Factors controlling the structure of alkylzinc amidinates: on the role of N -substituents

• Published in: Dalton transactions : an international journal of inorganic chemistry Vol. 52; no. 9; pp. 2712 - 2721
• Main Authors: Terlecki, Michał, Justyniak, Iwona, Leszczyński, Michał K, Bernatowicz, Piotr, Lewiński, Janusz
• Format: Journal Article
• Language: English
• Published: England Royal Society of Chemistry 28.02.2023
• Subjects: Chemical synthesis; Coordination; Crystallography; Ligands; Materials science; Molecular structure; NMR; Nuclear magnetic resonance; Single crystals; Steric hindrance; Structural stability; Zinc
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/d2dt03722j

Despite various applications of alkylzinc complexes supported by , -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 , '-diphenylformamidinate ligands as model , '-unsubstituted and , '-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] -type amidinate moieties are essentially unstable and tend to undergo Schlenk equilibria-mediated ligand scrambling leading to more thermodynamically stable non-stoichiometric [R Zn L ]- and [R Zn L ]-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 -substituents.