Understanding Synthetic Peculiarities of Cationic Molybdenum(VI) Imido Alkylidene N‐Heterocyclic Carbene Complexes. Issue 14 (26th March 2019)

• Record Type: Journal Article
• Authors: Schowner, Roman; Frey, Wolfgang; Buchmeiser, Michael R.
• Is Part Of: European journal of inorganic chemistry. Issue 14(2019)
• Page Start: 1911
• Page End: 1922
• Publication Date: 2019-03-26
• Subjects: Carbene ligands -- Olefin metathesis -- Molybdenum -- Synthesis design; Chemistry, Inorganic -- Periodicals; Organometallic chemistry -- Periodicals; Bioinorganic chemistry -- Periodicals; Solid state chemistry -- Periodicals; 546
• DOI: 10.1002/ejic.201900021
• Languages: English
• ISSNs: 1434-1948

Abstract

Abstract : We report on novel synthetic approaches to molybdenum imido alkylidene N‐heterocyclic carbene (NHC) complexes including the first NHC alkylidene complexes featuring pentafluorophenyl‐substituted imido ligands, highly basic 6‐Mes (6‐Mes = 1, 3‐dimesityl‐3, 4, 5, 6‐tetrahydropyrimidin‐2‐ylidene) NHC ligands and the preparation of the first representatives of cationic 14‐electron Mo imido alkylidene NHC catalysts bearing sterically demanding anionic terphenoxide ligands. Also, the Mo imido alkylidene and alkylidyne NHC bisalkoxide complexes [Mo(NR)(CHCMe2 Ph)(NHC)(OR′)2 ], [Mo(NH‐C6 F5 )(CCMe2 Ph)( a IMes){OCMe(CF3 )2 }2 ] ( a IMes = 1, 3‐dimesitylimidazol‐5‐ylidene, an abnormally C5 ‐bound imidazolylidene) and [Mo(NH‐2‐CF3 ‐C6 H4 )(CCMe2 Ph)(6‐Mes){OCMe(CF3 )2 }2 ] are presented. Anionic Mo amido alkylidyne complexes have been found to form preferentially in the presence of sterically demanding NHC and alkoxide ligands. The first Mo imido alkylidene NHC complexes containing the strongly basic 6‐Mes ligand, namely [Mo( N ‐C6 F5 )(CHCMe2 Ph)(6‐Mes)(Br)2 ], [Mo( N ‐2‐CF3 ‐C6 H4 )(CHCMe2 Ph)(6‐Mes)(Br)2 ] and [Mo(N‐2, 6‐Me2 ‐C6 H3 )(CHCMe2 Ph)(6‐Mes)(Br)2 ], were synthesized from the corresponding Mo imido dibromo alkylidene‐DME complexes (DME = 1, 2‐dimethoxyethane) and transformed into their cationic monobromo or monoalkoxide derivatives. Finally, we developed the high yield synthesis of Mo imido alkylidene NHC dichloro complexes via direct protonation of [Mo( N ‐Adamantyl)2 (CH2 CMe2 Ph)2 ] with HCl followed by stabilization with NHCs. Abstract : New, previously inaccessible neutral and cationic molybdenum imido alkylidene N‐heterocyclic carbene complexes have been prepared and characterized employing several synthetic approaches.