Tetranuclear Group 7/8 Mixed-Metal and Open Trinuclear Group 7 Metal Carbonyl Clusters Bearing Bridging 2-mercapto-1-methylimidazole Ligands

The reactivity of group 7 metal dinuclear carbonyl complexes [M2(CO)6(μ-SN2C4H5)2] (1, M = Re; 2, M = Mn) toward group 8 metal trinuclear carbonyl clusters were examined. Reactions of 1 and 2 with [Os3(CO)10(NCMe)2] in refluxing benzene furnished the tetranuclear mixed-metal clusters [Os3Re(CO)13(μ3-SN2C4H5)] (3) and [Os3Mn(CO)13(μ3-SN2C4H5)] (4), respectively. Similar treatment of 1 and 2 with Ru3(CO)12 yielded the ruthenium analogs [Ru3Re(CO)13(μ3-SN2C4H5)] (5), and [Ru3Mn(CO)13(μ3-SN2C4H5)] (6), but in the case of 2 a secondary product [Mn3(CO)10(μ-Cl)(μ3-SN2C4H5)2] (7) was also formed. Compounds 3–6 have a butterfly core of four metal atoms with the M (Mn or Re) at a wingtip of the butterfly and containing a noncrystallographic mirror plane of symmetry. This result provides a potential method for the synthesis of a series of new group 7/8 mixed metal complexes containing a bifunctional heterocyclic ligand. Compound 7 is a unique example of a 54-electron trimanganese complex having bridging 2-mercapto-1-methylimidazolate and chloride ligands. Interestingly, the reaction of 1 with Fe3(CO)12 at 70–75 °C furnished the tri- and dirhenium complexes [Re3(CO)10(μ-H)(μ3-SN2C4H5)2] (8) and [Re2(CO)6(N2C4H5)(μ-SN2C4H5)2] (9), respectively instead of the expected formation of the mixed-metal clusters. The former is an interesting example of a 52-electron trirhenium-hydridic complex containing bridging 2-mercapto-1-methylimidazolate ligand, while the latter can be viewed as a 1-methylimidazole adduct of 1. No mixed Fe–Re complexes were produced in this reaction. The molecular structures of the new compounds 3–5 and 7–9 were established by single-crystal X-ray diffraction analyses and the DFT studies of compounds 5, 7 and 8 are reported

3d-4f heterometallic complexes by the reduction of transition metal carbonyls with bulky LnII^{II} amidinates

The redox chemistry between divalent lanthanide complexes bearing bulky amidinate ligands has been studied with 3d transition metal carbonyl complexes (iron and cobalt). The reaction of [(DippForm)$_{2}$Sm$^{ǁ}$(thf)$_{2}$] (DippForm = N,N′-bis(2,6-diisopropylphenyl)formamidinate) with [Co$_{2}$(CO)$_{8}$] resulted in the formation of a tetranuclear Sm–Co complex, [{(DippForm)$_{2}$Sm$^{ǁǀ}$(thf)}$_{2}${(μ-CO)$_{2}$Co(CO)$_{2}$}$_{2}$]. The product of the reaction of [(DippForm)$_{2}$Yb$^{ǁ}$(thf)$_{2}$] and [Co$_{2}$(CO)$_{8}$] gives the dinuclear Yb–Co complex [{(DippForm)$_{2}$Yb$^{ǁǀ}$(thf)}{(μ-CO)Co(CO)$_{3}$}] in toluene. The reaction of [(DippForm)$_{2}$Sm$^{ǁ}$(thf)$_{2}$] was also carried with the neighbouring group 8 carbonyl complexes [Fe$_{2}$(CO)$_{9}$] and [Fe$_{3}$(CO)$_{12}$], resulting in a pentanuclear Sm$^{ǁǀ}$–Fe complex, [{(DippForm)$_{2}$Sm$^{ǁǀ}$}$_{2}${(μ$_{3}$-CO)$_{2}$Fe$_{2}$(CO)$_{9}$}], featuring a triangular iron carbonyl cluster core

NH3_{3}-SCR over V-W/TiO2_{2} Investigated by Operando X-ray Absorption and Emission Spectroscopy

V–W/TiO$_{2}$-based catalysts, which are used for the removal of NO$_{x}$ from the exhaust of diesel engines and stationary sources via selective catalytic reduction with NH$_{3}$ (NH$_{3}$-SCR), were studied by operando X-ray absorption spectroscopy (XAS) and emerging photon-in/photon-out techniques. In order to minimize the influence of highly X-ray absorbing tungsten and the fluorescence of titanium, we used a high-energy-resolution fluorescence setup that is able to separate efficiently the V Kβ$_{1,3}$ emission lines and additionally allows to record valence-to-core (vtc) X-ray emission lines. High-energy resolution fluorescence-detected XAS (HERFD-XAS) and vtc X-ray emission spectroscopy (vtc-XES) proved to be the only way to perform an operando V K edge X-ray spectroscopic study on industrially relevant V–W/TiO$_{2}$ catalysts so far. The V–W/TiO$_{2}$ and V/TiO$_{2}$ samples synthesized by incipient wetness impregnation and grafting exhibited high activity toward NH$_{3}$-SCR. Raman spectroscopy showed that they mainly contained highly dispersed, isolated, and polymeric V-oxo species. HERFD-XAS and XES identified redox cycling of vanadium species between V$^{4+}$ and V$^{5+}$. With respect to most of the potential NH$_{3}$ adsorption complexes, density functional theory calculations further showed that vtc-XES is more limited than surface-sensitive techniques such as infrared spectroscopy; hence, a combination of X-ray techniques with IR or similar spectroscopies is required to unequivocally identify the mechanism of NH$_{3}$-SCR over vanadia-based catalysts

Multi-pyridine decorated Fe(ii) and Ru(ii) complexes by Pd(0)-catalysed cross couplings: new building blocks for metallosupramolecular assemblies

Eight metal complexes of the type [M(tpy)2]2+ (tpy = 2,2′:6′,2′′-terpyridine) featuring four pendant pyridine rings are reported and characterised by NMR, MS, absorption spectroscopy and electrochemical methods. Palladium-mediated Suzuki and Sonogashira cross-coupling reactions were performed on both free 4′-(3,5- dibromophenyl)-tpy and its Ru(ii) complex in good yields. The ready N-alkylation of the pendant pyridyl units has significant influence on the absorption and electrochemical reduction of the complexes, processes which are localised on the periphery and leaves the [Ru(tpy)2]2+ core essentially unaffected. The binding of metal ions by the free pyridines is also demonstrated as means of assembling larger ordered non-covalent structures. This journal i

Synthesis and structure of an anionic aluminium-nitrogen compound containing a ladder-shaped core

An X-ray crystallographic study of the aluminum-nitrogen compound C52H78Al4Li2N4 showed it to possess a ladder-shaped (AIN)(4) core. The mesityl ligands of the inner nitrogen atoms are each metallated by one of their neighbouring aluminium atoms, while on the outer negative charge is localised. The reported structure is the first tetrameric anionic Al-N compound

Lewis base mediated autoionization of GeCl2 and SnCl2.

Cationic and anionic species of heavier low-valent group 14 elements are intriguing targets in main group chemistry due to their synthetic potential and industrial applications. In the present study, we describe the synthesis of cationic (MCl+) and anionic (MCl3–) species of heavier low-valent group 14 elements of germanium(II) and tin(II) by using the substituted Schiff base 2,6-diacetylpyridinebis(2,6-diisopropylanil) as Lewis base (LB). Treatment of LB with 2 equiv of GeCl2·dioxane and SnCl2 in toluene gives compounds [(LB)GeIICl]+[GeIICl3]− (1) and [(LB)SnIICl]+[SnIICl3]− (2), respectively, which possess each a low-valent cation and an anion. Compounds 1 and 2 are well characterized with various spectroscopic methods and single crystal X-ray structural analysis