Thiophene-linked azacryptand sites for dicopper and disilver; Thiophene sulfur as an inert spacer?

Two disilver cryptates of the thiophene-spaced azacryptand hexa Schiff bases N[(CH2)(n)N=CHRHC=N(CH2)(n)]N-3 (n = 2 or 3, R = thiophene-2,5-diyl) and with the dicopper(I) cryptate where n? = 2 have been structurally characterised. The dinuclear separation increases by 0.36 Angstrom on going from the disilver complex of the n = 2 cryptand, to the n = 3 analogue, with that in the dicopper(I) cryptate intermediate, but little difference in cryptand conformation is observed in the three complexes. Proton NMR spectra show three-bond (H-C=N-Ag) coupling of each imino CH proton to Ag-109,Ag-107, confirmed by an Ag-109 insensitive nuclei enhanced by polarisation transfer experiment. No copper(II) cryptates were obtained with the hexa(Schiff-base) cryptands. The analogous octaamino compounds, generate dicopper(II) cryptates which accommodate bridging anions in cascade fashion, with a bridging disposition collinear, Cu-NNN-Cu, in the mu-azido-, but non-linear, Cu-O(H)-Cu, in the mu-hydroxo-cryptate. Both the hexa(Schiff-base) and octaamino cryptates are very similar to inert-spacer azacryptates and give no evidence for hemico-ordination of thiophene sulfur.