On the Stability of Trimeric Beryllium Hydroxide Scorpionate Complexes

The controlled hydrolysis of TpBeCl {Tp = trispyrazolylborate [HB(C3N2H3)3]–} with H2O and D2O in the presence of N,N‐diisopropylethylamine (DIPEA) yields the trimeric beryllium hydroxide scorpionate complexes [Be3(µ‐OX)3(Tp)3] (X = H: 1, D: 2) quantitatively. The complexes contain six‐membered Be3O3 rings according to single‐crystal X‐ray diffraction studies and theoretical calculations. Temperature‐dependent 1H and 9Be NMR spectroscopy established that 1 has a dynamic structure in solution. In addition, the structure of [Be3(µ‐OH)3(Br)3(thf)6], which was obtained from hydrolysis of a solution of BeBr2 in tetrahydrofuran and CHCl3, is reported. Two trimeric beryllium hydroxide scorpionate complexes [Be3(µ‐OX)3(Tp)3] (X = H: 1, D: 2) and [BeBr3(µ‐OH)3(Br)3(thf)6] were structurally characterized. The six‐membered Be3O3 ring of 1 is stable in both solution and the gas phase as was shown by temperature‐dependent 1H and 9Be NMR spectroscopy and theoretical calculations.