Synthesis and Structural Characterization of Magnesium‐Substituted Polystibides [(LMg)4Sb8]

Redox reactions of [(L^1,2Mg)₂] and Sb₂R₄ (R=Me, Et) yielded the first Mg‐substituted realgar‐type Sb₈ polystibides [(L^1,2Mg)₄(μ₄,η^2:2:2:2‐Sb₈)] (L¹=HC[C(Me)N(2,4,6‐Me₃C₆H₂)]₂, L²=HC[C(Me)N(2,6‐i‐Pr₂C₆H₃)]₂). Compounds [(L^1,2Mg)₂] serve both as reducing agents, initiating the cleavage of the Sb?C bonds, and as stabilizers for the resulting Sb₈ polyanion. The polystibides were characterized by NMR and IR spectroscopies, elemental analysis, and X‐ray structure analysis. In addition, results from quantum chemical calculations are presented.     

Group 13 Ligand Supported Heavy‐Metal Complexes: First Structural Evidence for Gallium–Lead and Gallium–Mercury Bonds

Heavy‐metal complexes of lead and mercury stabilized by Group 13 ligands were derived from the oxidative addition of Ga(ddp) (ddp=HC(CMeNC₆H₃‐2,6‐iPr₂)₂, 2‐diisopropylphenylamino‐4‐diisopropyl phenylimino‐2‐pentene) with corresponding metal precursors. The reaction of Me₃PbCl and Ga(ddp) afforded compound [{(ddp)Ga(Cl)}PbMe₃] ( 1 ) composed of Ga? Pb^IV bonds. In addition, the monomeric plumbylene‐type compound [{(ddp)Ga(OSO₂CF₃)}₂Pb(thf)] ( 2 a ) with an unsupported Ga‐Pb^II‐Ga linkage was obtained by the reaction of [Pb(OSO₂CF₃)₃] with Ga(ddp) (2 equiv). Compound 2 a falls under the rare example of a discrete plumbylene‐type compound supported by a nonclassical ligand. Interesting structural changes were observed when [Pb(OSO₂CF₃)₃] ? 2 H₂O was treated with Ga(ddp) in a 1:2 ratio to yield [{(ddp)Ga(μ‐OSO₂CF₃)}₂(OH₂)Pb] ( 2 b ) at below ?10 °C. Compound 2 b consists of a bent Ga‐Pb‐Ga backbone with a bridging triflate group between the Ga? Pb bond and a weakly interacting water molecule at the gallium center. Similarly, the reaction of mercury thiolate Hg(SC₆F₅) with Ga(ddp) (2 equiv) produced the bimetallic homoleptic compounds anti‐[{(ddp)Ga(SC₆F₅)}₂Hg] ( 3 a ) and gauche‐[{(ddp)Ga(SC₆F₅)}₂Hg] ( 3 b ), respectively, with a linear Ga‐Hg‐Ga linkage. Compounds 1 – 3 were structurally characterized and these are the first examples of compounds comprised of Ga? Pb^II, Ga? Pb^IV, and Ga? Hg bonds.     

Temperature‐Dependent Electron Shuffle in Molecular Group 13/15 Intermetallic Complexes

Monovalent RAl (R=HC[C(Me)N(2,6‐iPr₂C₆H₃)]₂) reacts with E₂Et₄ (E=Sb, Bi) with insertion into the weak E? E bond and subsequent formation of RAl(EEt₂)₂ (E=Sb 1 ; Bi 2 ). The analogous reactions of RGa with E₂Et₄ yield a temperature‐dependent equilibrium between RGa(EEt₂)₂ (E=Sb 3 ; Bi 4 ) and the starting reagents. RIn does not interact with Sb₂Et₄ under various reaction conditions, but formation of RIn(BiEt₂)₂ ( 5 ) was observed in the reaction with Bi₂Et₄ at low temperature.     

A Versatile Precursor System for Supercritical Fluid Electrodeposition of Main‐Group Materials

For the first time, a versatile electrolyte bath is described that can be used to electrodeposit a wide range of p‐block elements from supercritical difluoromethane (scCH₂F₂). The bath comprises the tetrabutylammonium chlorometallate complex of the element in an electrolyte of 50×10^?3 mol dm^?3 tetrabutylammonium chloride at 17.2 MPa and 358 K. Through the use of anionic ([GaCl₄]^?, [InCl₄]^?, [GeCl₃]^?, [SnCl₃]^?, [SbCl₄]^?, and [BiCl₄]^?) and dianionic ([SeCl₆]^2? and [TeCl₆]^2?) chlorometallate salts, the deposition of elemental Ga, In, Ge, Sn, Sb, Bi, Se, and Te is demonstrated. In all cases, with the exception of gallium, which is a liquid under the deposition conditions, the resulting deposits are characterised by SEM, energy‐dispersive X‐ray analysis, XRD and Raman spectroscopy. An advantage of this electrolyte system is that the reagents are all crystalline solids, reasonably easy to handle and not highly water or oxygen sensitive. The results presented herein significantly broaden the range of materials accessible by electrodeposition from supercritical fluid and open up the future possibility of utilising the full scope of these unique fluids to electrodeposit functional binary or ternary alloys and compounds of these elements.     

Stereoselective Solid‐State Synthesis of Substituted Cyclobutanes Assisted by Pseudorotaxane‐like MOFs

Regioselective photodimerization of trans‐4‐styrylpyridine (4‐spy) derivatives is performed using pseudorotaxane‐like Zn‐based metal organic frameworks MOFs as templates. The formation of rctt‐HT (head‐to‐tail) dimers is achieved by confining pairs of coordinated 4‐spy derivative ligands within hexagonal windows and then irradiating them with UV light. It is also possible to achieve a photodimerization reaction where two different substituted 4‐spy ligands are included in such a MOF material. The ether bond formation is employed to protect the sensitive ‐OH group of HO‐spy and the methyl group of CH₃O‐spy is subsequently removed after the formation of cyclobutane derivative in the CH₃O‐spy‐based MOF. Introducing substituents at the 2‐ or 3‐position of the phenyl group of 4‐spy does not significantly affect the rate of the dimerization process except in the case of the strongly electron‐withdrawing nitro group where the rate is significantly decreased. These results are in striking contrast to the mixtures of photoproducts and low yields obtained by untemplated photodimerization in organic solvents.     

Coaxing Solid‐State Phosphorescence from Tellurophenes

The synthesis of the first examples of tellurophenes exhibiting phosphorescence in the solid state and under ambient conditions (room temperature and in air) is reported. Each of these main‐group‐element‐based emitters feature pinacolboronates (BPin) as ring‐appended side groups. The nature of the luminescence observed was also investigated using computational methods.     

Photocontrolled Ring‐Opening Polymerization of Strained Dicarba[2]Ferrocenophanes: A Route to Well‐Defined Polyferrocenylethylene Homopolymers and Block Copolymers

The ring‐opening polymerization (ROP) behavior of a variety of substituted 1,1′‐ethylenylferrocenes, or dicarba[2]ferrocenophanes, is reported. The electronic absorption spectra and tilted solid‐state structures of the monomers rac‐[Fe(η⁵‐C₅H₄)₂(CHiPr)₂] ( 7 ), [Fe(η⁵‐C₅H₄)₂(C(H)MeCH₂)] ( 8 ), and rac‐[Fe(η⁵‐C₅H₄)₂(CHPh)₂] ( 9 ) are consistent with the presence of substantial ring strain, which was exploited to synthesize soluble, well‐defined polyferrocenylethylenes (PFEs) [Fe(η⁵‐C₅H₄)₂(C(H)MeCH₂)]_n ( 12 ) and [Fe(η⁵‐C₅H₄)₂(CHPh)₂]_n ( 13 ) through photocontrolled ROP. Polymer chain lengths could be controlled by the monomer‐to‐initiator ratio up to about 50 repeat units and, consistent with the “living” nature of the polymerizations, sequential block copolymerization with a sila[1]ferrocenophane led to polyferrocenylethylene–polyferrocenylsilane (PFE‐b‐PFS) block copolymers ( 14 and 15 ). PFE polymers 12 and 13 showed two reversible oxidation waves, indicative of appreciable Fe???Fe interactions along the polymer backbone. The diblock copolymers were characterized by NMR spectroscopy, GPC analysis, and cyclic voltammetry.     

Low‐Valent Organometallics—Synthesis,Reactivity, and Potential Applications

General concepts for the synthesis and stabilization of low‐valent organometallic complexes of Groups 2, 12, 13, and 15 metals and common structural motifs are described. While kinetically stabilized complexes are in the focus for more than two decades, the principle of base‐stabilization only recently allowed the synthesis of unforeseen compounds. As‐prepared complexes not only show fascinating structural diversities, but exhibit also very interesting chemical properties. Low‐valent complexes are of particular interest in the synthesis of novel molecular complexes, but may also find applications as tailor‐made precursors for the synthesis of nanosized materials.     

Synthesis and Solid‐State Structures of a Tetrathiafulvalene‐Conjugated Bistetracene

A tetrathiafulvalene (TTF)‐conjugated bistetracene was synthesized and characterized in the molecular electronic structures based on the spectroscopic measurements and the single‐crystal X‐ray diffraction analysis. UV/Vis absorption and electrochemical measurements of 5 revealed the considerable electronic communication between two tetracenedithiole units by through‐bond and/or through‐space interactions. The difference in the crystal‐packing structures of 5 , showing polymorphism, results in a variety of intermolecular electronic‐coupling pattern. Of these, the π‐stacking structure of 5 A gave a large transfer integral of HOMOs (97 meV), which value is beyond hexacene and rubrene, thus, quite beneficial to achieve the high hole mobility.     

From a Si3‐Cyclopropene to a Si3S‐Bicyclo[1.1.0]butane to a Si3S‐Cyclopropene to a Si3S2‐Bicyclo[1.1.0]butane: Back‐and‐Forth,and In‐Between

Compact and highly reactive bicyclo[1.1.0]butanes constitute one of the most fascinating classes of organic compounds. Furthermore, interplay of bicyclo[1.1.0]butanes with their valence isomers, such as buta‐1,3‐dienes and cyclobutenes, is among the fundamental pericyclic transformations in organic chemistry. Herein we report the back‐and‐forth interconversion between the cyclotrisilenes and thiatrisilabicyclo[1.1.0]butanes, allowing for the synthesis of novel representatives of such classes of highly reactive organometallics. The peculiar structural and bonding features of the newly synthesized compounds, as well as the mechanism of their isomerization, were verified both experimentally and computationally.     

From a Si3‐Cyclopropene to a Si3S‐Bicyclo[1.1.0]butane to a Si3S‐Cyclopropene to a Si3S2‐Bicyclo[1.1.0]butane: Back‐and‐Forth,and In‐Between

Compact and highly reactive bicyclo[1.1.0]butanes constitute one of the most fascinating classes of organic compounds. Furthermore, interplay of bicyclo[1.1.0]butanes with their valence isomers, such as buta‐1,3‐dienes and cyclobutenes, is among the fundamental pericyclic transformations in organic chemistry. Herein we report the back‐and‐forth interconversion between the cyclotrisilenes and thiatrisilabicyclo[1.1.0]butanes, allowing for the synthesis of novel representatives of such classes of highly reactive organometallics. The peculiar structural and bonding features of the newly synthesized compounds, as well as the mechanism of their isomerization, were verified both experimentally and computationally.     

A Step‐by‐Step Assembly of a 3D Coordination Polymer in the Solid‐State by Desolvation and [2+2] Cycloaddition Reactions

Two solid‐state structural transformations that occur in a stepwise and a controlled manner are described. A combination of desolvation and cycloaddition reactions has been employed to synthesise a 3D coordination polymer (CP) from 1D CP [Cd(bdc)(4‐spy)₂(H₂O)]?2 H₂O?2 DMF (bdc=1,4‐benzenedicarboxylate, 4‐spy=4‐styrylpyridine) presumably via a 2D layered structure, [Cd₂(bdc)₂(4‐spy)₄]. In the absence of single crystals to follow the course of the photocycloaddition reaction, thermogravimetry, XAFS and NOESY NMR experiments were used to propose the formation of layered and pillared layered structures. Further, the present strategy enables us to synthesise new multidimensional architectures that are otherwise inaccessible by the self‐assembly process.     

On the Nature of Bridging Metal Atoms in Intermetalloid Clusters: Synthesis and Structure of the Metal‐Atom‐Bridged Zintl Clusters [Sn(Ge9)2]4− and [Zn(Ge9)2)]6−

The addition of Sn and Zn ions to [Ge₉] clusters by reaction of [Ge₉]^4? with SnPh₂Cl₂, ZnCp*₂ (Cp*=pentamethylcyclopentadienyl), or Zn₂[HC(Ph₂P=NPh)₂]₂ is reported. The resulting Sn‐ and Zn‐bridged clusters [(Ge₉)M(Ge₉)]^q? (M=Sn, q=4; M=Zn, q=6) display various coordination modes. The M atoms that coordinate to the open square of a C_4v‐symmetric [Ge₉] cluster form strong covalent multicenter M?Ge bonds, in contrast to the M atoms coordinating to triangular cluster faces. Molecular orbital analyses show that the M atoms of the Ge₉M fragments coordinate to a second [Ge₉] cluster with similar orbitals but in different ways. The [Ge₉Sn]^2?unit donates two electrons to the triangular face of a second [Ge₉]^2? cluster with D_3h symmetry, whereas [Ge₉Zn]^2?acts as an electron acceptor when interacting with the triangular face of a D_3h‐symmetric [Ge₉]^4? unit.     

A Mixed‐Valence Tri‐Zinc Complex, [LZnZnZnL] (L=Bulky Amide), Bearing a Linear Chain of Two‐Coordinate Zinc Atoms

Reduction of a variety of extremely bulky amido Group 12 metal halide complexes, [LMX(THF)_0,1] (L=amide; M=Zn, Cd, or Hg; X=halide) with a magnesium(I) dimer gave a homologous series of two‐coordinate metal(I) dimers, [L′MML′] (L′=N(Ar^?)(SiMe₃), Ar^?=C₆H₂{C(H)Ph₂}₂Prⁱ‐2,6,4); and the formally zinc(0) complex, [L*ZnMg(^MesNacnac)] (L*=N(Ar*)(SiPrⁱ₃); Ar*=C₆H₂{C(H)Ph₂}₂Me‐2,6,4; ^MesNacnac=[(MesNCMe)₂CH]^?, Mes=mesityl), which contains the first unsupported Zn? Mg bond. Two equivalents of [L*ZnMg(^MesNacnac)] react with ZnBr₂ or ZnBr₂(tmeda) to give the mixed valence, two‐coordinate, linear tri‐zinc complex, [L*Zn^IZn⁰Zn^IL*], and the first zinc(I) halide complex, [L*ZnZnBr(tmeda)], respectively. The analogues [L*ZnMZnL*] (M=Cd or Hg), were also prepared, the Cd species contains the first Zn? Cd bond in a molecular compound. Metal–metal bonding was studied by DFT calculations.     

Tris(3,5‐dimethylpyrazolyl)methane‐Based Heterobimetallic Complexes that Contain Zn and CdTransition‐Metal Bonds: Synthesis,Structures, and Quantum Chemical Calculations

Reactions of the tris(3,5‐dimethylpyrazolyl)methanide amido complexes [M′{C(3,5‐Me₂pz)₃}{N(SiMe₃)₂}] (M′=Mg ( 1 a ), Zn ( 1 b ), Cd ( 1 c ); 3,5‐Me₂pz=3,5‐dimethylpyrazolyl) with two equivalents of the acidic Group 6 cyclopentadienyl (Cp) tricarbonyl hydrides [MCp(CO)₃H] (M=Cr ( 2 a ), Mo ( 2 b )) gave different types of heterobimetallic complex. In each case, two reactions took place, namely the conversion of the tris(3,5‐dimethylpyrazolyl)methanide ligand (Tpmd*) into the ‐methane derivative (Tpm*) and the reaction of the acidic hydride M?H bond with the M′?N(SiMe₃)₂ moiety. The latter produces HN(SiMe₃)₂ as a byproduct. The Group 2 representatives [Mg(Tpm*){MCp(CO)₃}₂(thf)] ( 3 a / b ) form isocarbonyl bridges between the magnesium and chromium/molybdenum centres, whereas direct metal–metal bonds are formed in the case of the ions [Zn(Tpm*){MCp(CO)₃}]⁺ ( 4 a / b ; [MCp(CO)₃]^? as the counteranion) and [Cd(Tpm*){MCp(CO)₃}(thf)]⁺ ( 5 a / b ; [Cd{MCp(CO)₃}₃]^? as the counteranion). Complexes 4 a and 5 a / b are the first complexes that contain Zn?Cr, Cd?Cr, and Cd?Mo bonds (bond lengths 251.6, 269.8, and 278.9 pm, respectively). Quantum chemical calculations on 4 a / b* (and also on 5 a / b* ) provide evidence for an interaction between the metal atoms.