Zinc compounds supported by β-enaminone and β-diketiminate ligands: syntheses, characterization and catalytic behaviors toward cross-coupling of B2Pin2 with aryl iodides

The application of two β-enaminone ligands and one β-diketiminate ligand in the preparation of zinc complexes is reported. Three dinuclear zinc compounds [Zn₂(L¹)₂Et₂] (1), [Zn₂(L²)₂Et₂] (2) and [Zn₂(L³)Et₂] (3) were synthesized, and the catalytic potential of 1–3 for the cross-coupling of B₂Pin₂ with aryl iodides was investigated (HL¹ = 4-(mesitylamino)pent-3-en-2-one, HL² = 4-((2,4,6-tricyclopentyl- phenyl)amino)pent-3-en-2-one, H₂L³ = N,N′-((ethane-1,2-diylbis(azanylylidene)) bis(pent-2-en-2-yl-4-ylidene))bis(2,4,6-tricyclopentylaniline)). The purpose of this work was to examine the influence of changes in the backbones of the ligands on the catalytic properties of 1–3. The catalytic activity of 3 was the highest, revealing that the steric hindrance of the ligands coordinating with zinc ions affects the catalytic efficiency. The borylation of aryl iodides catalyzed by 3 can occur under mild conditions, and a series of substrates with different functional groups can be borylated smoothly in satisfactory yields.