Structure and characterisation of [Pt(Me2pipdt)2][Pt(mnt)2]2 and its unusual magnetic properties associated with a non-regular one-dimensional [Pt(mnt)2] stack

For electro-oxidation of [Pt(Me2pipdt)2][Pt(mnt)2] (Me2pipdtN,N′-dimethyl-piperazine-2,3-dithione; mnt = maleonitrile-2,3-dithiolate) (1a) the novel salt [Pt(Me2pipdt)2][Pt(mnt)2]2 (2a) has been prepared and characterised. 2a exhibits segregated chains of anionic and cationic complexes. The anions generate a non-regular stack with the separation between the planes. The cations are perpendicular to the anions and interposed between those stacks in a ribbon fashion. Magnetic measurements show the presence of a magnetic transition between the behaviour of an antiferromagnetic alternating-exchange chain and the behaviour of a set of antiferromagnetic dimers

DFT calculations, structural and spectroscopic studies on the products formed between IBr and N,N′-dimethylbenzoimidazole-2(3H)-thione and -2(3H)-selone

The NBO charge distribution calculated at DFT level on the [LEX]+ species [LE = N,N′-dimethylbenzoimidazole-2(3H)-thione (3) and -2(3H)-selone (4) (Scheme 1); X = I, Br] suggests that the most likely products from the reaction of 3 and 4 with IBr are the 10-X-2 charge-transfer (CT) adduct and the 10-Se-3 “T-shaped” hypervalent adduct featuring a linear Br–Se–I system, respectively. This prediction is confirmed by the synthesis, and X-ray diffraction analysis of 3·IBr (I) and 4·I0.72Br1.28 (II). In particular, II is a 10-Se-3 “T-shaped” hypervalent adduct containing an almost linear X–Se–X system [X–Se–X 179.07(3)°, X = I0.36/Br0.64], which is roughly perpendicular to the average plane of the benzoimidazole moiety. The FT-Raman spectra of I and II agree very well with their structural features. In particular, the complexity of the FT-Raman spectrum of II reflects the disorder in the X-ray crystal structure of this compound

Reactivity of the drug methimazole and its iodine adduct with elemental zinc

The reactivity of zinc complexes with N,S-donor molecules may be of relevance to the study of Zn-metalloproteins and -metalloenzymes. In this context, the zinc complex [Zn(MeImSH)2I2] was synthesised by the reaction of zinc powder with the 1:1 iodine adduct of the drug methimazole [(MeImSH)·I2]. The molecular structure of the complex, elucidated by X-ray diffraction analysis, showed a tetrahedral zinc(ii) centre coordinated by two neutral methimazole units (through the sulfur atoms) and two iodides. From the reaction of MeImSH and Zn powder, the complex [Zn(MeImSH)(MeImS)2] (MeImS = deprotonated form of methimazole) was separated and characterised. An analysis of the crystal packing of the neutral complexes [Zn(MeImSH)2X2] (X = I, Br and Cl) and the ionic complex [Zn(MeImSH)3I]I showed that in all of the complexes the sulfur atom, in addition to binding to the metal centre, contributes to the formation of 1-D chains built via C(4)-H⋯S and N-H⋯X interactions in the neutral complexes, and via C(4)-H⋯S and N-CH3⋯S interactions in the ionic complex [Zn(MeImSH)3I]I. The deprotonation/protonation of the coordinated methimazole units can modulate the coordination environment at the Zn core. From the reaction of complex [Zn(MeImSH)3I]I with a strong non-coordinating organic base, we have shown that, as a consequence of the NH deprotonation of methimazole S-coordinated to zinc(ii), the ligand coordination mode changes from S-monodentate to N,S-bridging. Correspondingly, in the complex [Zn(MeImSH)(MeImS)2], the MeImS that displays the N,S-bridging mode at zinc can be N-protonated and thereby changes to the S-monodentate coordination.</p