Studies in the flexibility of macrocycle ligands. Calculation of macrocycle cavity size by force-field methods. Crystal and molecular structures of [CoLCl][ClO4]2 and [CuL][PF6]2{L = 2,13-dimethyl-3,6,9,12,18-penta-azabicyclo[12.3.1]octadeca-1(18),14,16-triene}

Abstract

The crystal structures of the compounds [CoLCl][ClO₄]₂(1) and [CuL][PF₆]₂(2) have been determined {L = 2,13-dimethyl-3,6,9,12,18-penta-azabicyclo[12.3.1]octadeca-1(18),14,16-triene}. Complex (1) is orthorhombic, space group P2₁2₁2₁, Z= 4, with a= 12.931(8), b= 16.604(12), and c=11.441(9)Å; (2) is monoclinic, space group P2₁/c, Z= 4, with a= 14.145(11), b= 9.030(6), c= 16.743(11)Å, and β= 90.9(3)°. 1 336 (1) and 1 608 (2) above background reflections have been measured on a diffractometer, and the structures refined to R 0.086 and 0.076 respectively. Both structures contain discrete cations and anions. In complex (1) the cobalt atom is six-co-ordinate being bonded to the five donor atoms of the macrocycle [Co–N 1.812(16)–2.001(12)Å] and to the chloride ion [Co–Cl 2.173(5)Å] in an octahedral environment. In (2) the copper atom is five-co-ordinate being bonded to all five donor atoms of the macrocycle L with a geometry intermediate between a square pyramid and a trigonal bipyramid: Cu–N 1.930(14)–2.145(25)Å. The macrocycle adopts three different conformations in complexes (1), (2), and the related structure of [FeLCl₂][ClO₄] which is seven-co-ordinate. These conformations are investigated by force-field methods. In particular a general method is described to calculate a hole-size profile of macrocycles.