Terminal Ligand (L) Effects on Zero-Magnetic-Field Splitting in the Excited Triplet States of [{Mo6Br8}L6]2- (L = Aromatic Carboxylates)

Optoelectronic properties of octahedral molybdenum cluster-based materials at a single crystal level

Octahedral molybdenum (Mo6) clusters constitute suitable building blocks for the design of promising single crystal materials in the field of optoelectronics. Here, we prepared single crystals composed of hydroxo Mo6X8 (X = Br, Cl) cluster complexes interconnected by H-bonding interactions with water molecules and protons. The optoelectronic responses and the absorption and emission spectra of these cluster-based single crystals were acquired upon light irradiation, and they show dependency on the nature of the halogens, with the brominated cluster being the most conductive. A fast photoelectrical response was recorded and it showed remarkable stability after multiple illumination on/off cycles. The results obtained provide relevant information for the development of photonic and optoelectronic devices, sensors and photocatalysts.

Preparation, photoluminescence and excited state properties of the homoleptic cluster cation [(W6I8)(CH3CN)6]4

Solvated tungsten iodide cluster compounds are presented with the homoleptic cluster cation [(W₆I₈)(CH₃CN)₆]⁴⁺ and the heteroleptic [(W₆I₈)I(CH₃CN)₅]³⁺, synthesized from W₆I₂₂ in acetonitrile. Crystal structures were solved and refined on deep red single-crystals of [(W₆I₈)(CH₃CN)₆](I₃)(BF₄)₃·H₂O, [(W₆I₈)I(CH₃CN)₅](I₃)₂(BF₄), and on a yellow single-crystal of [W₆I₈(CH₃CN)₆](BF₄)₄·2(CH₃CN) on the basis of X-ray diffraction data. The structure of the homoleptic [(W₆I₈)(CH₃CN)₆]⁴⁺ cluster is based on the octahedral [W₆I₈]⁴⁺ tungsten iodide cluster core, coordinated by six apical acetonitrile ligands. The electron localisation function of [(W₆I₈)(CH₃CN)₆]⁴⁺ is calculated and solid-state photoluminescence and its temperature depedence are reported. Additionally, photoluminescence and transient absorption measurements in acetonitrile are shown. Results of the obtained data are compared to compounds containing [(M₆I₈)I₆]^2- and [(M₆I₈)L₆]^2- (M = Mo or W; L = ligand) clusters.

A 195Pt NMR study on zero-magnetic-field splitting and the phosphorescence properties in the excited triplet states of cyclometalated platinum(ii) complexes

We report the factors governing zero-magnetic-field splitting (zfs) in the lowest-energy electronically excited triplet (T1) states of cyclometalated platinum(ii) complexes, whose zfs energies between the lowest- (φ1) and highest-energy spin-sublevels (φ3) in the T1 states (ΔEzfs) are already known: [Pt(bhq)(dpm)] (1Pt), [Pt(thpy)(acac)] (2Pt), [Pt(ppy)(acac)] (3Pt), cis-[Pt(thpy)2 (4Pt), and cis-[Pt(ppy)2] (5Pt), where bhq, dpm, thpy, acac, and ppy are benzo[h]quinoline, dipivaloylmethane, 2-(2-thienyl)pyridine, acetylacetone, and 2-phenylpyridine, respectively. As one of the important findings, we show the relationship between the ΔEzfs and 195Pt NMR chemical shifts of the five Pt(ii) complexes. The implications of the ΔEzfs values on the emission properties of the Pt(ii) complexes in acetonitrile at 293 K are also discussed. In particular, we demonstrate that the radiative rate constants of the Pt(ii) complexes correlate with both ΔEzfs and 195Pt NMR chemical shifts.

Phosphorescent complexes of {Mo6I8}4+ with triazolates: [2+3] cycloaddition of alkynes to [Mo6I8(N3)6]2−

“Click” reaction of activated alkynes with [Mo₆I₈(N₃)₆]²⁻ produces novel emissive triazolate complexes with the {Mo₆I₈}⁴⁺ cluster core.