Reactions of Tetra(o-tolyl)diborane(4) with Organic Azides: Formation of Fluorescent Boron-Fused Hexazenes

The reaction of tetra(o-tolyl)diborane(4) with organic azides afforded three different compounds, diborylamines, diboryltriazenes, and B2 -hexazenes having a bicyclic B2 N6 ring system. The reaction with aryl azides gave diborylamines, while the reaction with 1 equiv. of alkyl azides furnished diboryltriazenes. In the case of the reaction with an excess amount of primary alkyl azide, a new heterocyclic B2 -hexazenes were obtained. The formation of the B2 N6 structure could be explained by one general reaction mechanism via the diboryltriazene intermediate according to the control experiments and DFT calculations. The B2 -hexazenes exhibited a strong fluorescence with a remarkably high fluorescent quantum yield of up to 96 %.

Isostructural bridging diferrous chalcogenide cores [FeII(μ-E)FeII] (E = O, S, Se, Te) with decreasing antiferromagnetic coupling down the chalcogenide series

Iron compounds containing a bridging oxo or sulfido moiety are ubiquitous in biological systems, but substitution with the heavier chalcogenides selenium and tellurium, however, is much rarer, with only a few examples reported to date. Here we show that treatment of the ferrous starting material [(^tBupyrpyrr₂)Fe(OEt₂)] (1-OEt₂) (^tBupyrpyrr₂ = 3,5-^tBu₂-bis(pyrrolyl)pyridine) with phosphine chalcogenide reagents E = PR₃ results in the neutral phosphine chalcogenide adduct series [(^tBupyrpyrr₂)Fe(EPR₃)] (E = O, S, Se; R = Ph; E = Te; R = ^tBu) (1-E) without any electron transfer, whereas treatment of the anionic starting material [K]₂[(^tBupyrpyrr₂)Fe₂(μ-N₂)] (2-N₂) with the appropriate chalcogenide transfer source yields cleanly the isostructural ferrous bridging mono-chalcogenide ate complexes [K]₂[(^tBupyrpyrr₂)Fe₂(μ-E)] (2-E) (E = O, S, Se, and Te) having significant deviation in the Fe-E-Fe bridge from linear in the case of E = O to more acute for the heaviest chalcogenide. All bridging chalcogenide complexes were analyzed using a variety of spectroscopic techniques, including ¹H NMR, UV-Vis electronic absorbtion, and ⁵⁷Fe Mössbauer. The spin-state and degree of communication between the two ferrous ions were probed via SQUID magnetometry, where it was found that all iron centers were high-spin (S = 2) Fe^II, with magnetic exchange coupling between the Fe^II ions. Magnetic studies established that antiferromagnetic coupling between the ferrous ions decreases as the identity of the chalcogen is tuned from O to the heaviest congener Te.

Non-redox reactivity of V(ii) and Fe(ii) formamidinates towards CO2 resulting in the formation of novel M(ii) carbamates

Multiple CO2 insertions into the M–N bonds of V(ii) and Fe(ii) bis(formamidinates) led to the isolation of three novel carbamates. The CO2 insertion effectivity depended on the solvent used and the metal centre's coordination sphere geometry.

Synthesis and reactivity of heteroleptic zinc(I) complexes toward heteroallenes

Heteroleptic zinc(I) complexes L^1,2Zn-ZnCp* (L¹ = HC[C(CF₃)NC₆F₅]₂1; L² = HC[C(Me)NDipp]₂; Dipp = 2,6-i-Pr₂C₆H₃2) are synthesized by reactions of Cp*₂Zn₂ with L¹H and L²ZnH. 2 reacts with t-BuNCO to give unprecedented carbamate complex (4), while reactions with RN₃ gave bis-hexazene, triazenide, and trimeric azide complexes (5-7).

Properties and Promise of Catenated Nitrogen Systems As High-Energy-Density Materials

The properties of catenated nitrogen molecules, molecules containing internal chains of bonded nitrogen atoms, is of fundamental scientific interest in chemical structure and bonding, as nitrogen is uniquely situated in the periodic table to form kinetically stable compounds often with chemically stable N-N bonds but which are thermodynamically unstable in that the formation of stable multiply bonded N₂ is usually thermodynamically preferable. This unique placement in the periodic table makes catenated nitrogen compounds of interest for development of high-energy-density materials, including explosives for defense and construction purposes, as well as propellants for missile propulsion and for space exploration. This review, designed for a chemical audience, describes foundational subjects, methods, and metrics relevant to the energetic materials community and provides an overview of important classes of catenated nitrogen compounds ranging from theoretical investigation of hypothetical molecules to the practical application of real-world energetic materials. The review is intended to provide detailed chemical insight into the synthesis and decomposition of such materials as well as foundational knowledge of energetic science new to most chemists.

Persistent four-coordinate iron-centered radical stabilized by π-donation

Dinuclear iron carbonyl complex 2, which contains an elongated unsupported Fe-Fe bond, was synthesized by the reaction between Fe₂(CO)₉ and phosphinyl radical 1. Thermal Fe-Fe bond homolysis led to the generation of a four-coordinate carbonyl-based iron-centered radical, 3, which is stabilized by π-donation. Complex 3 exhibited high reactivity toward organic radicals to form diamagnetic five-coordinate Fe(ii) complexes.

Neutral diiron(iii) complexes with Fe2(μ-E)2 (E = O, S, Se) core structures: reactivity of an iron(i) dimer towards chalcogens

Three neutral guanidinato bis(μ-chalcogenido)diiron(iii) complexes (e.g. see picture) have been prepared from reactions of an iron(i) dimer with elemental chalcogens.

MeL2Zn2(μ-1,6-Ph2-N6) – a building block for new hexazene complexes

^MeL₂Zn₂(μ-1,6-Ph₂-N₆) 1 (^MeL = HC[C(Me)N(2,4,6-Me₃C₆H₂)]₂) serves as hexazene transfer reagent in reactions with main group metal and transition metal complexes containing M–Me units.

The Chemistry of Guanidine, Guanidinium, and Guanidinate Compounds

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