Effects of Halo-substitution on 2'-Chloro-5'-halo-phenyl-1,2,3,5-dithiadiazolyl Radicals: A Crystallographic, Magnetic and EPR Case Study

The syntheses and characterization of the aryl-substituted dithiadiazolyls, 2ʹ-Cl-5ʹ- X-C6H3CNSSN• [1 (X = F), 2 (X = Cl), 3 (X = Br), 4 (X = I)] are described. In all four cases the radicals adopt distorted stacks of π*-π* dimers with inter-stack S···X contacts. In 1 (monoclinic P2/c) S···Cl contacts are manifested through a non-crystallographic 3-fold axis forming supramolecular trimers whereas the inter-stack S…X contacts in 2 (triclinic P-1), 3 and 4 (which form an isostructural pair, orthorhombic Pna21) form supramolecular chains. While all the structures adopt π*-π* cis-oid dimer motifs, tuning the halogen modifies the intra-dimer S···S distance. Variable temperature SQUID magnetometry and X-band CW-EPR studies revealed the presence of a thermally accessible triplet state in all cases, with the singlet-triplet separation appearing in the order 1 > 2 > 3 > 4, consistent with a reduction in the overlap integral with increasing intra-dimer S···S separation. Variable temperature structural studies on both 2 and 4 reveal a structural evolution from a distorted π-stack motif towards a regular π-stacked array on warming. This is particularly pronounced in 2 where the intermolecular S…S separations along the stacking direction converge on a regular 3.6 Å spacing at ambient temperature

Crystal Structure and Solid-State Packing of 4-Chloro-5H-1,2,3-dithiazol-5-one and 4-Chloro-5H-1,2,3-dithiazole-5-thione

The crystal structure and solid-state packing of 4-chloro-5H-1,2,3-dithiazol-5-one and two polymorphs of 4-chloro-5H-1,2,3-dithiazole-5-thione were analyzed and compared to structural data of similar systems. These five-membered S,N-rich heterocycles are planar with considerable bond localization. All three structures demonstrate tight solid-state packing without voids which is attributed to a rich network of short intermolecular electrostatic contacts. These include Sδ+…Nδ−, Sδ+…Oδ−, Sδ+…Clδ− and Sδ+…Sδ− interactions that are well within the sum of their van der Waals radii (∑VDW). B3LYP, BLYP, M06, mPW1PW, PBE and MP2 were employed to calculate their intramolecular geometrical parameters, the Fukui condensed functions to probe their reactivity, the bond order, Bird Index and NICS(1) to establish their aromaticity

Access to 1,4-Dihydrobenzo[<i>e</i>][1,2,4]triazin-4-yl Derivatives

A simple, one-pot method for the preparation of 1-aryl-3-phenyl-1,4-dihydrobenzo­[<i>e</i>]­[1,2,4]­triazin-4-yl radicals by addition of aryllithium to the readily available 3-phenylbenzo­[<i>e</i>]­[1,2,4]­triazine followed by aerial oxidation is described. The intermediate anion is also trapped as an <i>N</i>-benzyloxycarbonyl derivative and purified prior to deprotection and oxidation to the radical. The method was demonstrated for nine (het)­arenes, and the regioselectivity of nucleophilic addition to the benzo­[<i>e</i>]­[1,2,4]­triazine and trapping of the intermediate anion with electrophiles was assessed computationally

From Blatter Radical to 7-Substituted 1,3 - Diphenyl-1,4 - Dihydrothiazolo [5′,4′:4,5] Benzo[1,2-e][1,2,4] Triazin-4-yls : Toward Multifunctional Materials

A Blatter radical is oxidized to benzotriazin-7(H)-one which after amination and subsequent acyl- and aroylation gives N-(benzotriazin-6-yl) carboxamides that undergo ring closure with P 2S 5 to afford the corresponding thiazolo[5′,4′:4,5]benzo[1,2-e][1,2,4]triazin-4- yls. These highly delocalized radicals are air stable and show good reversible electrochemical behavior. © 2012 American Chemical Societ

Novel PANK2 mutation in the first Greek compound heterozygote patient with pantothenate-kinase-associated neurodegeneration

Pantothenate-kinase-associated neurodegeneration is the most common autosomal recessive form of neurodegeneration with brain iron accumulation. Less than 100 mutations in PANK2 gene (20p13) are responsible for classic and atypical cases. We report here the first Greek case of atypical pantothenate-kinase-associated neurodegeneration, confirmed by molecular analysis that revealed two trans-acting mutations. Our findings highlight the possible role of rare variants contributing to disease risk and possibly to variable clinical phenotype

Crystal structures, EPR and magnetic properties of 2-ClC6H4CNSSN˙ and 2,5-Cl2C6H3CNSSN˙

The β-sheet structure associated with chlorinated aromatics (dClCl ≈ 4.0 Å) has been implemented to drive formation of π-stacked structures of dithiadiazolyl radicals. Both title compounds exhibit an increase in paramagnetism above 150 K but solid-state EPR studies indicate that the origin of the paramagnetism in these two systems is different