Polyamine and ‐imine Manganese(II) Complexes with Tetra‐, Penta‐ and Hexaselenide Ligands: Coligand and Solvent Influence on the Polyselenide Nuclearity and Coordination Mode

Solvothermal reaction of {(L)Mn} 2+ fragments (L = tren, cyclam, tacn, terpy) with Se in the presence of a mineralizer A 2 CO 3 (A = Na, Cs) at 150 °C leads to formation of polyselenide complexes, in which the nuclearity of the $\rm Se^{\2-}_{n}$ ( n = 4−6) ligands can depend on the polarity of the reaction medium or the hapticity and binding mode of the coligand L. For instance, whereas methanolothermal treatment of [MnCl 2 (tren)] with Se affords the 1D polymers $^{1}_{\infty}\rm [Mn_{2}(Se_{4})_{2}(tren)_{2}]$ ( 1a ) and $^{1}_{\infty}\rm [Mn_{2}(Se_{4})(tren)]$ ( 1b ), employment of superheated water as the reaction medium allows the isolation of dinuclear [{Mn(Se 6 )(tren)} 2 ]. Whereas 1a contains both bridging μ‐1κ Se 1 :2κ Se 4 and terminal κ Se 1 tetraselenide ligands, only the former mode is adopted by the $\rm Se^{\2-}_{4}$ ligands in 1b . The analogous reaction of Se with [MnCl 2 (cyclam)]Cl yields the chelate complex [Mn(Se 4 )(cyclam)] 2 in superheated methanol and dinuclear [{Mn(Se 6 )(cyclam)} 2 ] ( 7 ) under hydrothermal conditions. 7 exhibits C s symmetry and contains two μ‐1κ Se 1 :2κ Se 6 bridging hexaselenide ligands. In contrast to the {(tren)Mn} 2+ , {(cyclam)Mn} 2+ and {(terpy)Mn} 2+ fragments, only one product ( 3 ) could be isolated for the tridentate fac ‐{(tacn)Mn} 2+ fragment. Whereas the $\rm Se^{\2-}_{4}$ ligands in dinuclear [{(tacn)Mn} 2 (μ‐Se 4 ) 2 ] ( 3 ) adopt a μ‐1κ 2 Se 1 , Se 4 :2κ Se 4 mode, κ 2 Se 1 , Se 4 chelating $\rm Se^{\2-}_{4}$ ligands are observed in the methanolothermal product [Mn(Se 4 )(terpy)] ( 4 ). Hydrothermal reaction of Se with [MnCl 2 (terpy)] affords the chelate complex [Mn(Se 5 )(terpy)] ( 5 ), in contrast. On blocking five of the six octahedral sites by tacn and en ligands, terminal $\rm Se^{\2-}_{5}$ ligands were obtained in [Mn(Se 5 )(en)(tacn)] ( 6 ), which can be prepared in both superheated methanol and water.