Arenkomplexe von einwertigem Gallium, Indium und Thallium

Synthesis and Reactivity of Cationic Gallium(I) [12]Crown-4 Complexes

The synthesis and reactivity of a gallium(I) cationic complex using [12]crown-4 as a stabilizing ligand were explored. The synthesis of [Ga([12]crown-4)][GaCl₄] was achieved in one step from commercially available starting materials. Anion exchange was utilized to replace the reactive tetrachlorogallate anion for the perfluorophenylborate anion. [Ga([12]crown-4)][B(C₆F₅)₄] was analyzed using XPS, which allowed for the classification of the gallium(I)-crown ether complex as electron-deficient. Reactions of the gallium(I)-crown ether complex with Cp*K and cryptand[2.2.2] demonstrated the facile synthesis of a known gallium(I) compound as well as the generation of new gallium(I) complexes, highlighting the use of the gallium(I)-crown ether complex as an effective starting material for new gallium(I) complexes.

Insights into the Composition and Structural Chemistry of Gallium(I) Triflate

"GaOTf" is a simple, convenient source of low-valent gallium for synthetic chemistry and catalysis. However, little is currently known about its composition or reactivity. In this work, 71 Ga NMR spectroscopy shows the presence of [Ga(arene)n ]+ salts on oxidation of Ga metal with AgOTf in arene solvents. However, a more complex picture of speciation is uncovered by X-ray diffraction studies. In all cases, mixed-valence compounds containing Ga-arene and Ga-OTf coordination motifs, in addition to an unusual "naked" [Ga]+ ion, are found. Addition of 18-crown-6 allows for the isolation of a discrete GaI crown complex. Evidence of a potential intermediate in the formation of "GaOTf" has been isolated in the form of the bimetallic silver(I)/gallium(I) cluster anion [Ag4 {Ga(OTf)3 }4 (μ-Ga)6 (OTf)4 ]2- .

A Simple Homoleptic Gallium(I) Olefin Complex: Mimicking Transition-Metal Chemistry at a Main-Group Metal?

The earth-metal olefin complex [GaI (COD)2 ]+ [Al(ORF )4 ]- (COD=1,5-cyclooctadiene; RF =C(CF3 )3 ) constitutes the first homoleptic olefin complex of any main-group metal accessible as a bulk compound. It is straight forward to prepare in good yield and constitutes an olefin complex of a main-group metal that-similar to many transition-metals-may adopt the +1 and +3 oxidation states opening potential applications. Crystallographic-, vibrational- and computational investigations give an insight to the atypical bonding between an olefin and a main-group metal. They are compared to classical transition-metal relatives.

Stack by Stack: From the Free Cyclopentadienylgermanium Cation Via Heterobimetallic Main-Group Sandwiches to Main-Group Sandwich Coordination Polymers

Heterobimetallic cationic sandwich complexes [M(μ-Cp)M'Cp]+ of group 13 (M=Ga, In) and group 14 (M'=Ge, Sn) elements have been prepared as [WCA]- salts (WCA=Al(ORF )4 ; ORF =OC(CF3 )3 ). Their molecular structures include free apical gallium or indium atoms. The sandwich complexes were formed in the reactions of [M(HMB)]+ [WCA]- (HMB=C6 Me6 ) with the free metallocenes [M'Cp2 ]. Their structures are related to known stannocene and stannocenium salts; the unprecedented germanium analogues, namely the free germanocenium cation [GeCp]+ and the corresponding triple-decker complex cation [CpGe(μ-Cp)GeCp]+ , are described herein. By variation of the reaction conditions, these sandwich complexes can be transformed into the group 13/14 mixed cationic coordination polymer [{In(HMB)(μ-SnCp2 )}n ][WCA]n . This polymeric chain motif was also successfully replicated by the synthesis of complexes [{Ga/In(HMB)(μ-FeCp2 )}n ][WCA]n containing FeCp2 as a bridging ligand.

Crystalline Divinyldiarsene Radical Cations and Dications

The divinyldiarsene radical cations [{(NHC)C(Ph)}As]2 (GaCl4 ) (NHC=IPr: C{(NDipp)CH}2 3; SIPr: C{(NDipp)CH2 }2 4; Dipp=2,6-iPr2 C6 H3 ) and dications [{(NHC)C(Ph)}As]2 (GaCl4 )2 (NHC=IPr 5; SIPr 6) are readily accessible as crystalline solids on sequential one-electron oxidation of the corresponding divinyldiarsenes [{(NHC)C(Ph)}As]2 (NHC=IPr 1; SIPr 2) with GaCl3 . Compounds 3-6 have been characterized by X-ray diffraction, cyclic voltammetry, EPR/NMR spectroscopy, and UV/vis absorption spectroscopy as well as DFT calculations. The sequential removal of one electron from the HOMO, that is mainly the As-As π-bond, of 1 and 2 leads to successive elongation of the As=As bond and contraction of the C-As bonds from 1/2→3/4→5/6. The UV/vis spectrum of 3 and 4 each exhibits a strong absorption in the visible region associated with SOMO-related transitions. The EPR spectrum of 3 and 4 each shows a broadened septet owing to coupling of the unpaired electron with two 75 As (I=3/2) nuclei.

Why Do Five Ga+ Cations Form a Ligand-Stabilized [Ga5 ]5+ Pentagon and How Does a 5:1 Salt Pack in the Solid State?

The reaction of the Ga⁺ source [Ga(PhF)₂ ]⁺ [Al(OR^F )₄ ]^- with the neutral σ-donor ligand dmap (4-Me₂ N-C₆ H₄ N) produces the unexpectedly large and fivefold positively charged cluster cation salt [Ga₅ (dmap)₁₀ ]⁵⁺ ([Al(OR^F )₄ ]^- )₅ . It includes a regular and planar Ga₅ pentagon with strong metal-metal bonding. Additionally, the compound represents the first salt in which an ionic 1:5 packing is realized. We discuss the nature of this structure which results from the conversion of the non-bonding 4s² lone-pair orbitals into fully Ga-Ga-bonding orbitals and the solid-state arrangement of the ions constituting the lattice as an almost orthohexagonal AX₅ lattice, possibly the aristotype of any 5:1 salt.

En Route to Bis-Carbene Analogues of the Heavier Group 13 Elements: Consideration of Bridging Group and Metal(I) Source

With the aim of exploring the effect of steric constraints imposed on the metal-metal interaction of bis-carbene analogues of thallium by the linking scaffold, seven dinuclear thallium diyls with a series of rigid, semirigid, and flexible bridging scaffolds were synthesized. The solid-state molecular structures were determined for four of these compounds by single-crystal XRD and compared with the results of DFT calculations, which were performed for all substances. These compounds serve as models to investigate the metal-metal distance in the absence of co-coordinated molecules (additional ligands, solvent molecules). In addition, the effect of the metal(I) precursor, and more specifically the counterion, on the synthetic access to bis-carbene analogues of indium and thallium was investigated. For indium, only InI yields the desired dinuclear indium diyl. With InBr no reaction was observed, and using InCl gave rise to a mononuclear indium(III) compound. For thallium, both TlI and TlBr allow access to the related bis-carbene analogue, although the yield with the latter is significantly lower. In contrast, no reactions were observed with TlCl and TlBF₄ .

Bis(triphenylphosphine)silver(i) perrhenate, a cyclic dimer

The 1 : 4 and 1 : 2 complexes of silver perrhenate and triphenylphosphine, [(Ph₃P)₄Ag]⁺ReO₄⁻and [(Ph₃P)₂AgReO₄]₂, have been prepared and their structures determined in the solid state by X-ray diffraction.

Univalent Gallium Complexes of Simple and ansa-Arene Ligands: Effects on the Polymerization of Isobutylene

Using [Ga(C6 H5 F)2 ]+ [Al(ORF )4 ]- (1) (RF =C(CF3 )3 ) as starting material, we isolated bis- and tris-η6 -coordinated gallium(I) arene complex salts of p-xylene (1,4-Me2 C6 H4 ), hexamethylbenzene (C6 Me6 ), diphenylethane (PhC2 H4 Ph), and m-terphenyl (1,3-Ph2 C6 H4 ): [Ga(1,4-Me2 C6 H4 )2.5 ]+ (2+ ), [Ga(C6 Me6 )2 ]+ (3+ ), [Ga(PhC2 H4 Ph)]+ (4+ ) and [(C6 H5 F)Ga(μ-1,3-Ph2 C6 H4 )2 Ga(C6 H5 F)]2+ (52+ ). 4+ is the first structurally characterized ansa-like bent sandwich chelate of univalent gallium and 52+ the first binuclear gallium(I) complex without a GaGa bond. Beyond confirming the structural findings by multinuclear NMR spectroscopic investigations and density functional calculations (RI-BP86/SV(P) level), [Ga(PhC2 H4 Ph)]+ [Al(ORF )4 ]- (4) and [(C6 H5 F)Ga(μ-1,3-Ph2 C6 H4 )2 Ga(C6 H5 F)]2+ {[Al(ORF )4 ] - }2 (5), featuring ansa-arene ligands, were tested as catalysts for the synthesis of highly reactive polyisobutylene (HR-PIB). In comparison to the recently published 1 and the [Ga(1,3,5-Me3 C6 H3 )2 ]+ [Al(ORF )4 ]- salt (6) (1,3,5-Me3 C6 H3 =mesitylene), 4 and 5 gave slightly reduced reactivities. This allowed for favorably increased polymerization temperatures of up to +15 °C, while yielding HR-PIB with high contents of terminal olefinic double bonds (α-contents=84-93 %), low molecular weights (Mn =1000-3000 g mol-1 ) and good monomer conversions (up to 83 % in two hours). While the chelate complexes delivered more favorable results than 1 and 6, the reaction kinetics resembled and thus concurred with the recently proposed coordinative polymerization mechanism.