Selectivity in the Self-Assembly of Organometallic Gold(I) Rings and [2]Catenanes

The selectivity of formation of organometallic rings or [2]catenanes [{X(4-C6H4OCH2C⋮CAu)2(μ-Ph2PZPPh2)}n], n =1 or 2, respectively, has been studied as a function of the
hinge group X and the diphosphine ligand [X = O, S, SO2, CH2, CMe2, CPh2, C(CF3)2, C6H10;
Z = (CH2)m with m = 2−5]. When Z = (CH2)3, mixing of pairs of compounds with different
C2v-symmetrical hinge groups (X, X‘ = SO2, CH2, CMe2, CPh2, C(CF3)2, C6H10) led to formation
of an equilibrium mixture containing the unsymmetrical [2]catenanes [{X(4-C6H4OCH2C⋮CAu)2(μ-Ph2PZPPh2)}{X‘(4-C6H4OCH2C⋮CAu)2(μ-Ph2PZPPh2)], as identified by NMR
spectroscopy. The complexes with Z = (CH2)4 exist in solution predominantly as the
macrocycles and so do not form analogous mixed diacetylide complexes. When the hinge
group contained a prochiral carbon center (X = CHMe, CMePh, 1,1-indanylidene), only achiral
macrocycles [X(4-C6H4OCH2C⋮CAu)2(μ-Ph2PZPPh2)] were formed in solution when Z =
(CH2)4, but mixtures containing both achiral macrocycles and chiral [2]catenane were formed
when Z = (CH2)3. In several cases, the solid-state structures of the isolated complexes were
not representative of the structures in solution, with macrocycles being dominant in solution
and [2]catenanes formed preferentially during crystallization.