Synthesis and crystal structure of bis­(9-mesityl-9,10-di­hydro-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 NH-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(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.