N-heterocyclic carbene complexes of Group 6 metals

• The first dedicated and comprehensive review on Group 6 metal NHC complexes.
• The syntheses, structures, reactivities and functions of ca. 500 complexes are reviewed.
• Some emerging trends and applications are summarized.

Across the periodic table, Group 6 metals (Cr, Mo, W) play an important role in the development of carbene chemistry. In this review, we highlight the synthetic methodologies, structures, reactivities and functions of about 500 N-heterocyclic carbene (NHC) complexes of these metals reported in the last four decades. Some emerging trends and applications are also summarized.