Synthesis and crystal structure of bis-(9-mesityl-9,10-di-hydro-10-aza-9-borabenzo[ h ]quinolinato-κ 2 N 1 , N 10 )zinc(II).

The title compound, [Zn(C 20 H 18 BN 2 ) 2 ] ( Zn L 2 ), is an overall uncharged chelate that consists of two units of an N H -deprotonated 10-aza-9-borabenzo[ h ]quinoline ligand ( L ) per Zn II center. It was synthesized in two steps by treating the protonated ligand HL with lithium bis-(tri-methyl-sil-yl)amide and further conversion with di-ethyl-zinc. Its asymmetric unit comprises one ZnL fragment; the mol-ecule is completed by application of inversion symmetry at Zn. Due to the fourfold coordination with nitro-gen atoms, the zinc(II) ion is located in a distorted tetra-hedral 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 inter-molecular π-π stacking inter-actions, while the polarized B-N bond is barely involved in any close atom contacts.