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The β-phase of the radical p-NCC6F4CNSSN (1β) crystallizes in the orthorhombic space group Fdd2 and orders as a canted antiferromagnet with TN = 36 K. Computational studies (B3LYP or M06-2X functional with the cc-pVTZ-PP(-F)+basis set) of the microscopic nearest-neighbour magnetic exchange coupling in 1β and in the hypothetical isomorphous phase of the selenium radical p-NCC6F4CNSeSeN (2β) revealed that replacement of S by Se should lead to a significant enhancement in the magnetic ordering temperature by ca. 20% (B3LYP) – 30% (M06-2X). Recrystallization of 2 from solution or via vacuum sublimation afforded only the known diamagnetic, dimeric phase, 2α. Computational studies indicated that both the molecular geometry and charge distribution for 1 and 2 are extremely similar and experimental approaches to form alloys of the general form 11−x2x were explored: attempts to cosublime 1 and 2in vacuo were unsuccessful, forming only 1β due to the low volatility of 2. Crystallization of pure 1 by solution evaporation was found to afford polymorph 1α (triclinic, P1¯) selectively, irrespective of the solvent employed (CH2Cl2, MeCN, PhMe or THF) but 1α transformed to 1β upon subsequent vacuum sublimation. Crystallization of 1 in the presence of 2 (up to 20 mol%) from solution evaporation was examined. At 20 mol% there was clear evidence for formation of both 1α and 2α as distinct crystallographic phases by powder X-ray diffraction (PXRD) but some evidence for doping of 2 into 1α at low concentration (≤15 mol percent) was observed. Attempts to sublime a sample of 10.920.1 led to phase separation with the isolation of needle-shaped crystals of pure 1β characterized by X-ray diffraction. [ABSTRACT FROM AUTHOR]

A tridentate ligand LH3 ((2-hydroxy-3-methoxybenzylidene)-2-(hydroxyimino)propanehydrazide) comprising o-vanillin, hydrazone and oxime donor groups has been employed to prepare a series of tetranuclear Ln(III) complexes. The reaction of ligand LH3 with Ln(NO3)3 [Ln = Sm, Eu, Gd, Tb, Dy, Ho, Er] in MeOH yielded Ln4(LH)6(MeOH)2 (Ln = Sm(1), Eu(2), Gd(3), Tb(4), Ho (6) and Er (7))] whereas the corresponding reaction with Dy(NO3)3 afforded Dy4(LH)4(LH2)2(OH)2 (5). All complexes were characterized by various analytical techniques including single crystal X-ray diffraction, IR spectroscopy, UV-Vis spectroscopy, and elemental analysis. To investigate the potential of these lanthanide complexes for wound healing applications, their effects on fibroblast viability, migration, and M2 macrophage polarization were evaluated. The cytotoxicity assessment revealed that complexes 2(Eu), 4(Tb), 5(Dy), and 7(Er) significantly enhanced fibroblast viability compared to the negative control (NC). In vitro wound healing assay demonstrated that complexes 2(Eu) and 7(Eu) substantially promoted fibroblast migration compared to the NC. Moreover, complex 2(Eu) exhibited significant anti-inflammatory effects by reducing the phagocytic ability of lipopolysaccharide (LPS)-stimulated macrophage cells and attenuating nitric oxide (NO) production. In conclusion, among the series of complexes tested, complex 2(Eu) displayed the most potent anti-inflammatory effect on macrophage cells, while simultaneously promoting fibroblast viability and migration. This unique combination of properties renders complex 2 (Eu) highly promising for wound healing applications. [ABSTRACT FROM AUTHOR]

A new asymmetrically substituted ONOO Schiff base ligand N-(2′-hydroxy-1′-naphthylidene)-3-amino-2-naphthoic acid (nancH2) was prepared from the condensation of 2–hydroxy–1–naphthaldehyde and 3–amino–2–naphthoic acid. nancH2 reacts with Cu2(O2CMe)4·2H2O in the presence of Gd(O2CMe)3·6H2O to afford a uniform one-dimensional homometallic chain, [CuII(nanc)]n (1). The structure of 1 was elucidated via single crystal X-ray diffraction studies, which revealed that the Cu(II) ions adopt distorted square planar geometries and are coordinated in a tridentate manner by an [ONO] donor set from one nanc2− ligand and an O− of a bridging carboxylate group from a second ligand. The bridging carboxylato group of the nanc2− ligand adopts a syn, anti-η1:η1:μ conformation linking neighboring Cu(II) ions, forming a 1D chain. The magnetic susceptibility of 1 follows Curie–Weiss law in the range 45–300 K (C = 0.474(1) emu K mol-1, θ = +7.9(3) K), consistent with ferromagnetic interactions between S = ½ Cu(II) ions with g = 2.248. Subsequently, the data fit well to the 1D quantum Heisenberg ferromagnetic (QHFM) chain model with g = 2.271, and J = +12.3 K. DFT calculations, implementing the broken symmetry approach, were also carried out on a model dimeric unit extracted from the polymeric chain structure. The calculated exchange coupling via the carboxylate bridge (J = +13.8 K) is consistent with the observed ferromagnetic exchange between neighbouring Cu(II) centres. [ABSTRACT FROM AUTHOR]

An efficient and mild reaction protocol for the decarbonylation of isocyanates has been developed using catalytic amounts of Lewis acidic boranes. The electronic nature (electron withdrawing, electron neutral, and electron donating) and the position of the substituents (ortho/meta/para) bound to isocyanate controls the chain length and composition of the products formed in the reaction. Detailed DFT studies were undertaken to account for the formation of the mono/di‐carboxamidation products and benzoxazolone compounds. [ABSTRACT FROM AUTHOR]

Mechanochemical synthesis provides new pathways for the rational design of multi-component crystals (MCCs) involving anionic or cationic components that offer molecular-level architectures unavailable to MCCs comprising strictly neutral components. Structural characterization of the products of mechanochemical syntheses is essential for divining clear relationships between the nature of coformers, milling conditions, reaction mechanisms, and intermolecular bonding. Notably, when powder X-ray diffraction and solid-state NMR (SSNMR) are combined with plane-wave density functional theory (DFT) calculations, they offer opportunities for NMR crystallographic solutions and structural refinements. Herein, we report mechanochemical syntheses of five urea-containing MCCs of the form NR4Cl:xUrea·yH2O (R = H, Et, n-Pr; x = 1, 2, 3; y = 0, 2), which can be made in high yields (> ca. 99%) and great rapidity (<40 minutes). We demonstrate the utility of 35Cl SSNMR for providing distinct fingerprints for each urea MCC and detecting chlorine-containing impurities. Dispersion-corrected plane-wave DFT-D2* calculations are used for structural refinement and relating 35Cl electric field gradient (EFG) tensors and chloride ion hydrogen bonding environments. Finally, ab initio molecular dynamics calculations are used to study the impact of molecular motions on 35Cl EFG tensors, and their concomitant use for site assignment and NMR crystallography. Together, these techniques show great promise for future development of crystal structure prediction protocols using NMR of quadrupolar nuclei. [ABSTRACT FROM AUTHOR]

Three-coordinate mononuclear copper(I) halide complexes (1 (I) and 2 (Br)) that bear a novel rigid diphosphine ligand derived from a benzimidazole skeleton were prepared and characterized. Structural analyses of 1 and 2 reveal that the rigidity of the functionalized diphosphine ligand leads to weak Cu⋯πimidazole interactions. Solid state luminescence studies show that the existence of cation–π interactions and the heavy atom effect facilitate orange-red emission (630 nm for 1 and 615 nm for 2) with high photoluminescence quantum yields (65% and 72% for 1 and 2, respectively) and decay times of a few tenths of microseconds. The combination of experimental results and quantum-chemical calculations reasonably reveals that the emission origin is assigned to TADF-assisted phosphorescence based on (metal + halide) to ligand transitions. This systematic study demonstrates that the introduction of a functional π-conjugated bridging moiety between the two P atoms in the diphosphine ligands is a promising strategy for developing new structures with high luminescence performance. [ABSTRACT FROM AUTHOR]

Cocrystallization of the dithiadiazolyl (DTDA) radicals p‐XC6F4CNSSN (X=F, Cl, Br, I, CN) with TEMPO afforded the 2 : 1 cocrystals [p‐XC6F4CNSSN]2[TEMPO] (1–5) whose structures all reflect a common S4⋅⋅⋅O supramolecular motif. The nature of this interaction was probed by DFT calculations (M06/aug‐cc‐pVDZ) on 1 which revealed that the enthalpy of formation of the [C6F5CNSSN]2[TEMPO] supramolecular motif from [C6F5CNSSN]2 and TEMPO is substantial (−54.0 kJ mol−1). Electronic structure calculations revealed a TEMPO‐based doublet S=1/2 configuration as the ground state with limited spin density on the DTDA rings (2.4 %). The corresponding spin quartet state is +78.9 kJ mol−1 higher in energy. An atoms‐in‐molecules analysis reveals four bond critical points (BCPs) between the TEMPO O and the DTDA S atoms as well as additional BCPs between selected DTDA S atoms and methyl H atoms of the TEMPO molecule. Herein, the structures of 2–5 are considered within the context of a hierarchical view of competing and complementary intermolecular interactions; in particular, the established supramolecular CN⋅⋅⋅S−S synthon is sacrificed in order to form the new S4⋅⋅⋅O interaction. [ABSTRACT FROM AUTHOR]

Oxidation of equimolar amounts of [p-Br[C.sub.6][H.sub.4]CNSSN]Cl and [p-[O.sub.2][NC.sub.6][H.sub.4]CNSSN]Cl with elemental [O.sub.2] in the presence of [Ph.sub.3]Sb in MeCN yields a mixture of the symmetric dithiatetrazocines, [O.sub.2]N[C.sub.6][H.sub.4]C[N.sub.4][S.sub.2]C[C.sub.6][H.sub.4]N[O.sub.2] (1) and Br[C.sub.6][H.sub.4]C[N.sub.4][S.sub.2]C[C.sub.6][H.sub.4]Br (2) as well as the unsymmetrically substituted derivative Br[C.sub.6][H.sub.4]C[N.sub.4][S.sub.2]C[C.sub.6][H.sub.4]N[O.sub.2] (3). The structures of compounds 1-3 are determined by X-ray diffraction: 1 crystallizes in the monoclinic space group [P2.sub.1]/c (a = 8.6397(4), b = 5.8359(4), c = 14.9767(11) [Angstrom], [beta] = 92.088(4)[degrees]) with half a molecule in the asymmetric unit; 2 crystallizes in the triclinic space group P1 (a = 6.5330(5), b = 8.2084(6), c = 14.7264(9) [Angstrom], [alpha] = 84.483(4)[degrees], [beta] = 77.112(4)[degrees], [gamma] = 87.879(3)[degrees]); 3 was found to crystallize in two forms: recrystallization from C[H.sub.2][Cl.sub.2] at room temperature yielded a solvent-free, triclinic phase, space group P1 (a = 6.5060(9), b = 7.0739(9), c = 9.1164(8) [Angstrom], [alpha] = 81.860(3)[degrees], [beta] = 83.406(5)[degrees], [gamma] = 66.589(5)[degrees]), whereas cooling a solution to -5[degrees]C yielded a solvated form, 3 C[H.sub.2][Cl.sub.2], which crystallizes in the monoclinic space group [P2.sub.1]/m (a = 6.179(1), b = 10.960(2), c = 13.884(3) [Angstrom], [beta] = 92.69(3)[degrees]). The N[O.sub.2] ... Br intermolecular interactions observed in the unsolvated structure of 3 are disrupted in the solvate structure; the C[H.sub.2][Cl.sub.2] molecule in the latter is aligned such that its molecular dipole interacts with both nitro and bromo groups, retaining a molecular chain motif. The structures are discussed in relation to their semi-empirically calculated molecular electrostatic potentials and calculations of intermolecular interactions using van der Waals forces combined with an electrostatic point charge model. Key words: dithiatetrazocine, crystal structure, crystal engineering, molecular electrostatic potential.

The synthesis and reactivity patterns of the strained dithiete ring are compared with their dimeric tetrathiocin counterparts and higher oligomers, highlighting: (i) their cycloaddition chemistry with organic dienophiles as a route to sulfur-containing heterocycles; (ii) their oxidative addition chemistry to low valent transition metal complexes to generate transition metal dithiolate complexes and; (iii) the base-catalysed isomerizations between different dithiete oligomers. [ABSTRACT FROM AUTHOR]

Tridentate ligands offer theree donor atoms to coordinate to metal ions. The remaining vacant coordination sites on the metal ions provided opportunities to implement additional co-ligands to generate complexes with desired properties. Herein we discuss selected examples of Cu(II) complexes with tridentate ligands utilizing combinations of N, O, S, and Se donors, focusing on effects of ligand flexibility/rigidity on their coordination modes, properties and applications. [ABSTRACT FROM AUTHOR]

The solid-state structures and magnetic properties of the first dithiazolyl radical are described to display a spin transition without thermal hysteresis. The comparison of the high- and low-temperature structures has shown that the phase transition occurs without cleavage of the intermolecular contacts.

A study shows that reduction of the radical cation [NSSNC-CNSNS][AsF6] with ferrocene leads to the novel biradical (super .)NSNSC-CNSSN(super .) exhibiting an exceptional pi*-pi* dimer between isomeric 1,2,3,5- and 1,3,2,4-dithiadiazolyl rings. It is shown that paramagnetism of the title biradical can be enhanced upon grinding by the magnetic susceptibility measurements.

The preparation of a series of 4,4′,5,5′-substituted benzo-fused 1,2,5,6-tetrathiocins X2C6H2S4C6H2X2 (1a–1g) were prepared from the reaction of S2Cl2 with 1,2-C6H4X2 (X = OMe, OEt; X2 = OCH2O, OCH2CH2O, OCH2CH2CH2O, MeNC(＝O)NMe, O(CH2CH2O)4). The oxidative addition of 1a–1g to zero-valent Pd2dba3 or Pt2dba3 (dba = dibenzylideneacetone) in the presence of bis (diphenylphosphino)ethane (dppe) resulted in formation of the substituted mononuclear benzenedithiolate complexes M(L)(dppe) [L = dithiolate ligand; 2a–2g (M = Pd) and 3a–3g (M = Pt)] in 37–89% yield based on recrystallized material. Representative examples of M(L)(dppf) [dppf = bis-diphenylphosphinoferrocene; 4a, 4g (M = Pd) and 5g (M = Pt)] were prepared in a similar fashion. The structures of all derivatives were determined by X-ray diffraction, multinuclear NMR and elemental analysis. The reactivity of the two crown ether dithiolate complexes, 2g and 4g, with 1 equivalent of NaBPh4 led to isolation of the 1 : 1 complexes in which the Na+ cation is bound in the macrocyclic crown, [Na(2g)(MeOH)2][BPh4] and [Na(4g)][BPh4] whose structures were determined by X-ray diffraction. Electrochemical studies supported through DFT calculations on the crown ether derivatives revealed a series of ligand-based oxidation waves corresponding to the dithiolate ligand (and dppf for 4g and 5g) whose redox potentials were shifted by ca. +0.1 V on binding to Na+. [ABSTRACT FROM AUTHOR]

Herein, we disclose the utilisation of iodonium ylides to access a range of boron dienolates. Heating of acyclic iodonium ylides in the presence of different aryl boranes leads to the formation of rare 1,3-carboboration products. This methodology could not be expanded to cyclic iodonium ylides which instead formed a Lewis acid–base adduct. Products proved to be remarkably stable under a wide range of conditions allowing for their long term storage. [ABSTRACT FROM AUTHOR]

The reaction of either toluene-3,4-dithiol or benzene dithiol with phosphorus(III) trihalides generates the corresponding benzo-fused 1,3,2-dithiaphospholes, RC6H3S2PX (R = Me (1), R = H (2); X = Cl, Br, I). The P-chloro-dithiaphospholes undergo: (a) halogen abstraction reactions with Lewis acids forming phosphenium cations; (b) substitution with LiHMDS base and; (c) reduction chemistry with sodium metal to generate the P--P σ-bonded dimer, (RC6H3S2P)2. Reduction catalysis of aldehydes with pinacolborane using dithiaphospholes is compared with their dioxaphosphole and diazaphosphole counterparts as precatalysts, revealing interesting differences in the reactivity of this series of compounds. [ABSTRACT FROM AUTHOR]

Inclusion of the dithiadiazolyl and diselenadiazolyl radicals PhCNEEN (E = S, Se) into the porous framework, Al(bdc)(OH) [MIL-53(Al); bdc = 1,4-benzenedicarboxylate] was achieved by vacuum sublimation. PXRD studies reveal the inclusion complexes adopt the orthorhombic space group Imma. Variable temperature PXRD studies coupled with thermal analysis reveal that for PhCNSSN@MIL-53(Al), radical elimination from the pores at elevated temperatures is accompanied by an opening of the pore channels. Radicals can also be extracted from the framework using an appropriate solvent. Oxidation of the radical guest within the host framework has been achieved with Cl2 or Br2 and led to complete radical oxidation (based on EPR studies) whereas the milder oxidant I2 leads to incomplete oxidation. [ABSTRACT FROM AUTHOR]

A tridentate ligand LH3 (C11H13N3O4) comprising o-vanillin, hydrazone and oxime donor groups has been employed to prepare a new class of di- and tetranuclear LnIII complexes. The reaction of LH3 with Ln(NO3)3·xH2O in the presence of a suitable base yields the dinuclear DyIII complex [Dy2(LH2)4(CH3OH)][NO3]2 (1) and the tetranuclear complexes [Dy4(LH)4(LH2)2(OH)2]·2H2O (2) and [Gd4(LH)4(LH2)2(OMe)2]·nH2O, (3). In these complexes, LH3 is either monodeprotonated (1) or a mixture of mono- and doubly-deprotonated ligands (2 and 3) binding lanthanide ions via Ndiazine, Ohydrazone, and Ovanillin donors, while the remaining vacant coordination sites are occupied by OMeOH (1), Ohydroxide (2) and methoxides (3). DC magnetic susceptibility studies on the isotropic tetranuclear GdIII complex (3) reveal weak antiferromagnetic exchange interactions between the LnIII ions. AC studies reveal that the dinuclear complex (1) exhibits field-induced slow relaxation of magnetization with Ueff = 43.4 K, whereas 2 is a single molecule magnet, exhibiting slow relaxation of magnetization under zero field below 18 K, which is modelled using a combination of Orbach (Ueff/kB = 26.7 K) and Raman relaxation processes. [ABSTRACT FROM AUTHOR]

The synthesis and characterization of a new chelating benzotriazinyl radical (Rad2) are described. Crystallographic studies coupled with SQUID magnetometry on Rad2 reveal the presence of discrete radical pairs which are antiferromagnetically coupled. The reaction of Rad2 with the 3d transition metal complexes M(hfac)2·xH2O (hfac− = hexafluoroacetylacetonate) led to mononuclear metal complexes of general formula M(hfac)2(Rad2) [M = Zn(II) (1); Ni(II) (2) and Co(II) (3)] whose structures have been determined by single crystal X-ray diffraction. Compounds 1–3 are isostructural and crystallize in the monoclinic space group P21/n with two molecules in the asymmetric unit. In the case of the Zn(II) complex (1) through-space intermolecular radical⋯radical antiferromagnetic exchange interactions via π*⋯π* contacts are observed, whereas strong intramolecular through-bond metal–radical ferromagnetic interactions [J = +59.3(9) cm−1] are observed for the Ni(II) complex (2). For the Co(II) complex (3), computational and magnetic studies reveal substantial zero field splitting and ferromagnetic metal–radical interactions. [ABSTRACT FROM AUTHOR]

A single-crystal electron paramagnetic resonance (EPR) studies on the beta-polymorph of the organic magnet p-NCC6F4CNSSN is presented. The results revealed that the crystallographic c-axis corresponds to the intermediate axis of magnetization with the magnetic easy axis parallel to the b-axis.

The reaction of (diphenylmethylene)hydrazone or 1,4-bis-hydrazone-ylidene(phenylmethyl)benzene with Lewis acidic boranes B(2,4,6-F3C6H2)3 or B(3,4,5-F3C6H2)3 generates the Lewis acid–base adducts. Alternatively, when (9H-fluoren-9-ylidene)hydrazone is employed several products were isolated including 1,2-di(9H-fluoren-9-ylidene)hydrazone, the 2 : 1 borane adduct of NH2–NH2 and the 1-(diarylboraneyl)-2-(9H-fluoren-9-ylidene)hydrazone in which one ArH group has been eliminated. The benzhydrazide starting material also initially gives an adduct when reacted with Lewis acidic boranes which upon heating eliminates ArH generating a CON2B heterocycle. [ABSTRACT FROM AUTHOR]

Reaction of the methyl-benzodithiazolyl radical (MBDTA) with M(hfac)2 complexes (M = Mn, Co, Zn) affords the complexes M(hfac)2(MBDTA)2. Strong antiferromagnetic exchange interactions are observed between M(II) ions and the two S = 1/2 radicals (M = Mn, Co), whereas weak antiferromagnetic interactions are observed between radicals when using the diamagnetic Zn(II) ion. Strong intermolecular exchange coupling is also evident in Mn(hfac)2(MBDTA)2 and attributed to π*–π* contacts between MBDTA radicals which are absent for the Co and Zn derivatives. [ABSTRACT FROM AUTHOR]

Reactions of 1,10‐phenanthroline (phen) and 2‐(3,4‐dichlorophenyl)acetic acid (dcaH) with Mn(CO3) (M = LiI, NaI and MgII; n = 1 and 2) in MeOH yield the mononuclear lithium complex aqua[2‐(3,4‐dichlorophenyl)acetato‐κO](1,10‐phenanthroline‐κ2N,N′)lithium(I), [Li(C8H5Cl2O2)(C12H8N2)(H2O)] or [Li(dca)(phen)(H2O)] (1), the dinuclear sodium complex di‐μ‐aqua‐bis{[2‐(3,4‐dichlorophenyl)acetato‐κO](1,10‐phenanthroline‐κ2N,N′)sodium(I)}, [Na2(C8H5Cl2O2)2(C12H8N2)2(H2O)2] or [Na2(dca)2(phen)2(H2O)2] (2), and the one‐dimensional chain magnesium complex catena‐poly[[[diaqua(1,10‐phenanthroline‐κ2N,N′)magnesium]‐μ‐2‐(3,4‐dichlorophenyl)acetato‐κ2O:O′] 2‐(3,4‐dichlorophenyl)acetate monohydrate], {[Mg(C8H5Cl2O2)(C12H8N2)(H2O)2](C8H5Cl2O2)·H2O}n or {[Mg(dca)(phen)(H2O)2](dca)·H2O}n (3). In these complexes, phen binds via an N,N′‐chelate pocket, while the deprotonated dca− ligands coordinate either in a monodentate (in 1 and 2) or bidentate (in 3) fashion. The remaining coordination sites around the metal ions are occupied by water molecules in all three complexes. Complex 1 crystallizes in the triclinic space group P with one molecule in the asymmetric unit. The Li+ ion adopts a four‐coordinated distorted seesaw geometry comprising an [N2O2] donor set. Complex 2 crystallizes in the triclinic space group P with half a molecule in the asymmetric unit, in which the Na+ ion adopts a five‐coordinated distorted spherical square‐pyramidal geometry, with an [N2O3] donor set. Complex 3 crystallizes in the orthorhombic space group P212121, with one Mg2+ ion, one phen ligand, two dca− ligands and three water molecules in the asymmetric unit. Both dcaH ligands are deprotonated, however, one dca− anion is not coordinated, whereas the second dca− anion coordinates in a bidentate fashion bridging two Mg2+ ions, resulting in a one‐dimensional chain structure for 3. The Mg2+ ion adopts a distorted octahedral geometry, with an [N2O4] donor set. Complexes 1–3 were evaluated against urease and α‐glucosidase enzymes for their inhibition potential and were found to be inactive. Reactions of 1,10‐phenanthroline (phen) and 2‐(3,4‐dichlorophenyl)acetic acid (dcaH) with Mn(CO3) (M = LiI, NaI and MgII; n = 1 and 2) in MeOH yield the mononuclear lithium complex, the dinuclear sodium complex and the one‐dimensional chain magnesium complex. In these complexes, phen binds via an N,N′‐chelate pocket, while the deprotonated dca− ligands coordinate either in a monodentate or bidentate fashion. [ABSTRACT FROM AUTHOR]

Formation of radical–radical cocrystals is an important step towards the design of organic ferrimagnets. We describe a simple approach to generate radical–radical cocrystals through the identification and implementation of well‐defined supramolecular synthons which favor cocrystallization over phase separation. In the current paper we implement the structure‐directing interactions of the E−E bond (E=S, Se) of dithiadiazolyl (DTDA) and diselenadiazolyl (DSDA) radicals to form close contacts to electronegative groups. This is exemplified through the preparation and structural characterization of three sets of radical cocrystals; the 2:2 cocrystal [PhCNSSN]2[MBDTA]2 (4) [MBDTA=methyl benzodithiazolyl] and the 2:1 cocrystals [C6F5CNEEN]2[TEMPO] (E=S, 5; E=Se, 6). In 4 the two types of radical are linked via bifurcated inter‐dimer δ+S⋅⋅⋅Nδ− interactions whereas 5 and 6 exhibit a set of five‐centre δ+E⋅⋅⋅Oδ− contacts (E=S, Se). SOMO wrestling: Cocrystallization of radicals requires different open‐shell molecules to interact with each other rather than themselves. This process can be driven by careful selection of favorable electrostatic interactions between molecules. [ABSTRACT FROM AUTHOR]

Reaction of 2,6-dicyanopyridine with 2 equiv. of 2-(propylthio)benzenamine in the presence of lithium bis(trimethylsilyl)amide, followed by ring-closing oxidation with N-chlorosuccinimide affords the novel tridentate ligand, 2,6-bis-(1′,2′,4′-benzothiadiazinyl)pyridine (LH2). Electrochemical studies on the free ligand LH2 reveal a single well-defined 2e− oxidation process with E1/2 = +0.90 V. EPR studies of the in situ chemical oxidation of LH2 reveal the generation of a benzotriazinyl radical. Reactions of ligand LH2 with a range of divalent transition metal salts in either MeOH or MeCN in a 2 : 1 ratio at ambient temperatures afforded mononuclear complexes with general formula [M(LH2)2][X]2 (M = Mn, X = CF3SO3 (1); Fe, X = CF3SO3 (2); Fe, X = BF4 (3); Co, X = Cl (4); Ni, X = Cl (5); Zn, X = CF3SO3 (6)) and the 1 : 1 complex [Cu(LH2)(NO3)2] (7). In all cases the LH2 ligand binds in a tridentate N,N′,N′′ chelate fashion via benzothiadiazinyl NBTDA and pyridyl Npy atoms. The low spin FeII complexes (2 and 3) were implemented for NMR and UV-Vis solution studies of ligand reactivity as well as cyclic voltammetry which reveal two 1e-oxidation waves. The metal complexes 1–6 are discussed and reveal a range of geometries between octahedral and trigonal prismatic with the greatest deviation from octahedral symmetry apparent for ions with no crystal field stabilisation energy, i.e. d10 ZnII and high spin d5 MnII ions. [ABSTRACT FROM AUTHOR]

We show that the αi and βj parameters developed by Hunter to describe the hydrogen‐bond donor and acceptor properties of particular functional groups can be successfully applied to understand favourable intermolecular interactions between molecules containing heavier p‐block elements, notwithstanding the increasing dispersion terms associated with these elements. Although dispersion is an important contribution to the dimerisation enthalpy of dithiadiazolyls, we show that many aspects of the crystal packing of dimers can successfully be interpreted through such an electrostatic analysis. This approach is exemplified through analysis of the crystal structures of a series of fluoro‐ and trifluoromethyl‐substituted 1,2,3,5‐dithiadiazolyl radicals. Comparison of fluoro‐ and trifluoromethyl‐substituted aryl dithiadiazolyls reveals that the trifluoromethyl group has a pronounced electron‐withdrawing effect, enhancing the electrostatic contribution, but also adding steric bulk. The possible intermolecular interactions between these molecules are close in energy, resulting in structural diversity and at least one case of polymorphism. Despite neglecting the significant favourable dimerisation enthalpy in the analysis of the electrostatic potential, this approach provides a very clear rationalisation of many aspects of the observed crystal structures.|||||| [ABSTRACT FROM AUTHOR]

The synthesis and coordination chemistry of a new series of open chain diazine based ligands (L3aH2, L3bH2, and L3cH2) is reported. The ligands comprise a central disubstituted bipyridine moiety with two bridging alkoxide oxygen donors, together with diazine and pyridine terminal groups strategically located to coordinate three metal centres. Reactions of L3aH2 and L3bH2 with CuX2 (X− = ClO4, Cl, NO3) yield a trinuclear complex (1) and 1-D copper chains (2, 3). In these complexes the ligands bind copper ions via Nbipyridne, trans Ndiazine, Ohydrazone, and Npyridne donors while vacant sites are occupied by counter ions or solvent molecules (methanol, water, acetonitrile). Reaction of L3cH2 with MnCl2 affords a linear trinuclear Mn complex (4), where the Mn(ii) ions are connected viaμ2-Ohydrazone linkers with no N–N bridging. Reaction of L3aH2 with Fe(SO3CF3)2 yields a tetranuclear mixed valence Fe complex (5), in which both trans N–N and Ohydrazone bridging is observed. Magnetic studies reveal the presence of moderate to strong antiferromagnetic interactions in complexes 1–4 while a mix of ferromagnetic and antiferromagnetic interactions is observed in complex 5. [ABSTRACT FROM AUTHOR]