TY  - JOUR
A1  - Zapf, Ludwig
A1  - Radius, Udo
A1  - Finze, Maik
T1  - 1,3-bis(tricyanoborane)imidazoline-2-ylidenate anion - a ditopic dianionic N-heterocyclic carbene ligand
JF  - Angewandte Chemie International Edition
N2  - The 1,3-bis(tricyanoborane)imidazolate anion 1 was obtained in high yield from lithium imidazolate and B(CN)\(_3\)−pyridine adduct. Anion 1 is chemically very robust and thus allowed the isolation of the corresponding H\(_5\)O\(_2\)\(^+\) salt. Furthermore, monoanion 1 served as starting species for the novel dianionic N-heterocyclic carbene (NHC), 1,3-bis(tricyanoborane)imidazoline-2-ylidenate anion 3 that acts as ditopic ligand via the carbene center and the cyano groups at boron. First reactions of this new NHC 3 with methyl iodide, elemental selenium, and [Ni(CO)\(_4\)] led to the methylated imidazolate ion 4, the dianionic selenium adduct 5, and the dianionic nickel tricarbonyl complex 6. These NHC derivatives provide a first insight into the electronic and steric properties of the dianionic NHC 3. Especially the combination of properties, such as double negative charge, different coordination sites, large buried volume and good σ-donor and π-acceptor ability, make NHC 3 a unique and promising ligand and building block.
KW  - inorganic chemistry
KW  - N-heterocyclic carbene
KW  - anioniccarbene
KW  - boron
KW  - cyanoborate
KW  - imidazolate
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-256498
VL  - 60
IS  - 33
ER  - 
TY  - JOUR
A1  - Zapf, Ludwig
A1  - Peters, Sven
A1  - Bertermann, Rüdiger
A1  - Radius, Udo
A1  - Finze, Maik
T1  - Tricyanoborane‐Functionalized Anionic N‐Heterocyclic Carbenes: Adjustment of Charge and Stereo‐Electronic Properties
JF  - Chemistry – A European Journal
N2  - The 1‐methyl‐3‐(tricyanoborane)imidazolin‐2‐ylidenate anion (2) was obtained in high yield by deprotonation of the B(CN)3‐methylimidazole adduct 1. Regarding charge and stereo‐electronic properties, anion 2 closes the gap between well‐known neutral NHCs and the ditopic dianionic NHC, the 1,3‐bis(tricyanoborane)imidazolin‐2‐ylidenate dianion (IIb). The influence of the number of N‐bonded tricyanoborane moieties on the σ‐donating and π‐accepting properties of NHCs was assessed by quantum chemical calculations and verified by experimental data on 2, IIb, and 1,3‐dimethylimidazolin‐2‐ylidene (IMe, IIa). Therefore NHC 2, which acts as a ditopic ligand via the carbene center and the cyano groups, was reacted with alkyl iodides, selenium, and [Ni(CO)\(_{4}\)] yielding alkylated imidazoles 3 and 4, the anionic selenium adduct 5, and the anionic nickel tricarbonyl complex 8, respectively. The results of this study prove that charge, number of coordination sites, buried volume (%V\(_{bur}\)) and σ‐donor and π‐acceptor abilities of NHCs can be effectively fine‐tuned via the number of tricyanoborane substituents.
KW  - N-heterocyclic carbene
KW  - anionic carbene
KW  - boron
KW  - cyanoborate
KW  - imidazolate
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-287200
VL  - 28
IS  - 39
ER  -