Srivastava Ravi, Moneuse Raphaël, Petit Julien, Pavard Paul-Alexis, Dardun Vincent, Rivat Madleen, Schiltz Pauline, Solari Marius, Jeanneau Erwann, Veyre Laurent, Thieuleux Chloé, Quadrelli Elsje Alessandra, Camp Clément
C2P2 UMR 5265, Institut de Chimie de Lyon, Université de Lyon, CNRS, Université Lyon 1, ESCPE Lyon, 43 Bd du 11 Novembre 1918, F-69616, Villeurbanne, France.
Centre de Diffractométrie Henri Longchambon, Université de Lyon, Université Lyon 1, Site CLEA-Bâtiment ISA, 5 rue de la Doua, 69100, Villeurbanne, France.
Chemistry. 2018 Mar 20;24(17):4361-4370. doi: 10.1002/chem.201705507. Epub 2018 Feb 26.
The straightforward synthesis of a new unsymmetrical hydroxy-tethered N-heterocyclic carbene (NHC) ligand, HL, is presented. The free ligand exhibits an unusual OH-carbene hydrogen-bonding interaction. This OH-carbene motif was used to yield 1) the first tantalum complex displaying both a Fischer- and Schrock-type carbene ligand and 2) a unique NHC-based early/late heterobimetallic complex. More specifically, the protonolysis chemistry between the ligand's hydroxy group and imido-alkyl or alkylidene-alkyl tantalum precursor complexes yielded the rare monometallic tantalum-NHC complexes [Ta(XtBu)(L)(CH tBu) ] (X=N, CH), in which the alkoxy-carbene ligand acts as a chelate. In contrast, HL only binds to rhodium through the NHC unit in [Rh(HL)(cod)Cl] (cod=cycloocta-1,5-diene), the hydroxy pendant arm remaining unbound. This bifunctional ligand scaffold successfully promoted the assembly of rhodium/tantalum heterobimetallic complexes upon either 1) the insertion of [Rh(cod)Cl] into the Ta-NHC bond in [Ta(NtBu)(L)(CH tBu) ] or 2) protonolysis between the free hydroxy group in [Rh(HL)(cod)Cl] and one alkyl group in [Ta(NtBu)(CH tBu) ].
本文介绍了一种新型不对称羟基连接的N-杂环卡宾（NHC）配体HL的直接合成方法。游离配体表现出一种不寻常的OH-卡宾氢键相互作用。这种OH-卡宾基序被用于制备：1）首个同时展示费舍尔型和施罗克型卡宾配体的钽配合物；2）一种独特的基于NHC的早期/晚期异双金属配合物。更具体地说，配体的羟基与亚氨基烷基或亚烷基烷基钽前体配合物之间的质子解化学过程产生了罕见的单金属钽-NHC配合物[Ta(XtBu)(L)(CH tBu) ]（X = N，CH），其中烷氧基卡宾配体作为螯合物。相比之下，HL仅通过[Rh(HL)(cod)Cl]（cod = 环辛-1,5-二烯）中的NHC单元与铑结合，羟基侧链保持未结合状态。这种双功能配体支架通过以下两种方式成功促进了铑/钽异双金属配合物的组装：1）将[Rh(cod)Cl]插入[Ta(NtBu)(L)(CH tBu) ]中的Ta-NHC键；2）[Rh(HL)(cod)Cl]中的游离羟基与[Ta(NtBu)(CH tBu) ]中的一个烷基之间的质子解反应。
