Chalcogen stabilized borate complexes of tantalum

In an attempt to isolate some electron precise early transition metal borate complexes, we have explored the reactions of [Cp*TaCl4] (Cp* = eta(5)-C5Me5) with chalcogen-based borate ligand Li[BH3(SPh)]. The room-temperature reaction yielded bimetallic borate complex [(Cp*Ta)(2)(mu-SPh){S(BH3)}{SPh(BH3)}] (1) that present two types of borate ligands, i.e., {BH3(SPh)} and {BH3(S)} ligands having unique coordination with the tantalum atoms. Interestingly, the {BH3(S)} ligand is coordinated to both the Ta centers in -eta(1):eta(2) fashion. On the other hand, thermolysis of [Cp*TaCl4] in the presence of Li[BH3(SPh)] yielded a bimetallic borate species [(Cp*Ta)(2)(mu-eta(3):eta(3)-B2H4S){mu-eta(2):eta(2)-S(C6H4)BH3}] (2). Compound 2 contains a triborane analog and a borate ligand, which are coordinated to two Ta atoms. This can also be considered as a notable example of Csingle bondH activated molecule, in which a B-C bond formation took place. Both the borate species have been characterized by mass spectrometry, IR spectroscopy, NMR spectroscopy, and single-crystal X-ray diffraction studies. The density functional theory (DFT) calculations further provided insights into the bonding and electronic structures of these bimetallic borate species.

Automated summary

Two electron precise early transition metal borate complexes were successfully synthesized by reacting with chalcogen-based borate ligands, showing unique coordination and structures. Characterization and DFT calculations provided insights into the bonding and electronic structures of these bimetallic borate species.