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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]

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 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 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]

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]

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 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]

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]

Herein, we demonstrate the use of 35Cl solid-state NMR (SSNMR) at moderate (9.4 T) and high (21.1 T) magnetic field strengths for the structural fingerprinting of hydrochloride (HCl) salts of active pharmaceutical ingredients (APIs) and several polymorphs, in both bulk and dosage forms. These include salts of metformin, diphenhydramine, nicardipine, isoxsuprine and mexiletine (the crystal structure of a mexiletine polymorph is reported herein). Signal-enhancing pulse sequences utilizing frequency-swept pulses and broadband cross polarization were employed to significantly decrease experimental times. In most cases, powder X-ray diffraction (pXRD) patterns and 13C SSNMR spectra are not useful for characterizing the APIs in dosage forms, due to interfering signals from the excipients (e.g., fillers and binders). However, it is demonstrated that 35Cl SSNMR can be used independently to fingerprint individual APIs and to detect the nature of the solid phases in the dosage forms without interference from the excipient. 35Cl SSNMR experiments were also conducted on systems with multiple polymorphs (i.e., isoxsuprine HCl and mexiletine HCl), and the solid phases of these APIs in their dosage forms are identified. 35Cl EFG tensors obtained from plane-wave DFT calculations on model systems are also presented and discussed in the context of their relationship to the local hydrogen-bonding environments of the chloride ions. This methodology shows great promise for identification of solid phases and detection of polymorphs and impurities, which are matters of importance for quality assurance in the pharmaceutical industry. [ABSTRACT FROM AUTHOR]

The benzo-fused dithia-chloro-arsole derivative C6H4S2AsCl (1) is found to crystallise in the triclinic space group P1̅ with 17 molecules in the asymmetric unit whereas the tolyl derivative, MeC6H3S2AsCl (2) is polymorphic with the α-phase crystallising in the monoclinic space group P21/c with a single molecule in the asymmetric unit and the β-phase adopting a triclinic structure with two molecules in the asymmetric unit. Reaction of these dithia-chloro-arsole derivatives with LiN(SiMe3)2 in a 3 : 1 mole ratio afforded the unique paddlewheel structure (MeC6H4S2As)3N (4). [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]

The phenanthrene-functionalised dithiadiazolyl radical 2 provides a rare example of a fluorescent radical, exhibiting bright blue fluorescence (410 nm) in solution (MeCN: ΦF = 0.11). The indirect participation of the radical electron in the fluorescence process is supported by (i) TD-DFT studies and (ii) the observation that the diamagnetic salt [2][GaCl4] also exhibits a similar broad emission at 410 nm. The large Stokes shift appears associated with significant molecular relaxation in the excited state, evidenced by the solvent-independent nature of the absorption profile but marked solvent-dependent emission spectrum. Incorporation of 2 into polymer matrices such as PMMA or polystyrene leads to substantial enhancement in air stability with evidence of efficient emission quenching at higher w/w radical : polymer ratios. [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]

Herein, we demonstrate the use of 35Cl solid-state NMR (SSNMR) at moderate (9.4 T) and high (21.1 T) magnetic field strengths for the structural fingerprinting of hydrochloride (HCl) salts of active pharmaceutical ingredients (APIs) and several polymorphs, in both bulk and dosage forms. These include salts of metformin, diphenhydramine, nicardipine, isoxsuprine and mexiletine (the crystal structure of a mexiletine polymorph is reported herein). Signal-enhancing pulse sequences utilizing frequency-swept pulses and broadband cross polarization were employed to significantly decrease experimental times. In most cases, powder X-ray diffraction (pXRD) patterns and 13C SSNMR spectra are not useful for characterizing the APIs in dosage forms, due to interfering signals from the excipients (e.g., fillers and binders). However, it is demonstrated that 35Cl SSNMR can be used independently to fingerprint individual APIs and to detect the nature of the solid phases in the dosage forms without interference from the excipient. 35Cl SSNMR experiments were also conducted on systems with multiple polymorphs (i.e., isoxsuprine HCl and mexiletine HCl), and the solid phases of these APIs in their dosage forms are identified. 35Cl EFG tensors obtained from plane-wave DFT calculations on model systems are also presented and discussed in the context of their relationship to the local hydrogen-bonding environments of the chloride ions. This methodology shows great promise for identification of solid phases and detection of polymorphs and impurities, which are matters of importance for quality assurance in the pharmaceutical industry. [ABSTRACT FROM AUTHOR]

Two mononuclear DyIII crown ether complexes [Dy(15C5)(H2O)4](ClO4)3·(15C5)·H2O (1) and [Dy(12C4)(H2O)5](ClO4)3·H2O (2) have been prepared and characterized. X-ray diffraction studies show that both compounds crystallize as half sandwich type structures with muffin and pseudo-capped square antiprismatic geometries respectively. Despite the comparable local environments of the DyIII ions they display remarkably different dynamic magnetic properties with only 1 displaying SMM properties in zero field. The solid state emission spectra for both 1 and 2 display sharp bands associated with f–f transitions. From the fine structure of the 4F9/2→6H15/2 band, the Stark splitting of the 6H15/2 ground state permitted the energy difference between the ground and first excited state to be determined. For 1 this value (ΔE = 58.0 ± 3.0 cm−1) is in excellent agreement with ab initio calculations and the experimentally observed SMM behaviour. For 2, the photoluminescence data and theoretical calculations support a less well isolated ground state (ΔE = 30 ± 3.0 cm−1) in which a rapid relaxation process affords no SMM behaviour in zero-field. [ABSTRACT FROM AUTHOR]

Treatment of the imine PhC(=NSiMe3)py with Et2BOMe or BF3·Et2O afforded bicyclic ketiminoboranes 4a and 4bvia intramolecular N-coordination. The basicity of the imine N is evidenced by their reactivity towards Brønsted and Lewis acids and the structures of 4a·HCl and 4b·BF3 are reported as well as the dipyridyl imine derivative 4c·HCl. [ABSTRACT FROM AUTHOR]

CuII-promoted aerial oxidation of a series of benzothiadiazines (1) under ambient conditions affords the first structurally characterised examples of thiadiazine S-oxides (2). The isolation of the homoleptic CuII 3-(2′-pyridyl)benzothiadiazide-S-oxide complex provides insight into the reaction mechanism. [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]

Reaction of the novel ligand 3-(2'-pyridyl)-benzo-1,2,4-thiadiazine (L) with the transition metal chloride salts MCl2·xH2O (MII = Mn, Fe, Co, Cu and Zn) in a 2 : 1 mole ratio afforded the mononuclear octahedral (high spin) complexes L2MCl2 (1a-1e respectively) in which L binds in a chelate fashion via N(2) and the pyridyl N atoms. In the case of CuCl2 the intermediate 1 : 1 four-coordinate complex LCuCl2 (2) was also isolated which adopts a polymeric structure with pseudo-square planar molecules linked via long CuS contacts (dCu...S = 2.938(1) Å) in the apical position. In the presence of non-interacting ions, 3 : 1 complexes are isolated, exemplified by the reaction of L with Fe(CF3SO3)2 in a 3 : 1 ratio which affords the low spin complex [L3Fe][CF3SO3]2 (3). Reaction of L with VCl3 in a 2 : 1 mole ratio under aerobic conditions afforded the vanadyl complex [L2V(vO)Cl][Cl] (4). [ABSTRACT FROM AUTHOR]

A series of dichlorophenyl dithiadiazolyls (DCP-DTDA) have been prepared and structurally characterized by X-ray diffraction (1 = 2,3-DCP-DTDA; 2 = 2,4-DCP-DTDA; 3 = 2,5-DCP-DTDA, 4 = 3,4-DCP-DTDA and 5 = 3,5-DCP-DTDA). All the radicals adopt -cofacial π*-π* dimers with intra-dimer S...S contacts in the range 3.119(8)--3.300(5) Å. The propensity for chloro-aromatics to adopt a β-sheet structure assists formation of lamellar structures in 1-5 with intra-stack Cl⋯Cl contacts in the range 3.44(1)-3.82(1) Å. Perpendicular to the stacking direction, the packing is dominated by formation of intermolecular S⋯Cl contacts. Variable-temperature magnetic susceptibility measurements on 1-5 in the range 5-300 K reveal the onset of paramagnetism around 200 K. Solid-state EPR studies reveal that this paramagnetism is associated with thermal population of a triplet excited state. A good fit to the Bleaney-Bowers model determined the exchange interactions (2 ) between the radicals in the dimers to be in the range -904 to -1529 cm-1. Computational studies of the dimerisation process indicate that at intra-dimer S⋯S distances in excess of 3.2 Å the closed-shell singlet becomes destabilized with respect to both the open-shell singlet and triplet state configurations. [ABSTRACT FROM AUTHOR]

4-([2,2'-Bi(1,3-dithiolylidene)]-4-yl)benzonitrile undergoes a [2 + 2] photocycloaddition reaction upon irradiation with polychromatic light, an unusual single-crystal-to-single-crystal transformation for a TTF derivative. In contrast, the closely related pyridylnitrile derivative adopts a different packing motif and is stable to light under the same conditions. [ABSTRACT FROM AUTHOR]

The syntheses of nine benzo-fused-1,2,4-thiadizines are reported. The use of microwave synthesis has been shown to afford high yields and short reaction times in several key reaction steps. The molecular geometries of these heterocycles are discussed and their solid state packing motifs reveal a strong tendency for the N-H group to form hydrogen bonded chains. [ABSTRACT FROM AUTHOR]

Air stable 1,3,7-triphenyl-1,4-dihydrothiazolo[5′,4′:4,5]benzo[1,2-e][1,2,4]triazin-4-yl packs in 1D π stacks made of radical pairs with alternate short and long interplanar distances. The magnetic susceptibility exhibits a broad maximum at 73 ± 5 K and is interpreted in terms of an alternating antiferromagnetic Heisenberg linear chain model with an average exchange interaction of J = −43.8 cm−1 and an alternation parameter α = 0.3 (gsolid = 2.0028). The enhanced overlap between the π-extended SOMO orbitals leads to strong antiferromagnetic interactions along the chains (J1 = −87.6 cm−1 and J2 = −26.3 cm−1). [ABSTRACT FROM AUTHOR]

Oxidative addition of the electron-rich tetra-methoxy-dibenzo-1,2,5,6-tetrathiocine [(MeO)2C6H2S2]2 to zero-valent group 10 transition metal complexes in the presence of diphenylphosphinoethane (dppe) affords the corresponding dithiolate complexes, [(DMOBD)M(dppe)] (DMOBD = dimethoxybenzenedithiolato, (MeO)2C6H2S2; M = Ni, Pd, Pt) in high yield which were characterized by single crystal X-ray diffraction. Whereas the Pd and Pt complexes exhibit two quasi-reversible 1e2-; M = Ni, Pd, Pt) in high yield which were characterized by single crystal X-ray diffraction. Whereas the Pd and Pt complexes exhibit two quasi-reversible 1e- oxidation processes, the nickel species undergoes a quasi-reversible 1e- reduction. [ABSTRACT FROM AUTHOR]

High loading of the radical PhCNSSN. (1) into faujasite has been achieved via gas phase diffusion. Whilst the large 12 Å pores can accommodate the enthalpically preferred dimer, the smaller pores dictate inclusion as a paramagnetic monomer. Powder X-ray diffraction studies reveal the host framework is unchanged whilst TGA reveal that the void space has high radical loadings. SQUID magnetometry coupled with EPR spectroscopy indicate that the majority of radicals adopt diamagnetic π*-π* dimers consistent with predominant location of 1 as dimers within the large cavities. [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]

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]