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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 open-chain diazine ligand (L4H2) containing bipyridine, oxime and hydrazone functionalities is reported. Reaction of L4H2 with CuCl2·2H2O affords the mononuclear complex [Cu(L4H2)Cl2] (1) in which the ligand acts as a neutral tridentate N,N′,N′′ donor, whereas treatment with a large excess of CuCl2·2H2O affords the dinuclear complex [Cu2(L4H)Cl3(CH3OH)(H2O)] (2) in which the ligand is singly-deprotonated at the diazine, offering N,N′,N′′ and N,N′ donor sets to two Cu(ii) ions. Reaction with Cu(NO3)2·3H2O yields the trinuclear complex, [Cu3(L4H)2(CH3OH)4(NO3)4] (3) in which the ligand is again singly deprotonated, but now presents a tetradentate N,N′,N′′,N′′′-donor set to the first Cu(ii) and behaves as an N,O-chelate to a second Cu(ii), with a conformational change from cis to trans at the diazine moiety. When the latter reaction is repeated in the presence of a mild base, a second trinuclear complex is isolated, [Cu3(L4)2(CH3CH2OH)](NO3)2 (4) in which both the diazine and oxime functionalities of the ligand are deprotonated which subsequently bridges all three Cu(ii) ions, acting as an N,N′,N′′ donor to the first Cu(ii), a N,N′ donor to a second Cu(ii) (similar to 2) and as a terminal O-donor to a third Cu(ii) ion. The Cu(ii) ions are linked mutually cis via the two-atom diazine bridge in the case of 2 and 4 and trans in the case of 3. Magnetic studies reveal the presence of weak ferromagnetic interactions in 2 (g = 2.2, J/k = +12.8 K) and strong antiferromagnetic interactions in both 3 and 4 (g = 2.093 J/k = −140 K and g = 2.24 J/k = −300 K respectively). [ABSTRACT FROM AUTHOR]

A new ligand, 3,3′-di(pyrazinamoyl)-2,2′-bipyridine, L3H2 has been prepared and is comprised of distinct binding domains capable of facilitating the formation of coordination polymers. Reaction of L3H2 with [Cu2(OAc)4(H2O)2] in the presence of Et3N·HCl affords the complex {[Cu6(L3)2(Cl)2(OAc)6]·2H2O·2MeOH}n (1) in which the [L3]2− anion binds two unique copper ions in a bis-tridentate fashion via amide and pyridyl N atoms. This bimetallic unit is linked to an equivalent unit via a pair of 1,3-acetato and μ-chloro bridges to afford a tetrameric [Cu4(L3)2Cl2(OAc)2] core. Coordination of one of the pyrazole substituents from each ligand to a third copper centre of a rigid paddlewheel [Cu2(OAc)4] unit leads to a unique 1-D polymeric structure. Magnetic studies of 1 reveal that the magnetism can be described in terms of two sets of exchange interactions; strong antiferromagnetic interactions between the two copper centres within the “paddle-wheel” (J/k = −190 K) and a combination of weaker ferro- and antiferro-magnetic interactions within the tetrameric core (J′/k = −5.7 K and J′′/k = +2.1 K). [ABSTRACT FROM AUTHOR]

Despite the differing size of the Cl- and PF6- counter-ions, the structures of the heteroleptic iridium(III) complexes, [Ir(dFphtl)2(btl)]Cl, [1]Cl, and [Ir(dFphtl)2(btl)]PF6, [1]PF6, (where dFphtl = 1-benzyl-4-(2,4-difluorophenyl)-1H-1,2,3-triazole and btl = 1,1'-dibenzyl-4,4'-bi-1H-1,2,3-triazolyl) are found to exhibit similar morphologies in which both structures adopt hydrogen-bonded networks driven by the hydrogen-bond donor and acceptor demands of the triazole functional group. The triazole thus can be used as a supramolecular synthon to control the internuclear distance in the solid-state. [ABSTRACT FROM AUTHOR]

Double deprotonation of N,N′-bis(2,6-diisopropylphenyl)-o-phenylenediamine (H2L) with n-BuLi in THF yields the dilithium complex Li2L(thf)3. The reaction of Li2L(thf)3 with FeBr2(thf)2 and subsequent replacement of the solvent with toluene yield LFe(η6-toluene), which can also be synthesized from Fe(HMDS)2(thf) and H2L in toluene. The NMR data, bond lengths obtained from an X-ray diffraction study, and DFT calculations indicate that the diamide ligand L2− undergoes oxidization to a radical ligand L1−. Reaction of LFe(η6-toluene) with 1 atm CO yields the tricarbonyl complex LFe(CO)3. MoCl4(thf)2 reacts with two equivalents of Li2L(thf)3 to yield (LiL)2MoCl2(thf)4 in which the phenylene backbone of the ligand has been dearomatized. One-electron oxidation of Li2L(thf)3 by EuCl3(dme)2 yields the open-shell species LiL(OEt2), which was characterized by X-ray crystallography and EPR spectroscopy. [ABSTRACT FROM AUTHOR]

Abstract: The perovskite-like salt [p-ClC6H4NH3]2CuCl4 1 exhibits a wealth of magnetic and structural phase transitions which have been probed by variable temperature single crystal X-ray diffraction, SQUID magnetometry, resonant ultrasound spectroscopy (RUS), EPR spectroscopy, DSC measurements and DFT calculations. Single crystal X-ray diffraction studies between room temperature and 3 K reveal a rich tapestry of structural changes; at 298 K the structure conforms to a monoclinic setting but undergoes a first order phase transition upon cooling below ∼275 K to a higher symmetry orthorhombic cell. This is facilitated by a transition to an intermediate phase at ∼277 K. Whilst the intermediate phase has a limited stability window (∼2 K) and has not been structurally determined, the two discrete phase transitions at 275.5 K and 277 K have been clearly detected by differential scanning calorimetry, EPR spectroscopy and RUS studies. On further cooling a dynamic relaxation process is observed in RUS measurements, evidenced by a Debye-like peak in the dissipation at ∼140 K. Residual electron density maps from single crystal X-ray diffraction studies reveal that this may be associated with a freezing out of the NH3⋯Cl hydrogen-bonding between cation and anion frameworks upon cooling. The activation barrier for this order/disorder process was estimated to be at least 27 kJ mol−1 from the RUS data. Variable temperature dc SQUID data reveal that 1 is a 2D ferromagnet with antiferromagnetic interactions between layers below 9 K. Analysis of the temperature dependence of the magnetic susceptibility for T > 40 K reveals that 1 exhibits Curie–Weiss behaviour with θ = +22.8 K indicative of dominant ferromagnetic interactions. Good agreement is observed between the strength of the ferromagnetic interaction extracted from the Weiss constant (J/k = +22.8 K) and that calculated by DFT (J/k = +25 to +28 K) and from EPR studies (J/k = +17 K). The presence of short range ferromagnetic interactions is reflected in a marked temperature dependence of the g-factors determined from EPR spectroscopy below 20 K and possibly a small elastic anomaly in the RUS data. RUS studies indicate a very small elastic anomaly associated with the transition to long range order, implying weak or no magnetoelastic effect. At fields above ∼15 G a spin flip transition is induced and 1 displays metamagnetic behaviour, with a saturation magnetization of 0.96 μ B. [Copyright &y& Elsevier]

Abstract: The interplay between electron count and molecular geometry is a central theme in main group chemistry. The structures of electron-precise cages, which offer three orbitals and three electrons for skeletal bonding, were rationalised by Mingos based on cage structures comprising n three-coordinate vertices (for n =4, 6, 8, 10, etc.). Whilst these offered a conceptual rationale, an increasing number of potential structural topologies exist with increasing cage size, thereby limiting the predictive nature of this approach (e.g. there are three possible cage topologies for 8 vertex polyhedra and five for 10-vertex polyhedra!). The current review re-examines the structural motifs possible for these electron-precise cages, focusing not only on the cage size (number of vertices) but also on the number and size of the faces of the cage. This approach reveals rather limited numbers of favourable topologies for the large family of hetero-atomic electron-precise cages (AB) x in which electrostatic contributions are maximised for topologies comprising only even-numbered (e.g. square and hexagonal) faces. This review focuses on larger cages (x ≥6) identifying the most favourable geometries for these structures up to 20-vertex molecular cages. Larger cages are illustrated with suitable examples where available. [Copyright &y& Elsevier]

Reaction of ArSNᆖC(py)2 [Ar = 2,4-dinitrophenyl, (O2N)2C6H3] with CuCl2·2H2O in DMF yielded the tetranuclear complex [Me2NH2][Cu4Cl6{py2CO2}{py2C(OH)O}] (1) through metal-catalysed hydrolysis of both DMF and the thiazyl chain. Notably direct reaction of dipyridylketone (py2CO) with CuCl2·2H2O in DMF yielded the mononuclear pseudo-octahedral complex [CuCl2(py2C(OH)2)(DMF)]·DMF (2) in which the 1,1-gem diol, py2C(OH)2 acts as a tripodal ligand. Heating of 2 in DMF/MeOH promoted aggregation and formation of the polymer [Cu2Cl3{py2(OMe)O}]∞ (3). The structures of 1–3 were determined by X-ray diffraction. [ABSTRACT FROM AUTHOR]

Abstract: EPR, electrochemical studies and neutron diffraction studies on a large range of 1,2,3,5-dithiadiazolyl radicals have shown that the spin density distribution is essentially unaffected by substituent effects. The variation of magnetic properties previously reported for a series of perfluorophenyl-dithiadiazolyl radicals p-XC6F4CNSSN (X=CN, Br, NO2 and NCC6F4) is therefore due to differences in molecular packing. The nearest-neighbour magnetic exchange interactions in these radicals are probed through DFT studies (B3LYP/6-311G**) and are shown to exhibit a variety of both ferromagnetic and antiferromagnetic interactions. All exchange interactions with | J |>1cm−1 coincide with close heterocyclic contacts between dithiadiazolyl rings (3.18–4.00Å) and produce | J | values up to 40K. An analysis of these interactions indicates that the dominant exchange pathway would appear to be a direct exchange mechanism between radical centres, with orthogonality of the singly-occupied molecular orbitals (SOMOs) favouring ferromagnetic interactions. [Copyright &y& Elsevier]

The asymmetric dithiadiazene BrC 6 F 4 NSNSC 6 H 4 NO 2 crystallizes in the space group P -1 and exhibits a 1D polar chain structure linked via structure-directing Br···O 2 N synthons. [ABSTRACT FROM AUTHOR]

Reaction of benzo-1,2,3-dithiazolyl, 1 , with Pt(PPh 3 ) 4 has been shown to produce the aminothiolate complex (amt)Pt(PPh 3 ) 2 [amt = HNC 6 H 4 S], via oxidative addition of 1 to Pt(PPh 3 ) 2 followed by S-abstraction by PPh 3 . Semi-empirical calculations (AM1 and EHT) have been used to probe the oxidative addition step of this reaction. These studies clearly reveal that close approach of 1 to Pt(PR 3 ) 2 induces electron transfer from Pt(PR 3 ) 2 to 1 with concomitant ring opening at the S--N bond and coordination to the metal centre. The SOMO of this complex retains the π* character of the dithiazolyl ring. [ABSTRACT FROM AUTHOR]

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]

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]

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 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]

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 of novel bis(trithio)phosphines is achieved by oxidative addition of tetrathiocins to the phosphorus(i) reagent [PIdppe][Br] in good yields under ambient conditions. These bis(trithio)phosphines and the related intermediate diphosphine species are characterized by X-ray diffraction and multinuclear NMR and a mechanism is proposed for the formation of these molecules. In contrast, the related reaction with diphenyldisulfide produces a mononuclear tris(phenylthio)phosphine. [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]

A new tetrathiafulvalene (TTF) donor covalently appended with a 1,5-diisopropylverdazyl radical through a cross-conjugated pyridyl linker ( 3) has been prepared and characterised. Reaction of 3 with tetracyanoquinonedimethane (TCNQ) afforded the 2:1 charge-transfer complex ( 3)2 ⋅TCNQ ( 4), in which the IR and structural data are consistent with 0.25 e− charge transfer from the TTF donor (D) to the TCNQ acceptor (A). The TTF and TCNQ molecules adopt a mixed-stack D⋅⋅⋅D⋅⋅⋅A arrangement that does not facilitate conduction. A solution EPR spectrum of 4 comprises a broad featureless singlet, which is consistent with the presence of a TCNQ radical anion. Theoretical studies were performed to probe the exchange interactions within selected fragments of 4 with and without charge transfer. In the absence of charge transfer, DFT calculations reveal weak antiferromagnetic exchange between verdazyl radicals within the ( 3)2 monoradical unit. However, partial oxidation of the dimer ( 3)2 to the diradical cation leads to an S= [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]

The syntheses, structures, and magnetic properties of three new coordination complexes, tetranuclear [Zn2L³(OAc)(OMe)]2⋅3MeOH⋅H2O (3), trinuclear [Ni3(L³)3]⋅6H2O (4), and a 1-D chain {[Cu2L³(OAc)2]2⋅H2O}n (6), of a polydentate, doubly deprotonated, 3,3'-disubstituted bipyridine ligand [L³]2- are reported. The X-ray crystal structures demonstrate that the ditopic ligand provides a flexible N3 donor set for transition metal ions where each binding pocket shifts from fac to intermediate fac/mer to the mer isomer affording a Ni3 triangle, a Zn4 tetramer, and a 1-D Cu(II) polymer, respectively. This variation in coordination preference is rationalized with the aim of designing future ligands with controlled coordination modes. Magnetic susceptibility studies on 4 reveal it belongs to the rare family of ferromagnetically coupled [Ni3] clusters. In contrast, magnetic studies of the 1-D chain 6 reveal weak antiferromagnetic interactions due to the poor orbital overlap of the singly occupied Cu(II) ... orbitals with the one-atom bridge that connects them along the Jahn-Teller distortion axis. [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]

The crystal structure of a novel dithiadiazolyl co-crystal, the second such co-crystal to be reported, has been determined, and is described in the context of the structures of the co-crystal formers. It is also shown that both known dithiadiazolyl co-crystals ([PhCN2S2][C6F5CN2S2] and [PhCN2S2][NC5F4CN2S2]) can be made via co-sublimation or by mixing co-crystal formers in solution, but not mechanochemically. DSC and theoretical calculations reveal that the thermodynamics of co-crystal formation in these systems is very finely balanced. [ABSTRACT FROM AUTHOR]

7-(4-Fluorophenyl) and 7-phenyl-substituted 1,3-diphenyl-1,4-dihydro-1,2,4-benzotriazin-4-yl radicals were characterized by X-ray diffraction analysis and variable-temperature magnetic susceptibility studies. The radicals pack in 1D π stacks of equally spaced slipped radicals with interplanar distances of 3.59 and 3.67 Å and longitudinal angles of 40.97 and 43.47°, respectively. Magnetic-susceptibility studies showed that both radicals exhibit antiferromagnetic interactions. Fitting the magnetic data revealed that the behavior is consistent with 1D regular linear antiferromagnetic chain with J=−12.9 cm−1, zJ′=−0.4 cm−1, g=2.0069 and J=−11.8 cm−1, zJ′=−6.5 cm−1, g=2.0071, respectively. Magnetic-exchange interactions in benzotriazinyl radicals are sensitive to the degree of slippage, and inter-radical separation and subtle changes in structure alter the fine balance between ferro- and antiferromagnetic interactions. [ABSTRACT FROM AUTHOR]

X-ray studies show that 1,3-diphenyl-7-(thien-2-yl)-1,4-dihydro-1,2,4-benzotriazin-4-yl ( 6) adopts a distorted, slipped π-stacked structure of centrosymmetric dimers with alternate short and long interplanar distances (3.48 and 3.52 Å). Cyclic voltammograms of 7-(thien-2-yl)benzotriazin-4-yl 6 show two fully reversible waves that correspond to the −1/0 and 0/+1 processes. EPR and DFT studies on radical 6 indicate that the spin density is mainly delocalized over the triazinyl fragment. Magnetic susceptibility measurements show that radical 6 obeys Curie-Weiss behavior in the 5-300 K region with C=0.378 emu K mol−1 and θ=+4.72 K, which is consistent with ferromagnetic interactions between S=1/2 radicals. Fitting the magnetic susceptibility revealed the behavior is consistent with an alternating ferromagnetic chain ( g=2.0071, J1=+7.12 cm−1, J2=+1.28 cm−1). [ABSTRACT FROM AUTHOR]

Manganese(II) hydrazide gels designed for Kubas-typehydrogen storagewere synthesized from the reaction between bis(trimethylsilylmethyl)manganese and anhydrous hydrazine. The synthetic materials were characterizedby X-ray powder diffraction, nitrogen adsorption, X-ray photoelectronspectroscopy, infrared spectroscopy, and elemental analysis. Hydrogenstorage measurements were conducted on materials with hydrazine:Mnratios of 0.5:1, 1:1. 1.5:1, and 2:1. The best results were obtainedwith the 1:1 material, which demonstrated as high as 1.01 wt % and32 kg/m3at 77 K and 85 bar and 1.06 wt % and 24.2 kg/m3at 298 K at 85 bar. Measurements up to 143 bar at 298 K ledto an adsorption value of 1.65 wt % and 37.7 kg/m3withoutsaturation. The isosteric enthalpy of this material rose with surfacecoverage from 1.3 to 39 kJ/mol. Excess void space was removed fromthe materials by compressing at 500 Psi and the resulting compressedgel pellets possess an absolute volumetric adsorption of 18.97 kg/m3at 298 K and 85 bar. The mechanism of hydrogen storage wasprobed with electron paramagnetic resonance (EPR), which showed signalenhancements when sample was held under 1 bar hydrogen, both at roomtemperature and at 77 K. This was interpreted as a perturbation dueto hydrogen binding to the Mn center. [ABSTRACT FROM AUTHOR]

The outcome of the oxidative addition reactions of bis(4′,5′-dimethoxybenzo)-1,2,5,6-tetrathiocin to Pd2dba3 under microwave conditions is sensitive to the nature of the phosphine coreagent; the bidentate phosphines dppm, dppe, and dppf afford the mononuclear dithiolates (dmobdt)Pd(dppm) (4), (dmobdt)Pd(dppe) (2), and (dmobdt)Pd(dppf) (5), whereas more labile monodentate phosphines lead to aggregation; Ph3P afforded the dinuclear dithiolate (dmobdt)2Pd2(PPh3)2 (6), whereas tBu3P generated the phosphine-free hexanuclear edge-capped octahedral complex Pd6(dmobdt)6 (7) [dmobdt = 4,5-dimethoxybenzenedithiolate, (MeO)2C6H2S22–]. [ABSTRACT FROM AUTHOR]

Oxidation of equimolar amounts of [p-BrC[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] NC[sub 6] H[sub 4] CN[sub 4] S[sub 2] CC[sub 6] H[sub 4] NO[sub 2] (1) and BrC[sub 6] H[sub 4] CN[sub 4] S[sub 2] CC[sub 6] H[sub 4] Br (2) as well as the unsymmetrically substituted derivative BrC[sub 6] H[sub 4] CN[sub 4] S[sub 2] CC[sub 6] H[sub 4] NO[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) Å, β = 92.088(4)°) 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) Å, α = 84.483(4)°, β = 77.112(4)°, γ = 87.879(3)°); 3 was found to crystallize in two forms: recrystallization from CH[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) Å, α = 81.860(3)°, β = 83.406(5)°, γ = 66.589(5)°), whereas cooling a solution to –5°C yielded a solvated form, 3·CH[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) Å, β = 92.69(3)°). The NO[sub 2] ···Br intermolecular interactions observed in the unsolvated structure of 3 are disrupted in the solvate structure; the CH[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.L'oxydation de quantités équimolaires de [p-BrC[sub 6] H[sub 4] CNSSN]Cl et de [p-O[sub 2] NC[sub 6] H[sub 4] CNSSN]Cl avec de l'oxygène élémentaire, en présence de Ph[sub 3] Sb, dans du MeCN, conduit à un mélange de dithiatétrazocines symétriques, O[sub 2] NC[sub 6] H[sub 4] CN[sub 4] S[sub 2] CC[sub 6] H[sub 4] NO[sub 2] (1) et BrC[sub 6] H[sub 4] CN[sub 4] S[sub 2] CC[sub 6] H[sub 4] Br (2), aux côtés du dérivé substitué de façon non symétrique, BrC[sub 6] H[sub 4] CN[sub 4] S[sub 2] CC[sub 6] H[sub 4] NO[sub 2] (3). On a déterminé les structures des composés 1–3 par diffraction des rayons X: le composé 1 cristallise dans le groupe d'espace monoclinique P2[sub 1] /c (a = 8,6397(4), b = 5,8359(4) et c = 14,9767(11) Å, β = 92,088(4)°), avec une demi-molécule dans la maille asymétrique; 2 cristallise dans le groupe d'espace triclinique P1 (a = 6,5330(5), b = 8,2084(6) et c = 14,7264(9) Å, α = 84,483(4)°, β = 77,112(4)° et γ = 87,879(3)°); on a trouvé que 3 cristallise sous deux formes, la recristallisation dans le CH[sub 2] Cl[sub 2] , à température ambiante, conduit à des cristaux ne contenant pas de solvant, de phase triclinique et de groupe d'espace P1 (a = 6,5060(9), b = 7,0739(9) et c = 9,1164(8) Å, α = 81,860(3)°, β = 83,406(5)° et γ = 66,589(5)°) alors que le refroidissement de la solution à –5°C livre une forme solvatée, 3·CH[sub 2] Cl[sub 2] qui cristallise dans le groupe d'espace monoclinique P2[sub 1] /m (a = 6,179(1), b = 10,960(2) et c = 13,884(3) Å, β = 92,69(3)°). Les interactions intermoléculaires NO[sub 2] ···Br observées dans la structure non solvatée de 3 sont interrompues dans la structure solvatée; la molécule de CH[sub 2] Cl[sub 2] de cette dernière est alignée d'une façon telle que son dipôle moléculaire interagit à la fois avec le groupe nitro et le bromo tout en maintenant un motif de chaîne moléculaire. On discute des structures en fonction de leurs potentiels électrostatiques moléculaires calculés de façon semi-empirique et de calculs d'interactions intermoléculaires à l'aide de forces de van der Waals combinées à un modèle de charge ponctuelle électrostatique.Mots clés : dithiatétrazocine, structure cristalline, génie cristallin, potentiel électrostatique moléculaire.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]

A new macrocyclic complex DyCl3(LN5)·4H2O (1) has been prepared in which the Dy(III) ion is equatorially bound by an N5-donor macrocycle (LN5). Ac susceptibility data reveal slow relaxation of the magnetisation in zero field below 15 K with a distribution of relaxation rates. [ABSTRACT FROM AUTHOR]

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]

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]

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]

Two homochiral M–O–M bridged mixed valence complexes [CoIII 2 CoII(mpm) 6 ]·(ClO 4) 2 (1) and [CoII 2 CoIII 2 (μ 3 -OMe) 2 (μ-mpm) 4 (NO 3) 2 (MeO) 2 ] (2) with linear and defect dicubane topologies respectively were prepared and characterized from the reaction of R - and S -mpmH (where mpmH = -methyl-2- pyridinemethanol) with an appropriate Co(II) salt. Two mixed-valence cobalt complexes, [CoIICoIII 2 (mpm) 6 ](ClO 4) 2 (1) and [CoII 2 CoIII 2 (μ 3 -OMe) 2 (μ-mpm) 4 (NO 3) 4 ] (2), where mpm is the deprotonated form of R or S α-methyl-2-pyridinemethanol, have been structurally and magnetically characterized. Both complexes crystallize in chiral space groups, where 1 is a trinuclear compound with a linear Co(III)–Co(II)–Co(III) topology and 2 is a tetranuclear cluster with a defect dicubane-type structure that has two missing vertices. In both cases the mpm− ligand bridges adjacent Co ions in a η1:η2:μ manner. The molecular geometries of the complexes reveal the Co ions are octahedral, where the greatest deviation from O h symmetry is apparent for the HS d7 Co(II) ions. The chirality of 1 and 2 were studied by circular dichroism spectroscopy where opposite Cotton effects are observed for the R- and S -enantiomers of both complexes. Magnetic susceptibility studies reveal the presence of largely quenched first order orbital angular momentum together with weak ion or intermolecular dipole exchange. [ABSTRACT FROM AUTHOR]

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]

A linear Cu 4 complex containing a combination of square pyramidal and octahedrally coordinated Cu(II) ions is reported. The metal centres are linked via diazine and chloride bridges. Magnetic studies reveal the presence of strong antiferromagnetic interactions via the diazine bridge and moderate ferromagnetic interactions via the chloro bridges. The pyrimidinyl hydrazone ligand O C{NHN C(Me)(pm)} 2 (pm = 2-pyrimidinyl) (L 3 H 2) has two potentially protic H atoms and multiple donor atoms. The reaction of L 3 H 2 with CuCl 2 ·2H 2 O yielded the tetranuclear complex [Cu 4 (L 3 H) 2 Cl 6 (CH 3 OH) 2 ] (1). Structural studies on 1 reveal the molecule is located about a crystallographic inversion centre, affording two crystallographically independent Cu(II) centres with the two symmetry equivalent [Cu 2 (L 3 H)Cl 3 CH 3 OH] units connected via µ 2 -Cl bridges to generate a linear tetranuclear copper complex. The ligand is singly deprotonated (L 3 H−) and twisted around the diazine N N′ bond, affording an N 3 donor set for the Cu1 centre and an N 2 O donor set for the Cu2 centre. The Cu1 ion is five coordinate with an [N 3 ] donor set from the L 3 H− ligand and the remaining two sites occupied by Cl− anions. The Cu2 ion is six coordinate with the L 3 H− ligand offering a mer [N 2 O] donor set, with the three remaining sites occupied by two Cl− anions and a MeOH molecule. Magnetic studies reveal the presence of strong antiferromagnetic interactions via the diazine bridge linking the Cu1 and Cu2 ions and moderate ferromagnetic interactions via the chloro bridges located about the inversion centre, connecting the Cu2 and Cu2i ions. [ABSTRACT FROM AUTHOR]

Abstract Reaction of the phenanthridine ligand (phend) with ZnBr 2 in DMSO/MeOH or MeOH yielded the complexes ZnBr 2 (phend)(DMSO) (1) and ZnBr 2 (phend) 2 (2) respectively. These complexes were characterized by single crystal X-ray diffraction, IR spectroscopy and elemental analyses. Sonochemical preparation of complexes 1 and 2 in methanolic solution generated porous texture (pt) crystals 1 pt and 2 pt. Comparison of the X-ray powder diffraction data confirmed identical crystal structures for 1 and 1 pt as well as 2 and 2 pt. The porous texture (the mixture of nano-porous and micro-pores) morphologies of the sonochemical products were confirmed by scanning electron microscopy. Reaction conditions, such as solvent and the concentration of the initial reagents, played important roles in the size and growth process of the crystalline products. Graphical abstract Image 1 Highlights • Changing solvent has a significant impact on the crystal packing of a series of Zn(II) coordination complexes. • The C H⋯Br hydrogen bonds interactions have a great role in the formation of the multi-dimensional crystal structure. • The C H.⋯Br hydrogen bonds and C H ... π interactions administer the crystal structure. [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). [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]

The synthesis of the novel redox active ligand 3-(2′,6′-pyrimidine)-benzo-1,2,4-thiadiazine (pmbtdaH) is reported. The radical pmbtda can be prepared by in situ 1 e − oxidation and its radical character confirmed by EPR spectroscopy, along with DFT calculations of the spin density distribution. Reaction of pmbtdaH with ZnCl 2 ·2H 2 O in a 1:1 mol ratio afforded the dinuclear complex Zn 2 Cl 4 (pmbtdaH) 2 ( 1 ) in which the two trigonal bipyramidal metal centres are linked via μ 2 -bridging Cl − ligands while the pmbtdaH ligand binds in an N,N′-chelate fashion via N(4) and the pyrimidinyl N(1) atom. The outcome of the reaction of pmbtdaH with Zn(hfac) 2 (hfac = hexafluoroacetylacetonate) proved sensitive to the crystallization method; the mononuclear octahedral complex Zn(hfac) 2 (pmbtdaH) ( 2 ) in which the ligand coordinates in a similar N,N′-chelate fashion to that observed in 1 was isolated by layering a concentrated CH 2 Cl 2 solution with hexane. Conversely the same reaction mixture afforded the tetranuclear complex Zn 4 (hfac) 6 (pmbtda ox ) 2 ( 3 ) when left undisturbed in a sealed vial. In 3 the ligand is both deprotonated and oxidized forming an anionic ligand in which there are two potential N,N′-chelate pockets and an additional S-oxide donor. The pmbtda ox − ligand bridges between a Zn(hfac) 2 and a Zn(hfac) unit to form Zn 2 (hfac) 3 (pmbtda ox ). Two such Zn 2 (hfac) 3 (pmbtda ox ) units dimerise through the S-oxide oxygen atom to form a centrosymmetric tetranuclear Zn 4 (hfac) 6 (pmbtda ox ) 2 cluster. The structures of 1 – 3 have been determined by X-ray diffraction, elemental analysis, IR and UV–Vis spectroscopies as well as 1 H NMR spectroscopy for complex 2 . [ABSTRACT FROM AUTHOR]

The pyren-1'-yl-functionalized dithiadiazolyl (DTDA) radical, C16H9CNSSN (1), is monomeric in solution and exhibits fluorescence in the deep-blue region of the visible spectrum (440 nm) upon excitation at 241 nm. The salt [1][GaCl4] exhibits similar emission, reflecting the largely spectator nature of the radical in the fluorescence process, although the presence of the radical leads to a modest quenching of emission (ΦF = 98% for 1+ and 50% for 1) through enhancement of non-radiative decay processes. Time-dependent density functional theory studies on 1 coupled with the similar emission profiles of both 1[sup +] and 1 are consistent with the initial excitation being of predominantly pyrene π-π* character. Spectroscopic studies indicate stabilization of the excited state in polar media, with the fluorescence lifetime for 1 (t = 5 ns) indicative of a short-lived excited state. Comparative studies between the energies of the frontier orbitals of pyren-1'-yl nitronyl nitroxide (2, which is not fluorescent) and 1 reveal that the energy mismatch and poor spatial overlap between the DTDA radical SOMO and the pyrene π manifold in 1 efficiently inhibit the non-radiative electron-electron exchange relaxation pathway previously described for 2. Solid-state films of both 1 and [1][GaCl4] exhibit broad emission bands at 509 and 545 nm, respectively. Incorporation of 1 within a host matrix for OLED fabrication revealed electroluminescence, with CIE coordinates of (0.205, 0.280) corresponding to a sky-blue emission. The brightness of the device reached 1934 cd/m² at an applied voltage of 16 V. The crystal structure of 1 reveals a distorted π-stacked motif with almost regular distances between the pyrene rings but alternating long-short contacts between DTDA radicals. Solid state measurements on a thin film of 1 reveal emission occurs at shorter wavelengths (375 nm) whereas conductivity measurements on a single crystal of 1 show a photoconducting response at longer wavelength excitation (455 nm). [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]

The 4'-alkoxy-tetrafluorophenyl dithiadiazolyls, ROC6F4CNSSN [R = Me (1), Et (2), nPr (3), nBu(4)] all adopt cis-oid dimers in the solid state. The methoxy derivative 1 adopts a p-stacked AA'AA' motif, whereas propoxy (3) and butoxy (4) derivatives exhibit an AA'BB' stacking. The ethoxy derivative (2) is polymorphic. The a-phase (2α) adopts an AA'BB' motif comparable with 3 and 4, whereas 2β and 2γ are reminiscent of 1 but combine a mixture of both monomers and dimers in the solid state. The structure of 2β exhibits Z' = 6 with two dimers and two monomers in the asymmetric unit but undergoes a thermally induced phase transition upon cooling below -25 °C to form 2γ (Z' = 14) with six dimers and two monomers in the asymmetric unit. The transition is associated with both rotation and translation of the dithiadiazolyl ring. Detailed differential scanning calorimetry and variable temperature powder X-ray diffraction studies coupled with SQUID magnetometry have been used to show that 2α converts irreversibly to 2β upon heating and that 2β and 2γ interconvert through a reversible phase transition with a small thermal hysteresis in its magnetic response. [ABSTRACT FROM AUTHOR]

The reductive chemistry of [Cp' 2 Ln( μ– H)(THF) x ] y [Ln = Y, Dy, Tb; Cp' = (C 5 H 4 SiMe 3 ) 1− ; x = 2, 0 and y = 2, 3] was examined to determine if these hydrides would be viable precursors for 4f n 5d 1 Ln 2+ ions that could form 5d 1 -5d 1 metal–metal bonded complexes. The hydrides were prepared by reaction of the chlorides, [Cp' 2 Ln( μ –Cl)] 2 , 1-Ln , with allylmagnesium chloride to form the allyl complexes, [Cp' 2 Y( η 3 –C 3 H 5 )(THF)], 2-Ln , which were hydrogenolyzed. The solvent-free reaction of solid 2-Ln with 60 psi of H 2 gas in a Fischer-Porter apparatus produced, in the Y case, the trimetallic species, [Cp' 2 Y( μ –H)] 3 , 3-Y , and in the Dy and Tb cases, the bimetallic complexes [Cp' 2 Ln( μ –H)(THF)] 2 , 4-Ln (Ln = Dy, Tb). The latter complexes could be converted to 3-Dy and 3-Tb by heating under vacuum. Isopiestic data indicate that 3-Y solvates to 4-Y in THF. Reductions of 4-Y , 4-Dy , and 4-Tb with KC 8 in the presence of a chelate such as 2.2.2-cryptand or 18-crown-6 all gave reaction products with intense dark colors characteristic of Ln 2+ ions. In the yttrium case, with either chelating agent, the dark green product gives a rhombic EPR spectrum (g 1 = 2.01, g 2 = 1.99, g 3 = 1.98, A = 24.1 G) at 77 K. However, the only crystallographically-characterizable products obtainable from these solutions were Ln 3+ polyhydride anion complexes of composition, [K(chelate)]{[Cp' 2 Ln( μ– H)] 3 ( μ– H)}. Reduction of 1-Y with KC 8 in the presence of 2.2.2-cryptand also yields an intensely colored product with an axial EPR spectrum (g x = g y = 2.05, A x = A y = 35.5 G; g z = 2.07, A z = 34.5) similar to that of (Cp' 3 Y) 1− ion, but crystals were not obtained from this system. [ABSTRACT FROM AUTHOR]

Inclusion of the dithiadiazolyl radical PhCNSSNṖ into the dynamically porous metallocycle [Cu2(L1)2Cl4], where L1 is the bidentate ligand 1,3-bis(imidazol-1-ylmethyl)-2,4,6-trimethylbenzene, has been achieved by gas phase diffusion. Single crystal X-ray diffraction, powder X-ray diffraction, UV-visible spectroscopy, EPR and SQUID magnetometry studies confirm inclusion of the radical into this seemingly non-porous material, and illustrate the antiferromagnetic coupling between the paramagnetic host and guest species. The radical guest is readily released by heating or by the addition of solvent (CH2Cl2). [ABSTRACT FROM AUTHOR]