Manganese(II) Complexes with Bridging Selenidoarsenate(III) Anions [AsSe 2 (Se 2 )] 3− and [(AsSe 2 ) 2 (μ‐Se 2 )] 4−

Solvothermal reaction of [MnCl 2 (terpy)] with elemental As and Se at a 1:1:2 molar ratio in H 2 O/trien (10:1) at 150 °C affords the linear trimanganese(II) complex [{Mn(terpy)} 3 (μ‐AsSe 4 ) 2 ] ( 1 ). The tridentate [AsSe 2 (Se 2 )] 3− anions of 1 chelate the terminal {Mn(terpy)} 2+ fragments and bridge these through their remaining Se atom to the central {Mn(terpy)} 2+ moiety. Weak interactions of Mn1···Se and Mn3···Se bonds with length 2.914(7) and 3.000(7) Å link the molecules of 1 into infinite chains. Treatment of [MnCl 2 (cyclam)]Cl with As and Se at a 1:1:2 molar ratio in superheated H 2 O/CH 3 OH (1:1) at 150 °C yields the dinuclear complex [{Mn(cyclam)} 2 (μ‐As 2 Se 6 )] ( 2 ), whose novel [(AsSe 2 ) 2 (μ‐Se 2 )] 4− ligands bridge the Mn II atoms in a μ‐1κ 2 Se 1 , Se 2 : 2κ 2 Se 5 , Se 6 manner.