@article{PhilippBertermannRadius2023,
  author    = {Philipp, Michael S. M. and Bertermann, R{\"u}diger and Radius, Udo},
  title     = {Activation of Ge-H and Sn-H Bonds with N-Heterocyclic Carbenes and a Cyclic (Alkyl)(amino)carbene},
  series = {Chemistry - A European Journal},
  volume    = {29},
  journal   = {Chemistry - A European Journal},
  number    = {3},
  doi       = {10.1002/chem.202202493},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-311929},
  year      = {2023},
  abstract  = {A study of the reactivity of several N-heterocyclic carbenes (NHCs) and the cyclic (alkyl)(amino)carbene 1-(2,6-di-iso-propylphenyl)-3,3,5,5-tetramethyl-pyrrolidin-2-ylidene (cAAC\(^{Me}\)) with the group 14 hydrides GeH2Mes2 and SnH2Me2 (Me=CH\(_{3}\), Mes=1,3,5-(CH\(_{3}\))\(_{3}\)C\(_{6}\)H\(_{2}\)) is presented. The reaction of GeH\(_{2}\)Mes\(_{2}\) with cAAC\(^{Me}\) led to the insertion of cAAC\(^{Me}\) into one Ge-H bond to give cAAC\(^{Me}\)H-GeHMes\(_{2}\) (1). If 1,3,4,5-tetramethyl-imidazolin-2-ylidene (Me\(_{2}\)Im\(^{Me}\)) was used as the carbene, NHC-mediated dehydrogenative coupling occurred, which led to the NHC-stabilized germylene Me\(_{2}\)Im\(^{Me}\)⋅GeMes\(_{2}\) (2). The reaction of SnH\(_{2}\)Me\(_{2}\) with cAAC\(^{Me}\) also afforded the insertion product cAAC\(^{Me}\)H-SnHMe\(_{2}\) (3), and reaction of two equivalents Me\(_{2}\)Im\(^{Me}\) with SnH\(_{2}\)Me\(_{2}\) gave the NHC-stabilized stannylene Me\(_{2}\)Im\(^{Me}\)⋅SnMe\(_{2}\) (4). If the sterically more demanding NHCs Me\(_{2}\)Im\(^{Me}\), 1,3-di-isopropyl-4,5-dimethyl-imidazolin-2-ylidene (iPr\(_{2}\)Im\(^{Me}\)) and 1,3-bis-(2,6-di-isopropylphenyl)-imidazolin-2-ylidene (Dipp\(_{2}\)Im) were employed, selective formation of cyclic oligomers (SnMe\(_{2}\))\(_{n}\) (5; n=5-8) in high yield was observed. These cyclic oligomers were also obtained from the controlled decomposition of cAAC\(^{Me}\)H-SnHMe\(_{2}\) (3).},
  language  = {en}
}
@article{PhilippBertermannRadius2022,
  author    = {Philipp, Michael S. M. and Bertermann, R{\"u}diger and Radius, Udo},
  title     = {N-Heterocyclic Carbene and Cyclic (Alkyl)(amino)carbene Adducts of Germanium(IV) and Tin(IV) Chlorides and Organyl Chlorides},
  series = {European Journal of Inorganic Chemistry},
  volume    = {2022},
  journal   = {European Journal of Inorganic Chemistry},
  number    = {32},
  doi       = {10.1002/ejic.202200429},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-293865},
  year      = {2022},
  abstract  = {A study on the reactivity of N-heterocyclic carbenes (NHCs) and the cyclic (alkyl)(amino)carbene cAAC\(^{Me}\) with selected germanium(IV) and tin(IV) chlorides and organyl chlorides is presented. The reactions of the NHCs Me\(_{2}\)Im\(^{Me}\), iPr\(_{2}\)Im\(^{Me}\) and Dipp2Im with the methyl chlorides ECl\(_{2}\)Me\(_{2}\) afforded the adducts NHC ⋅ ECl\(_{2}\)Me\(_{2}\) (E=Ge (1), Sn (2)), NHC=Me\(_{2}\)Im\(^{Me}\) (a), iPr\(_{2}\)Im\(^{Me}\) (b), Dipp\(_{2}\)Im (c)). The reaction of Me2Im\(^{Me}\) with GeCl\(_{4}\) led to isolation of Me\(_{2}\)Im\(^{Me}\) ⋅ GeCl\(_{4}\) (3), the reaction of iPr\(_{2}\)Im\(^{Me}\) with SnCl\(_{4}\) in THF afforded the THF adduct iPr\(_{2}\)Im\(^{Me}\) ⋅ SnCl\(_{4}\) ⋅ THF (4). Dipp\(_{2}\)Im ⋅ GeCl\(_{2}\)Me\(_{2}\) (1 c) isomerized into the backbone coordinated imidazolium salt [aDipp\(_{2}\)Im ⋅ GeClMe\(_{2}\)][Cl] (5) upon thermal treatment. The reactions of cAAC\(^{Me}\) with (i) ECl\(_{2}\)R\(_{2}\) (E=Ge, Sn) gave the adducts cAAC\(^{Me}\) ⋅ ECl\(_{2}\)R\(_{2}\) (R=Me: E=Ge (6); Sn (7); Ph: E=Ge (8)), with (ii) GeClMe\(_{3}\) and GeCl\(_{4}\) the salts [cAAC\(^{Me}\) ⋅ GeMe\(_{3}\)][Cl] (9) and [cAACMeCl][GeCl\(_{3}\)] (10), and (iii) with SnCl\(_{4}\) the salt [cAACMeCl][SnCl\(_{3}\)] (11) and the adduct cAAC\(^{Me}\) ⋅ SnCl\(_{4}\) (12). Reduction of 2 a with KC\(_{8}\) afforded the NHC-stabilized stannylene Me\(_{2}\)Im\(^{Me}\) ⋅ SnMe\(_{2}\) 13, reduction of 7 with either KC8 or 1,4-bis-(trimethylsilyl)-1,4-dihydropyrazin in the presence of SnCl\(_{2}\)Me\(_{2}\) yielded cAAC\(^{Me}\) ⋅ SnMe\(_{2}\) ⋅ SnMe\(_{2}\)Cl\(_{2}\) (14).},
  language  = {en}
}
@article{ZapfPetersBertermannetal.2022,
  author    = {Zapf, Ludwig and Peters, Sven and Bertermann, R{\"u}diger and Radius, Udo and Finze, Maik},
  title     = {Tricyanoborane-Functionalized Anionic N-Heterocyclic Carbenes: Adjustment of Charge and Stereo-Electronic Properties},
  series = {Chemistry - A European Journal},
  volume    = {28},
  journal   = {Chemistry - A European Journal},
  number    = {39},
  doi       = {10.1002/chem.202200275},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-287200},
  year      = {2022},
  abstract  = {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.},
  language  = {en}
}