A readily accessible chiral nnn pincer ligand with a pyrrole backbone and its Ni(II) chemistry: syntheses, structural chemistry, and bond activations
A new class of chiral C2-symmetric N-donor pincer ligands, 2,5-bis(2-oxazolinyldimethylmethyl)pyrroles (PdmBox)H, was synthesized starting from the readily available ethyl 2,2-dimethyl-3-oxobutanoate (1). The synthesis of the ligand backbone was achieved by oxidative enole coupling with CuC12 follow...
Saved in:
| Main Authors: | , , |
|---|---|
| Format: | Article (Journal) |
| Language: | English |
| Published: |
20 March 2017
|
| In: |
Inorganic chemistry
Year: 2017, Volume: 56, Issue: 6, Pages: 3631-3643 |
| ISSN: | 1520-510X |
| DOI: | 10.1021/acs.inorgchem.7b00077 |
| Online Access: | Verlag, Volltext: http://dx.doi.org/10.1021/acs.inorgchem.7b00077 Verlag, Volltext: https://doi.org/10.1021/acs.inorgchem.7b00077 
|
| Author Notes: | Jan Wenz, Alexander Kochan, Hubert Wadepohl, and Lutz H. Gade |
| Summary: | A new class of chiral C2-symmetric N-donor pincer ligands, 2,5-bis(2-oxazolinyldimethylmethyl)pyrroles (PdmBox)H, was synthesized starting from the readily available ethyl 2,2-dimethyl-3-oxobutanoate (1). The synthesis of the ligand backbone was achieved by oxidative enole coupling with CuC12 followed by Paal-Knorr-type pyrrole synthesis. The corresponding protioligands (RPdmBox)H (R = iPr: 5a; Ph: 5b) were obtained by condensation with amino alcohols and subsequent zinc-catalyzed cyclization. Reaction of the lithiated ligands with [NiCl2(dme)] yielded the corresponding square-planar nickel(II) complexes [(RPdmBox)NiCl] (6a/b). Salt metathesis of 6a with the corresponding alkali or cesium salts in acetone led to the formation of air- and moisture-stable [(iPrPdmBox)NiX] (X = F (7), X = Br (8), X = I (9), X = N3 (10), X = OAc (11). Furthermore, the conversion of [(iPrPdmBox)NiF] (7) with hydride transfer reagents such as PhSiH3 led to the stable hydrido species [(iPrPdmBox)NiH] (27), the stoichiometric transformations of which were studied. Treatment of 6a with organometallic reagents such as ZnEt2, PhLi, PhC≡CLi, NsLi, or (4FBn)2Mg(THF)2 gave the corresponding alkyl, alkynyl, or aryl complexes. The availability of the new nonisomerizable PdmBox pincer ligands allowed the comparative study of their ligation to square-planar complexes as helically twisted spectator ligands as opposed to the enforced planar rigidity of their iso-PmBox analogues and the way this influences the reactivity of the Ni complexes. |
|---|---|
| Item Description: | Gesehen am 26.11.2018 |
| Physical Description: | Online Resource |
| ISSN: | 1520-510X |
| DOI: | 10.1021/acs.inorgchem.7b00077 |