Chemistry of N,S‐Heterocyclic Carbene and Metallaboratrane Complexes: A New η 3 ‐BCC‐Borataallyl Complex

A high‐yielding synthetic route for the preparation of group 9 metallaboratrane complexes [Cp*MBH(L) 2 ], 1 and 2 ( 1 , M=Rh, 2 , M=Ir; L=C 7 H 4 NS 2 ) has been developed using [{Cp*MCl 2 } 2 ] as precursor. This method also permitted the synthesis of an Rh–N,S‐heterocyclic carbene complex, [(Cp*Rh)(L 2 )(1‐benzothiazol‐2‐ylidene)] ( 3 ; L=C 7 H 4 NS 2 ) in good yield. The reaction of compound 3 with neutral borane reagents led to the isolation of a novel borataallyl complex [Cp*Rh(L) 2 B{CH 2 C(CO 2 Me)}] ( 4 ; L=C 7 H 4 NS 2 ). Compound 4 features a rare η 3 ‐interaction between rhodium and the B‐C‐C unit of a vinylborane moiety. Furthermore, with the objective of generating metallaboratranes of other early and late transition metals through a transmetallation approach, reactions of rhoda‐ and irida‐boratrane complexes with metal carbonyl compounds were carried out. Although the objective of isolating such complexes was not achieved, several interesting mixed‐metal complexes [{Cp*Rh}{Re(CO) 3 }(C 7 H 4 NS 2 ) 3 ] ( 5 ), [Cp*Rh{Fe 2 (CO) 6 }(μ‐CO)S] ( 6 ), and [Cp*RhBH(L) 2 W(CO) 5 ] ( 7 ; L=C 7 H 4 NS 2 ) have been isolated. All of the new compounds have been characterized in solution by mass spectrometry, IR spectroscopy, and 1 H, 11 B, and 13 C NMR spectroscopies, and the structural types of 4 – 7 have been unequivocally established by crystallographic analysis.