Labile Low-Valent Tin Azides: Syntheses, Structural Characterization, and Thermal Properties

Abstract

The first two examples of the class of tetracoordinate low-valent, mixed-ligand tin azido complexes, Sn(N)(L), are shown to form upon reaction of SnCl with NaN and SnF with MeSiN in either pyridine or 4-picoline (2, L = py; 3, L = pic). These adducts of Sn(N) are shock- and friction-insensitive and stable at r.t. under an atmosphere of pyridine or picoline, respectively. A new, fast, and efficient method for the preparation of Sn(N) (1) directly from SnF, and by the stepwise de-coordination of py from 2 at r.t., is reported that yields 1 in microcrystalline form, permitting powder X-ray diffraction studies. Reaction of 1 with a nonbulky cationic H-bond donor forms the salt-like compound {C(NH)}Sn(N) (4) which is comparably stable despite its high nitrogen content (55%) and the absence of bulky weakly coordinating cations that are conventionally deemed essential in related systems of homoleptic azido metallates. The spectroscopic and crystallographic characterization of the polyazides 1-4 provides insight into azide-based H-bonded networks and unravels the previously unknown structure of 1 as an important lighter binary azide homologue of Pb(N). The atomic coordinates for 1 and 2-4 were derived from powder and single crystal XRD data, respectively; those for 1 are consistent with predictions made by DFT-D calculations under periodic boundary conditions.

A Pathway to the Athermal Impact Initiation of Energetic Azides

“…22 J, 74 although other sources quote it as completely insensitive. 19 For reference, it is worth noting that Sn(N 3 ) 2 is believed to have a similar sensitivity as that of its structural homologue, Pb(N 3 ) 2 45 (ca. 1.7 J by the Picatinny Arsenal apparatus 73 ).…”

“…Others, such as Cu­(N 3 ) 2 , are so sensitive that they cannot be used for any practical application. With such wide-spanning physical properties, there is much interest in their continued development as novel energetic materials …”

“…With such wide-spanning physical properties, there is much interest in their continued development as novel energetic materials. 45 The breadth of initiation energies displayed by the simple inorganic azides is astonishing. The typical rationales of bond dissociation energies no longer apply, given that the energetic molecule, the azide anion, is the same in each case.…”

Tuning the metal–ligand bond in theσ‐complexes of stannylenes and azabenzenes

“…The vast majority of the structures carry ligands which are either substituted azabenzenes 24–28 or polycyclic molecules possessing an azabenzene moiety 28–33 . There has been a slowly growing interest in the complexes formed by simple stannylenes and unsubstituted azabenzenes 34–43 . However, these studies exclusively address stannylene complexes bearing pyridine donor ligands.…”

“…[28][29][30][31][32][33] There has been a slowly growing interest in the complexes formed by simple stannylenes and unsubstituted azabenzenes. [34][35][36][37][38][39][40][41][42][43] However, these studies exclusively address stannylene complexes bearing pyridine donor ligands. Based on Mössbauer spectroscopy it was unraveled that one SnX 2 (X = Cl, Br) molecule and one pyridine molecule can form a stable σ-complex in solid state.…”