Abstract The field of multimetallic catalysis is rapidly developing and some complexes catalyze organic transformations to yield the desired products in more efficient ways owing combined action different metals a cooperative fashion. This Concept article describes recent advances playing systems such as homo‐multimetallic with short metal‐metal distances, long hetero‐multimetallic metallocene‐based special attention towards redox‐switchable catalysis. Examples are illustrated which use show...

Multifunctional ligands with podand topology provide intrinsically well-defined coordination geometries. Several subgroups of multidentate ligand systems comprising dual functionality have been developed so far. Recent advances made in this research area reflect its topicality. Work on metal complexes ambiphilic consisting Lewis-acidic Group 13 element bridgehead atoms and additional donor functionalities is the current focus interest. The intrinsic tetradentate may introduce a fascinating...

Make or break: Stable biradicaloid main group element compounds could provide deep insight into fundamental processes of bond making and breaking. Whereas for a long time such were only known as highly reactive intermediates postulated transition states, recently through the isolation stable crystalline 1,3-diphospha-2,4-diborabicyclo[1.1.0]butane (1) decisive step has been taken towards achieving better understanding steps involved in breaking bonds. Radicals play crucial role bond-forming...

Systematic catalytic tests and <italic>in situ</italic>/<italic>operando</italic> spectroscopy uncovered structure–performance relationships determining the seagull profile of NO_x conversion for Cu-SSZ-13 catalysts.

The quantification of Lewis acidity is fundamental and applied importance in chemistry. However, if neutral charged acids are compared, a coherent ranking has been elusive, severe uncertainties were accepted. With this study, we present systematic computational analysis base affinities 784 mono-, di- tricationic their comparison with 149 representative acids. Evaluating vacuum fluoride ion (FIA) reveals charge-caused clustering that prohibits any meaningful ranking. Instead, solvation-corrected FIA

Abstract Iridium( I ) complexes containing a (5 H ‐dibenzo[ , d ]cyclohepten‐5‐yl)‐phosphane (tropp R ; = phosphorus‐bound substituent Ph, Cyc) as rigid, concave‐shaped, mixed phosphane olefin ligand were prepared and tested catalyst precursors in the hydrogenation of imines. With complex [Ir(tropp Cyc )(cod)]OTf, turnover frequencies (TOFs) &gt;6000 h −1 reached N ‐phenyl‐benzylidenamine, PhNCHPh. Lower activities (TOF&gt;80 are observed with ‐phenyl‐(1‐phenylethylidene)amine, PhNCMePh....

A split decision: Efficient heterolytic hydrogen splitting is achieved with novel tetracoordinate rhodium(I) amides. This reaction reversible, and DFT calculations imply that the cleavage a one-step process relatively low activation barrier. Ketones imines are hydrogenated by amide complexes without need for further additives. Supporting information this article available on WWW under http://www.wiley-vch.de/contents/jc_2002/2005/z500773_s.pdf or from author. Please note: The publisher not...

We report on the successful synthesis of Si5Mes6 (Mes = 2,4,6-trimethylphenyl), which consists an archetypal [1.1.1] cluster core featuring two ligand-free, "inverted tetrahedral" bridgehead silicon atoms. The separation between Si atoms is much longer, and bond strength weaker, than usually observed for a regular Si−Si single bond. A detailed analysis electronic characteristics reveals low-lying excited triplet state, indicative some biradical(oid) character. Reactivity studies provide...

Straightforward access to a new cyanide-bridged {Fe4Co4} "molecular box" containing potassium ion, namely K⊂{[FeII(Tp)(CN)3]4[CoIII(pzTp)]3[CoII(pzTp)]} (1) (with Tp and pzTp = tris- tetrakis(pyrazolyl)borate, respectively), is provided, alongside its full characterisation. A detailed analysis of the molecular structure (X-ray diffraction, mass spectrometry, NMR spectroscopy) electronic properties (EPR spectroscopy, SQUID magnetometry, UV/Vis cyclic voltammetry) reveals that 1 shows slow...

A stable cyclic (alkyl)(amino)carbene (CAAC) 1 inserts into the para-CF bond of pentafluoropyridine, and after fluoride abstraction, iminium-pyridyl adduct [3](+) was isolated. voltammetry study shows a reversible three-state redox system involving , [3](⋅) [3](-) . The CAAC-pyridyl radical obtained by reduction with magnesium, has been spectroscopically crystallographically characterized. In contrast to lack π communication between CAAC pyridine units in cation unpaired electron is...

The synthesis, structure, and full characterization of a redox-switchable germylene based on [3]ferrocenophane ligand arrangement, [Fc(NMes)2 Ge] (4), is presented. mesityl (Mes)-substituted title compound readily available from Fc(NHMes)2 (2) Ge{N(SiMe3 )2 }2 , or the dilithiated, highly air- moisture-sensitive Fc(NLiMes)2 ⋅3 Et2 O (3) GeCl2 . Cyclic voltammetry studies are provided for 4, confirming above-mentioned view metalloligand. Although several 1:1 RhI IrI complexes 4 (5-7) cleanly...

A series of redox-responsive ferrocenyl-substituted boranes and boronic esters were synthesized. Oxidation the ferrocenyl ligand to ferrocenium resulted in a drastic increase Lewis acidity beyond strength SbF5 , which was investigated experimentally computationally. The resulting highly acidic boron compounds used for catalytic C-F S-F bond activation.

Knüpfen und Spalten: Stabile biradikaloide Hauptgruppenelementverbindungen ermöglichen einen tiefen Einblick in grundlegende Prozesse der Bindungsbildung -spaltung. Waren solche Verbindungen lange nur als hochreaktive Intermediate oder postulierte Übergangszustände bekannt, gelang nun vor kurzem mit Isolierung des stabilen kristallinen 1,3-Diphospha-2,4-diborabicyclo[1.1.0]butans 1 ein entscheidender Schritt, zu einem besseren Verständnis elementaren Vorgänge beim Entstehen Brechen von...

A simple three-step synthesis of chiral dibenzo[a,e]cyclooctenes (dbcot) starting from commercially available dibenzosuberenone was developed. These compounds give highly stable and robust rhodium(I) iridium(I) diene complexes the type [M(Rdbcot)(L1)(L2)] (M = Rh, Ir; L1, L2 MeCN, Cl, diamine, chloride). The complex [Rh((R)-Phdbcot)((R)-(+)-1,1'-binaphthyl-2,2'-diamine)]+OTf- could be obtained in enantiomerically pure form catalyzes enantioselective 1,2-addition PhB(OH)2 to α,β-unsaturated...

The approach of two atoms with an unpaired electron each results in the formation a σ bond. Snapshots primary step large atom-to-atom distance and parallel spin both electrons final product, consisting butterfly structure short AlAl bond, have been identified for [R2PAl(PR2)AlPR2] compound using quantum chemical calculations X-ray crystallography (see scheme).

Time to B radical: One-electron reduction of 1-ferrocenyl-2,3,4,5-tetraphenylborole results in a radical anion with 5 π electrons the borole ring. Both EPR spectroscopic investigations and spin density calculations confirm formation borol (see picture). Further stimulates an intramolecular [(C5H5)Fe] migration from cyclopentadienyl dianion.

Abstract Compounds including the free or coordinated gas‐phase cations [Ag(η 2 ‐C H 4 ) n ] + ( =1–3) were stabilized with very weakly coordinating anions [A] − (A=Al{OC(CH 3 )(CF } , =1 1 ); Al{OC(H)(CF =2 Al{OC(CF =3 5 {(F C) CO} Al‐F‐Al{OC(CF 6 )). They prepared by reaction of respective silver(I) salts stoichiometric amounts ethene in CH Cl solution. As a reference we also isobutene complex [(Me CCH )Ag(Al{OC(CH )] ). The compounds characterized multinuclear solution‐NMR, solid‐state...

Reaction of HC(Me2pz)3 with Mg{N(SiMe3)2}2 gave the zwitterionic amide complex Mg{C(Me2pz)3}{N(SiMe3)2} (13), containing a "free" pyramidal carbanion and cationic {Mg-N(SiMe3)2}+ moiety. less bulky Mg{N(SiHMe2)2}2 RC(Me2pz)3 (R = H or D) four-coordinate adducts Mg{κ2N-RC(Me2pz)3}{N(SiHMe2)2}2 (15) D (15-d)). A similar complex, Mg{κ2N-HC(Me2pz)3}{N(SiMe3)2}2 (14), was observed by NMR spectroscopy at low temperatures. On warming, 15, 15-d, 14 eliminated RN(SiR′Me2)2 (R′ Me) to form...

Abstract A new C‐nucleoside structurally based on the hydroxyquinoline ligand was synthesized that is able to form stable pairs in DNA both absence and presence of metal ions. The interactions between centers adjacent Cu II ‐mediated base were probed by electron paramagnetic resonance (EPR) spectroscopy. metal–metal distance falls into range previously reported values. Fluorescence studies with a donor–DNA–acceptor system indicate photoinduced charge‐transfer processes across these...

The heterolytic splitting of hydrogen by two types [2.2]paracyclophane derived bisphosphines (1, 2a and 2b) in combination with tris(pentafluorophenyl)borane (3) at room temperature is described. corresponding frustrated Lewis pairs (FLPs) exhibit different behavior the activation hydrogen. This results from diverse steric electronic properties bisphosphines. reactivity was exploited first diastereoselective domino hydrosilylation/hydrogenation reaction catalyzed FLPs.

Unexpected linkage: The use of dicationic RuIV complexes in the Friedel–Crafts-type allylation aromatic alcohols leads unexpectedly to formation a new CC bond and not phenolation product (see scheme). NMR spectroscopy, diffusion data, DFT calculations, X-ray diffraction analysis provide insights with respect mechanism this reaction.

The chiral tetrachelating amino−olefins (R,R)-N,N'-bis(5H-dibenzo[a,d]cyclohepten-5-yl)-1,2-diaminocyclohexane ((R,R)-trop2dach) and (S,S)-N,N'-bis(5H-dibenzo[a,d]cyclohepten-5-yl)-1,2-diphenyl-1,2-ethylenediamine ((S,S)-trop2dpen) were prepared used as ligands in the complexes (R,R)-[Rh(trop2dach)]OTf (S,S)-[Rh(trop2dpen)]OTf (OTf- = CF3SO3-). Quasi-reversible reductions, d8-[RhI(trop2diamine)]+ + e- → d9-[Rh0(trop2diamine)] d10-[Rh-I(trop2diamine)]-, at rather negative potentials...

Graphical Abstract Branching out: A previously unrecognized ruthenium carbonate intermediate is formed during the reaction of an allylic tert-butoxycarbonate with complex [Ru(Cp*)(CH3CN)3]PF6 (1; see scheme). The isolatable carbonate–allyl functions very effectively as alkylation catalyst. These results provide new insights into mechanism this ruthenium-catalyzed reaction.