Twelve-vertex polyhedral carbaborane chemistry. Isostructural cations and anions: The ‘globule–globule’ salt [H3NCH2C2B10H11][H3CCH2CB11H11]

Abstract In an attempt to make the [H 3 NCH 2 C 2 B 10 H 11 ][H 3 CCH 2 CB 11 H 11 ] salt 3 , in which anion and cation are isostructural, the monocarbaborane anion [1-H 3 CCH 2 - closo -1-CB 11 H 11 ] − 2 was first made from the [ closo -1-CB 11 H 12 ] − anion by treatment with n -BuLi followed by CH 3 CH 2 I. Together with the known dicarbaborane cation [1-(H 3 NCH 2 )- closo -1,2-C 2 B 10 H 11 ] + 1 this yielded the water solvate [H 3 NCH 2 C 2 B 10 H 11 ] + [H 3 CCH 2 CB 11 H 11 ] − [H 2 O] 3a . Cation 1 was susceptible to condensation with (CH 3 ) 2 CO to give the cation [1-{(CH 3 ) 2 C NHCH 2 }- closo -1,2-C 2 B 10 H 11 ] + , and thence the salt [(CH 3 ) 2 C NHCH 2 C 2 B 10 H 11 ] + [H 3 CCH 2 CB 11 H 11 ] − (compound 4 ) was also characterised. Single-crystal X-ray diffraction results are presented for salts 3a and 4 , and also the Ag + salt 2b of anion 2 . Intermolecular associative aspects within the crystal lattices are presented and discussed.