Ferrocenyl Functional Coordination Polymers Based on Mono-, Bi-, and Heterotrinuclear Organometallic Building Blocks: Syntheses, Structures, and Properties

Abstract

Seven ferrocenyl functional coordination polymers with the formulas [Zn2(μ2-O2CRFc)4(4,4′-bpy)]n [(R = (CH2)m with m = 0 (1), 1 (2), 2 (3), 3 (4)], [Zn(O2C(CH2)4Fc)2(H2O)2(4,4′-bpy)]n (5), [Zn2Ca(μ2-O2CCH2Fc)6·Zn2(μ2-O2CCH2Fc)4(4,4′-bpy)2]n (6) and [Zn2Ca(μ2-O2C(CH2)2Fc)6(4,4′-bpy)]n (7) (Fc = ferrocene) have been synthesized and characterized. Single-crystal X-ray diffraction studies reveal that their one-dimensional (1-D) chain structures consist of various organometallic building blocks held together by 4,4′-bpy linkers. Polymers 1−4 are based on the paddle-wheel binuclear motif [Zn2(O2CRFc)4]. Polymer 5 is built from the mononuclear unit [Zn(O2CRFc)2(H2O)2]. Polymer 7 is assembled by the linear heterotrinuclear cluster [Zn2Ca(O2CRFc)6] which has been rarely reported up to now. The structure of polymer 6 is a particularly fascinating 1-D chain in which two kinds of building blocks ([Zn2(O2CRFc)4] and [Zn2Ca(O2CRFc)6]) are connected alternately by 4,4′-bpy linkers. These results demonstrate that the total numbers of incorporated ferrocene moieties as well as the structures of 1−7 are closely related to the variation of metal nuclearity (from mononuclear to trinuclear) of the three kinds of organometallic building blocks. The electrochemical studies reveal a good correlation between the Fc/Fc+ redox potentials of 1−7 and the number of methylene in ferrocenyl carboxylates.