We report the synthesis and characterization of tantalum-boronate trimetallic clusters of general formula {[Cp*Ta](3)(mu(2)-RB(O)(2))(3)(mu(2)-OH)(mu(2)-O)(2)(mu(3)-OH)) (R= 4-(C6H5)(C6H4) (Ta-3-4Ph), 4-(C6H5O)(C6H4) (Ta-3-4OPh), 4-(C7H7O)(C6H4) (Ta-3-4OBn), 4-(C8H5)(C6H4) (Ta-3-4PhEt), and 4-(C12H7)(C6H4) (Ta-3-4Napht)). All complexes have been characterized by NMR spectroscopy and X-ray diffraction. The trimetallic species feature a large Lewis acid type cavity allowing for substrate binding in both the solid and the liquid state using a unique electrostatic interaction and a hydrogen bond. Delta H degrees and Delta S degrees values for association of acetone with the complexes vary between -2.0 and -4.1 kcal.mol(-1) and -3 and 2 cal.mol(-1).K-1, respectively, showing weaker binding than smaller cavitands of the same type. The barrier for acetone exchange at equilibrium is similar for all complexes, and Delta H-double dagger values vary between 8.2 and 11.4 kcal.mol(-1).