Triorganyl‐ and Diorganyloxozirconium Hydridoborates – Synthesis and Structures

The reactions of Zr(OBu) 4 and Zr(OEt) 4 with H 3 B · THF in THF led to HB(OR) 2 and B(OR) 3 , but no zirconium tetrahydroborate [(RO) 4– n Zr(BH 4 ) n ] could be isolated. On the contrary, the reactions of [ t Bu 3 CO] 4– n ZrCl n and [ t Bu 3 SiO] 4– n ZrCl n with LiBH 4 generated the tetrahydroborates [(RO) 3 Zr(BH 4 )] and [(RO) 2 Zr(BH 4 ) 2 ]. These can be used to produce by hydroborate exchange dihydridodiorganyl borates [(RO) 4– n Zr(H 2 BC 8 H 14 ) n ] and byproducts. The structures of the new zirconium hydridoborates have been determined by X‐ray crystallography. Compound [( t Bu 3 CO) 3 Zr(H 2 BC 8 H 14 )] shows site‐disordered dihydroborate units with agostic Zr–H–C interactions, while [( t Bu 3 SiO) 2 Zr(H 2 BC 8 H 14 ) 2 ] is quite symmetric ( C 2 / c ). The corresponding tetrahydridoborates possess in most cases μ 3 1 ‐bonded ZrH 3 BH groups.