Oxidation of Ni-ECp* Complexes: Stable Open-Shell Ni^I Cations [Ni(ECp*)_<i>n</i>(PPh₃)_4–<i>n</i>]⁺ (<i>n</i> = 2, 4; E = Al, Ga)

Uncommon Ni^I cationic complexes were synthesized by treating [Ni­(ECp*)₂(PPh₃)₂] (E = Al, Ga; Cp* = pentamethylcyclopentadienyl) with 1 equiv of [FeCp₂]­[BAr₄^F]. All compounds have been prepared readily in high yield. The paramagnetic compounds were characterized by single-crystal X-ray crystallography, mass spectrometry, elemental analysis, magnetic susceptibility, and electron paramagnetic resonance spectroscopy

Diverse Reactivity of ECp* (E = Al, Ga) toward Low-Coordinate Transition Metal Amides [TM(N(SiMe₃)₂)₂] (TM = Fe, Co, Zn): Insertion, Cp* Transfer, and Orthometalation

The reactivity of the carbenoid group 13 metal ligands ECp* (E = Al, Ga) toward low valent transition metal complexes [TM­(btsa)₂] (TM = Fe, Co, Zn; btsa = bis­(trimethylsilyl)­amide) was investigated, revealing entirely different reaction patterns for E = Al and Ga. Treatment of [Co­(btsa)₂] with AlCp* yields [Cp*Co­(μ-H)­(Al­(κ²-(CH₂SiMe₂)­NSiMe₃)­(btsa))] (<b>1</b>) featuring an unusual heterometallic bicyclic structure that results from the insertion of AlCp* into the TM–N bond with concomitant ligand rearrangement including C−H activation at one amide ligand. For [Fe­(btsa)₂], complete ligand exchange gives FeCp*₂, irrespective of the employed stoichiometric ratio of the reactants. In contrast, treatment of [TM­(btsa)₂] (TM = Fe, Co) with GaCp* forms the 1:1 and 1:2 adducts [(GaCp*)­Co­(btsa)₂] (<b>2</b>) and [(GaCp*)₂Fe­(btsa)₂] (<b>3</b>), respectively. The tendency of AlCp* to undergo Cp* transfer to the TM center appears to be dependent on the nature of the TM center: For [Zn­(btsa)₂], no Cp* transfer is observed on reaction with AlCp*; instead, the insertion product [Zn­(Al­(η²-Cp*)­(btsa))₂] (<b>4</b>) is formed. In the reaction of [Co­(btsa)₂] with the trivalent [Cp*AlH₂], transfer of the amide ligands without further ligand rearrangement is observed, leading to [Co­(μ-H)₄(Al­(η²-Cp*)­(btsa))₂] (<b>5</b>)

Hume–Rothery Phase-Inspired Metal-Rich Molecules: Cluster Expansion of [Ni(ZnMe)₆(ZnCp*)₂] by Face Capping with Ni⁰(η⁶‑toluene) and Ni^I(η⁵‑Cp*)

The novel all-hydrocarbon ligand-stabilized binuclear clusters of metal–core composition Ni₂Zn₇E, [(η⁵-Cp*)­Ni₂(ZnMe)₆(ZnCp*)­(ECp*)] (<b>1-Zn</b>, E = Zn; <b>1-Ga</b>, E = Ga) and [(η⁶-toluene)­Ni₂(ZnCp*)₂(ZnMe)₆] (<b>2</b>; Cp* = pentamethylcyclopentadienyl), were obtained via Ga/Zn and Al/Zn exchange reactions using the starting compounds [Ni₂(ECp*)₃(η²-C₂H₄)₂] (E = Al/Ga) and an excess of ZnMe₂ (Me = CH₃). Compounds <b>1-Zn</b> and <b>1-Ga</b> are very closely related and differ only by one Zn or Ga atom in the group 12/13 metal shell (Zn/Ga) around the two Ni centers. Accordingly, <b>1-Zn</b> is EPR-active and <b>1-Ga</b> is EPR-silent. The compounds were derived as a crystalline product mixture. All new compounds were characterized by ¹H and ¹³C NMR and electron paramagnetic resonance (EPR) spectroscopy, mass spectrometric analysis using liquid-injection field desorption ionization, and elemental analysis, and their molecular structures were determined by single-crystal X-ray diffraction studies. In addition, the electronic structure has been investigated by DFT and QTAIM calculations, which suggest that there is a Ni1–Ni2 binding interaction. Similar to Zn-rich intermetallic phases of the Hume–Rothery type, the transition metals (here Ni) are distributed in a matrix of Zn atoms to yield highly Zn-coordinated environments. The organic residues, ancillary ligands (Me, Cp*, and toluene), can be viewed as the “protecting” shell of the 10-metal-atom core structures. The soft and flexible binding properties of Cp* and transferability of Me substituents between groups 12 and 13 are essential for the success of this precedence-less type of cluster formation reaction

The Organozinc Rich Compounds [Cp*M(ZnR)₅] (M = Fe, Ru; R = Cp*, Me, Cl, Br)

Organozinc (ZnR with R = Cp*, Me, Cl, Br) ligated transition metal (M) half-sandwich compounds of general formula [Cp*M­(ZnR)₅] (M = Fe, Ru) are presented in this work. The new compounds were obtained by treatment of various GaCp* ligated precursors with suitable amounts of ZnMe₂ to exchange Ga against Zn. This exchange follows a strict Ga:Zn ratio of 1:2. Accordingly, a Ga/Zn mixed compound [{Cp*Ru­(GaCp*)­(ZnCp*)­(ZnCl)₂}₂] can be obtained if the amount of ZnMe₂ is reduced so that one GaCp* remains coordinated to the transition metal. All new compounds were characterized by elemental analysis, ¹H and ¹³C NMR spectroscopy as well as by single crystal X-ray diffraction techniques, if applicable. The coordination polyhedra of [Cp*M­(ZnR)₅] can be derived from the pseudo homoleptic parent compound [Ru­(ZnCp*)₄(ZnMe)₆], as emphasized by continuous shape measures analysis (CShM). Computational investigations at the density functional theory (DFT) level of theory were performed, revealing no significant attractive interaction of the zinc atoms and therefore these compounds are best described as classical complexes, rather than cluster compounds. The Ru-L bond strength follow the order Cp* > ZnCl > ZnMe > ZnCp*

Clusters [M_<i>a</i>(GaCp*)_<i>b</i>(CNR)_<i>c</i>] (M = Ni, Pd, Pt): Synthesis, Structure, and Ga/Zn Exchange Reactions

Reactions of homoleptic isonitrile ligated complexes or clusters of d¹⁰-metals with the potent carbenoid donor ligand GaCp* are presented (Cp* = pentamethylcyclopentadienyl). Treatment of [Ni₄(CN<i>t</i>-Bu)₇], [{M­(CNR)₂}₃] (M = Pd, Pt) and [Pd­(CNR)₂Me₂] (R = <i>t</i>-Bu, Ph) with suitable amounts of GaCp* lead to the formation of the heteroleptic, tri- and tetranuclear clusters [Ni₄(CN<i>t</i>-Bu)₇(GaCp*)₃] (<b>1</b>), [{M­(CN<i>t</i>-Bu)}₃(GaCp*)₄] (M = Pd: <b>2a</b>, Pt: <b>2b</b>), and [{Pd­(CNR)}₄(GaCp*)₄] (R = <i>t</i>-Bu: <b>3a</b>, Ph: <b>3b</b>). The reactions involve isonitrile substitution reactions, GaCp* addition reactions, and cluster formation reactions. The new compounds were investigated for their ability to undergo Ga/Zn exchange reactions when treated with ZnMe₂. The novel tetranuclear Zn-rich clusters [Ni₄GaZn₇(Cp*)₂Me₇(CN<i>t</i>-Bu)₆] (<b>4</b>) and [{Pd­(CNR)}₄(ZnCp*)₄(ZnMe)₄] (R = <i>t</i>-Bu: <b>5a</b>, Ph: <b>5b</b>) were obtained and isolated. The electronic situation and geometrical arrangement of atoms of all compounds will be presented and discussed. All new compounds are characterized by solution ¹H, ¹³C NMR and IR spectroscopy, elemental analysis (EA), liquid injection field desorption ionization mass spectrometry (LIFDI-MS) as well as single crystal X-ray crystallography

Clusters [M_<i>a</i>(GaCp*)_<i>b</i>(CNR)_<i>c</i>] (M = Ni, Pd, Pt): Synthesis, Structure, and Ga/Zn Exchange Reactions

Reactions of homoleptic isonitrile ligated complexes or clusters of d¹⁰-metals with the potent carbenoid donor ligand GaCp* are presented (Cp* = pentamethylcyclopentadienyl). Treatment of [Ni₄(CN<i>t</i>-Bu)₇], [{M­(CNR)₂}₃] (M = Pd, Pt) and [Pd­(CNR)₂Me₂] (R = <i>t</i>-Bu, Ph) with suitable amounts of GaCp* lead to the formation of the heteroleptic, tri- and tetranuclear clusters [Ni₄(CN<i>t</i>-Bu)₇(GaCp*)₃] (<b>1</b>), [{M­(CN<i>t</i>-Bu)}₃(GaCp*)₄] (M = Pd: <b>2a</b>, Pt: <b>2b</b>), and [{Pd­(CNR)}₄(GaCp*)₄] (R = <i>t</i>-Bu: <b>3a</b>, Ph: <b>3b</b>). The reactions involve isonitrile substitution reactions, GaCp* addition reactions, and cluster formation reactions. The new compounds were investigated for their ability to undergo Ga/Zn exchange reactions when treated with ZnMe₂. The novel tetranuclear Zn-rich clusters [Ni₄GaZn₇(Cp*)₂Me₇(CN<i>t</i>-Bu)₆] (<b>4</b>) and [{Pd­(CNR)}₄(ZnCp*)₄(ZnMe)₄] (R = <i>t</i>-Bu: <b>5a</b>, Ph: <b>5b</b>) were obtained and isolated. The electronic situation and geometrical arrangement of atoms of all compounds will be presented and discussed. All new compounds are characterized by solution ¹H, ¹³C NMR and IR spectroscopy, elemental analysis (EA), liquid injection field desorption ionization mass spectrometry (LIFDI-MS) as well as single crystal X-ray crystallography

Dizinc Cation [Zn₂]²⁺ Trapped In A Homoleptic Metalloid Coordination Environment Stabilized by Dispersion Forces: [Zn₂(GaCp*)₆][BAr₄^F]₂

The synthesis and characterization of the cationic mixed metal Ga/Zn cluster [Zn₂(GaCp*)₆]²⁺ (<b>1</b>) is presented. The reaction of [Zn₂Cp*₂] with [Ga₂Cp*]­[BAr₄^F] leads to the formation of the novel complex being the first example of a [Zn₂]²⁺ core exclusively ligated by metalloid group-13 organyl-ligands. Compound <b>1</b> exhibits two different coordination modes: In the solid state, two of the six GaCp* ligands occupy bridging positions, whereas VT ¹H NMR indicates the coexistence of a second isomer in solution featuring six terminal GaCp* ligands. Quantum chemical calculations have been carried out to assign the gallium and zinc positions; the bonding situation in <b>1</b> is characterized and the importance of dispersion forces is discussed

Dizinc Cation [Zn₂]²⁺ Trapped In A Homoleptic Metalloid Coordination Environment Stabilized by Dispersion Forces: [Zn₂(GaCp*)₆][BAr₄^F]₂

The synthesis and characterization of the cationic mixed metal Ga/Zn cluster [Zn₂(GaCp*)₆]²⁺ (<b>1</b>) is presented. The reaction of [Zn₂Cp*₂] with [Ga₂Cp*]­[BAr₄^F] leads to the formation of the novel complex being the first example of a [Zn₂]²⁺ core exclusively ligated by metalloid group-13 organyl-ligands. Compound <b>1</b> exhibits two different coordination modes: In the solid state, two of the six GaCp* ligands occupy bridging positions, whereas VT ¹H NMR indicates the coexistence of a second isomer in solution featuring six terminal GaCp* ligands. Quantum chemical calculations have been carried out to assign the gallium and zinc positions; the bonding situation in <b>1</b> is characterized and the importance of dispersion forces is discussed

All-Hydrocarbon-Ligated Superatomic Gold/Aluminum Clusters

Key strategies in cluster synthesis include the use of modulating agents (e.g., coordinating additives). We studied the influence of various phosphines exhibiting different steric and electronic properties on the reduction of the Au(I) precursor to Au(0) clusters. We report a synthesis of the bimetallic clusters [Au6(AlCp*)6] = [Au6Al6](Cp*)6 (1) and [HAu7(AlCp*)6] = [HAu7Al6](Cp*)6 (2) (Cp* = pentamethylcyclopentadiene) using Au(I) precursors and AlCp*. The cluster [Au2(AlCp*)5] = [Au2Al5](Cp*)5 (3) was isolated and identified as an intermediate species in the reactions to 1 and 2. The processes of cluster growth and degradation were investigated by in situ 1H NMR and LIFDI-MS techniques. The structures of 1 and 2 were established by DFT geometry optimization. These octahedral clusters can both be described as closed-shell 18-electron superatoms