Metal–Metal Synergy in Well-Defined Surface Tantalum–Iridium Heterobimetallic Catalysts for H/D Exchange Reactions

Sébastien Lassalle (1) , Ribal Jabbour (2) , Pauline Schiltz (1) , Pierrick Berruyer (2) , Tanya K Todorova (3) , Laurent Veyre (1) , David Gajan (2) , Anne Lesage (2) , Chloé Thieuleux (1) , Clément Camp (1)

1 C2P2 - Laboratoire de Chimie, Catalyse, Polymères et Procédés, R 5265
2 CRMN - Centre de RMN à très hauts champs de Lyon
3 LCPB - Laboratoire de Chimie des Processus Biologiques

A novel heterobimetallic tantalum/iridium hydrido complex, [{Ta(CH2 t Bu)3}{IrH2(Cp*)}] 1, featuring a very short metal-metal bond, has been isolated through an original alkane elimination route from Ta(CH t Bu)(CH2 t Bu)3 and Cp*IrH4. This molecular precursor has been used to synthesize well-defined silica-supported low-coordinate heterobime-tallic hydrido species [≡SiOTa(CH2 t Bu)2{IrH2(Cp*)}] 5 and [≡SiOTa(CH2 t Bu)H{IrH2(Cp*)}] 6 using a surface organometallic chemistry approach (SOMC). The SOMC methodology prevents undesired dimerization as encountered in solution and leading to a tetranuclear species [{Ta(CH2 t Bu)2}(Cp*IrH)]2, 4. This approach therefore allows access to unique low-coordinate species not attainable in solution. These original supported Ta/Ir species exhibit drastically enhanced catalytic performances in H/D exchange reactions with respect to (i) monometallic analogues as well as (ii) homogeneous systems. In particular, material 6 promotes the H/D exchange between fluorobenzene and C6D6 or D2 as deuterium sources with excellent productivity (TON up to 1422; TOF up to 23.3 h-1) under mild conditions (25°C, subatmospheric D2 pressure) without any additives.

Mots clés: Surface organometallic chemistry; early/late heterobimetallics; H/D exchange; catalysis; hydrides; tantalum; iridium

Domaines: Chimie

Sébastien Lassalle, Ribal Jabbour, Pauline Schiltz, Pierrick Berruyer, Tanya K Todorova, et al.. Metal–Metal Synergy in Well-Defined Surface Tantalum–Iridium Heterobimetallic Catalysts for H/D Exchange Reactions. Journal of the American Chemical Society, 2019, ⟨10.1021/jacs.9b08311⟩. ⟨hal-02382262⟩