Transition-Metal(II)–Crown-Ether–Polyiodides

The crown-ethers 12-crown-4 (12c4) and benzo-12-crown-4 (b12c4) encapsulate divalent manganese, iron, cobalt, and nickel cations building large sandwich-type dications with square-antiprismatic coordination polyhedra; benzo-15-crown-5 (b15c5) forms in-cavity complexes with six-plus-one coordinate Mn(II) and Co(II). The anions are a variety of polyiodides, I 3 –, I 5 –, I 7 –, I 12 2–, I 16 2–, and I 18 4– . The crystal structures of 12 new compounds have been determined, 8 of which contain 12-crown-4: Mn(12c4) 2 (I 3 ) 2 (12c4) ( 1 ) and Co(12c4) 2 (I 3 ) 2 (12c4) ( 2 ) are isotypic (monoclinic, C 2/ c, No. 15) and contain isolated triiodide anions. Isotypic Mn(12c4) 2 (I 5 ) 2 ( 3 ) and Ni(12c4) 2 (I 5 ) 2 ( 4 ) (monoclinic, Cm, No. 8) feature V/L-shaped I 5 – anions which are connected to zigzag chains. The hexadecaiodides, built of nonaiodide and heptaiodide subunits, in the isotypic compounds Mn(12c4) 2 (I 16 ) ( 5 ), Fe(12c4) 2 (I 16 ) ( 6 ), Co(12c4) 2 (I 16 ) ( 7 ) (orthorhombic, Pna 2 1, No. 33) exhibit a new structural motif for I 16 2– anions. The elusive octadecaiodide I 18 4– in Co(12c4) 2 2 (I 18 ) ( 8 ) (monoclinic, C 2/ c, No. 15) consists of a linear pentaiodide to which iodine and triiodide are attached. Analogous reactions with benzo-12-crown-4 yielded the pentaiodides Mn(b12c4) 2 (I 5 ) 2 ( 9 ) and Co(b12c4) 2 (I 5 ) 2 ( 10 ). 9 features a trans -pentaiodide chain to which an additional pentaiodide is connected; it also contains an isolated pentaiodide anion. The crystal structure of 10 contains isolated V/L-shaped pentaiodide anions exclusively. The anionic parts in Co(b15c5) 2 (MeCN)(H 2 O)(I 7 ) 2 ( 11 ) (monoclinic, Cc, No. 9) and Mn(b15c5) 2 (H 2 O) 2 (I 12 ) ( 12 ) (monoclinic, P 2 1 / c, No. 14) are determined by polymeric pyramidal heptaiodides in 11 and by a two-dimensional network of dodecaiodide anions with twisted sawhorse geometry in 12 .