Mononuclear Transition Metal Cymantrenecarboxylates as Precursors for Spinel-Type Manganites.

Novel mononuclear cymantrenecarboxylate complexes of transition metals, [Co(H 2 O) 6 ](CymCO 2 ) 2 ·4H 2 O (Cym = (η 5 -C 5 H 4 )Mn(CO) 3 ) ( 1 ), [Ni(H 2 O) 6 ](CymCO 2 ) 2 ·4H 2 O ( 2 ), [Zn(H 2 O) 6 ](CymCO 2 ) 2 ·4H 2 O ( 3 ), [Co(CymCO 2 ) 2 (imz) 2 ] (imz = imidazole, 4 ), [Co(CymCO 2 ) 2 (bpy) 2 ]·2PhMe (bpy = 2,2'-bipyridyl, 5 ), [Ni(CymCO 2 )(bpy) 2 (H 2 O)][CymCO 2 ]·0.5MePh·2H 2 O ( 6 ), [Cu(CymCO 2 ) 2 (imz) 2 ] ( 7 ), and [Cu(CymCO 2 ) 2 (bpy)(H 2 O)] ( 8 ), were obtained and characterized by single-crystal X-ray analysis. Complexes 1 - 3 are isostructural. Magnetism of the Co complexes 1 , 4 , and 5 was studied; it was shown that they exhibit the properties of field-induced single-molecule magnets with magnetization reversal barriers (ΔE/k B ) of 44, 13, and 10 K, respectively. Thermal decomposition of complexes 1 - 8 was studied by means of DSC and TGA methods. The final products of thermolysis of 1 - 6 in air, according to powder XRD data, are the pure spinel phases MMn 2 O 4 ; for the cases of copper complexes, the mixtures of CuMn 2 O 4 and CuO were found in the products.