigated.…”