Terlecki M, Justyniak I, Leszczyński MK, Bernatowicz P, Lewiński J. Factors controlling the structure of alkylzinc amidinates: on the role of
N-substituents.
Dalton Trans 2023;
52:2712-2721. [PMID:
36748844 DOI:
10.1039/d2dt03722j]
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Abstract
Despite various applications of alkylzinc complexes supported by N,N-bidentate ligands in chemistry and materials science, the corresponding organozinc amidinates still represent an insufficiently explored area. To gain a more in-depth understanding of factors controlling the structure and stability of alkylzinc amidinates, we selected benzamidinate and N,N'-diphenylformamidinate ligands as model N,N'-unsubstituted and N,N'-diaryl substituted ligands, respectively, to systematically modify the secondary coordination sphere of the Zn center. A series of new alkylzinc amidinates has been synthesized and their molecular structures identified in both the solid state (single-crystal X-ray crystallography) and solution (NMR and FTIR spectroscopy). The results indicate that [RZnL]x-type amidinate moieties are essentially unstable and tend to undergo Schlenk equilibria-mediated ligand scrambling leading to more thermodynamically stable non-stoichiometric [R2Zn3L4]- and [R3Zn4L5]-type complexes. This process is significantly influenced by the secondary coordination sphere noncovalent interactions as well as the steric hindrance provided by both zinc-bounded alkyl groups and the N-substituents.
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