f-Element Zintl Chemistry: Actinide-Mediated Dehydrocoupling of H2Sb1- Affords the Trithorium and Triuranium Undeca-Antimontriide Zintl Clusters [{An(TrenTIPS)}3(µ3-Sb11)] (An = Th, U; TrenTIPS = {N(CH2CH2NSiiPr3)3}3-).

Reaction of the cesium antimonide complex [Cs(18C6)2][SbH2] (1, 18C6 = 18-crown-6 ether) with the triamidoamine actinide separated ion pairs [An(TrenTIPS)(L)][BPh4] (TrenTIPS = {N(CH2CH2NSiiPr3)3}3-; An/L = Th/DME (2Th); U/THF (2U)) affords the triactinide undeca-antimontriide Zintl clusters [{An(TrenTIPS)}3(µ3-Sb11)] (An = Th (3Th), U (3U)) by dehydrocoupling. Clusters 3Th and 3U provide two new examples of the Sb113- Zintl trianion and are unprecedented examples of molecular Sb113- being coordinated to anything since all previous reports featured isolated Sb113- Zintl trianions in separated ion quadruple formulations with noncoordinating cations. Quantum chemical calculations describe dominant ionic An-Sb interactions in 3Th and 3U, though the data suggest that the latter exhibits slightly more covalent An-Sb linkages than the former. Complexes 3Th and 3U have been characterized by single crystal X-ray diffraction, NMR, IR, and UV/vis/NIR spectroscopies, elemental analysis, and quantum chemical calculations.

Thorium(IV)-antimony complexes exhibiting single, double, and triple polar covalent metal-metal bonds.

There is continued burgeoning interest in metal-metal multiple bonding to further our understanding of chemical bonding across the periodic table. However, although polar covalent metal-metal multiple bonding is well known for the d and p blocks, it is relatively underdeveloped for actinides. Homometallic examples are found in spectroscopic or fullerene-confined species, and heterometallic variants exhibiting a polar covalent σ bond supplemented by up to two dative π bonds are more prevalent. Hence, securing polar covalent actinide double and triple metal-metal bonds under normal experimental conditions has been a fundamental target. Here we exploit the protonolysis and dehydrocoupling chemistry of the parent dihydrogen-antimonide anion, to report one-, two- and three-fold thorium-antimony bonds, thus introducing polar covalent actinide-metal multiple bonding under normal experimental conditions between some of the heaviest ions in the periodic table with little or no bulky-substituent protection at the antimony centre. This provides fundamental insights into heavy element multiple bonding, in particular the tension between orbital-energy-driven and overlap-driven covalency for the actinides in a relativistic regime.

Easy access to strongly fluorescent higher homologues of BODIPY.

We present the easy and high yield synthesis of several group 13 MesDPM compounds (Al-In) with alkyl substituents at the metal atom. All these compounds were fully characterized using techniques including X-ray diffraction analysis and photoluminescence measurements. It shows that for aluminium and gallium pronounced green fluorescence is observed, which is absent for indium. DFT calculations confirm that the first electronic transition corresponds to a ligand-based π-π* transition.

Formation and Reactivity of heavy Group 14-15 bonds.

A series of low-valent Group 14-15 compounds were obtained starting from [(Dipp2 NacNac)MCl] (M=Ge-Pb) (I-III) (Dipp2 NacNac=HC{C(Me)N(Dipp)}2 ) and M'E(SiMe3 )2 (M'=Li, E=As; M'=K, E=Sb, Bi) (IV-VI). In the course of this investigations we were able to fully characterize all permutations except Pb-Bi for compounds of the composition [(Dipp2 NacNac)ME(SiMe3 )2 ] (1E : M=Ge, 2E : M=Sn, 3E : M=Pb). Thus, we report the first low valent tetrelene with Sn-Bi bond. All isolated compounds, were examined by NMR spectroscopy, IR spectroscopy and except compound 1As by X-ray structure analysis. Moreover, were examined UV-Vis spectroscopy and investigated the reactivity of these compounds towards different substrates in more detail. Starting with the compound [(Dipp2 NacNac)SnAs(SiMe3 )2 ] (2As ), the reaction with red selenium yields [(Dipp2 NacNac)Sn-Se-As(SiMe3 )2 ] (4) which exhibits a Sn-Se-As chain.

Beryllium-Mediated Halide and Aryl Transfer onto Silicon.

The reactivity of hexamethylcyclotrisiloxane (D3 ) towards BeCl2 , BeBr2 , BeI2 and [Be3 Ph6 ]3 was investigated. While BeCl2 only showed unselective reactivity, BeBr2 , BeI2 and [Be3 Ph6 ] cleanly react to the trinuclear complexes [Be3 Br2 (OSiMe2 Br)4 ], [Be3 I2 (OSiMe2 I)4 ] and [Be3 Ph2 (OSiMe2 Ph)4 ]. These unprecedented bromide, iodide and phenyl transfer reactions from a group II metal onto silicon offer a versatile access to previously unknown diorgano bromo and iodo silanolates.

Bismuth Cations: Fluoride Ion Abstraction, Isocyanide Coordination, and Impact of Steric Bulk on Lewis Acidity.

Invited for the cover of this issue are the groups of Carsten von Hänisch and Crispin Lichtenberg at the Philipps University of Marburg. The image depicts a bismuth kraken, eagerly grabbing Lewis basic substrates, thereby solving scientific puzzles about bismuth-based Lewis acidity. Read the full text of the article at 10.1002/chem.202204012.

Bismuth Cations: Fluoride Ion Abstraction, Isocyanide Coordination, and Impact of Steric Bulk on Lewis Acidity.

The molecular compound [BiDipp2 (SbF6 )], containing the bulky, donor-free bismuth cation [BiDipp2 ]+ has been synthesized and fully characterized (Dipp=2,6-iPr2 -C6 H3 ). Using its methyl analog [BiMe2 (SbF6 )] as a second reference point, the impact of steric bulk on bismuth-based Lewis acidity was investigated in a combined experimental (Gutmann-Beckett and modified Gutmann-Beckett methods) and theoretical approach (DFT calculations). Reactivity studies of the bismuth cations towards [PF6 ]- and neutral Lewis bases such as isocyanides C≡NR' revealed facile fluoride ion abstraction and straightforward Lewis pair formation, respectively. The first examples of compounds featuring bismuth-bound isocyanides have been isolated and fully characterized.

Heavy Chains: Synthesis, Reactivity and Decomposition of Interpnictogen Chains with Terminal Diaryl Bismuth Fragments.

Invited for the cover of this issue is the group of Carsten von Hänisch at the Philipps-University Marburg. The image depicts a bismuth crystal, a chain formed from it and the molecular structures of different chain molecules with diaryl-bismuth groups. Read the full text of the article at 10.1002/chem.202202932.

Heavy Chains: Synthesis, Reactivity and Decomposition of Interpnictogen Chains with Terminal Diaryl Bismuth Fragments.

In this work, we report the preparation of multiple interpnictogen chain compounds with three consecutive pnictogen atoms and terminal Ar2 Bi fragments (Ar=Ph, Mes). Symmetrical compounds of the form Ar2 Bi-E(tBu)-Bi2 Ar (1: Ar=Ph, E=P; 2: Ar=Ph, Mes, E=As) as well as ternary interpnictogen compounds of the form Ar2 Bi-E1 (tBu)-E2 tBu2 (Ar=Ph, Mes; 4: E1 =P, E2 =As; 5: E1 =P, E2 =Sb; 6: E1 =As, E2 =P) were prepared. The decomposition in solution at room temperature and under the influence of light was studied for compounds 1-6. The reactivity of 1Ph and 2Ph with the small N-heterocyclic carbene 1,3,4,5-tetramethylimidazol-2-ylidene (Me2 IMe) was also studied. In the case of 1Ph , the formation and consecutive decomposition of Me2 IMe=PtBu (8) was observed in solution. Hence, it was shown that 1Ph can react as a "masked phosphinidene". In the case of 2Ph , no reaction with Me2 IMe was observed. All isolated compounds were analysed by NMR and IR spectroscopy, mass spectrometry, elemental analysis and single-crystal X-ray diffraction.

Synthesis and Application of Alkali Metal Antimonide-A New Approach to Antimony Chemistry.

Alkali metal dihydrogen-antimonides [M(L)x SbH2 ], short: alkali metal antimonides (M=Li, Na, K, Rb, Cs; 1: L=pmdta; 2: L=crown-ether), were prepared from stibine and n-Butyllithium, M(hmds) (hmds=hexamethyldisilazane) or MOtBu, respectively. We developed a generally applicable synthesis route for these compounds and the obtained compounds were examined on their stability depending on the alkali metal and stabilizing additives used, whereby the use of appropriate crown-ethers allowed their isolation and characterization at room temperature. Moreover, the 1,4-dioxane adduct [Na(dioxane)x SbH2 ] was the appropriate starting compound for the synthesis of the first primary silylstibane (Me3 Si)3 SiSbH2 (3) which was characterized by NMR and IR spectroscopy. Reaction of 3 with (Dipp2 NacNac)Ga (Dipp2 NacNac=HC{C(Me)N(Dipp)}2 ; Dipp=2,6-iPr2 C6 H3 ) resulted in the formation of (Dipp2 NacNac)GaH(SbHSi(SiMe3 )3 ) (4) which was furthermore characterized by single crystal x-ray diffraction.

Binary interpnictogen compounds bearing diaryl bismuth fragments bound to all lighter pnictogens.

Multiple interpnictogen compounds with covalent single bonds between a diarylbismuth fragment and all lighter pnictogens were prepared from the corresponding diarylhalido bismuthanes. The aminobismuthanes Ph2BiNMe2 (1) and Mes2BiNMe2 (2) (Mes = 2,4,6-trimethylphenyl-) have been obtained via a salt metathesis reaction and compound 2 was successfully reacted with tBuNH2 in a condensation reaction to yield Mes2BiNHtBu (3). The bismuthanyl phosphanes Ar2BiPtBu2 (Ar = Ph: 4 and Ar = Mes: 5) and arsanes Ar2BiAstBu2 (Ar = Ph: 8 and Ar = Mes: 9) were also obtained via salt metathesis. Through a trimethylsilyl halide abstraction reaction of the diaryl halido bismuthanes and EtBu(SiMe3)2 (E = P and As), the bismuthanyl phosphanes Ar2BiPtBu(SiMe3) (Ar = Ph: 6; Ar = Mes: 7) and the arsanes Ar2BiAstBu(SiMe3) (Ar = Ph: 10; Ar = Mes: 11) have been prepared. Bismuthanyl stibanes were accessed via a condensation reaction of Mes2SbH with 1 or 2, respectively. The compound Ph2BiSbMes2 (12), which has different substituents at the bismuth and antimony atoms, was isolated and fully characterised. In contrast, the isolation of Mes2BiSbMes2 (13) was not possible due to a dynamic equilibrium with Mes4Bi2 and Mes4Sb2 which was investigated via low-temperature 1H-NMR spectroscopy in solution. The isolated compounds with a single bond between bismuth and the heavy pnictogens arsenic and antimony are rare examples of their kind. All isolated compounds (1-12) were characterised by NMR and IR spectroscopy, mass spectrometry, elemental analysis and single crystal X-ray diffraction.

Trapping reactions with highly unstable hydrides of antimony and bismuth.

(Dipp2NacNac)Ga (Dipp2NacNac = HC{C(Me)N(Dipp)}2; Dipp = 2,6-iPr2C6H3) was used as a trapping reagent for the unstable compounds tBuSbH2 and MeBiH2 to yield (Dipp2NacNac)GaH(SbHtBu) (1) and {(Dipp2NacNac)GaH(BiMe)}2 (2). Moreover, its reactions with a row of alkylated or arylated dichloro-bismuthenes resulted in either bridged species or the formation of a dibismuthane.

Revealing the Significance of Catalytic and Alkyl Exchange Reactions during GaAs and GaP Growth by Metal Organic Vapor Phase Epitaxy.

Tertiarybutylarsine (TBAs) and tertiarybutylphosphine (TBP) are getting more and more established as group V precursors for the growth of V/III semiconductors by metal organic vapor phase epitaxy (MOVPE). Due to this development, the thermal decomposition of these precursors was studied during the growth of GaAs and GaP utilizing the Ga precursors, trimethylgallium (TMGa), triethylgallium (TEGa), and tritertiarybutylgallium (TTBGa), in a horizontal AIXTRON AIX 200 GFR MOVPE system. The decomposition and reaction products were measured in line with a real-time Fourier transform quadrupole ion trap mass spectrometer from Carl Zeiss SMT GmbH. The decomposition temperatures and the related activation energies were determined for all the mentioned precursors under comparable reactor conditions. The decomposition curves suggest, on the one hand, a catalytic effect of the GaAs surface on the decomposition of TBAs. On the other hand, the decomposition products indicate alkyl exchange as a relevant step during the bimolecular decomposition of TBAs and TBP with the Ga precursors TMGa, TEGa, and TTBGa. The catalytic reaction reduces the decomposition temperature of TBAs and TBP by up to 200 °C. In addition, for the growth of GaAs with TBAs and TEGa and for the growth of GaP with TBP and TEGa, a significant decrease of the decomposition temperature with an increasing V/III ratio is observed. This behavior, which is related to an alkyl exchange reaction, gives insights into the low-temperature growth of GaAs and GaP and is converted into an effective V/III ratio. Finally, the growth of GaAs with TTBGa and TBAs is realized at 300 °C below the unimolecular decomposition temperature of TBAs, underlining the catalytic effect of the GaAs surface. Altering the growth surface with trimethylbismuth led to the prevention of the catalytic effect.

Stibine as a reagent in molecular chemistry - targeted synthesis of primary and secondary stibanyl-gallanes and their lighter homologues.

The reactions of SbH3 with one or two equivalents of (Dipp2NacNac)Ga (Dipp2NacNac = HC{C(Me)N(Dipp)}2; Dipp = 2,6-iPr2C6H3) yield the primary and secondary stibanes (Dipp2NacNac)GaH(SbH2) (3) and {(Dipp2NacNac)GaH}2(SbH) (5). Their lighter homologs were obtained from the analogous reactions with phosphine and arsine. All compounds were characterized using heteronuclear NMR-spectroscopy, IR-spectroscopy and single-crystal X-ray diffraction.

Construction of Inorganic Crown Ethers by s-Block-Metal-Templated Si-O Bond Activation.

We herein report the synthesis, structures, coordination ability, and mechanism of formation of silicon analogs of crown ethers. An oligomerization of 2 D2 (I) (2 Dn ,=(Me4 Si2 O)n ) was achieved by the reaction with GaI3 and MIx (M=Li, Na, Mg, Ca, Sr). In these reactions the metal cations serve as template and the anions (I- /[GaI4 ]- ) are required as nucleophiles. In case of MIx =LiI, [Li(2 D3 )GaI4 ] (1) is formed. In case of MIx =NaI, MgI2 , CaI2 , and SrI2 the compounds [M(2 D4 )(GaI4 )x ] (M=Mg2+ (3), Ca2+ (4), Sr2+ (5) are obtained. Furthermore the proton complex [H(2 D3 )][Ga2 I7 ] (6) was isolated and structurally characterized. All complexes were characterized by means of multinuclear NMR spectroscopy, DOSY experiments and, except for compound 3, also by single crystal X-ray diffraction. Quantum chemical calculations were carried out to compare the affinity of M+ to 2 Dn and other ligands and to shed light on the formation of larger rings from smaller ones.

A Second Modification of Beryllium Bromide: ß-BeBr2.

The synthesis of a second beryllium bromide modification, ß-BeBr2, was accomplished through recrystallization of α-BeBr2 from benzene in the presence of cyclo-decamethylpentasiloxane. This phase was analyzed via single-crystal X-ray diffraction and IR and Raman spectroscopy as well as density functional theory calculations. This enabled a comparison to α-BeBr2 and the α and ß phases of beryllium chloride and iodide.

Synthesis of a Molecule with Five Different Adjacent Pnictogens.

The first molecular compound with all five pnictogens was obtained by a multi-step reaction. Lithiation of the (bisamido)diazadiarsetidine (tBuNAs)2 (tBuNH)2 in aliphatic solvents leads to the dimeric metallated species [(tBuNAs)2 (tBuNLi)2 ]2 (12 ). Upon reactions with AsCl3 , SbCl3 and BiCl3 the polycyclic compounds [(tBuNAs)2 (tBuN)2 ]PnCl (Pn=As (2), Sb (3), Bi (4)) can be obtained. Conversion of 2-4 with [tBu2 SbP(tBu)Li(OEt2 )]2 leads to the remarkable interpnictogens [(tBuNAs)2 (tBuN)2 ]PnP(tBu)SbtBu2 (Pn=As (5), Sb (6), Bi (7)), whereby 7 is the first example of a molecule containing all five Group 15 elements. The compound with adjacent AsNBiPSb-chains is surprisingly stable and does not show high sensibility against light as the labile Bi-P bond might suggest.

Coordination polymers of alkali metal cyclosiloxazanides with one- and two-dimensional structures.

The reaction of O(Si2Me4Cl)2 with ammonia yielded the cyclic siloxazane O(Si2Me4)2NH (1), which was used as a precursor for the synthesis of siloxazanide-type alkali metal salts. The metalation of 1 with the strong bases BzA (A = Na, K, Rb, Cs and Bz = benzyl) results in different dimensional structures depending on the alkali metal ion used. These results give new insights into framework design with inorganic building blocks and the coordination ability of siloxanes.

Low-Valent Group†14 Phosphinidenide Complexes [({SIDipp}P)2 M] Exhibit P-M pπ-pπ Interaction (M=Ge, Sn, Pb).

Herein, the synthesis of new low-valent Group 14 phosphinidenide complexes [({SIDipp}P)2 M] exhibiting P-M pπ-pπ interactions (SIDipp=1,3-bis(2,6-diisopropylphenyl)-imidazolidin-2-ylidene, M=Ge, Sn, Pb), is presented. These compounds were investigated by means of structural, spectroscopic, and quantum-chemical methods. Furthermore, the monosubstituted compounds [(SIDippP)MX]2 (M=Sn, X=Cl; M=Pb, X=Br) are presented, which show dimeric structures instead of multiple bonding interaction.

Not Non-Coordinating at All: Coordination Compounds of the Cyclodimethylsiloxanes Dn (D = Me2SiO; n = 6, 7) and Group 2 Metal Cations.

We present the coordination chemistry of the cyclodimethylsiloxanes D6 and D7 toward alkaline earth metal salts. The coordination chemistry of these macrocycles toward alkaline earth metals has been unprecedented to date, and we could show that these ligands coordinate better than previously thought. Direct reaction of alkaline earth metal salts with these ligands yields stable complexes even with a relatively strongly coordinating iodide anion. A handful of counterintuitive coordination compounds could be characterized by single-crystal X-ray diffraction analysis. Quantum chemical calculations of suited Born-Haber cycles showed that these complexes are indeed stable, for Mg2+ and Ca2+ even with iodide employed as the anion and for Sr2+ and Ba2+ in the presence of GaI3.