Synthesis of a tethered dibenzotetramethyltetraaza[14]annulene macrocycle and the di-nickel(ii) derivative

Abstract

Selective reaction of 2,6-isophthaloyl chloride at the methine positions of two dibenzotetramethyltetraaza[14]annulene (tmtaa) units results in tethering of the macrocycles by either one or two 2,6-isophthaloyl bridging groups. The single tethered dibenzotetramethyltetraaza[14]annulene derivative (SIT-tmtaa) was isolated and characterized by X-ray crystallography, ESI-MS, ¹H and ¹³C NMR. The syn conformation of the two tmtaa units observed in the crystal structure, has tetraaza[14]annulene macrocycles that are more distorted from planarity than in the structure of the parent tmtaa. The di-nickel(II) complex was prepared and characterized by ESI-HRMS, ¹H and ¹³C NMR. DFT computations place the LUMO on the 2,6-isophthaloyl bridge rather than on the tethered tmtaa units and suggest that the 2,6-isophthaloyl tether provides a level of flexibility in the inter tmtaa distances that is comparable to the Pacman Effect observed for tethered porphyrins.