Current Inorganic Chemistry (v.5, #1)

Meet Our Editor-in-Chief: by Yann Garcia (1-1).

Meet Our Editorial Board Member: by Antonio Laguna (2-2).

The review covers structures and properties of compounds, possessing porous crystal lattices, or coordination polymers, which are assembled on the basis of polynuclear oximate or hydroxamate complexes of 3d metals. It is shown that magnetic properties of such systems are governed by the exchange interactions in the polynuclear building blocks and can be pre-determined by the appropriate choice of starting compound. In contrast, the structure and topology of the framework, obtained on the basis of polynuclear oximate or hydroxamate, do not correlate with the quantity of vacancies in coordination spheres of metal ions in the starting compound, as well as they do not correlate with the quantity of ligand donor atoms. Some of the compounds, considered in this review, show ability to absorb different substrates. Such absorption is different from "classical" filling of micropores; sorption capacity is governed by the energy of host-guest interactions rather than the volume of rigid micropores in crystal lattice.

Doubly Thiocyanato(S,N)-Bridged Dinuclear Complexes of Mercury(II) from the Use of 2-pyridyl Oximes as Capping Ligands by Panagiota Danelli, Zoi G. Lada, Catherine P. Raptopoulou, Vassilis Psycharis, Theocharis C. Stamatatos, Spyros P. Perlepes (26-37).
The reactions between Hg(SCN)2 and the 2-pyridyl oximes, 2-pyridine aldoxime (paoH), methyl 2-pyridyl ketone oxime (mepaoH), pyridine-2-amidoxime (NH2paoH) and di-2-pyridyl ketone oxime (dpkoxH), have been investigated. The products in Me2CO or Me2CO/MeOH are the dinuclear complexes [Hg2(SCN)4(paoH)2] (1), [Hg2(SCN)4(mepaoH)2] (2), [Hg2(SCN)4(NH2paoH)2] (3) and [Hg2(SCN)4(dpkoxH)2] (4), whose structures have been determined by single-crystal X-ray crystallography. The molecular structures consist of centrosymmetric dinuclear molecules in which the two HgII ions are bridged by two bidentate bridging 1: 1: (1,3) SCN- groups forming a planar (1, 2) or non-planar (3, 4), 8-membered metallacyclic ring. The HgII centers are each chelated by a N(2-pyridyl), N(oxime)-bidentate ligand and are bound to one terminal S-bonded thiocyanato group. Due to the very long HgII-N (bridging SCN-) distances in 3, this complex can also be described as pseudodimer. The second 2-pyridyl ring of each dpkoxH ligand in 4 remains uncoordinated. The 2D lattice of 1 and 2 is built through H-bonding and - stacking interactions. Hydrogen bonds and S...S interactions generate 3D networks in 3 and 4. The IR spectra of the complexes are discussed in terms of the coordination modes of the ligands involved (SCN-, 2-pyridyl oximes). 1H NMR spectra in d6-DMSO indicate that the complexes decompose in solution.

Cyanoximes represent a new subclass of oximes and have the general formula NCC(= NOH)-R, where R is an electron-withdrawing group such as CN, amide / thioamide, keto-, carboxylic ester, and a variety of aryls and heterocycles. A group of 40 cyanoximes (including 4 biscyanoximes) and their metal complexes has been synthesized and characterized using a variety of spectroscopic methods and X-ray crystallography. Cyanoximes demonstrate a rich stereochemistry and exist as 4 main principal geometrical isomers such as cis / trans (with respect to the oxime C=N bond orientation relative to the size/heteroatom ranking) and syn / anti (with respect to the oxime N-OH fragment orientation relative to the CNgroup). The latter isomers are also erroneously called E or Z by analogy with isomers of C=C compounds. Contrary to organic compounds, cyanoximes frequently undergo a thermally-induced interconversion of syn and anti isomers around the C=N bond at relatively low temperatures, and, in this case the latter terminology was offered to distinguish them from classic, organic C=C compounds. All four isomers represent diastereomers. In this work, we summarize literature data for simultaneously co-crystallized syn and anti diastereomers of several cyanoximes and present new structural data for some metal complexes with monovalent Ag. Cyanoximes also have shown a remarkable ability to form HL2 - anions in their metal derivatives, including alkali metal salts of Werner-type complexes. In the anion, one H-atom is confined between two cyanoxime molecules via strong intermolecular H-bonding. Thus, compounds of a Kat[HL2] type represent acid salts (Kat = Na, K, Cs, where L = mono-cyanoxime; or NiL2 2+; where L = bis-cyanoxime). In this work we present our data for five new acid salts and review available literature data on that subject.

Two new Ni(II) complexes with phenyl 2-pyridyl ketoxime ligand are reported, displaying unprecedented basket-like topologies of their complex cores. The compounds are studied by X-ray diffraction, EDX and IR spectroscopy, confirming uncommon coordination of a DMF ligand in one of them.The reaction system is described in detail and some of the products are analyzed by EDX/SEM, including EDX mapping analyses of the elemental distribution.

Reactivity of Coordinated α-Dioximate Ribbed Fragments of the iron (II) Clathrochelate Framework in the System DMSO–H2O–Fe(II)–H2O2 by Alexey B. Burdukov, Mikhail A. Vershinin, Natalie V. Pervukhina, Ilia V. Eltsov, Yan Z. Voloshin (71-76).
Transformations of bis-α-benzyldioximate iron(II) dichloroclathrochelate FeBd2(Cl2Gm) (BF)2 (where Bd2– and Cl2Gm2– are -benzyldioxime and dichloroglyoxime dianions, respectively) in the system DMSO – FeII – H2O2 – H2O predominantly gave macrobicyclic products resulted from methylation of -dioximate chelate fragments of its cage framework. Both the nature and yields of these products depend on the concentration of H2O2: at its low concentrations a degree of conversion of such dichloroclathrochelate precursor is rather small, and two main macrobicyclic products are the methylchloroglyoximate complex FeBd2(ClGmCH3)(BF)2 and the clathrochelate FeBd2(ClGm(O2SCH3))(BF)2 with methylsulfonyl ribbed substituent, whereas at high H2O2 concentrations the yield of the clathrochelate products of freeradical methylation reaction increases and this process becomes dominating over nucleophilic substitution: the initial clathrochelate products FeBd2(ClGmCH3)(BF)2 and FeBd2Dm(BF)2 (where Dm2– is dimethylglyoxime dianion), resulted from the subsequent attacks by methyl radicals on the N=C–Cl fragments of a macrobicyclic tris-dioximate ligand, undergo further methylation of the azomethine fragment giving the oximatohydroxylamine cage complex. The obtained diamagnetic low-spin iron(II) complexes were characterized using TLC, 1H, 11B, 19F, 15N and 13C{1H} NMR spectra, and by X-ray diffraction.