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

Abstract

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, I3–, I5–, I7–, I122–, I162–, and I184–. The crystal structures of 12 new compounds have been determined, 8 of which contain 12-crown-4: [Mn(12c4)2](I3)2(12c4) (1) and [Co(12c4)2](I3)2(12c4) (2) are isotypic (monoclinic, C2/c, No. 15) and contain isolated triiodide anions. Isotypic [Mn(12c4)2](I5)2 (3) and [Ni(12c4)2](I5)2 (4) (monoclinic, Cm, No. 8) feature V/L-shaped I5– anions which are connected to zigzag chains. The hexadecaiodides, built of nonaiodide and heptaiodide subunits, in the isotypic compounds [Mn(12c4)2](I16) (5), [Fe(12c4)2](I16) (6), [Co(12c4)2](I16) (7) (orthorhombic, Pna21, No. 33) exhibit a new structural motif for I162– anions. The elusive octadecaiodide I184– in [Co(12c4)2]2(I18) (8) (monoclinic, C2/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](I5)2 (9) and [Co(b12c4)2](I5)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)(H2O)](I7)2 (11) (monoclinic, Cc, No. 9) and [Mn(b15c5)2(H2O)2](I12) (12) (monoclinic, P21/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.