Site-selective and stepwise complexation of two M(cod)+ (M = Rh, Ir) fragments with calix[4]arene

Abstract

The reaction of [(cod)M(μ-OMe)]₂ (M = Rh, Ir; cod = cycloocta-1,5-diene) with calix[4]arenes (LH₄) in the molar ratio of 0.5–0.6∶1 gave the rhodium and iridium π-arene complexes [(cod)M(η⁶-LH₃)], while that in the molar ratio of 1.1–1.5∶1 (M = Rh) led to the selective formation of the dinuclear complexes [{(cod)Rh}₂(η⁶:η²-LH₂)] in which one of the Rh(cod)⁺ fragments is coordinated by an η⁶-aryl group and the other by two phenolic oxygen atoms; the stepwise synthesis of the Rh–Ir heterobimetallic analogue of the latter complex was further achieved.