Seven‐Coordinate Mo II −Diiodo Complexes with Benzothiazole−N‐Heterocyclic‐Carbene Ligands and Their Mo 0 Precursors: Synthesis, Structures, and Catalytic Application in the Epoxidation of cis ‐Cyclooctene

The oxidative addition of I 2 to molybdenum(0) complexes [Mo(CO) 4 (L NC )] ( 1 – 3 ; L NC1 =1‐(benzothiazolin‐2‐yl)‐3‐allyl‐2‐ylidene; L NC2 =1‐(benzothiazolin‐2‐yl)‐3‐benzylimidazol‐2‐ylidene; L NC3 =1‐(benzothiazolin‐2‐yl)‐3‐methylimidazol‐2‐ylidene) afforded the first isolable and crystallographically elucidated seven‐coordinate Mo II −diiodo complexes, [Mo(CO) 3 I 2 (L NC )] ( 4 – 6 ), with N‐heterocyclic carbene (NHC) ligands . The application of complexes 1 – 6 as precatalysts for the epoxidation of cis ‐cyclooctene with tert ‐butyl hydroperoxide (TBHP) as an oxidant has also been studied. Complexes 1 – 3 performed better than previously reported Mo 0 −carbonyl−NHC complexes, thereby producing the epoxide in 80–90 % yield after 24 h. Complexes 4 – 6 were superior to complexes 1 – 3 . Complex 5 was the most‐active Mo II −NHC complex, thereby achieving the epoxide in quantitative yield after 6 h.