[(1-Methyl­cytosine)₂H]I, an asymmetric base pair

The X-ray crystal structure of the title compound, 1-methyl­cytosinium iodide 1-methyl­cytosine, [(1-MeC)₂H]I (1-MeC is 1-methyl­cytosine) or C₅H₈N₃O⁺·I^-·C₅H₇N₃O, has been determined at 163 K. In this compound, one protonated (1-MeCH⁺) and one neutral methyl­cytosine (1-MeC) moiety form an asymmetric base pair comprising three hydrogen bonds. A previous structure determination [Krüger, Bruhn & Steinborn (2004). Org. Biomol. Chem. 2, 2513-2516] showed the same cell parameters but a centrosymmetric base pair in space group P2₁/c. At low temperature, however, we discovered the title compound to be a racemic twin showing pseudo-centrosymmetry.

The first aluminium-bridged [1.1]­ferrocenophane

The structure of the title compound, bis(μ-ferrocene-1,1′-diyl)­bis­[chloro(N,N,N′N′-tetra­methyl­ethyl­enedi­amine)­aluminium], [Al₂Fe₂Cl₂(C₅H₄)₄(C₆H₁₆N₂)₂], possesses a center of inversion and an anti conformation. Bound to each Al atom in the bridging position are one Cl atom and one mol­ecule of N,N,N′N′-tetra­methyl­ethyl­enedi­amine (TMEDA). The angle between the least-squares planes of the two cyclo­penta­dienyl (Cp) ligands is 3.6 (3)°. The five C atoms in the Cp rings are staggered on average at an angle of 10.3 (5)°.

A monomeric fourfold-coordinated indium dihalide with an unusual coordination geometry

The single-crystal X-ray analysis of the title compound, {[dimeth­yl(2-pyrid­yl)sil­yl]bis­(trimethyl­silyl)meth­yl}diiodoindium(III), [In(C₁₄H₂₈NSi₃)I₂], revealed monomeric mol­ecules containing tetra­coordinated In with an unusual trigonal-pyramidal geometry.