Chelladurai Ganesamoorthy

The Intermetalloid Cluster [(Cp*AlCu)6H4], Embedding a Cu6 Core Inside an Octahedral Al6 Shell: Molecular Models of Hume–Rothery Nanophases†

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)].

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.

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

Redox reactions of [(L(1,2) Mg)2 ] and Sb2 R4 (R=Me, Et) yielded the first Mg-substituted realgar-type Sb8 polystibides [(L(1,2) Mg)4 (μ4 ,η(2:2:2:2) -Sb8)] (L(1) =HC[C(Me)N(2,4,6-Me3 C6 H2)]2, L(2) =HC[C(Me)N(2,6-i-Pr2 C6 H3)]2). Compounds [(L(1,2) Mg)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.

A Gallium-Substituted Distibene and an Antimony-Analogue Bicyclo[1.1.0]butane: Synthesis and Solid-State Structures.

RGa {R=HC[C(Me)N(2,6-iPr2C6H3)]2} reacts with Sb(NMe2)3 with insertion into the Sb-N bond and elimination of RGa(NMe2)2 (2), yielding the Ga-substituted distibene R(Me2N)GaSb=SbGa(NMe2 )R (1). Thermolysis of 1 proceeded with elimination of RGa and 2 and subsequent formation of the bicyclo[1.1.0]butane analogue [R(Me2N)Ga]2Sb4 (3).

Reduction of [Cp*Sb]4 with Subvalent Main-Group Metal Reductants: Syntheses and Structures of [(L1Mg)4(Sb4)] and [(L2Ga)2(Sb4)] Containing Edge-Missing Sb4 Units

[Cp*Sb]4 (Cp*=C5 Me5 ) reacts with [L1 Mg]2 and L2 Ga with formation of [(L1 Mg)4 (μ4 ,η1:2:2:2 -Sb4 )] (L1 =iPr2 NC[N(2,6-iPr2 C6 H3 )]2 , 1) and [(L2 Ga)2 (μ,η2:2 -Sb4 )] (L2 =HC[C(Me)N(2,6-iPr2 C6 H3 )]2 , 2). The cleavage of the Sb-Sb and Sb-C bonds in [Cp*Sb]4 are the crucial steps in both reactions. The formation of 1 occurred by elimination of the Cp* anion and formation of Cp*MgL1 , while 2 was formed by reductive elimination of Cp*2 and oxidative addition of L2 Ga to the Sb4 unit. 1 and 2 were characterized by heteronuclear NMR spectroscopy and single-crystal X-ray diffraction, and their bonding situation was studied by quantum chemical calculations.

Synthesis, Structure, and Reactivity of Ga-Substituted Distibenes and Sb-Analogues of Bicyclo[1.1.0]butane

Monovalent gallanediyl LGa {L=HC[C(Me)N(2,6-iPr2 C6 H3 )]2 } reacts with SbX3 to form the Ga-substituted distibenes [(LGaX)2 Sb2 ] (X=NMeEt 1, Cl 2). Upon heating, 2 reacts to the bicyclo[1.1.0]butane analogue [(LGaCl)2 (μ,η1:1 -Sb4 )] 3 containing a [Sb4 ]2- dianion. Moreover, 2 reacts with Li amides LiNR2 in salt elimination reactions that form the corresponding amido-substituted compounds 1 and [(LGaNMe2 )2 Sb2 ] 4, whereas reactions of 4 and [(LGaNMe2 )2 (μ,η1:1 -Sb4 )] 5 with two equivalents of GaCl3 resulted in the formation of 2 and 3, respectively. 1, 2 and 3 were characterized by 1 H and 13 C NMR spectroscopy, elemental analysis, and single crystal X-ray diffraction. In addition, their bonding situation was analyzed by quantum chemical calculations.

From stable Sb- and Bi-centered radicals to a compound with a Ga=Sb double bond

Neutral stibinyl and bismuthinyl radicals are typically short-lived, reactive species. Here we show the synthesis and solid-state structures of two stable stibinyl [L(Cl)Ga]2Sb· 1 and bismuthinyl radicals [L(I)Ga]2Bi· 4, which are stabilized by electropositive metal centers. Their description as predominantly metal-centered radicals is consistent with the results of NMR, EPR, SQUID, and DFT studies. The Lewis-acidic character of the Ga ligands allow for significant electron delocalization of the Sb- and Bi- unpaired radical onto the ligand. Single-electron reduction of [L(Cl)Ga]2Sb· gave LGaSbGa(Cl)L 5, the first compound containing a Ga=Sb double bond. The π-bonding contribution is estimated to 9.56 kcal mol−1 by NMR spectroscopy. The bonding situation and electronic structure is analyzed by quantum mechanical computations, revealing significant π backdonation from the Sb to the Ga atom. The formation of 5 illustrates the high-synthetic potential of 1 for the formation of new compounds with unusual electronic structures.Radicals of heavy main-group elements represent important intermediates in chemical synthesis, yet few have been isolated. Here the authors stabilize neutral stibinyl and bismuthinyl radicals using gallium-based ligands, and reduce the former to afford a Ga=Sb double bond-containing complex.

The Mackay-Type Cluster [Cu43Al12](Cp*)12: Open-Shell 67-Electron Superatom with Emerging Metal-Like Electronic Structure

The paramagnetic cluster [Cu43 Al12 ](Cp*)12 was obtained from the reaction of [CuMes]5 and [AlCp*]4 (Cp*=η5 -C5 Me5 ; Mes=mesityl). This all-hydrocarbon ligand-stabilized M55 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 Cu43 Al12 core.

catena-Poly[[(tetrahydrofuran-κO)potassium]-μ-(η5:η5)-2,3,4,5-tetramethyl-1-n-pentylcyclopentadienyl].

The title compound, [K(C14H23)(C4H8O)]n, comprises zigzag chains of alternating bridging 2,3,4,5-tetramethyl-1-n-pentylcyclopentadienyl ligands and potassium ions, with an ancillary tetrahydrofuran ligand in the coordination environment of potassium. The coordination polymer strands so formed extend by 21 screw symmetry in the b-axis direction. The chemically modified cyclopentadienyl ligand, with a tethered n-pentyl group, was synthesized from 2,3,4,5-tetramethylcyclopent-2-enone by a Grignard reaction.

Comprehensive Study on Reactions of Group 13 Diyls with Tetraorganodipentelanes

L1Ga {L1 = HC[C(Me)N(2,6- iPr2C6H3)]2} reversibly reacts with E2Ph4 (E = Sb, Bi) in a temperature-dependent equilibrium reaction with insertion into the E-E bond and formation of L1Ga(EPh2)2 (E = Sb 1, Bi 2). Analogous findings were observed in the reactions of L2Ga {L2 = (C6H11)2NC[N(2,6- iPr2C6H3)]2} with E2R4 (R = Ph, Et), yielding L2Ga(EPh2)2 (E = Sb 3, Bi 4) and L2Ga(EEt2)2 (E = Sb 5, Bi 6). 1-3 and 5 were isolated by fractional crystallization at low temperature, whereas 4 and 6 could not be isolated in their pure form even at low temperature. In contrast, reactions of [Cp*Al]4 (Cp* = C5Me5) with Sb2R4 (R = Ph, Et) and Bi2Et4 did not proceed with insertion into the E-E bonds but with formation of (Cp*Al)3E2 (E = Sb, 7; Bi, 8), whereas the reaction with Bi2Ph4 yielded metallic bismuth. 8 was also formed in the reaction of [Cp*Al]4 and BiEt3 at ambient temperature, whereas the analogous reaction of [Cp*Al]4 with SbEt3 did not yield 7 even under drastic reaction conditions (120 °C, 3 days). In contrast, Cp*Ga and Sb2R4 (R = Ph, Et) were found to react only at elevated temperature (120 °C) with formation of antimony metal.