Structures of compounds of 2,5,5,7,9,12,12,14-octamethyl-1,4,8,11-tetraazacyclotetradecane with nickel(II)

The cyclic tetraamine 2RS, 7SR, 9SR, 14RS-2,5,5,7,9,12,12,14-octamethyl-1,4,8,11-tetraazacyclotetradecane (meso-meso-1-L) reacts slowly with nickel acetate to incorporate the nickel(II) ion into the macrocycle. The addition of perchlorate while this reaction is proceeding causes separation of yellow crystals, which had been assigned as a configurational isomer of previously characterised [Ni(meso-meso-1-III-L)](ClO4)(2) (where III indicates the 1RS, 4RS, 8SR, 11SR configuration). These crystals are found to be of a phase 0.333[Ni(meso-meso-1-III-L)]0.667[H-2(meso-meso-1-L)](ClO4)(2). A yellow product formed by the slow reaction of nickel(II) acetate with [H-2(meso-meso-1-L)](ClO4)(2) is [H-2(meso-meso-1-L)](ClO4)(2) isomorphously incorporating 5.5% of [Ni(meso-meso-1-III-L)](ClO4)(2). The structure of [H-2(meso-meso-1L)](ClO4)(2) was determined for comparison and that of [Ni(meso-meso-1-III-L)](ClO4)(2) re-determined at 120 K. These compounds are all isomorphous. (C) 2014 Elsevier B.V. All rights reserved.