A Dimetalloxycarbene Bonding Mode and Reductive Coupling Mechanism for Oxalate Formation from CO2 |
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| Authors: | Albert Paparo Dr Jared S Silvia Dr Christos E Kefalidis Dr Thomas P Spaniol Prof?Dr Laurent Maron Prof?Dr Jun Okuda Prof?Dr Christopher C Cummins |
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| Institution: | 1. Institute of Inorganic Chemistry, RWTH Aachen University, Landoltweg 1, 52056 Aachen (Germany);2. Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, MA 02139 (USA);3. Université de Toulouse et CNRS, INSA, UPS, CNRS;4. UMR 5215 LPCNO, 135 Avenue de Rangueil, 31077 Toulouse (France) |
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| Abstract: | We describe the stable and isolable dimetalloxycarbene (TiX3)2(μ2‐CO2‐κ2C,O:κO′)] 5 , where X=N‐(tert‐butyl)‐3,5‐dimethylanilide, which is stabilized by fluctuating μ2‐κ2C,O:κ1O′ coordination of the carbene carbon to both titanium centers of the dinuclear complex 5 , as shown by variable‐temperature NMR studies. Quantum chemical calculations on the unmodified molecule indicated a higher energy of only +10.5 kJ mol?1 for the μ2‐κ1O:κ1O′ bonding mode of the free dimetalloxycarbene compared to the μ2‐κ2C,O:κ1O′ bonding mode of the masked dimetalloxycarbene. The parent cationic bridging formate complex (TiX3)2(μ2‐OCHO‐κO:κO′)]B(C6F5)4], 4 B(C6F5)4], was simply deprotonated with the strong base K(N(SiMe3)2) to give 5 . Complex 5 reacts smoothly with CO2 to generate the bridging oxalate complex (TiX3)2(μ2‐C2O4‐κO:κO′′)], 6 , in a C? C bond formation reaction commonly anticipated for oxalate formation by reductive coupling of CO2 on low‐valent transition‐metal complexes. |
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| Keywords: | anilides carbene ligands CO2 fixation structure elucidation titanium |
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