An Extremely Electron Poor Cationic Triazoliumylidene N-Heterocyclic Carbene: Experimental and Computational Studies

被引：17

作者：

Hoelzel, Torsten ^{[1
]}

Otto, Maximilian ^{[1
]}

Buhl, Hannes ^{[1
]}

Ganter, Christian ^{[1
]}

机构：

[1] Heinrich Heine Univ Dusseldorf, Inst Anorgan Chem & Strukturchem, Univ Str 1, D-40225 Dusseldorf, Germany

来源：

ORGANOMETALLICS | 2017年 / 36卷 / 22期

关键词：

TRANSITION-METAL-COMPLEXES; CATALYTIC TRANSFER HYDROGENATION; PI-ACCEPTOR PROPERTIES; STABLE CARBENES; NMR-SPECTROSCOPY; CHEMICAL-SHIFTS; REACTIVITY; LIGANDS; HYDROSILYLATION; SUBSTITUENT;

D O I：

10.1021/acs.organomet.7b00670

中图分类号：

O61 [无机化学];

学科分类号：

070301 ; 081704 ;

摘要：

The electronic properties of the long-known cationic 1,2,4-triazoliumylidene 3a have been determined. The Se-77 NMR chemical shift of its Se adduct 9 (delta = 138 ppm) indicates that 3a is only moderately pi-acidic. M(CO)(2)Cl complexes of 3a (M = Rh, Ir) allowed the IR spectroscopic determination of a TEP value of 2073 cm(-1), the highest value known to date for a N-heterocyclic carbene (NHC). The properties of cationic 3a were compared to those of the related neutral triazolylidene 5, which was prepared for comparison. Density functional theory calculations support the experimental findings. Overall, the cationic carbene 3a has to be considered a very poor sigma-donor. Nevertheless, 3a is able to form di- (19) and even tricationic bis-NHC complexes (20 and 21).

引用

页码：4443 / 4450

页数：8

共 103 条

[1]

ALCARAZO M, 2010, ANGEW CHEM, V122, P2596

[2] Steering the Surprisingly Modular π-Acceptor Properties of N-Heterocyclic Carbenes: Implications for Gold Catalysis [J].