Novel multinuclear Ni^IIAu₂ⁱ and Ni ^IIAu₃ⁱ complexes containing D-penicillaminate and bis(diphenylphosphino)methane: Rational expansion of 8-membered to 12-membered chelating metalloring

A digold(I) complex, [Au₂(D-Hpen-S)₂(dppm)] ([1]), newly prepared from [Au₂Cl₂(dppm)] and D-H₂pen, readily reacted with Ni²⁺ to give a S-bridged Ni^IIAu ₂^I trinuclear complex having an 8-membered chelating metalloring, [Au₂(dppm)-{Ni(D-pen-N,O,S)₂)] ([2]). Complex [2] was reversibly converted to a Ni^IIAu₃^I tetranuclear complex having a 12-membered metalloring, [Au₃(dppm) ₂{Ni(D-pen-N,O,S)₂)]Cl ([3]Cl), retaining the coordination environment about a Ni^II center.