Defined molecular models for the surface chemistry of Hume-Rothery nanophases related to catalysis are very rare. The Al-Cu intermetalloid cluster [(Cp*AlCu)6H4] was selectively obtained from the clean reaction of [(Cp*Al)4] and [(Ph3PCuH)6]. The stronger affinity of Cp*Al towards Cu sweeps the phosphine ligands from the copper hydride precursor and furnishes an octahedral Al6 cage to encapsulate the Cu6 core. The resulting hydrido cluster M12H4 reacts with benzonitrile to give the stoichiometric hydrometalation product [(Cp*AlCu)6H3(N=CHPh)].

Atom-precise, ligand-stabilized metalloid clusters have emerged as outstanding model systems to study fundamental structure and bonding situations of compositionally related molecules and extended solid phases. However, this fascinating field of research is still largely restricted to homometallic and pseudo-heterometallic systems of closely related d-block metals. In this review, we will highlight our own and others' efforts to project the structural and compositional diversity of intermetallics with dissimilar d- and p-block metal combinations, particularly the Zintl and Hume-Rothery phases, onto the molecular level in order to bridge the still gaping chasm between heterometallic molecular coordination chemistry and solid-state intermetallics. Herein, fundamental synthetic approaches, as well as structural and electronic properties of thus accessible "molecular alloys" will be addressed, and placed against their exceptional position as intermediates on the way to nanomaterials.

The paramagnetic cluster [Cu Al ](Cp*) was obtained from the reaction of [CuMes] and [AlCp*] (Cp*=η -C Me ; Mes=mesityl). This all-hydrocarbon ligand-stabilized M magic atom-number cluster features a Mackay-type nested icosahedral structure. Its open-shell 67-electron superatom configuration is unique. Three unpaired electrons occupy weakly antibonding jellium states. The situation prefigures the formation of a conduction band, which is in line with the measured temperature-independent magnetism. Steric protection by twelve Cp* ligands suppresses the intrinsic polyradicalar reactivity of the Cu Al core.

The reactivity of the carbenoid group 13 metal ligands ECp* (E = Al, Ga) toward low valent transition metal complexes [TM(btsa)] (TM = Fe, Co, Zn; btsa = bis(trimethylsilyl)amide) was investigated, revealing entirely different reaction patterns for E = Al and Ga. Treatment of [Co(btsa)] with AlCp* yields [Cp*Co(μ-H)(Al(κ-(CHSiMe)NSiMe)(btsa))] (1) 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)], complete ligand exchange gives FeCp*, irrespective of the employed stoichiometric ratio of the reactants. In contrast, treatment of [TM(btsa)] (TM = Fe, Co) with GaCp* forms the 1:1 and 1:2 adducts [(GaCp*)Co(btsa)] (2) and [(GaCp*)Fe(btsa)] (3), 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)], no Cp* transfer is observed on reaction with AlCp*; instead, the insertion product [Zn(Al(η-Cp*)(btsa))] (4) is formed. In the reaction of [Co(btsa)] with the trivalent [Cp*AlH], transfer of the amide ligands without further ligand rearrangement is observed, leading to [Co(μ-H)(Al(η-Cp*)(btsa))] (5).

A series of heteroleptic complexes [Ni­(PEt3)4–n (ECp*) n ] (E = Al, Ga, Cp* = pentamethylcyclopentadienyl, n = 0–4) was prepared and characterized by experimental as well as computational means. The series of compounds was studied with respect to ligand dissociation processes which are fundamental for reactivity. In contrast to the homoleptic complexes [Ni­(PR3) n ] phosphine dissociation is remarkably suppressed in the heteroleptic title complexes. Single crystal X-ray structures as well as density functional theory calculations reveal a gradual decrease of the Ni–PEt3 distances with increasing number of coordinated group-13 ligands ECp*. Accordingly, variable-temperature UV–vis studies of [Ni­(PEt3)4–n (AlCp*) n ] in solution indicate no ligand dissociation equilibrium for n ≥ 2. Energy decomposition analysis with the natural orbital for chemical valence extension shows higher Ni–P interaction energies for [Ni­(PEt3)4–n (AlCp*) n ] than for [Ni­(PEt3)4] which is mainly a result of an increase in columbic attraction forces induced by Ni–PEt3 bond polarization upon ECp* coordination.

Development of two new neodymium containing precursors and their successful implementation in the MOCVD of luminescent Nd2S3 thin films.

The reactivity of GaCp* toward different Ni 0 olefin complexes is investigated. The reaction of GaCp* with [Ni(cdt)] (cdt = all-trans-1,5,9-cyclododecatriene) leads to simple adduct formation and the 18 valence electron (ve) compound [Ni(GaCp*)(cdt)] (1). In contrast, [Ni 2 (dvds) 3 ] (dvds = 1,1,3,3-tetramethyl-1,3-divinyldisiloxane) is converted to the undercoordinated and highly reactive 16 ve complex [Ni(GaCp*)(dvds)] (2), which represents an intermediate in the formation of the propeller-shaped M 7 cluster [Ni 4 Ga 3 ](Cp*) 3 (dvds) 2 (3). Extensive characterization of the latter compound by experimental and computational means reveals the Cp* transfer from Ga to Ni. Therefore, the title compound can be best expressed by the structural formula [(μ 2 -GaCp*)(Ni 2 )(μ 2 -GaNiCp*) 2 (dvds) 2 ]. The flexible dvds ligands stabilize this arrangement via alkene−Ni and O−Ga interactions. Furthermore, compound 2 exhibits a fast GaCp* ligand exchange with external GaCp*, which is rather unexpected for the [TM(ECp*) a ] compounds; they usually do not undergo substitution reactions with two electron donor ligands like CO, phosphines, or GaCp*.

Der paramagnetischeC luster [Cu 43 Al 12 ](Cp*) 12 entsteht bei der Reaktion von [CuMes] 5 mit [AlCp*] 4 (Cp* = h 5 -C 5 Me 5 ;M es = Mesityl). Dieser ausschließlich durchK ohlenwasserstoff-Liganden stabilisierte "magische" Cluster mit 55 Atomen im Clusterkern weist eine ummantelte Ikosaeder-Struktur des Mackay-Typs auf.D ie Superatomkonfiguration von 67 Elektronen und offener Valenzschale ist einzigartig, wobei drei ungepaarte Elektronen schwacha ntibindende Jellium-Zustände besetzen. Diese Situation deutet auf die Bildung eines Leitungsbands hin, was durch die Temperaturunabhängigkeit des Magnetismus bestätigt wird.D ie sterische Abschirmung durch 12 Cp*-Liganden unterdrückt die intrinsische polyradikalische Reaktivitätdes Cu 43 Al 12 -Kerns.