Synthesis and crystal structure of bis(9-mesityl-9,10-dihydro-10-aza-9-borabenzo[h]quinolinato-κ2 N 1,N 10)zinc(II)

Abstract

The title compound, [Zn(C20H18BN2)2] (Zn L 2 ), is an overall uncharged chelate that consists of two units of an NH-deprotonated 10-aza-9-borabenzo[h]quinoline ligand (L) per ZnII center. It was synthesized in two steps by treating the protonated ligand HL with lithium bis(trimethylsilyl)amide and further conversion with diethylzinc. Its asymmetric unit comprises one ZnL fragment; the molecule is completed by application of inversion symmetry at Zn. Due to the fourfold coordination with nitrogen atoms, the zinc(II) ion is located in a distorted tetrahedral environment. Besides the relatively short N—Zn bonds, Zn L 2 is characterized by the significant protrusion of the central ion from the plane of the ligand backbone. The crystal structure is consolidated by intra- and intermolecular π–π stacking interactions, while the polarized B—N bond is barely involved in any close atom contacts.