Azide Chemistry – An Inorganic Perspective, Part II^[‡] [3+2]‐Cycloaddition Reactions of Metal Azides and Related Systems

Abstract

Abstract. In whatever state of bonding -whether covalent to an organic residue or a heteroatom, or polar to ionic in contact with a metal -the azide moiety N 3 is characterized by its high potential of reactivity which essentially manifests itself in two basic processes: the elimination of dinitrogen and the entry into 1,3-dipolar cycloadditions with suitable dipolarophiles, the latter of which clearly predominates the chemistry of azide, also that of its metal compounds. In a preceding review entitled "Part I -Metal Azides: Overview, General Trends and Recent Developments" which was meant to lay the foundations for the present paper, these and other reactions have already been touched upon. The present review -Part II -now focusses in great detail on the formation of five-membered heterocyclestetrazol(at)es, triazol(at)es, triazolin(at)es, thiatriazol(at)es, etc. as well as various consecutive products -from azide and nitriles, isocyanides, alkynes, alkenes and heteroallenes (CS 2 , RN=C=S) in the ligand sphere of the metal. Generally, these [3+2]-cycloadditions are found to CONTENTS

Electronic Influences on the Stability and Kinetics of Cp* Rhodium(III) Azide Complexes in the iClick Reaction with Electron‐Poor Alkynes

“…[33] Only two series of rhodium complexes with triazolate or triazolium ligands have been structurally characterized so far, [38] both of which, however, feature Rh I centers carrying additional donor groups at the 4-and 5-or 1-and 3-positions of the five-membered ring. [38,39] Our own attempts have so far failed to provide single crystals suitable for X-ray structure analysis for the two title compounds 8 and 9, but by comparison with our recently reported manganese(I) compound and literature reports, for example on [Rh(Cp*)(triazolate CF3,CF3 )(PPh 3 )], [23,40] it is assumed that the triazolate is symmetrically coordinated via the N2 nitrogen atom.…”

Borane Adducts of Hydrazoic Acid and Organic Azides: Intermediates for the Formation of Aminoboranes

“…"Atthe beginning of azide chemistry,HN 3 was assumed to have ac yclic 1H-triazirine structure,t hat is,athreemembered N 3 ring attached to ahydrogen atom. [6,[11][12][13][14][15][16][17][18][19] Thef irst report on the reaction of organic azides with borane (Et 3 B) was published by Brown and co-workers in 1971. [8,9] Only in 2011, the solid-state structure of HN 3 confirmed unequivocally the presence of hydrogen-bonded tetramers of (HN 3 ) 4 in an early planar network of eight-membered rings always featuring trans-bent HN 3 molecules.…”

“…As shown by variabletemperature 1 Ha nd 19 FNMR studies in solution (see the Supporting Information, Figure S7), the release of molecular nitrogen occurs almost simultaneously with the formation of the adduct 1H at temperatures above À20 8 8C, so that amixture of the adduct and an ew BN species (2H,S cheme 2) was always observed (1H: d = 5.07 ppm, free HN 3 : d = 5.43, new BN species 2H: d = 6.00 ppm;s ee below). Structure elucidation confirmed the existence of an HN 3 ·B(C 6 F 5 ) 3 adduct (1H;F igure 1), which is further stabilized by h 6 -type N 3 ÀH···aryl hydrogen bonding with the aromatic ring system of one molecule of m-xylene (1H·xyl).…”

Boran‐Addukte von Stickstoffwasserstoffsäure und Organischen Aziden: Intermediate bei der Bildung von Aminoboranen

“…Zu Beginn der Azidchemie wurde angenommen, dass HN 3 eine zyklische 1H-Triazirin-Struktur aufweist, d. h. einen dreigliedrigen N 3 -Ring,d er an Wasserstoff gebunden ist. [6,[11][12][13][14][15][16][17][18][19] Die erste Reaktion von organischen Aziden mit Boran (Et 3 B) wurde 1971 von Brown et al verçffentlicht. [8,9] Erst 2011 bewies die Festkçrperstruktur von HN 3 eindeutig das Vorhandensein von wasserstoffbrückengebundenen Te trameren, (HN 3 ) 4 ,i ne inem nahezu planaren Netzwerk von achtgliedrigen Ringen aus HN 3 -Molekülen in einer trans-bent-Konformation.…”

“…Wied urch temperaturabhängige 1 H-und 19 F-NMR-Studien in Lçsung gezeigt (Hintergrundinformationen, Abbildung S7), erfolgte die Freisetzung von Stickstoff bei Te mperaturen > À20 8 8Cnahezu gleichzeitig zur Adduktbildung von 1H,s odass stets eine Mischung aus dem Addukt und einer neuen BN-Spezies (2H,S chema 2) beobachtet wurde (1H: 5.07 ppm, vgl. Die Strukturaufklärung bestätigte das Vorliegen eines HN 3 ·B(C 6 F 5 ) 3 -Addukts (1H,A bbildung 1), das durch eine h 6 -artige Wasserstoffbrückenbindung mit dem aromatischen Ringsystem eines Moleküls m-Xylol (1H·xyl) weiter stabilisiert wird.…”