A structural probe for organogold(I) rings and [2]catenanes

The digold( I) diacetylides [4-RC6H9(4-C6H4OCH2C=CAu)(2)], which contain a cyclohexylidene hinge group 4-RC6H9 with R = H or t-Bu, react with diphosphine ligands Ph(2)PZPPh(2) to give the corresponding macrocycles or [2] catenanes [{4-RC6H9(4-C6H4OCH2C=CAu)(2)(mu-Ph(2)PZPPh(2))}(y)] [Z = C=C, (CH2)(2), (CH2)(3), or (CH2)(4); y = 1, 2, or 4]. When R = t-Bu, the bulky tert-butyl group locks the cyclohexane ring conformation and so provides a good NMR spectroscopic probe of the structure. The organogold( I) [2]-catenane complexes are chiral when R = t-Bu, and the complex with Z = (CH2)(4) gives an equilibrium in solution between ring, double-ring, and [2] catenane. When R = H and Z = (CH2)(3), the variable-temperature NMR spectra give new insight into the fluxionality in the [2] catenane complex, and when R = H and Z = (CH2)(4), it is shown that the complex exists in solution as the ring structure, although it crystallizes as a doubly braided [2] catenane.