BIS(PYRAZOLYL)BORATE AND TRIS(PYRAZOLYL)BORATE COMPLEXES OF THE HEAVIER ALKALINE-EARTH ELEMENTS CA, SR AND BA

Sandwich complexes of the composition MTp(2)[Tp* = hydrotris(3,5-dime thylpyrazolyl)borate; M = Ca, 1; Sr, 2; Ba, 3] have been generated by the direct reaction of the iodides MI(2) with Ktp. Attempts to prepar e the half-sandwich compounds MTp(I) have met with no success when M = Ca, Sr, but the reaction of BaI2 with 1 equiv. of KTp in THF produc ed BaTp(I)(THF)(n) (4a), which can be readily converted into the rela ted adduct BaTp(I)(HMPA)(2) [4b, HMPA = OP(NMe(2))(3)]. The above com pounds have been characterized by analytical and spectroscopic methods , and the structures proposed have been confirmed by X-ray studies car ried out with the Ba derivatives 3 and 4b. Attempts to derivatize comp ounds 4 led mostly to undesired products, but treatment with KTp and KBp [Bp* = dihydrobis(3,5-dimethylpyrazolyl)borate] resulted in the f ormation of 3 and BaTpBp*(THF), 6, respectively. Bis(pyrazolyl)borate derivatives of the composition M(Bp')(2)(THF)(n) have also been obtai ned by the direct reaction of MI(2) (M = Ca, Sr, Ba) with KBp or TlBp dagger [Bp dagger = dihydrobis(3-t-butyl-pyrazolyl)borate]. Copyright (C) 1996 Elsevier Science Ltd