Azido Derivatives of Low-Valent Group 14 Elements:  Synthesis, Characterization, and Electronic Structure of [(n-Pr)₂ATI]GeN₃ and [(n-Pr)₂ATI]SnN₃ Featuring Heterobicyclic 10-π-Electron Ring Systems

Abstract

Treatment of THF solutions of [(n-Pr)2ATI]MCl (where [(n-Pr)2ATI]- = N-(n-propyl)-2-(n-propylamino)troponiminate; M = Ge and Sn) with sodium azide affords the compounds [(n-Pr)2ATI]MN3 in excellent yield. X-ray analyses revealed that these Ge(II) and Sn(II) compounds feature linear azide moieties and planar heterobicyclic C7N2M ring systems. Germanium and tin atoms adopt a pyramidal geometry. IR spectra of [(n-Pr)2ATI]GeN3 and [(n-Pr)2ATI]SnN3 display a nu asym(N3) band at 2048 and 2039 cm-1, respectively. DFT calculations on the corresponding methyl-substituted species demonstrate that the geometrical and electronic structure of these two species are very similar, and the dominant canonical form of the metal-azide moiety is M-N-N identical to N. The tin system is, as expected, slightly more ionic. A comparative CASSCF/DFT study on the model system H-Sn-N3 illustrates that the DFT approach is viable for the calculation of the structures of these species.

Three‐coordinate divalent Group 14 element derivatives and related compounds

“…Thus, the presence of ligands with donor side arms on the germanium or the tin element can (by transfer of electron density) reduce the deficit on 37 is, to our knowledge, the first example of an intramolecular base stabilized homoleptic dialkylgermylene. Various amino-, phosphino-, thioalkoxy-, alkoxy-and aryloxy-divalent species have also been isolated in monomeric form owing to this method of stabilization; one should mention in particular the studies of Jutzi and co-workers, 28,32,54,71 Veith and coworkers, 15,18,40,66 Parkin and co-workers, 67 Jurkschat and co-workers, 77,78 Dias and co-workers 31,35,42,69,80,81 and Roesky and co-workers. …”

New stable germylenes, stannylenes, and related compounds. 5. Germanium(II) and tin(II) azides [N3-E14-OCH2CH2NMe2]2 (E14=Ge, Sn): synthesis and structure

“…The bonding in the E 14 N 3 species may be described by two main canonical forms: E 14 -N@N@N and E 14 -N-N"N. In addition, an ionic resonance form [E 14 ] (+) [N 3 ] (À) may also contribute to a certain degree to the overall bonding pattern. It was found previously that the dominant canonical form of the E 14 -azide moieties in 3, 4, 6 and 8 is E 14 -N@N@N [9][10][11][12], whereas that in 5, 7, 9 and 10 is E 14 -N-N"N [11][12][13]. In compounds 1 and 2 the N a -N b bonds of the azide groups (1.226(5) Å for 1 and 1.214(7) Å for 2) are longer than the N b -N c bonds (1.153(5) Å for 1 and 1.149(8) Å for 2), the difference DNN 0.073 Å for 1 and 0.065 Å for 2 is comparable to that observed for 5 (DNN = 0.053 Å ), 7 (DNN = 0.083 Å ), 9 (DNN = 0.047 Å ), and 10 (DNN = 0.099 Å ).…”

“…Some of these are commercially available as well. In contrast, very little is known about the azide derivatives of low-valent group 14 elements [9][10][11][12][13][14][15]. One of the difficulties in isolating such species is their tendency to decompose with the elimination of molecular nitrogen, leading to high-valent group 14 compounds.…”

“…There are only a very few structurally characterized compounds of this type in the literature to our knowledge. Those include [HB(3,5-Me 2 Pz) 3 ]GeN 3 (3) [9], [CpCo{P(O)(OEt) 2 } 3 ]-GeN 3 (4) [10], [(n-Pr) 2 ATI]E 14 N 3 (E 14 = Ge (5) or Sn (6); ATI = aminotroponiminate ligand) [11], [HB(3,5-(CF 3 ) 2 Pz) 3 ]AgE 14 (N 3 )[(n-Pr) 2 ATI] (E 14 = Ge (7) or Sn (8)) [12], [(Mes) 2 DAP]E 14 N 3 (E 14 = Ge (9) or Sn (10); DAP = diazapentadienyl ligand) [13], {[t-BuO(Me 2 )-Si] 2 NGe-l-N 3 -} 2 (11) [14] and Pb(N 3 ) 2 (12) [15] (Scheme 1).…”

Reactions of some organogermanium(II) chlorides

“…CpZrCl 3 serves as a chloride abstracting agent in the reaction. The synthesis and structural characterization of organogermanium(II) derivatives, [( i Pr) 2 ATI]GeOSO 2 CF 3 (30) [18], [( i Pr) 2 ATI]GeN 3 (31a) [19] have also been reported. Compound 30 was synthesized by a metathesis reaction of 28a with AgOSO 2 CF 3 to yield yellow crystals, while 31 was obtained from the reaction of 28a and NaN 3 .…”