Electrochemical and X-ray crystallographic studies on three macrocyclic dicopper(I) complexes

Abstract

The crystal structures of the compounds [Cu₂L¹(NCMe)₂][BPh₄]₂1′, [Cu₂L²(NCMe)₂][ClO₄]₂2 and [Cu₂L³(NCMe)₂][ClO₄]₂3 have been determined {L¹= 23,24-dioxa-3,7,14,18-tetraazatricyclo-[18.2.1.1^9,12]tetracosa-1(22),2,7,9,11,13,18,20-octaene, L²= 5,5,16,16-tetramethyl derivative of L¹, L³= 23,24-dithia analogue of L¹}. Complex 1′ is monoclinic, space group P2₁/n, Z= 2 with a= 10.45(1), b= 15.72(1), c= 18.08(1)Å and β= 97.0(1)°, 2 is triclinic, space group P, Z= 1, with a= 7.447(8), b= 12.094(9), c= 10.731(9)Å, α= 118.6(1), β= 78.8(1) and γ= 103.7(1)° and 3 is monoclinic, space group P2₁/c, Z= 2, with a= 8.15(1), b= 9.41(1), c= 19.35(2)Å and β= 100.0(1)°; 1122, 1298 and 1071 reflections have been refined to R= 0.079, 0.055 and 0.072 respectively. All structures contain discrete cations and anions with the cations containing crystallographic centres of symmetry. In the cations the copper atoms are three-co-ordinate being bound to two nitrogen atoms of the macrocycle and one of an NCMe group in a pyramidal co-ordination sphere, Cu–N bond lengths ranging from 1.855(5) to 1.991(11)Å. The Cu ⋯ S distances in 3 are 3.07(1) and 2.89(1)Å indicating a fairly strong interaction. This distorts the planar part of the macrocycle and leads to a large Cu ⋯ Cu separation of 4.654(3)Å. The corresponding value of 3.675(1)Å in 2 is larger than that of 3.395(4)Å in 1 due to repulsion between the additional methyl groups in L².