Preparation and properties of uncommon Cd‐Mn carboxylate complexes—per se and as precursors for CdMn₂O₄‐based ceramics

Abstract

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.

Insight into the Structure and Redox Chemistry of [Carbonatotetraamminecobalt(III)] Permanganate and Its Monohydrate as Co-Mn-Oxide Catalyst Precursors of the Fischer-Tropsch Synthesis

“…An easy and convenient reaction route for the preparation of the simple and mixed nanosized transition metal oxides [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]-especially for the synthesis of catalytically active spinel oxides [19][20][21][22][23][24][25][26][27][28][29][30]-is the thermal decomposition of complexes having reducing ligands and oxidizing anions [31][32][33][34][35][36][37][38]. These processes consisted of a solid-phase quasiintramolecular redox reaction between an oxidizing anion and a reducing ligand.…”

Mononuclear Transition Metal Cymantrenecarboxylates as Precursors for Spinel-Type Manganites

“…In addition to purely rare-earth cymantrenecarboxylates, we have also obtained mixed 3d-4f-complexes containing, along with the lanthanide ions, the Mn 2+ ions which appeared as a result of oxidative destruction of the cymantrene fragment during the synthesis [ 23 , 24 ]. In addition, we have obtained a mononuclear cymantrenecarboxylate complex of cadmium [Cd(κ 2 -CymCO 2 )(κ 1 -CymCO 2 )(phen) 2 ]·2MeCN, which was found to undergo unusual single-crystal-to-single-crystal transformation [ 25 ], as well as a number of several cadmium cymantrenecarboxylates with mononuclear, binuclear and polymeric structures [ 26 ]. It was of interest to develop the chemistry of cymantrenecarboxylates further into the area of 3d-transition metals, in particular, to study the effect of a sterically complicated cymantrene fragment on the structural features of the complexes, as well as to explore their oxidative thermolysis, which can bring about bimetallic mixed oxides promising as functional materials.…”