Adamantane-type clusters: compounds with a ubiquitous architecture but a wide variety of compositions and unexpected materials properties

The research into adamantane-type compounds has gained momentum in recent years, yielding remarkable new applications for this class of materials. In particular, organic adamantane derivatives (AdR4) or inorganic adamantane-type compounds of the general formula [(RT)4E6] (R: organic substituent; T: group 14 atom C, Si, Ge, Sn; E: chalcogenide atom S, Se, Te, or CH2) were shown to exhibit strong nonlinear optical (NLO) properties, either second-harmonic generation (SHG) or an unprecedented type of highly-directed white-light generation (WLG) - depending on their respective crystalline or amorphous nature. The (missing) crystallinity, as well as the maximum wavelengths of the optical transitions, are controlled by the clusters' elemental composition and by the nature of the organic groups R. Very recently, it has been additionally shown that cluster cores with increased inhomogeneity, like the one in compounds [RSi{CH2Sn(E)R'}3], not only affect the chemical properties, such as increased robustness and reversible melting behaviour, but that such 'cluster glasses' form a conceptually new basis for their use in light conversion devices. These findings are likely only the tip of the iceberg, as beside elemental combinations including group 14 and group 16 elements, many more adamantane-type clusters (on the one hand) and related architectures representing extensions of adamantane-type clusters (on the other hand) are known, but have not yet been addressed in terms of their opto-electronic properties. In this review, we therefore present a survey of all known classes of adanmantane-type compounds and their respective synthetic access as well as their optical properties, if reported.

An Improved Synthesis of PN-adamantanoid Cages P4 (NR)6 and a Mechanistic Study of their Fourfold Oxidation

Phosphorus-nitrogen (PN) adamantanoid cages are valuable precursors for materials chemistry, but their syntheses are based on harsh methods that sometimes require access to restricted reagents. We report a new and scalable synthesis of PN adamantanoid compounds by chlorosilane elimination between bis-silylated amines and phosphorus trichloride. We further study the mechanism of the recently-reported four-fold oxidation of such cages with Me3 SiN3 to yield tetravalent tetrahedral connectors for materials chemistry. Reaction monitoring and kinetic modelling revealed the key rate-limiting step, but attempts to accelerate this using Lewis acid additives were unsuccessful. Nevertheless, a new four-fold oxidized PN-adamantanoid cage has been prepared and structurally characterized.

O,N-Heterocyclic germylenes as efficient catalysts for hydroboration and cyanosilylation of benzaldehyde

Novel O,N-heterocyclic germylenes were examined as catalysts for cyanosilylation and hydroboration of benzaldehyde.

Novel Stannatrane N(CH2CMe2O)2(CMe2CH2O)SnO-t-Bu and Related Oligonuclear Tin(IV) Oxoclusters. Two Isomers in One Crystal

The syntheses of the alkanolamine N(CH₂CMe₂OH)₂(CMe₂CH₂OH) (1), of the stannatrane N(CH₂CMe₂O)₂(CMe₂CH₂O)SnO-t-Bu (2), and of the trinuclear tin oxocluster 3 consisting of the two isomers [(μ₃-O)(O-t-Bu){Sn(OCH₂CMe₂)(OCMe₂CH₂)₂N}₃] (3a) and [(μ₃-O)(μ₃-O-t-Bu){Sn(OCH₂CMe₂)(OCMe₂CH₂)₂N}₃] (3b) as well as the isolation of a few crystals of the hexanuclear tin oxocluster [LSnOSn(OH)₃LSnOH]₂ [L = N(CH₂CMe₂O)₂(CMe₂CH₂O)] (4) are reported. The compounds were characterized by ¹H, ¹³C, ¹⁵N, and ¹¹⁹Sn (1-3) nuclear magnetic resonance and infrared spectroscopy, electrospray ionization mass spectrometry, and single-crystal X-ray diffraction analysis (1-4). A graph set analysis was performed for compound 1. The relative energies of 3a and 3b were estimated by density functional theory calculations that show that the energy differences are small.

Synthesis, characterization, and electronic structures of a methyl germyliumylidene ion and germylone-group VI metal complexes

The reaction of germylone (L)Ge (1) [L = 3-Ad-1-{C(^tBu) = N(Mes)}C₃H₄N₂] with 1 equivalent of MeOTf afforded a germyliumylidene ion [(L)GeMe]⁺OTf⁻ (2), while reactions with M(CO)₅(thf) (M = Cr, Mo, W) gave the corresponding germylone-metal complexes [(L)Ge]M(CO)₅ (3–5).