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Backbone Reactivity of Lithium β‐Diketiminate (NacNac) Complexes with CO 2 , t BuNCO and i PrNCO
Author(s) -
Gauld Richard M.,
McLellan Ross,
Kennedy Alan R.,
Barker Jim,
Reid Jacqueline,
Mulvey Robert E.
Publication year - 2019
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201904013
Subject(s) - chemistry , dimer , lithium (medication) , amide , ligand (biochemistry) , carboxylate , monomer , chelation , medicinal chemistry , stereochemistry , crystallography , inorganic chemistry , receptor , organic chemistry , polymer , medicine , biochemistry , endocrinology
Though alkali metal NacNac (β‐diketiminate) complexes have been utilised in synthesis as NacNac‐transfer agents, studies of them in their own right with small molecules are exceptionally rare. Here, the lithium compound of the common 2,6‐diisopropylphenyl‐β‐methyldiketiminate [NacNac(Dipp, Me)] ligand is investigated with carbon dioxide and isocyanates. In all four cases reaction occurs at the backbone γ‐C atom of the NacNac ligand, which redistributes electronically into a diimine. Insertion of CO 2 gives an eight‐atom carboxylate (Li 2 O 4 C 2 ) ring at the γ‐C site in a dimer. Insertion of t BuNCO gives a secondary amide at the γ‐C site in a monomer with TMEDA chelating lithium. Double insertion of t BuNCO and (adventitious) oxygen gives a dimer with a (LiO) 2 central core involving the latter source. Insertion of less bulky ( i PrNCO) gives a dimer with dimerisation through the C=O bonds of the emergent secondary amide function.