The Chemistry of Aluminum(I), Silicon(II), and Germanium(II)

Can low-valent germanium chemistry be practiced under ambient conditions? A tale of a water-stable yet reactive germylene monochloride complex

A germylene monochloride complex ((DPM)GeCl, 1) that is water stable was isolated for the first time. Interestingly, it reacts with cesium fluoride under ambient conditions (non-inert atmosphere and water-containing solvent) to afford water stable germylene monofluoride complex ((DPM)GeF, 2). Due to the usage of DPM (dipyrrinate) ligand, germylene monohalides 1 and 2 show fluorescence in the visible region at 555 and 538 nm, respectively. Compounds 1 and 2 are the first fluorescent germylene complexes and were characterized by multinuclear NMR spectroscopy. The structure of compound 1 was also proved by single crystal X-ray diffraction studies.

Germanium-centered free radicals studied by muon spin spectroscopy

Transverse-field muon spin rotation (TF-μSR) spectra have been recorded for free radicals formed by positive muon irradiation of nine different divalent germanium compounds. Muon-electron hyperfine coupling constants (Aμ) were determined from the spectra and compared with values predicted from density functional theory molecular orbital (DFT-MO) calculations on the muoniated radicals formed by muonium addition to the germanium atom. The muon hyperfine constants for germylenes containing N–Ge bonds are generally quite large, from 593 to 942 MHz, indicating strong interaction between the muon and the unpaired electron in these radicals. The radical derived from one of the germylenes exhibited a significantly lower muon hyperfine constant, suggesting that in this case the muoniated germyl radical undergoes a coupling reaction to form a digermanyl radical, which is what is detected by μSR.

Coordination of non-stabilized germylenes, stannylenes, and plumbylenes to transition metals

Complexes of transition metals with heavy analogs of carbenes (tetrylenes) as ligands have been studied now for some 40 years. The current review attempts to provide an overview about complexes with non-stabilized (having no π-donating substituents) germylenes, stannylenes, and plumbylenes. Complexes are known for groups 4–11. For groups 6–10 not only examples of monodentate tetrylene ligands, but also of bridging ones are known. While this review covers almost 200 complexes, the field in general has been approached only very selectively and real attempts for systematic studies are very scarce. Although some isolated reports exist which deal with the reactivity of the tetrylene complexes most of the so far published work concentrates on synthesis and characterization.

Steric effects in the reactions of amidinate germylenes with ruthenium carbonyl: isolation of a coordinatively unsaturated diruthenium(0) derivative

Coordinatively unsaturated germylene-bridged diruthenium(0) complexes have been prepared by treating [Ru₃(CO)₁₂] with amidinate germylenes of the type Ge(R¹bzamR²)(HMDS), but only when the amidinate contains just one very bulky R group (^tBu) (not two).

Heterocyclic substituted methanides as promising alternatives to the ubiquitous nacnac ligand

A series of group 13 complexes containing deprotonated bisheterocyclomethanes have been prepared as well as structurally and spectroscopically characterised.

Synthesis, structure and a nucleophilic coordination reaction of Germanetellurones

A germylene germanetellurone adduct L(Cp)GeTe(GeCl₂), a pentafluorophenyl gold(i) germanethione and germaneselone compounds L(Me)GeE(AuC₆F₅) (E = S and Se) are herein reported.

A Class of Computationally Designed Tri-Coordinate Cyclic Silylenes RSi(µ-R)2AlR2

With the aim of designing novel low-valent silylenes, herein we report the first systematic investigation of the SiAlR5 system. Based on the ‘topology’ isomeric search strategy, four classes of isomers, i.e. RSi(μ-R)2AlR2 1, R3Si-AlR2 2, R2Si(μ-R)AlR2 3, and R2Si-AlR3 4 were identified. For 12 groups with an electron lone-pair, i.e. R = F, NH2,OH, SH, OMe, PMe2, SMe, OEt, PEt2, SEt, OPh, and PPh2, the tri-coordinate silylene 1 is the most stable structure, which contains two sets of intermolecular donor–acceptor interactions. In accordance with the ‘silylene’ term, the Si-centre can undergo both a nucleophilic reaction and insertion reaction. Moreover, coupling AlR3 (R = OR′ and PR′2) (R′ = H, Me, Et, and Ph) with the known cyclic di-coordinate silylene could lead to stable tri-coordinate silylenes. These novel tri-coordinate silylenes strongly welcome laboratory studies in near future.

Synthesis, bonding, and reactivity of a cerium(IV) fluoride complex

Oxidation of Ce[N(SiMe3)2]3 in the presence of PF6(-) or BF4(-) afforded isolation of CeF[N(SiMe3)2]3. Structural and electrochemical characterization shows that this compound is in its tetravalent oxidation state and contains a terminal fluoride ligand. Spectroscopy and density functional theory have been used to characterize the Ce-F bond as ionic, which is reinforced by an initial reactivity study that demonstrates the nucleophilicity of the fluoride ligand.

Five-coordinate silicon(II) compounds with Si-M bonds (M = Cr, Mo, W, Fe): Bis[N,N'-diisopropylbenzamidinato(-)]silicon(II) as a ligand in transition-metal complexes

Reaction of the donor-stabilized silylene 1 with [Cr(CO)6], [Mo(CO)6], [W(CO)6], or [Fe(CO)5] leads to the formation of the transition-metal silylene complexes 2-5, which contain five-coordinate silicon(II) moieties with Si-M bonds (M = Cr, Mo, W, Fe). These compounds were characterized by NMR spectroscopic studies in the solid state and in solution and by crystal structure analyses. These experimental investigations were complemented by computational studies to gain insight into the bonding situation of 2-5. The nature of the Si-M bonds is best described as a single bond.

Syntheses, characterizations and thermal analyses of four novel unsymmetrical β-diketiminates

Four novel unsymmetrical β-diketiminates 2-(2,6-diisopropylphenyl)amino-4-(phenyl)imino-2-pentene (4a), 2-(2,6-diisopropylphenyl)amino-4-(4-methylphenyl)imino-2-pentene (4b), 2-(2,6-diisopropylphenyl)amino-4-(4-methoxyphenyl)imino-2-pentene (4c) and 2-(2,6-diisopropylphenyl)amino-4-(4-chlorophenyl)imino-2-pentene (4d) were synthesized with a 77-84% yield, and were characterized by spectroscopic methods (¹H NMR, ¹³C NMR, IR and mass spectrometry), elemental analysis, and X-ray single-crystal diffraction, respectively. Spectroscopic and X-ray single-crystal diffraction analyses determined the structures of the four β-diketiminates. While thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) showed two distinct endothermic peaks for each β-diketiminate at temperatures of 92.55°C and 221.50°C (4a), 93.51°C and 238.82°C (4b), 109.60°C and 329.22°C (4c), 115.43°C and 243.25°C (4d), respectively, corresponding to their melting and boiling points.