Hexacarbonyls and Carbonyl Complexes of Carbon σ-Bonded Ligands of Chromium, Molybdenum and Tungsten

Chromium bis(phosphoranimine) complexes; bridging chromium carbenes with no CO or Cp supporting ligands†

“…[2][3][4][5] Chromium carbene chemistry is dominated by lowvalent derivatives stabilized in general by carbonyl ligands. 6 High valent chromium carbene derivatives are rare [7][8][9] in contrast to the heavier group 6 metals, molybdenum and tungsten, which provide numerous examples of carbonyl-free carbene complexes. 3,4,10 Only three carbonyl-free chromium carbene complexes have been structurally characterized [11][12][13] although several attempts to make such chromium systems have been reported.…”