Synthesis and investigation of the configurational stability of some dimethylammonium borate salts

Two borate salts, dimethylammonium bis[3-isopropylbenzene-1,2-diolato(2-)-O ,O']borate and dimethylammonium 3,3 " -ethylenebis(3'-methylbiphenyl-2,2'-d iolato(2-)-O,O')borate, were synthesised from the corresponding catechol an d tetraphenol respectively. The configurational stability of these salts wa s determined by variable temperature H-1 NMR spectroscopy; the activation e nergies for the racemisation process were determined to be 85 and 79 kJ mol (-1) respectively. Mechanisms are proposed to explain the configurational i nstability observed.