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- Title
Nickel(II) Complexes with Tritopic N<sup>imine</sup>C<sup>NHC</sup>N<sup>amine</sup> Pincer Ligands.
- Authors
Ren, Xiaoyu; Wesolek, Marcel; Braunstein, Pierre
- Abstract
Abstract: Tritopic NCNHCN′ ligands containing a central N‐heterocyclic carbene (NHC) donor flanked by two chemically‐different nitrogen donors (Nimine and Namine) were evaluated as potential tridentate pincer‐type ligands in NiII complexes. The imidazolium chloride [(ImH){C(Me)=NDipp}(C2NMe2)]Cl (1) and the ammonium‐imidazolium dichlorides [(ImH){C(Me)=NDipp}(C2NHMe2)]Cl2 (4) and [(ImH){C(Me)=NDipp}(C3NHMe2)]Cl2 (5), differing by the length (C2 or C3) of the alkyl spacer were used as precursors. Oxidative addition of 1 to [Ni(cod)2] afforded the dinuclear bis‐NHC NiII complex [Ni2Cl2{μ‐C(Me)=NDipp‐κ2Nimine,C}{μ‐Im(C2NMe2)‐κ3Namine,CNHC,Nimid}{Im[C(Me)=NDipp](C2NMe2)‐κ1CNHC}] (2) resulting from partial ligand rearrangement. A dinuclear byproduct 3 was also isolated. The salt [NiCl{Im[C(Me)=NDipp](C2NMe2)‐κ3Nimine,CNHC,Namine}]2[NiCl4] (6) containing two NimineCNHCNamine pincer NiII complex cations was obtained from 4. In contrast, the reaction of closely related 5 yielded [NiCl{Im[C(Me)=NDipp](C3NMe2)‐κ2Nimine,CNHC}{μ‐Im[C(Me)=NDipp](C3NMe2NiCl3}‐κ2Namine,CNHC}] (7 a), a dinickel(II) complex that contains a Nimine,CNHC‐chelating and a bridging κ2Namine,CNHC ligand. The molecular structures of 2, 3, 6, 7 a⋅THF, 7 b, an isomer of 7 a, and 8⋅CH2Cl2 have been determined by single‐crystal X‐ray diffraction. Our results emphasize the often‐underestimated importance of seemingly minor changes in the length of the spacers connecting a NHC donor group to its N‐bound lateral functionalities.
- Subjects
NICKEL isotopes; METAL complexes; AMINE analysis; LIGANDS (Chemistry); HETEROCYCLIC chemistry; CARBENE derivatives
- Publication
Chemistry - A European Journal, 2018, Vol 24, Issue 55, p14794
- ISSN
0947-6539
- Publication type
Article
- DOI
10.1002/chem.201802969