There is a need for validation methods to ensure the quality and consistency of reported data, but a recent article by Raymond and Girolami [Acta Cryst. (2023), C79, https://doi.org/10.1107/S2053229623007088] will alert chemists, crystallographers, referees, and editors to not always trust the crystal structure but also to ensure that the chemistry is consistent with previous chemistry.

The synthesis and characterization of a family of uranium derivatives featuring the phenyltris(4,4-dimethyl-2-oxazolinyl)borate (ToM) ligand framework was achieved. Uranium(IV) halide compounds, specifically ToMUCl3(THF) and ToMUI3, were generated by adding 1 equiv of Tl[ToM] to either UCl4 or UI3(THF)4, respectively. The tetravalent derivatives ToMUCl2(NPh2) and ToMUI(═N-Ad)(THF) were also synthesized, showing that ToM supports uranium amido and imido species. Attempts to make bis(phenyltris(oxazolinyl)borate) compounds were unsuccessful. However, when the smaller hydrotris(pyrazolyl)borate (Tp) ligand was used, a mixed bis(ligand) derivative, TpToMUI, was isolated. All of the compounds were characterized by 1H NMR, infrared, and electronic absorption spectroscopies. Where possible, X-ray crystallography was used to assess structural parameters.

The synthesis of a redox series of neodymium species bearing the redox active pyridine(diimine) ligand, MesPDIMe, is reported. Spectroscopic and structural characterization supports each compound has a Nd(iii) centre, with the MesPDIMe ligand existing in four oxidation states.

Uranium complexes (MesDAE)2U(THF) (1-DAE) and Cp2U(MesDAE) (2-DAE) (MesDAE = [ArN-CH2CH2-NAr]; Ar = 2,4,6-trimethylphenyl (Mes)), bearing redox-innocent diamide ligands, have been synthesized and characterized for a full comparison with previously published, redox-active diimine complexes, (MesDABMe)2U(THF) (1-DAB) and Cp2U(MesDABMe) (2-DAB) (MesDABMe = [ArN═C(Me)C(Me)═NAr]; Ar = Mes). These redox-innocent analogues maintain an analogous steric environment to their redox-active ligand counterparts to facilitate a study aimed at determining the differing electronic behavior around the uranium center. Structural analysis by X-ray crystallography showed 1-DAE and 2-DAE have a structural environment very similar to 1-DAB and 2-DAB, respectively. The main difference occurs with coordination of the ene-backbone to the uranium center in the latter species. Electronic absorption spectroscopy reveals these new DAE complexes are nearly identical to each other. X-ray absorption spectroscopy suggests all four species contain +4 uranium ions. The data also indicates that there is an electronic difference between the bis(diamide)-THF uranium complexes as opposed to those that only contain one diamide and two cyclopentadienyl rings. Finally, magnetic measurements reveal that all complexes display temperature-dependent behavior consistent with uranium(IV) ions that do not include ligand radicals. Overall, this study determines that there is no significant bonding difference between the redox-innocent and redox-active ligand frameworks on uranium. Furthermore, there are no data to suggest covalent bonding character using the latter ligand framework on uranium, despite what is known for transition metals.

Three molybdenum(VI) cis-dioxo catalysts (8-10) were synthesized with the goal of developing stable and selective oxidation catalysts for sulfoxidation. Their reactivities were investigated with a variety of substrates. We have demonstrated the usefulness of these catalysts for the chemoselective sulfoxidation of sulfides in the presence of reactive moieties, which has important applications for total synthesis processes. Notably, these catalysts are able to oxidize compounds analogous to sulfur mustard and can be used as an alternative to sodium periodate or meta-chloroperoxybenzoic acid (m-CPBA) for the oxidation of various organic sulfides without sacrificing total conversion. As the catalysts are tolerant of water and hydrogen peroxide, they allow for the design of completely green oxidation reactions, particularly for sulfur-containing amino acids.

Several nickel(II) complexes of cyclams bearing aryl groups on the carbon backbone were prepared and evaluated for their propensity to catalyze the electrochemical reduction of CO2 to CO and/or H+ to H2, representing the first catalytic analysis to be performed on an aryl-cyclam metal complex. Cyclic voltammetry (CV) revealed the attenuation of catalytic activity when the aryl group bears the strong electron-withdrawing trifluoromethyl substituent, whereas the phenyl, p-tolyl, and aryl-free derivatives displayed a range of catalytic activities. The gaseous-product distribution for the active complexes was determined by means of controlled-potential electrolysis (CPE) and revealed that the phenyl derivative is the most active as well as the most selective for CO2 reduction over proton reduction. Stark differences in the activity of the complexes studied are rationalized through comparison of their X-ray structures, absorption spectra, and CPE profiles. Further CV studies on the phenyl derivative were undertaken to provide a kinetic insight.

The synthesis and characterization of four new CrIII–bis(alkynyl) complexes bearing the macrocyclic tetraaza ligand DMC (DMC = 5,12‐dimethyl‐1,4,8,11‐tetraazacyclotetradecane) are reported. Complexes trans‐[Cr(DMC)(C2R)2]X (R = Ph ([1]X), Fc ([2]X), X = Cl, ClO4. C2H ([3]X′); X′ = ClO4, BPh4) and cis‐[Cr(DMC)(C4TMS)2]Cl ([4]Cl) were studied using UV/Vis and FTIR spectroscopy, and their identities were verified with ESI‐MS and elemental analysis. The three trans complexes, [1]Cl, [2](ClO4), and [3](BPh4), were structurally characterized using single‐crystal X‐ray diffraction, which revealed a pseudo‐octahedral geometry around the Cr center with the nitrogen atoms occupying the equatorial plane and the alkynyl ligands residing in the apical positions. Spectroscopic analysis of [1]Cl, [3](BPh4) and [4]Cl shows highly structured d–d bands between 320 and 500 nm. All CrIII complexes reported herein are emissive, and detailed studies were performed for [1]Cl, [3](BPh4), and [4]Cl, yielding phosphorescence lifetimes (77 K) of 380, 358, and 160 µs, respectively, and room temperature quantum yields of 0.01 % for complex [1]Cl and 0.15 % for complex [4]Cl. Voltammetric studies of complex [2](ClO4) indicate a weak but discernible coupling between two ferrocenyl groups across the C2–Cr–C2 bridge.

The reactions between Ru-2 (DMBA)(4)(NO3)(2) (DMBA = N, N'-dimethylbenzamidinate) and meta-phenylene diethynylenes bearing 5-ester substituents (-CO2i Pr, L1; -CO2Bn, L2) in the presence of Et2NH afforded a series of oligomeric compounds with meta-phenylene diethynylene bridge, namely L-[Ru-2 (DMBA)(4)L](m) with m as integers. With L1, the compounds with m = 1-3 (1a, 2a and 3a) were separated and fully characterized. With L2, only the compound with m = 1 (1b) was successfully isolated. In addition to routine spectroscopic characterizations, the structures of both compounds 1b and 2a were determined using single crystal X-ray diffraction. For the series of 1a, 2a and 3a, both the voltammetric and absorption spectroscopic characteristics bear close resemblance to those of simple Ru-2 (DMBA)(4)(C2R)(2) compounds, indicating the absence of significant inter-unit electronic couplings in the oligomers. (C) 2017 Elsevier B.V. All rights reserved.

Unusual cis-oxidative addition of methyltrioxorhenium (MTO) to [PtMe2(bpy)], (bpy = 2,2'-bipyridine) (1) is described. Addition of MTO to 1 first gives the Lewis acid-base adduct [(bpy)Me2Pt-Re(Me)(O)3] (2) and subsequently affords the oxidative addition product [(bpy)Me3PtReO3] (3). All complexes 1, MTO, 2, and 3 are in equilibrium in solution. The structure of 2 was confirmed by X-ray crystallography, and its dissociation constant in solution is 0.87 M. The structure of 3 was confirmed by extended X-ray absorption fine structure and X-ray absorption near-edge structure in tandem with one- and two-dimensional NMR spectroscopy augmented by deuterium and 13C isotope-labeling studies. Kinetics of formation of compound 3 revealed saturation kinetics dependence on [MTO] and first-order in [Pt], complying with prior equilibrium formation of 2 with oxidative addition of Me-Re being the rate-determining step. Exposure of 3 to molecular oxygen or air resulted in the insertion of an oxygen atom into the platinum-rhenium bond forming [(bpy)Me3PtOReO3] (4) as final product. Density functional theory analysis on oxygen insertion pathways leading to complex 4, merited on the basis of Russell oxidation pathway, revealed the involvement of rhenium peroxo species.

Single-crystal X-ray structures of four nickel dithiocarbamate complexes, the homoleptic mixed-organic bis-dithiocarbamates Ni[S2CN(isopropyl)(benzyl)](2), Ni[S2CN(ethyl)(n-butyl)](2), and Ni[S2CN(phenyl)(benzyl)](2), as well as the heteroleptic mixed-ligand complex NiCl[P(phenyl)(3)][(S2CN(phenyl)(benzyl)], were determined. A slightly distorted square-planar nickel coordination environment was observed for all four complexes. The organic residues adopt conformations to minimize steric interactions. Steric effects also may determine puckering, if any, about the nickel and nitrogen atoms, both of which are planar or nearly so. A trans-influence affects the Ni-S bond distances. Nitrogens interact with the CS2 carbons with a bond order near two; the other substituents on nitrogen display transoid conformations. There are no strong intermolecular interactions, consistent with prior observations of the volatility of nickel dithiocarbamate complexes. A preliminary thermolysis study of the homoleptic species results in production of 1:1 nickel sulfide phases, indicating the potential utility of these species as single-source precursors.[GRAPHICS].

A new diruthenium compound, Ru2(η2-DmAniF)2(μ-DmAniF)2(OAc)(O) (1), where DmAniF is N,N′-di(m-methoxyphenyl)formamidinate, was isolated as a secondary product from the reaction between Ru2(DmAniF)3(OAc)Cl and K2CO3, and its formulation was established using both single crystal X-ray diffraction and high resolution mass-spectrometry techniques. Compound 1 has an S = 3/2 ground state, and exhibits an unusually large zero-field splitting (D = 308 cm−1) as revealed by the measurement of temperature dependent magnetism.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Described in this work are the preparation and characterization of a family of polyynediyl-bridged (μ-C2n) dimers of CoIII(cyclam)Cl (cyclam = 1,4,8,11-tetraazacycloctetradecane) for n = 2–4. The complexes are robust to ambient conditions and are prepared under mild conditions without requiring anaerobic or anhydrous environments. Voltammetric analysis revealed weak Co–Co interaction through the bridge, which is attenuated by polyyne length. The orbital origin of the Co–Co interaction has been rationalized through DFT analysis.

A series of Co-III(cyclam) complexes ([1a,b]Cl, [2a-c]PF6, [3]Cl-2, [4a](OTf)(4), [4b](PF6)(2), and [5]Cl-2) (cyclam = 1,4,8,11- tetraazacycloctetradecane) bearing a geminal-diethynylethene ligand (gem-DEE) is reported. Syntheses of these acyclic cross-conjugated complexes were accomplished in satisfactory yields, and structural characterizations established that the geometrical feature of gem-DEE is largely preserved upon metalation. Combined structural and electrochemical studies suggest that the gem-DEE ligand, as a sigma-donor, is weaker than phenylethynyl but stronger than butadiynyl in Co-III(cyclam) complexes. Voltammetric analysis indicated a weak but discernible Co-Co coupling across the gem-DEE bridge in [3]Cl-2 and [4a](OTf)(4), while the addition of a second acetylide in the trans position diminished such coupling in [4b](PF6)(2). DFT analysis revealed significant d pi-pi mixing around the cobalt centers with extended pi-overlap in the highest occupied orbitals and substantial sigma-based mixing in the lowest unoccupied orbitals of [3]Cl-2 and [4a](OTf)(4), the latter of which likely contributes to the weak Co-Co coupling.

The goal of this work has been to synthesize and investigate Pd(TC3), an intercalating porphyrin that has conformable substituents capable of groove binding to B-form DNA. (TC3 denotes the doubly deprotonated form of 5,10,15,20-tetra[3-(3'-methylimidazolium-1'-yl)prop-1-yl]porphyrin.) Palladium(ii) is an apt choice for the central metal ion because it remains strictly four-coordinate and provides for a luminescent triplet excited state with a long lifetime. The DNA hosts are hairpin-forming sequences programmed to differ in base composition. Luminescence, absorbance, and circular dichroism results are consistent with the idea that congruent structural reorganization takes place at the host and ligand during uptake. Photoexcitation of DNA-bound Pd(TC3) generates a comparatively modest steady state concentration of singlet oxygen, due to a relatively slow reaction with molecular oxygen in solution. The sheer size of the substituent groups disfavors quenching, but groove-binding interactions compound the problem by inhibiting mobility. The results show how ligand design affects adduct structure as well as function.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

The generation of uranium(III) alkyls supported by hydrotris(pyrazolyl)borate (Tp) and pentamethylcyclopentadienyl (Cp*) ligands is reported. Mixed ancillary ligand frameworks were synthesized by treating TpUI(2)(THF)(3) (1) and Cp*UI2(THF)(3) with potassium hydrotris(pyrazolyl)borate salts. Addition of one equivalent of potassium hydrotris(3,5-dimethylpyrazolyl)borate (Tp*) generated TpTp*UI (2), while treatment of Cp*UI2(THF)(3) with either KTp or KTp* resulted in the respective formation of Cp*TpUI(THF) (3) or Cp*Tp*UI(THF) (4). Alkylation of 2 with KCH2Ph or NaCH2SiMe3 furnished TpTp*UCH2Ph (2-CH2Ph) or TpTp*UCH2SiMe3 (2-CH2SiMe3). Similarly, treatment of 3 with NaCH2SiMe3 formed Cp*TpUCH(2)SiMe(3) (3-CH2SiMe3), whereas treatment of 4 with KCH2Ph generated Cp*Tp*UCH2Ph (4-CH2Ph). All compounds were characterized by multinuclear NMR, IR, and electronic absorption spectroscopy. Compounds 2-CH2Ph, 3, and 3-CH2SiMe3 were structurally characterized using X-ray crystallography as well.