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This article discusses the synthesis and characterization of rare-earth-metal complexes using ligands that adhere to the CHON principle. The complexes were studied using various spectroscopic and electrochemical techniques, as well as computational studies. The tren-based ligands showed lower ion pairing compared to their SP-analogues, and exhibited a greater propensity to complex with lutetium. Selectivity studies showed that the ligands favored complexation with lutetium and samarium, and py3tren was found to be the most selective ligand. The research aims to contribute to the development of sustainable solutions for nuclear waste management. [Extracted from the article]

A series of substituted ferrocenyl boron derivatives was synthesized. The oxidation of the ferrocenyl unit resulted in a significant increase of the boron‐centered Lewis acidity. The neutral and cationic Lewis acids were characterized by NMR spectroscopy, crystal structure analysis and by computational methods. The new Lewis acids were then applied in the Meinwald rearrangement of epoxides, predominantly furnishing aldehydes as the kinetic products. [ABSTRACT FROM AUTHOR]

The carbonyl cluster compound [GeRu6(CO)18HI] is unique in regard to its structure and bonding with a GeRu6 cluster core, a planar GeRu4HI unit, extensive multi‐center bonding, and an aromatic ring current similar to benzene (9‐10 nA T−1). The open‐shell cluster core is a Ge‐centered five‐membered Ru4(Ru2) ring with CO ligands and an additional H and I atom, each bridging two Ru atoms on opposite sides of the cluster core. The compound is prepared at 130 °C in a weakly‐coordinating ionic liquid. [ABSTRACT FROM AUTHOR]

The quantification of Lewis acidity is of fundamental and applied importance in chemistry. However, if neutral and charged Lewis acids are compared, a coherent ranking has been elusive, and severe uncertainties were accepted. With this study, we present a systematic computational analysis of Lewis base affinities of 784 mono‐, di‐ and tricationic Lewis acids and their comparison with 149 representative neutral Lewis acids. Evaluating vacuum fluoride ion affinities (FIA) reveals a charge‐caused clustering that prohibits any meaningful ranking. Instead, solvation‐corrected FIAsolv is identified as a metric that overcomes charge sensitivity in a balanced manner, allowing for a coherent evaluation of Lewis acidity across varying charge states. Analyzing the impact of molecular volume on solvation‐induced FIA damping provides rationales for fundamental trends and guidelines for the choice or design of neutral and cationic Lewis acids in the condensed phase. Exploring alternative scales, explicit counteranion effects, and selected experimental case studies reaffirms the advantages of solvation‐corrected FIAsolv as the most versatile and practical approach for the quantitative ranking of general (thermodynamic) Lewis acidity. [ABSTRACT FROM AUTHOR]

The quantification of Lewis acidity is of fundamental and applied importance in chemistry. However, if neutral and charged Lewis acids are compared, a coherent ranking has been elusive, and severe uncertainties were accepted. With this study, we present a systematic computational analysis of Lewis base affinities of 784 mono‐, di‐ and tricationic Lewis acids and their comparison with 149 representative neutral Lewis acids. Evaluating vacuum fluoride ion affinities (FIA) reveals a charge‐caused clustering that prohibits any meaningful ranking. Instead, solvation‐corrected FIAsolv is identified as a metric that overcomes charge sensitivity in a balanced manner, allowing for a coherent evaluation of Lewis acidity across varying charge states. Analyzing the impact of molecular volume on solvation‐induced FIA damping provides rationales for fundamental trends and guidelines for the choice or design of neutral and cationic Lewis acids in the condensed phase. Exploring alternative scales, explicit counteranion effects, and selected experimental case studies reaffirms the advantages of solvation‐corrected FIAsolv as the most versatile and practical approach for the quantitative ranking of general (thermodynamic) Lewis acidity. [ABSTRACT FROM AUTHOR]

Copyright of Angewandte Chemie is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

We report on the synthesis and characterization of a series of (mostly) air‐stable diorganyl bis(pyridylimino) isoindolide (BPI) aluminum complexes and their chemistry upon visible‐light excitation. The redox non‐innocent BPI pincer ligand allows for efficient charge transfer homolytic processes of the title compounds. This makes them a universal platform for the generation of carbon‐centered radicals. The photo‐induced homolytic cleavage of the Al−C bonds was investigated by means of stationary and transient UV/Vis spectroscopy, spin trapping experiments, as well as EPR and NMR spectroscopy. The experimental findings were supported by quantum chemical calculations. Reactivity studies enabled the utilization of the aluminum complexes as reactants in tin‐free Giese‐type reactions and carbonyl alkylations under ambient conditions, which both indicated radical‐polar crossover behavior. A deeper understanding of the physical fundamentals and photochemical process was provided, furnishing in turn a new strategy to control the reactivity of bench‐stable aluminum organometallics. [ABSTRACT FROM AUTHOR]

Herein, we report the synthesis of a novel ferrocenyl‐functionalized bis(phosphinimino)methane ligand (CH2(PPh2NFc)2). Deprotonation of CH2(PPh2NFc)2 with KN(SiMe3)2 gave the dimeric species [K{CH(PPh2NFc)2}]2, which was further reacted with ECl2 (E=Ge, Sn) to yield the tetrylene compounds [{CH(PPh2NFc)2}ECl]. The ligand and the resulting tetrylenes were examined for their electrochemical properties with the aid of cyclic voltammetry. Furthermore, the reaction of the tetrylenes [{CH(PPh2NFc)2}ECl] with [AuC6F5(tht)] resulted in the bimetallic complexes [{(AuC6F5)CH(PPh2NFc)2}ECl] with an unusual Au coordination on the ligand backbone. [ABSTRACT FROM AUTHOR]

Herein, we present that the radicals [Ph3PC(Me)EMes2]˙ (2Si and 2Ge) can be generated from the α-silylated and α-germylated phosphorus ylides Ph3PC(Me)E(Cl)Mes2 (1Si and 1Ge) through one-electron reduction with Jones' dimer (MesNacNacMg)2 in benzene. Although isolation of the free radicals was not possible, the products of the intramolecular addition of the radicals to a phenyl substituent of the phosphorus moiety, followed by subsequent reaction with 2Si or 2Ge to the isolated species 3Si and 3Ge, respectively, were observed. This transformation witnesses a dearomative 1,4-addition of tetryl radical species to the phenyl scaffold in a stereoselective anti-fashion. [ABSTRACT FROM AUTHOR]

We report on so‐called "hidden FLPs" (FLP: frustrated Lewis pair) consisting of a phosphorus ylide featuring a group 13 fragment in the ortho position of a phenyl ring scaffold to form five‐membered ring structures. Although the formation of the Lewis acid/base adducts was observed in the solid state, most of the title compounds readily react with carbon dioxide to provide stable insertion products. Strikingly, 0.3–3.0 mol% of the reported aluminum and gallium/carbon‐based ambiphiles catalyze the reduction of CO2 to methanol with satisfactory high selectivity and yields using pinacol borane as stoichiometric reduction equivalent. Comprehensive computational studies provided valuable mechanistic insights and shed more light on activity differences. [ABSTRACT FROM AUTHOR]

We report the isolation and characterization of an unknown reaction product from the reaction of AlBr3 with three equivalents of t‐BuLi. The polymeric and solvent‐free lithium alanate {Li[t‐Bu2AlH2]}n was characterized by X‐ray structure analysis, NMR and IR spectroscopy. The title compound was found to be a suitable starting material for the synthesis of [t‐Bu2AlH]3 by reacting it with readily available [t‐Bu2AlBr]2. [ABSTRACT FROM AUTHOR]

The synthesis of three novel imidazolyl‐substituted sulfur‐containing heteroacenes is reported. These heteroacenes consisting of annelated benzo‐ and naphthothiophenes serve as precursors for the generation of open‐shell quinoid heteroacenes by oxidation with alkaline ferric cyanide. Spectroscopic and computational experiments support the formation of reactive open‐shell quinoids, which, however, quickly produce paramagnetic polymeric material. [ABSTRACT FROM AUTHOR]

Non‐innocent ligands (NILs) like bis(pyridylimino)isoindolide (BPI) play crucial roles in coordination chemistry, biosciences, catalysis and material sciences. Investigating the isolated redox states of NILs is inevitable for understanding their redox‐activity and fine‐tuning the properties of corresponding metal complexes. The limited number of fundamental studies on the coordination behavior and redox chemistry of reduced BPI species is suggested to hamper further applications of the title compounds. This work describes for the first time the isolation of alkali metal complexes of BPI and Me2BPI in three different oxidation states and their characterization by means of NMR or EPR spectroscopy, DFT calculations, and SC‐XRD studies. The latter revealed the connection between bond orders in the ligand scaffold and its oxidation state. The paramagnetic compound Me2BPI‐K2 was isolated as a coordination copolymer with 18‐crown‐6, which enabled the characterization of the dianionic BPI radical. Furthermore, the so‐far unknown trianionic state of BPI was reported by the isolation of BPI‐K3. This divulges an unprecedented bis(amidinato)isoindolide coordination mode. [ABSTRACT FROM AUTHOR]

The rare earth element complexes (Ln=Y, La, Sm, Lu, Ce) of several podant κ6N‐coordinating ligands have been synthetized and thoroughly characterized. The structural properties of the complexes have been investigated by X‐ray diffraction in the solid state and by advanced NMR methods in solution. To estimate the donor capabilities of the presented ligands, an experimental comparison study has been conducted by cyclic voltammetry as well as absorption experiments using the cerium complexes and by analyzing 89Y NMR chemical shifts of the different yttrium complexes. In order to obtain a complete and detailed picture, all experiments were corroborated by state‐of‐the‐art quantum chemical calculations. Finally, coordination competition studies have been carried out by means of 1H and 31P NMR spectroscopy to investigate the correlation with donor properties and selectivity. [ABSTRACT FROM AUTHOR]

Copyright of Angewandte Chemie is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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

The synthesis of heterobimetallic AuI/RuII complexes of the general formula syn‐ and anti‐[{AuCl}(L1∩L2){Ru(bpy)2}][PF6]2 is reported. The ditopic bridging ligand L1∩L2 refers to a P,N hybrid ligand composed of phosphine and bipyridine substructures, which was obtained via a post‐functionalization strategy based on Diels‐Alder reaction between a phosphole and a maleimide moiety. It was found that the stereochemistry at the phosphorus atom of the resulting 7‐phosphanorbornene backbone can be controlled by executing the metal coordination and the cycloaddition reaction in a different order. All precursors, as well as the mono‐ and multimetallic complexes, were isolated and fully characterized by various spectroscopic methods such as NMR, IR, and UV‐vis spectroscopy as well as cyclic voltammetry. Photophysical measurements show efficient phosphorescence for the investigated monometallic complex anti‐[(L1∩L2){Ru(bpy)2}][PF6]2 and the bimetallic analogue syn‐[{AuCl}(L1∩L2){Ru(bpy)2}][PF6]2, thus indicating a small influence of the {AuCl} fragment on the photoluminescence properties. The heterobimetallic AuI/RuII complexes syn‐ and anti‐[{AuCl}(L1∩L2){Ru(bpy)2}][PF6]2 are both active catalysts in the P‐arylation of aryldiazonium salts promoted by visible light with H‐phosphonate affording arylphosphonates in yields of up to 91 %. Both dinuclear complexes outperform their monometallic counterparts. [ABSTRACT FROM AUTHOR]

The article titled "Titelbild: Aktivierung von Diorganyl‐bis(pyridylimino)isoindolid‐Aluminiumkomplexen mit sichtbarem Licht und deren organometallische Radikalreaktivität (Angew. Chem. 19/2024)" discusses the activation of diorganyl-bis(pyridylimino)isoindolid-aluminium complexes using visible light and their organometallic radical reactivity. The cover picture shows one of the title complexes, where a chelating ligand is coordinated to the central aluminum atom. The picture highlights a homolytic bond rupture event, with one of the phenyl rings being "blown" away by light. The article also mentions another research study on the synthesis of unstable polyoxometalates using a coordination cage approach. [Extracted from the article]

The article titled "Cover Picture: Visible-Light Activation of Diorganyl Bis(pyridylimino) Isoindolide Aluminum(III) Complexes and Their Organometallic Radical Reactivity" discusses the coordination of a chelating ligand to an aluminum atom in a complex. The ligand is coordinated by three nitrogen donors, and the aluminum atom has two phenyl rings as substituents. The article highlights a homolytic bond rupture event where one of the phenyl rings is "blown" away by light, indicating its radical nature. The study is reported by Andreas-Neil Unterreiner, Frank Breher, and others. Additionally, the article mentions another research article by Cui-Lian Liu, Tatjana N. Parac-Vogt, and others, which demonstrates a "ship-in-a-bottle" approach for the synthesis of unstable polyoxometalates using a coordination cage. [Extracted from the article]

The synthesis and characterisation of a homologous series of quinoid sulfur‐containing imidazolyl‐substituted heteroacenes is described. The optoelectronic and magnetic properties were investigated by UV/vis, fluorescence and EPR spectroscopy as well as quantum‐chemical calculations, and were compared to those of the corresponding benzo congener. The room‐temperature and atmospherically stable quinoids display strong absorption in the NIR region between 678 and 819 nm. The dithieno[3,2‐b:2′,3′‐d]thiophene and the thieno[2′,3′:4,5]thieno[3,2‐b]thieno[2,3‐d]thiophene derivatives were EPR active at room temperature. For the latter, variable‐temperature EPR spectroscopy revealed the presence of a thermally accessible triplet state, with a singlet‐triplet separation of 14.1 kJ mol−1. [ABSTRACT FROM AUTHOR]

The overall neutral α-borylated phosphorus ylide Ph3PC(Me)BEt2 behaves like a polar borataalkene and can act as acyclic, ambiphilic π-type ligand with L- and Z-type functionalities side by side. In the complexes [MX{η2-Ph3PC(Me)BEt2}] (M = Cu, (Ag), Au; X = Cl, NTf2), the bonding is dominated by the highly nucleophilic ylidic carbon atom (L-type ligand). The Lewis acidic boron atom furnishes nonetheless a small but significant bonding contribution (Z-type ligand). [ABSTRACT FROM AUTHOR]

The synthesis and full characterization of novel 1,1′‐difunctionalized ferrocene metalloligands is described. While one cyclopentadienyl ring has been functionalized with 2,2′‐bipyridine for secondary coordination, the second Cp ring has been decorated with different aryl moieties containing electron withdrawing groups such as 4‐(CF3)C6H4 (2A) 3,5‐(CF3)2C6H3 (2B) or 4‐(NO2)C6H4 (2C). The newly developed metalloligands were reacted with [Pd(cod)Cl2] (3A–C), CuCl2 (4A–C) and trans‐[(PPh3)2Ni(Mes)Br] (5A,B) to obtain the corresponding square‐planar and dimeric square‐pyramidal complexes. The electrochemical behaviour of the ligands and complexes was investigated with the aid of cyclic voltammetry and compared with the corresponding monofunctionalized derivatives. The influence of the implemented functional groups on the nickel complexes was then confirmed for the reductive elimination reaction of an aryl ether induced by oxidation of the corresponding methoxides (6A,B,D). The experimental findings are supported by quantum chemical calculations. [ABSTRACT FROM AUTHOR]

The synthesis and full characterization of α‐silylated (α‐SiCPs; 1–7) and α‐germylated (α‐GeCPs; 11–13) phosphorus ylides bearing one chloride substituent R3PC(R1)E(Cl)R22 (R=Ph; R1=Me, Et, Ph; R2=Me, Et, iPr, Mes; E=Si, Ge) is presented. The molecular structures were determined by X‐ray diffraction studies. The title compounds were applied in halide abstraction studies in order to access cationic species. The reaction of Ph3PC(Me)Si(Cl)Me2 (1) with Na[B(C6F5)4] furnished the dimeric phosphonium‐like dication [Ph3PC(Me)SiMe2]2[B(C6F5)4]2 (8). The highly reactive, mesityl‐ or iPr‐substituted cationic species [Ph3PC(Me)SiMes2][B(C6F5)4] (9) and [Ph3PC(Et)SiiPr2][B(C6F5)4] (10) could be characterized by NMR spectroscopy. Carrying out the halide abstraction reaction in the sterically demanding ether iPr2O afforded the protonated α‐SiCP [Ph3PCH(Et)Si(Cl)iPr2][B(C6F5)4] (6 dec) by sodium‐mediated basic ether decomposition, whereas successfully synthesized [Ph3PC(Et)SiiPr2][B(C6F5)4] (10) readily cleaves the F−C bond in fluorobenzene. Thus, the ambiphilic character of α‐SiCPs is clearly demonstrated. The less reactive germanium analogue [Ph3PC(Me)GeMes2][B{3,5‐(CF3)2C6H3}4] (14) was obtained by treating 11 with Na[B{3,5‐(CF3)2C6H3}4] and fully characterized including by X‐ray diffraction analysis. Structural parameters indicate a strong CYlide−Ge interaction with high double bond character, and consequently the C−E (E=Si, Ge) bonds in 9, 10 and 14 were analyzed with NBO and AIM methods. [ABSTRACT FROM AUTHOR]

Novel multistimuli‐responsive phosphine ligands comprising a redox‐active [3]dioxaphosphaferrocenophane backbone and a P‐bound imidazolin‐2‐ylidenamino entity that allows switching by protonation are reported. Investigation of the corresponding metal complexes and their redox behaviour are reported and show the sensitivity of the system towards protonation and metal coordination. The experimental findings are supported by DFT calculations. Protonation and oxidation events are applied in Rh‐catalysed hydrosilylations and demonstrate a remarkable influence on reactivity and/or selectivity. [ABSTRACT FROM AUTHOR]

We report on the synthesis of N‐heterocyclic tetrylenes ligated by the NON‐donor framework 4,5‐bis(2,6‐diisopropylphenyl‐amino)‐2,7‐di‐tert‐butyl‐9,9‐dimethylxanthene. The molecular structures of the germylene (3), stannylene (4) and plumbylene (5) where determined by X‐ray diffraction studies. Furthermore, we present quantum chemical studies on the σ‐donor and π‐acceptor properties of 3–5. Additionally, we report on the reactivity of the tetrylenes towards the transition metal carbonyls [Rh(CO)2Cl]2, [W(CO)6] and [Ni(CO)4]. The isolated complexes (6 and 7) show the differing reactivity of NHTs compared to NHCs. Instead of just forming the anticipated complex [(NON)Sn−Rh(CO)2Cl], 4 inserts into the Rh−Cl bond to afford [(NON)Sn(Cl)Rh(CO)(C6H6)] (6, additional CO/C6H6 exchange) and [(NON)Sn(Cl)Rh2(CO)4Cl] (7). By avoiding halogenated transition metal precursors in order to prevent insertion reactions, germylene 3 shows "classical" coordination chemistry towards {Ni(CO)3} forming the complex [(NON)Ge−Ni(CO)3] (8). [ABSTRACT FROM AUTHOR]

We herein report on the synthesis of biphenylenes substituted with a pyridine (N), a phosphine (P) and a carbene (C′) donor as well as a carbene donor with additional pyridine in the lateral position. We describe the synthesis and structures of derived gold(I) complexes, which we tried to use for the synthesis of non-palindromic [(C^C^D)AuIII] pincer complexes by means of an intramolecular oxidative addition of the strained biphenylene ring. However, the anticipated formation of gold(III) complexes failed due to kinetic and thermodynamic reasons, which we extensively investigated by quantum chemical calculations. Furthermore, we shed light on the oxidative addition of biphenylene to two different gold(I) systems reported in the literature. Our comprehensive quantum-chemical analysis is complemented by NMR experiments. [ABSTRACT FROM AUTHOR]

The field of multimetallic catalysis is rapidly developing and some multimetallic complexes catalyze organic transformations to yield the desired products in more efficient ways owing to the combined action of different metals in a cooperative fashion. This Concept article describes the recent advances of cooperative catalysis playing in multimetallic systems such as homo‐multimetallic complexes with short metal‐metal distances, homo‐multimetallic complexes with long metal‐metal distances, hetero‐multimetallic complexes and metallocene‐based multimetallic complexes with special attention towards redox‐switchable catalysis. Examples are illustrated in which the use of multimetallic complexes show clear enhancement of catalytic outcomes when compared with the sum of their corresponding mononuclear counterparts. Furthermore, several examples are discussed showing the effects of electronic communication in cooperative systems. [ABSTRACT FROM AUTHOR]

We herein report on new synthetic strategies for the preparation of pyridine and imidazole substituted 2,2'‐dihalo biphenyls. These structures are pre‐ligands suitable for the preparation of respective stannoles. The latter can successfully be transmetalated to K[AuCl4] forming non‐palindromic [(C^C^D)AuIII] pincer complexes featuring a lateral pyridine (D=N) or N‐heterocyclic carbene (NHC, D=C') donor. The latter is the first report on a pincer complex with two formally anionic sp2 and one carbenic carbon donor. The [(C^C^D)AuIII] complexes show intense phosphorescence in solution at room temperature. We discuss the developed multistep strategy and touch upon synthetic challenges. The prepared complexes have been fully characterized including X‐ray diffraction analysis. The gold(III) complexes' photophysical properties have been investigated by absorption and emission spectroscopy as well as quantum chemical calculations on the quasi‐relativistic two‐component TD‐DFT and GW/Bethe–Salpeter level including spin–orbit coupling. Thus, we shed light on the electronic influence of the non‐palindromic pincer ligand and reveal non‐radiative relaxation pathways of the different ligands employed. [ABSTRACT FROM AUTHOR]

A highly luminescent non-palindromic [(C^C^N)Pd] pincer complex forms upon reacting pyridine-substituted 2,2′-diiodo-biphenyl with [Pd(PPh3)4]. This case study establishes for the first time that the title compound is formed via a double oxidative addition – comproportionation sequence. DFT and TDDFT calculations complement mechanistic and photophysical characterizations. [ABSTRACT FROM AUTHOR]

This work reports on a series of polynuclear complexes containing a trinuclear Cu, Ag, or Au core in combination with the fac‐isomer of the metalloligand [Ru(pypzH)3](PF6)2 (pypzH=3‐(pyridin‐2‐yl)pyrazole). These (in case of the Ag and Au containing species) newly synthesized compounds of the general formula [{Ru(pypz)3}2M3](PF6) (2: M=Cu; 3: M=Ag; 4: M=Au) contain triple‐stranded helical structures in which two ruthenium moieties are connected by three N‐M‐N (M=Cu, Ag, Au) bridges. In order to obtain a detailed description of the structure both in the electronic ground and excited states, extensive spectroscopic and quantum chemical calculations are applied. The equilateral coinage metal core triangle in the electronic ground state of 2–4 is distorted in the triplet state. Furthermore, the analyses offer a detailed description of electronic excitations. By using time‐resolved IR spectroscopy from the microsecond down to the nanosecond regime, both the vibrational spectra and the lifetime of the lowest lying electronically excited triplet state can be determined. The lifetimes of these almost only non‐radiative triplet states of 2–4 show an unusual effect in a way that the Au‐containing complex 4 has a lifetime which is by more than a factor of five longer than in case of the Cu complex 2. Thus, the coinage metals have a significant effect on the electronically excited state, which is localized on a pypz ligand coordinated to the Ru atom indicating an unusual cooperative effect between two moieties of the complex. [ABSTRACT FROM AUTHOR]

Targeting the synthesis of Al/C based ambiphilic molecules, we investigated the dehydrohalogenation of a series of (benz)imidazole alane adducts. Depending on the steric bulk of the heterocycle, different dimeric products with various ring sizes were obtained. Dehydrohalogenation of the adduct of 1‐mesityl imidazole (MesIm) and 0.5 [tBu2AlBr]2 furnished the dimer 2, featuring a "classical" N‐heterocyclic carbene (NHC) and a mesoionic or "abnormal" NHC (aNHC) subunit within a single molecule. The dimer is bound loosely enough to allow thermally induced isomerization of 2 into the isomers 2NHC (all NHC) and 2aNHC (all aNHC). Dehydrohalogenation of the adduct of 1‐mesityl‐2‐methyl imidazole (MesImMe) and 0.5 [tBu2AlBr]2 (4) yielded the dimeric compound 5 consisting of two N‐heterocyclic olefin (NHO) subunits. Although these six‐ and eight‐membered heterocycles show no FLP‐type reactivity towards small molecules like H2, CO or CO2, we observed an ambiphilic behavior of the imidazolyl alanes during our studies. Salt metathesis reactions using MesIm resulted in the formation of 3, which can be viewed as tBu2AlBr adduct of an Al/N ambiphile. Utilizing heterocycles such as benzimidazole or spiroindole provided the entry point to C–H (7, 9) and N–H (10) activation products, most likely resulting from a reactivity of intermediate species as Al/C ambiphiles. [ABSTRACT FROM AUTHOR]

The synthesis, characterisation and reactivity of new phosphine-functionalised tris(pyrazolyl)methane ligands (TpmPR2, 2a–c, with R = Ph, nBu, iPr) are presented. The reaction of 2a–c with [Rh(CO)2Cl]2 furnished N,P-heterochelate carbonyl complexes (3a–c), which were used to quantify the donor abilities of the ligands via IR spectroscopy. The coordination flexibility was demonstrated by treating representative members of this new ligand class with [CpRu(acn)3][PF6] (acn = acetonitrile), [(tht)AuCl] (tht = tetrahydrothiophene) and [Pd(allyl)Cl]2 providing either a N,N,P-heteroscorpionate complex (4) or the P-coordinated complexes (5,6) without any involvement of the pyrazolyl entities. With 2a and [Pd(cod)Cl2], another P,N-heterochelate complex (7) was obtained, which served as a precursor for a heterobimetallic complex containing palladium and copper (8). Detailed NMR spectroscopic and X-ray crystallographic investigations have been performed on all new complexes. [ABSTRACT FROM AUTHOR]

The influence of substituents on α‐borylated phosphorus ylides (α‐BCPs) has been investigated in a combined experimental and quantum chemical approach. The synthesis and characterization of Me3PC(H)B(iBu)2 (1), consisting of small Me substituents on phosphorous and iBu residues on boron, is reported. Compound 1 is accessible through a novel synthetic approach, which has been further elucidated through DFT studies. The reactivity of 1 towards various small molecules was probed and compared with that of a previously published derivative, Ph3PC(Me)BEt2 (2). Both α‐BCPs react with NH3 to undergo heterolytic N−H bond cleavage. Different di‐ and trimeric ring structures were observed in the reaction products of 1 with CO and CO2. With PhNCO and PHNCS, the expected insertion products [Me3PC(H)(PhNCO)B(iBu)2] and [Me3PC(H)(PhNCS)B(iBu)2], respectively, were isolated. [ABSTRACT FROM AUTHOR]

Very high activities were observed in the redox-induced hydroamination of alkynes by employing a redox-active gold(i) complex featuring an electron-deficient, terphenyl-substituted phosphonite-based ligand. The hydroamination proceeds roughly two-fold faster with the in situ oxidized catalysts than with their reduced form. [ABSTRACT FROM AUTHOR]

The concept and the first example for electronic frustration within a C−B π‐bond arising from the competition for a lone pair of electrons is reported. The α‐borylated phosphorus ylide (α‐BCP) Ph3PC(CH3)BEt2 (1) has been synthesized, characterized, and investigated with the aid of density functional theory calculations. These show the presence of a highly polarized C−B π‐bond, induced by the electron‐withdrawing Ph3P+ substituent. This competition for the C‐based lone pair of electrons leads to an FLP‐type reactivity (FLP=frustrated Lewis pair), which has been demonstrated by reacting 1 with various small molecules: the dimeric insertion products [Ph3PC(CH3)COBEt2]2 (2) and [Ph3PC(CH3)(CO2)BEt2]2 (5) result from the reaction of 1 with CO and CO2, respectively, whereas monomeric products of the general formula [Ph3PC(CH3)(XYZ)BEt2] were obtained by treating 1 with COS (3), CS2 (4) or the heterocumulenes PhNCO (6) and PhNCS (7). A strained C−B π‐bond: The concept and the first example for electronic frustration within a C−B π‐bond arising from the competition for a lone pair of electrons is reported. The α‐borylated phosphorus ylide (α‐BCP) Ph3PC(CH3)BEt2 (1) has been synthesized, characterized, and investigated with the aid of density functional theory calculations. 1 has been demonstrated to react with various small molecules. [ABSTRACT FROM AUTHOR]

The synthesis and characterization of several rhodium(I) complexes of amidinate and linker‐bridged bis(amidinate) ligands are presented. The amidinate ligands for the mononuclear complexes CH3{C(NMes)2Rh(cod)} (1), CH3{C(NDipp)2Rh(cod)} (2), and HCC{C(NDipp)2Rh(cod)} (3) (cod = 1,5‐cyclooctadiene) were synthesized by reacting the corresponding organometallic precursor [Rh(cod)Cl]2 with the alkali metal amidinates CH3{C(NR)2Li} L1Li (R = Mes = 2,4,6‐Me3C6H2) and L2Li (R = Dipp = 2,6‐iPr2C6H3). Analogously, the alkynyl‐functionalized sodium amidinate (HCC{C(NDipp)2Na}·2DME, L3Na) could be further deprotonated and reacted with carbodiimine to form the alkyne‐bridged bis(amidinate) CC{C(NDipp)2Na(thf)}2 (L4Na), which serves as suitable starting material for the synthesis of CC{C(NDipp)2Rh(cod)}2 (4). The bis(amidinate) ligands for the corresponding para‐ (5) and meta‐ (6) phenylene‐bridged complexes p‐/m‐C6H4{C(NMes)2Rh(cod)}2 were accessible through the reaction of phthalic acids with trimethylsilyl polyphosphate and mesitylamine and subsequent deprotonation of the obtained amidines. Tetramesityl oxalamidinate was used to synthesize the dinuclear complex {C(NMes)2Rh(cod)}2 (7) and its carbonylation product {C(NMes)2Rh(CO)2}2 (8). All compounds under study were fully characterized by various spectroscopic methods. In particular the alkali metal salt of the linker‐bridged bis(amidinate) L5Na forms a one‐dimensional coordination polymer in the solid state. Reaction of L5Na and L6Na with [Rh(cod)Cl]2 leads to dinuclear complexes in which the metal–metal distance can be adjusted, enabling us to study their reactivity, including possible cooperative effects in catalysis. [ABSTRACT FROM AUTHOR]

The magnetic properties of three spin‐crossover complexes, [FeII(R‐bik)3](BF4)2·nH2O (1–3), based on bis(imidazolyl)ketone ligands, were investigated in solution and the solid state. Their properties were compared with those of the ketone‐free analogue, [FeII(bim)3](OTf)2 (4). The alkyl and vinyl R groups have weak influence on the transition temperature, T1/2, in solution, while stronger differences are observed in the solid state, because different intermolecular interactions occur in 1–3. The spin‐state equilibria in solution were followed by SQUID magnetometry and the Evans NMR spectroscopy method. Interestingly, the equilibria can also be simply and efficiently probed by following the temperature dependence of an adequately chosen 1H chemical shift. Overall, these experiments give coherent results, with T1/2 located between 320 and 335 K, a narrow range, in comparison with the solid state. DFT calculations have allowed the rationalization of the magnetic differences. The molecular‐orbital and spin‐density calculations reveal that the presence of the C=O group between the imidazolyl units in the ligands of 1–3 leads to an extended aromatic system, an effective π‐acceptor effect, stabilizing the LS state and reducing the LS–HS gap, in comparison with 4. [ABSTRACT FROM AUTHOR]

The recently published purely metallo-organic NiI salt [Ni(cod)2][Al(ORF)4] (1, cod=1,5-cyclooctadiene, RF= C(CF3)3) provides a starting point for a new synthesis strategy leading to NiI phosphine complexes, replacing cod ligands by phosphines. Clearly visible colour changes indicate reactions within minutes, while quantum chemical calculations (PBE0-D3(BJ)/def2-TZVPP) approve exergonic reaction enthalpies in all performed ligand exchange reactions. Hence, [Ni(dppp)2][Al(ORF)4] (2, dppp=1,3-bis(diphenylphosphino) propane), [Ni(dppe)2][Al(ORF)4] (3, dppe=1,3-bis(diphenyl- phosphino)ethane), three-coordinate [Ni(PPh3)3] [Al(ORF)4] (4) and a remarkable two-coordinate NiI phosphine complex [Ni(PtBu3)2][Al(ORF)4] (5) were characterised by single crystal X-ray structure analysis. EPR studies were performed, confirming a nickel d9 -configuration in complexes 2, 4 and 5. This result is supported by additional magnetization measurements of 4 and 5. Further investigations by cyclic voltammetry indicate relatively high oxidation potentials for these NiI compounds between 0.7 and 1.7 V versus Fc/Fc+. Screening reactions with O2 and CO gave first insights on the reaction behaviour of the NiI phosphine complexes towards small molecules with formation of mixed phosphine- CO-NiI complexes and oxidation processes yielding new NiI and/or NiII derivatives. Moreover, 4 reacted with CH2Cl2 at RT to give a dimeric NiII ylide complex (4c). As CH2Cl2 is a rather stable alkyl halide with relatively high C@Cl bond energies, 4 appears to be a suitable reagent for more general C@Cl bond activation reactions. [ABSTRACT FROM AUTHOR]

The synthesis and characterisation of several metal complexes of a redox-active, mesityl(Mes)-substituted [1]phosphaferrocenophane, FcPMes ( 1), are reported. Cyclic voltammetry studies on the bimetallic complexes [M(κ1 P- 1)(cod)Cl] (M=Rh: 2; M=Ir: 4), [Rh(κ1 P- 1)2(CO)Cl] ( 3) and [AuCl(κ1 P- 1)] ( 5), in conjunction with DFT calculations, provided indications for a good electronic communication between the metal atoms. To confirm that the ferrocenophane unit might be able to electrochemically influence the reactivity of the coordinated transition metal, the rhodium complex 2 was employed as stimuli-responsive catalyst in the hydrosilylation of terminal alkynes. All reactions were greatly accelerated with in situ generated 2+ as a catalyst as compared to 2. Even more importantly, a markedly different selectivity was observed. Both factors were attributed to different mechanisms operating for 2 and 2+ (alternative Chalk-Harrod and Chalk-Harrod mechanism, respectively). DFT calculations revealed relatively large differences for the activation barriers for 2 and 2+ in the reductive elimination step of the classical Chalk-Harrod mechanism. Thus, the key to the understanding is a cooperative 'oxidatively induced reductive elimination' step, which facilitates both a higher activity and a markedly different selectivity. [ABSTRACT FROM AUTHOR]

The synthesis, structure, and full characterization of a redox-switchable germylene based on a [3]ferrocenophane ligand arrangement, [Fc(NMes)2Ge] ( 4), is presented. The mesityl (Mes)-substituted title compound is readily available from Fc(NHMes)2 ( 2) and Ge{N(SiMe3)2}2, or from the dilithiated, highly air- and moisture-sensitive compound Fc(NLiMes)2⋅3 Et2O ( 3) and GeCl2. Cyclic voltammetry studies are provided for 4, confirming the above-mentioned view of a redox-switchable germylene metalloligand. Although several 1:1 RhI and IrI complexes of 4 ( 5- 7) are cleanly formed in solution, all attempts to isolate them in pure form failed due to stability problems. However, crystalline solids of [Mo(κ1 Ge- 4)2(CO)4] ( 8) and [W(κ1 Ge- 4)2(CO)4] ( 9) were isolated and fully characterized by common spectroscopic techniques ( 8 by X-ray diffraction). DFT calculations were performed on a series of model compounds to elucidate a conceivable interplay between the metal atoms in neutral and cationic bimetallic complexes of the type [Rh(κ1 E- qE)(CO)2Cl]0/+ ( qE=[Fc(NPh)2E] with E=C, Si, Ge). The bonding characteristics of the coordinated Fc-based metalloligands ( qE/ qE+) are strongly affected upon in silico oxidation of the calculated complexes. The calculated Tolman electronic parameter (TEP) significantly increases by approximately 20 cm−1 (E=C) to 25 cm−1 (E=Si, Ge) upon oxidation. The change in the ligand-donating abilities upon oxidation can mainly be attributed to Coulombic effects, whereas an orbital-based interaction appears to have only a minor influence. [ABSTRACT FROM AUTHOR]

The Lewis superacid activates almost inert carbon-fluorine and sulfur-fluorine bonds for reductions, alkylations, and arylations to form new chemical bonds. Keywords: C-F-Bindungsaktivierung; Ferrocen; Fluor; Lewis-Supersäuren; S-F-Bindungsaktivierung DE C-F-Bindungsaktivierung Ferrocen Fluor Lewis-Supersäuren S-F-Bindungsaktivierung 1 1 1 03/15/23 20230320 NES 230320 B One-electron oxidation b converts the ferrocene-substituted borane into a Lewis superacid, as reported by Frank Breher, Jan Paradies, and co-workers in their Communication (e202216959). [Extracted from the article]

C-F Bond Activation, Ferrocene, Fluorine, Lewis Superacids, S-F Bond Activation Keywords: C-F Bond Activation; Ferrocene; Fluorine; Lewis Superacids; S-F Bond Activation EN C-F Bond Activation Ferrocene Fluorine Lewis Superacids S-F Bond Activation 1 1 1 03/15/23 20230320 NES 230320 B One-electron oxidation b converts the ferrocene-substituted borane into a Lewis superacid, as reported by Frank Breher, Jan Paradies, and co-workers in their Communication (e202216959). Back Cover: Boron-Centered Lewis Superacid through Redox-Active Ligands: Application in C-F and S-F Bond Activation (Angew. [Extracted from the article]

A dinuclear gold(I) bis(carbene) complex based on a 1,5-dihydropyrazolo[3,4- f]indazoline-3,7-diylidene ligand framework is reported. The bridging bis(carbene) ligand is the first example of a ditopic cyclic (aryl)(amino)carbene (CArAC). The ligand precursor 2,6-diethyl-1,5-diphenyl-1,5-dihydropyrazolo[3,4- f]indazole-2,6-diium ( 2H2) is readily available from the literature-known starting material 1,5-diphenyl-1,5-dihydropyrazolo[3,4- f]indazole ( 1) and two equivalents of the Meerwein salt [Et3O][BF4]. The NHC gold(I) hydroxide complex [IPrAuOH] proved to be a valuable precursor for the synthesis of the dinuclear gold complex [(IPr)2Au2(μ- 2)][BF4]2 ( 3) [IPr = 1,3-bis(2,6-diisopropylphenyl)imidazole-2-ylidene]. The compounds under study were fully characterized by various methods, also including X-ray crystallographic studies on single crystals of 2H2 and 3. The ligand was developed in order to explore a possibly enhanced mediation of electronic metal-to-metal communication via the π-system. Density functional theory calculations revealed, however, that the electronic communication in the parent system, or in other ring-substituted derivatives, is only small and predominantly mediated by the σ-bond framework. The calculations also predict that the introduction of an additional donor functionality to the central arene ring of the ditopic bis(carbene), which is able to act as bridging entity and forms an additional metal-ligand bond, increases the communication between the two central metal atoms. The amount of electronic communication in the bis(carbene) complexes under study appears to be a direct function of the number of metal-ligand contacts. [ABSTRACT FROM AUTHOR]

The synthesis and characterisation of two aluminium diphosphamethanide complexes, [Al( tBu)2{κ2 P, P′-Mes*PCHPMes*}] ( 3) and [Al(C6F5)2{κ2 P, P′-Mes*PCHPMes*}] ( 4), and the silylated analogue, Mes*PCHP(SiMe3)Mes* ( 5), are reported. The aluminium complexes feature four-membered PCPAl core structures consisting of diphosphaallyl ligands. The silylated phosphine 5 was found to be a valuable precursor for the synthesis of 4 as it cleanly reacts with the diaryl aluminium chloride [(C6F5)2AlCl]2. The aluminium complex 3 reacts with molecular dihydrogen at room temperature under formation of the acyclic σ2λ3,σ3λ3-diphosphine Mes*PCHP(H)Mes* and the corresponding dialkyl aluminium hydride [ tBu2AlH]3. Thus, 3 belongs to the family of so-called hidden frustrated Lewis pairs. [ABSTRACT FROM AUTHOR]

Reaction of [Si(3,5-Me2pz)4] (1) with [Cu(MeCN)4][BF4] (2) gave the mono- and dinuclear copper complexes [Cu2(FTp*)2] (3) and [Cu(FTp*)2] (4). Both complexes contain the so-far unprecedented boron-fluorinated FTp* ligand ([FB(3,5-Me2pz)3]- with pz=pyrazolyl) originating from 1, acting as a pyrazolyl transfer reagent, and the [BF4]- counter anion of 2, serving as the source of the {BF} entity. The solid-state structures as well as the NMR and EPR spectroscopic characteristics of the complexes were elaborated. Pulsed gradient spin echo (PGSE) experiments revealed that 3 retains (almost entirely) its dimeric structure in benzene, whereas dimer cleavage and formation of acetonitrile adducts, presumably [Cu(FTp*)(MeCN)], is observed in acetonitrile. The short Cu⋯Cu distance of 269.16 pm in the solid-state is predicted by DFT calculations to be dictated by dispersion interactions between all atoms in the complex (the Cu-Cu dispersion contribution itself is only very small). As revealed by cyclic voltammetry studies, 3 shows an irreversible (almost quasi-reversible at higher scan rates) oxidation process centred at Epa=-0.23 V (E01/2=-0.27 V) (vs. Fc/Fc+). Oxidation reactions on a preparative scale with one equivalent of the ferrocenium salt [Fc][BF4] (very slow reaction) or air (fast reaction) furnished blue crystals of the mononuclear copper(II) complex [Cu(FTp*)2] (4). As expected for a Jahn-Teller-active system, the coordination sphere around copper(II) is strongly distorted towards a stretched octahedron, in accordance with EPR spectroscopic findings. [ABSTRACT FROM AUTHOR]

Reaction of [Si(3,5-Me2pz)4] ( 1) with [Cu(MeCN)4][BF4] ( 2) gave the mono- and dinuclear copper complexes [Cu2(FTp*)2] ( 3) and [Cu(FTp*)2] ( 4). Both complexes contain the so-far unprecedented boron-fluorinated FTp* ligand ([FB(3,5-Me2pz)3]− with pz=pyrazolyl) originating from 1, acting as a pyrazolyl transfer reagent, and the [BF4]− counter anion of 2, serving as the source of the {BF} entity. The solid-state structures as well as the NMR and EPR spectroscopic characteristics of the complexes were elaborated. Pulsed gradient spin echo (PGSE) experiments revealed that 3 retains (almost entirely) its dimeric structure in benzene, whereas dimer cleavage and formation of acetonitrile adducts, presumably [Cu(FTp*)(MeCN)], is observed in acetonitrile. The short Cu⋅⋅⋅Cu distance of 269.16 pm in the solid-state is predicted by DFT calculations to be dictated by dispersion interactions between all atoms in the complex (the Cu−Cu dispersion contribution itself is only very small). As revealed by cyclic voltammetry studies, 3 shows an irreversible (almost quasi-reversible at higher scan rates) oxidation process centred at Epa=−0.23 V ( E01/2=−0.27 V) (vs. Fc/Fc+). Oxidation reactions on a preparative scale with one equivalent of the ferrocenium salt [Fc][BF4] (very slow reaction) or air (fast reaction) furnished blue crystals of the mononuclear copper(II) complex [Cu(FTp*)2] ( 4). As expected for a Jahn-Teller-active system, the coordination sphere around copper(II) is strongly distorted towards a stretched octahedron, in accordance with EPR spectroscopic findings. [ABSTRACT FROM AUTHOR]