Establishing a congruent approach to delivering a pnictide atom (Pn 3− = P, As, and Sb) to transition metal ions is a challenge, especially for the heavier congeners As and Sb, and when varying the transition metal. We showcase here a convenient route to molecular forms of one coordinate stibide ligands bound to Zr IV and Ti IV ions, represented by the discrete salts [K(L)][(PN) 2 M≡Sb] (M = Zr ( 2 ), Ti ( 10 ); PN − = (N‐(2‐P i Pr 2 ‐4‐methylphenyl)‐2,4,6‐Me 3 C 6 H 2 ; L = 2,2,2‐Kryptofix or 18‐C‐6 crown‐ether/2THF), which were prepared via H 2 extrusion from [K(18‐C‐6)(THF)SbH 2 ] added to the Zr IV cyclometallated‐hydride, [(PN)(PN’)Zr(H)] ( 1 ), and the Ti II precursor [K(18‐C‐6)][(PN) 2 TiCl] ( 8 ) respectively. This strategy was extended to the lighter congeners Pn = As, P using [K(18‐C‐6)(THF)AsH 2 ] (M = Zr ( 3 )), and NaPH 2 (M = Ti ( 6 )). Structural and computational studies were applied to understand the bonding trends in the pnictide series, and the role of the metal ion.

We present the extension of the system of error-consistent segmented contracted Gaussian basis sets (Karlsruhe def2-bases [Weigend and Ahlrichs, Phys. Chem. Chem. Phys., 2005, 7, 3297-3305]) for the lanthanide large core effective core potentials (lcECPs) designed by Dolg, Stoll, Savin and Preuss, Theor. Chim. Acta, 1989, 75, 173-194. For La-Lu, sets of double zeta ("split", S), triple zeta (TZ), and quadruple zeta (QZ) valence (V) quality were optimized in atomic Hartree-Fock calculations for each of the different lcECPs that model the occupations fn-k, k = 0, 1, 2, and n being the (typical) ground state f shell occupation; e.g. for Pr, n = 3, for each of the occupations f3, f2, and f1, an SV, TZV, and QZV basis were optimized and termed lcecp-k-XV (k = 0, 1, 2, X = S, TZ, QZ). Polarization functions for the quadruple zeta valence bases were taken from Weigand, Cao, Yang, and Dolg, Theor. Chem. Acc., 2010, 126, 117-127, for the smaller basis sets they were appropriately reduced. The conformity with the def2-series in regards to error-consistency was assessed for a set of 120 molecules by comparing distances, bond angles, vibration frequencies and exchange reaction energies in regards to the basis set limit and also to all-electron scalar relativistic calculations.

We present a new class of linear dianionic sandwich-type species of Sm(II), Eu(II) and Yb(II), in which the central metal ion is exclusively coordinated by two planar dianionic heterocycles. These complexes were synthesized by salt metathesis. Treatment with (2.2.2)-cryptand or 18-crown-6 afforded ion pairs featuring linear monomeric bis(metalollediide) Ln(II) sandwich dianions.

Salt metathesis reactions of the tris-amide zirconium iodide complex ([NRR’]3ZrI (1-I) (with NRR’ = 3,5-Xylyl-tert-butylamide, N(Xyl)(tBu)) and sodium 2-phosphaethynthiolate (Na(diox)3SCP) or 2-arsaethynthiolate (Na(diox)3SCAs) in THF result in the formal [3+2] cycloaddition of the two SCE (E = P, As) units forming novel five membered 2-thio-1,3,4-thiadiphosphole and 2-thio-1,3,4-thiadiarsole heterocyclic ligands with an exocyclic sulfur atom, bridging two zirconium fragments with the general formula (N(RR’)3Zr(-C,S-(SCE)2-Zr(NRR’)3 with E = P (2-PP) or As (3-AsAs). The reactions are regioselective and only the P,P / As,As isomers are formed in THF. Switching the solvent to toluene, salt metathesis with NaSCP results in the selective formation of the other regioisomer 2-SP, with a 3-thio-1,2,4-thiadiphosphole bridge, while for NaSCAs both regioisomers with an As-As bond (3-AsAs) and an S-As bond (3-SAs; 3-thio-1,2,4-thiadiarsole bridge) are observed. Quantum chemical investigations to elucidate the mechanism and solvent dependency suggest a concerted ring formation (in line with a [3+2] cycloaddition reaction) with 2-SP and 3-AsAs being the thermodynamic products of the reaction.

Element-element bonded multiply charged cationic species are well known as dimers or small cyclic oligomers in the condensed phase. However, the smallest acyclic version, a trinuclear unit possessing greater than a monocationic charge, has remained elusive. Here we introduce a bis(phosphine) supported low valent triantimony-based tricationic compound as a new entrant in this field. Structural elucidation and electronic understanding reveal a W-shaped tricationic unit comprising of a three-center four-electron sigma-bonded triantimony moiety that is terminally capped by bis(phosphine) ligands, with the central antimony atom having two lone pairs of electrons. The unique counter trianion [Sb(O)2(OTf)4]3- (OTf = CF3SO3) possesses reactive polar Sbδ+-Oδ- bonds, the structure of which is determined from single crystal X-ray diffraction analysis. The ensemble of reactive molecular fragments found in this highly charged antimony-based compound makes it thermally unstable. Nonetheless, this fully characterized fleeting species shows a diverse reactivity profile, advancing the isolation of various novel antimony compounds, including the formation of a distinct low-valent antimony-cobalt carbonyl cluster.

Delocalized [4n + 2]π-aromaticity in cyclic planar unsaturated organic molecules conceptually underpins organic chemistry. Recently, the study of all-metal aromaticity has burgeoned, but although there has been interest in cyclo-{E3} (E = P, As, Sb, Bi) species as cyclopropenium analogues, the formation of cyclo-{Bi3} remains rare. Thus, the potential aromaticity of 2/6π-cyclo-Bi3+/3-, as the heaviest 6p analogue of cyclopropylium, has remained open to different interpretations. Here we report the formation of diuranium and dithorium 6π-cyclo-Bi33- inverse sandwich complexes, complementing the small number of acyclic- and cyclic-Bin (n = 3-5) compounds. The 6π-cyclo-Bi33- ring exhibits substantial ring currents, similar to 6π-benzene, 2π-(C3H3)+ or 6π-(C3H3)3-. Calculations reveal similar ring currents for 6π-cyclo-Bi33-, 2π-cyclo-Bi3+ and 0π-cyclo-Bi33+, demonstrating σ-aromaticity that is dominant over π-aromaticity in cyclo-Bi33-, despite the favourability of describing cyclo-Bi33- with localized rather than delocalized bond descriptions. Confirmation of 6π-cyclo-Bi33- σ-aromaticity provides the heaviest all-metal 6p analogue to π-aromatic (C3H3)+/3-, leading to organic-inorganic aromaticity benchmarking.

The development of single-molecule magnets for high-density data storage has advanced from poly(metallic) cages to lanthanide complexes. Since 2017, highly axial dysprosium bis(cyclopentadienide) complexes have demonstrated exceptional energy barriers to magnetic reversal (Ueff) and high hysteresis temperatures (TH), with further enhancement achieved in 2025 using bulky amide ligands. Recently, dianionic heavy group 14 cyclopentadienides have emerged as promising ligands due to their higher charge density. Here we report the synthesis of two isostructural homoleptic bis(stannolediide) complexes [Ln(η5-LSn)2K(thf)4] (Ln = Tb(III) or Dy(III)). The Dy(III) complex exhibits single-molecule magnet behaviour with a Ueff of 1,502(4) K and a blocking temperature of 55 K, whereas the Tb(III) analogue shows Raman-dominated relaxation <~6 K. Removal of the potassium cation yields [Tb(η5-LSn)2]- or a divalent complex [Dy(η5-LSn)2]2-. The Dy(II) complex displays weak magnetic anisotropy. These results highlight bis(stannolediide) ligands as a promising new class for high‑barrier lanthanide single-molecule magnets.

Isomer interconversion rate probed by ion mobility spectrometry.

The role of the equatorial ligands and their influence on the electronic structures and bonding properties of uranyl and other actinyls are not well understood and are thus at the forefront of actinide research. In the study presented here, we found that the good energy match of uranyl(VI) with F- valence orbitals leads to substantial changes in the uranyl electronic structure, compared to uranyl-Cl- and uranyl-Br-. The good energy match between uranyl(VI) and F- likely enhances the stability of the uranyl-F- bond, contributing to the higher U-F- affinity in aqueous solution compared to uranyl-Cl-/Br-, which is also demonstrated for plutonyl(VI). These findings are based on studies of equatorial and axial ligand covalency in three uranyl halides: NaRb8(UO2)5F19·2H2O, Rb2UO2Cl4·2H2O, and Rb2UO2Br4·2H2O. We describe covalent uranium-halide interactions, following the trend Br- ≈ Cl- > F-. Ligand K-edge XANES and DFT (including TDDFT and LFDFT) reveal significant electronic structure differences, with the F-based compound having a uranyl-based HOMO, while Cl- and Br-based compounds show predominant ligand p character in the HOMO. A newly introduced theoretical index evaluates bond covalency. U M4 edge HR-XANES and RIXS exhibit unexpected σ* peak trends not directly correlated with U═O bond lengths but well explained by LFDFT RIXS calculations.

Tellurocyanate, [TeCN] − , is the heaviest group 16 congener of the cyanate anion, [OCN] − . Due to the relative instability of the C─Te bond, tellurocyanate chemistry has seen only scarce attention. Here, we present the facile synthesis and thorough characterization of [K@crypt-222][TeCN]. The anion is essentially linear with interatomic distances C─N = 1.150(6)Å and C─Te = 2.051(4)Å, thus approximating a C≡N triple bond and for C─Te a bond order between 1 and 2. Fully 13 C and 15 N labeled [Te 13 C 15 N] − allowed for the extraction of chemical shifts and all possible coupling constants ( 13 C = 77.8 ppm, 15 N = 285.7 ppm, 125 Te = −566 ppm, 1 J 13C-15N  = 8 Hz, 1 J 13C-125Te  = 748 Hz, 2 J 15N-125Te  = 55 Hz), which were also determined independently by quantum chemical calculations. In the series [ Ch CN] − ( Ch  = O─Te), [TeCN] − shows the strongest spin-orbit coupling (SOC) induced heavy-atom effect on the light-atom shielding (SO-HALA-effect). In contrast, 15 N shifts are also well described without considering relativistic effects and/or SOC. Negative-ion photoelectron spectroscopy was used to extract the electron affinity (EA = 3.034 eV) and spin-orbit splitting (3807 cm −1 ) of [TeCN] • . These values continue the trends of falling EA and rising SOC in the series [ Ch CN] • .

Ion mobility spectrometry (IMS) (also including IMS-IMS measurements) as well as DFT calculations have been used to study isomer distributions and isomer interconversion in a range of electrospray-generated lanthanide chloride cluster anions, LnxCl3x+1- (where x = 1-6, and Ln corresponds to the 15 lanthanide elements (except for radioactive Pm)). Where measurement and structural rearrangement timescales allow, we obtain almost quantitative agreement between experiment and theory thus confirming isomer predictions and reproducing isomer intensity ratios. LnxCl3x+1- structures reflect strong ionic bonding with limited directionality. Ring and chain motifs dominate for smaller clusters while for larger clusters more compact three-dimensional structures become favourable. At cluster sizes with two or more closely lying isomers, the lanthanide contraction can lead to systematic variations in structure types across the series.

This paper presents a thorough prediction and investigation of ionization energies, atomic levels, and crystal-field splittings in lanthanide ions. We show that a two-component complete active space (CAS) configuration interaction (CI) approach based on two-component density functional theory (DFT) reference states is suitable to yield accurate excitation energies for lower energy terms. DFT references are further shown to be superior to Hartree-Fock (HF) references for predicting both atomic levels and ionization energies. Especially in the Green's function based GW method used to determine ionization energies, the deficiencies of the wave function based HF references are severe, leading to sizable errors. Two-electron contributions to spin-orbit coupling are found to be an important ingredient for obtaining accurate atomic levels. These contributions are taken into account using a screened-nuclear-spin-orbit (SNSO) approach, which is shown to be very accurate. DFT based CAS-CI is further used to calculate crystal-field splittings. The results are well suited to predict the subtle splittings in complexes with unpaired 4f electrons.

Monocyclic π-aromatic compounds are ubiquitous throughout almost all fields of natural sciences—as synthons in industrial processes, as ligands of metal complexes for catalysis or sensing and as bioactive molecules. Planar organocycles stand out through their specific way of overcoming electron deficiency by a non-localizable set of (4n + 2)π electrons. By contrast, all-metal aromatic monocycles are still rare, as metal atoms prefer to form clusters with multiply bonded atoms instead. This limits the knowledge and potential of corresponding compounds in chemical syntheses or for innovative materials. Here we report the successful generation of Bi5−, the heaviest analogue of (C5H5)−. Its use as a ligand in [IMesCo2(µ,η5:η5-Bi5)] (1) was realized by reacting (TlBi3)2− with [(IMes)2CoCl] (where IMes is bis(1,3-(2,4,6-trimethylphenyl))imidazol-2-ylidene) in ortho-difluorobenzene. Compound 1 is mixed-valence Co0/CoI as verified by µ-SQUID measurements and density functional theory, and embeds the planar Bi5− cycle in an inverse-sandwich-type manner. Capturing Bi5− represents a landmark in the chemistry of all-metal aromatic molecules and defines a new era for aromatic compounds. All-metal aromatic monocycles are still rare, in contrast to their ubiquitous organic counterparts, because metal atoms tend to form clusters with multiply bonded atoms instead. Now a planar aromatic Bi5− ring has been synthesized as part of a mixed-valence Co0/CoI inverse-sandwich-type complex.

The design of molecular rare earth complexes to achieve unique magnetic and bonding properties is a growing area of research with possible applications in advanced materials and molecular magnetics. Recent efforts focus on developing ligand frameworks that can enhance magnetic characteristics. Here we show the synthesis and characterization of a class of rare earth complexes, [(η5-C4R4Sb)Ln(η8-C8H8)] and [(η5-C4R4Bi)Ln(η8-C8H8)], featuring η5-coordinated stibolyl and bismolyl ligands. The ligand aromaticity and bonding situation within these complexes are investigated by quantum chemical calculations. Magnetic studies of the ErIII analogues reveal large barriers and intriguing properties, including waist-restricted hysteresis and slow relaxation of the magnetization, making them single-molecule magnets. Comparison between the experimental barrier and CASSCF-SO calculations indicates that relaxation in all systems occurs through high-energy excited states. These findings suggest that stibolyl and bismolyl ligands can be promising candidates for achieving high-energy barriers in Er-based SMMs, offering a pathway to molecular designs with enhanced magnetic properties.

Lead halide perovskites and related hybrid metal halides exhibit exceptional semiconductor properties, enabling diverse applications in photovoltaics, solid-state lighting, and photocatalysis. Multinary halido metalates, combining multiple metals, offer unique opportunities to tune the optical and electronic properties of these materials for specific applications. Here, we present the synthesis and characterization of (Hpiz)4BiCu4I11·2MeCN (piz = piperazine), the most copper-rich molecular iodido bismuthate reported to date, featuring a Cu/Bi ratio of 4:1. It extends the "all-in-one" design concept of halido cuprates with cationic ligands to multinary systems and exhibits a low optical band gap of 1.82 eV (681 nm) and broad red photoluminescence centered at 1.69 eV (735 nm), making it a promising candidate for light-harvesting and near-infrared emission applications. Quantum chemical analyses attribute the reduced band gap to strong electronic interactions between Cu-(I) and Bi-(III). Additionally, the monometallic analogs (H2piz)-CuI3 and (H2piz)-Bi2I8 reveal the role of heterometallic interactions in modulating the optical properties. This study provides valuable insights into the design of copper-bismuth iodide systems, enriching the library of hybrid materials with customized semiconductor characteristics.

Lewis acid-base adducts between [Na(diox)PCO] (diox = 1,4-dioxane) and trimethyltriels EMe3 (E = B-In) were synthesized and crystallized using 18-crown-6 (18c6) as ligand for the sodium ions. In the course of these investigations, we were able to characterize the compounds [Na(18c6)][PCO(EMe3)2] (1: E = B; 2: E = Al) and [Na(18c6)][PCO(EMe3)] (3: E = Ga; 4: E = In). All compounds were examined by NMR spectroscopy, IR spectroscopy, and elemental analysis. X-ray structure analysis was performed for compounds 1, 3, and 4. The obtained adducts of negatively charged PCO- anions with Lewis acids illustrate the HSAB concept, as the soft Lewis acids GaMe3 and InMe3 always coordinated at the soft phosphorus atom.

Photochemical action plots are a powerful tool for investigating the wavelength-dependent efficiency of photochemical processes. Herein, we apply the photochemical action plot methodology developed by the Barner-Kowollik team to a photocatalytic reaction, resulting in the first examples of photocatalytic action plots, paving the way for future in-depth explorations of the wavelength dependence of similar reactions. Specifically, we investigate the wavelength dependence of the catalytic oxidation capabilities of an Eosin Y functionalized polymer photocatalyst (P1) as well as a small molecule representative of the polymer bound Eosin Y moieties (EY) for the oxidation of triphenylphosphine. Introduction of zinc(II) ions into the system proved to drastically influence the optical absorption properties of both catalysts, accompanied by a pronounced influence on their wavelength-dependent reactivity profiles which is not predictable based on the absorption spectra. For P1, these changes can be reversed by metal-mediated single-chain nanoparticle (SCNP) formation upon base addition, giving access to a stimuli-responsive polymeric photocatalyst. Detailed analysis of the photocatalytic action plots enabled the identification of a suitable wavelength for the realization of an on-off switchable polymeric photocatalytic system.

ABSTRACT Carbazolide complexes of lanthanum and terbium with cyclooctatetraenediide (COT) and THF coligands of the type [( dtbp Cbz)LnCOT(thf) n ] (n = 2 for La, 1 for Tb) were synthesized by salt metathesis reactions. The THF molecules were found to be labile, and drying under vacuum led to their partial removal with concomitant formation of the dinuclear complexes [( dtbp Cbz) 2 Ln 2 (COT) 2 (thf)]. The luminescence of both lanthanum and terbium complexes was investigated, and at cryogenic temperatures, strongly temperature‐dependent phosphorescence was observed. The terbium complexes show the expected element‐characteristic emission with narrow lines between 480 and 700 nm upon excitation at 370 nm. Beyond that, broad emission was induced selectively by excitation at lower energy. Related phosphorescence was found for the lanthanum complex, which implies intra‐ or inter‐ligand excitation as source for the latter. This interpretation was corroborated by TD‐DFT computations.

Commonly, multi-decker sandwich complexes can either be formed in a one-step reaction or in a stepwise fashion by stacking deck by deck. Herein, we showcase a new reaction pathway, in which for the first time a lanthanide half-sandwich unit inserts into an existing sandwich complex. As a result of the insertion of a cyclocene half-sandwich fragment {Ln II ( η 8 -Cot TIPS )} (Cot TIPS  = 1,4-( i Pr 3 Si) 2 C 8 H 6 2− ) into a classical divalent sandwich complex [Ln II ( η 9 -Cnt) 2 ] (Ln = Sm, Eu, Yb; Cnt = C 9 H ), the unprecedented triple-decker sandwich complexes of the type [( η 9 -Cnt)Ln II ( μ - η 8 :η 8 -Cot TIPS )Ln II ( η 9 -Cnt)] were obtained. A plausible reaction pathway was determined by quantum chemical calculations. Additionally, we synthesize the same lanthanide sandwich complexes in a traditional, stepwise fashion. For this, we initially present the novel inverse sandwich compounds [Ln II I(thf) 2 ( μ - η 8 :η 8 -Cot TIPS )Ln II I(thf) 2 ] (Ln = Sm, Eu, thf = tetrahydrofuran) and [Yb II (BH 4 )(thf) 2 ( μ - η 8 :η 8 -Cot TIPS )Yb II (BH 4 )(thf) 2 ] consisting of a cyclooctatetraene middle deck sandwiched between two divalent lanthanides as precursors. Subsequent salt metathesis reactions with [K(Cnt)] (Cnt = C 9 H ) gave rise to the title compounds [( η 9 -Cnt)Ln II ( μ - η 8 :η 8 -Cot TIPS )Ln II ( η 9 -Cnt)]. The unique feature of these compounds is the combination of the two largest aromatic all-carbon rings known in coordination chemistry—the 8- and 9-membered rings—into lanthanide triple-decker sandwich compounds.

A series of transition metal-pnictogenide compounds were prepared starting from [(Dipp2NacNac)MCl] (M=Cr, Mn, Fe, Zn) (Dipp2NacNac=HC{C(Me)N(Dipp)}2) and [M'E(SiMe3)2] (M'=Li, K; E=P, As, Sb) as well as [Li(Et2O)nPH2] and [Li(tmeda)AsH2]. In the course of these investigations we were able to characterize all permutations for compounds of the composition [(Dipp2NacNac)ZnE(SiMe3)2] (E=P, As, Sb) and [(Dipp2NacNac)ZnEH2] (E=P, As). Moreover, the synthesis of selected compounds of type [(Dipp2NacNac)ME(SiMe3)2] for M=Cr, Mn, Fe and E=P-Sb are described. As part of our efforts, we established a number of bonding motifs that are underexplored in the literature to date. All isolated compounds, were examined by NMR spectroscopy, IR spectroscopy, Elemental analysis and X-Ray structure analysis. DFT calculations on the chromium compounds were performed to investigate the binding situation between chromium and the group 15 element in more detail. image