Preparation and properties of uncommon Cd-Mn carboxylate complexes—per se and as precursors for CdMn2O4-based ceramics
Carboxycymantrene CymCOOH (Cym = (η5-C5H4)Mn (CO)3) was applied to assemble a series of uncommon Cd-Mn carboxylate complexes comprising 1D-polynuclear [Cd (OOCCym)(acac)]n (1) as well as oligonuclear species, [Cd2(OOCCym)4(EtOH)4)] (2), [Cd (OOCCym)2(bpy)(H2O] (3, bpy = 2,2′-bipyridine) and [Cd (OOCCym)2(phen)2]·EtOH (4, phen = 1,10-phenantroline). Compound 2 was found to be a product of irreversible SCSC transition from [Cd2(OOCCym)4(EtOH)3(H2O)]·EtOH (2_100K) initially formed in corresponding syntheses. This transition is accompanied by two-fold decrease in cell volume and increase in cell symmetry. Recrystallyzation of 2–4 from common organic solvents affects the nuclearity of products (in case of 2 and 3) or subtly alters the structure of [Cd (OOCCym)2(phen)2] units (4). The optimal Cd to Mn ratio inspired studying solid-state thermal decomposition of 2–4 as a route to CdMn2O4-based ceramics. As a result, oxide samples with a predominance of tetragonal (Cd1-xMnx)Mn2O4 spinel have been prepared and characterized by powder XRD, SEM, EDX, and IR revealing the interplay between the preparation technique and the features of morphology and composition. The retaining of Cd to Mn ratio upon recrystallyzation of 2–4 implies possibility of further elaboration of CdMn2O4-based materials in various morphologies (polycrystalline ones, films, etc.). Notably, 2–4 is also the first series of related heterometallic Cd-Mn complexes being studied as individual precursors for CdMn2O4-based oxide systems.