NON‐Ligated N‐Heterocyclic Tetrylenes

Abstract

We report on the synthesis of N-heterocyclic tetrylenes ligated by the NON-donor framework 4,5-bis(2,6-diisopropylphenylamino)-2,7-di-tert-butyl-9,9-dimethylxanthene. The molecular structures of the germylene (3), stannylene (4) and plumbylene (5) where determined by X-ray diffraction studies. Furthermore, we present quantum chemical studies on the σ-donor and πacceptor properties of 3-5. Additionally, we report on the reactivity of the tetrylenes towards the transition metal carbonyls [Rh(CO) 2 Cl] 2 , [W(CO) 6 ] and [Ni(CO) 4 ]. The isolated complexes (6 and 7) show the differing reactivity of NHTs compared to NHCs. Instead of just forming the anticipated complex [(NON) SnÀ Rh(CO) 2 Cl], 4 inserts into the RhÀ Cl bond to afford [(NON) Sn(Cl)Rh(CO)(C 6 H 6 )] (6, additional CO/C 6 H 6 exchange) and [(NON)Sn(Cl)Rh 2 (CO) 4 Cl] (7). By avoiding halogenated transition metal precursors in order to prevent insertion reactions, germylene 3 shows "classical" coordination chemistry towards {Ni(CO) 3 } forming the complex [(NON)GeÀ Ni(CO) 3 ] (8).

Crystalline Germanium(I) and Tin(I) Centered Radical Anions

“…2‐Ge and 2‐Sn represent the first structurally characterized monometallic Ge(I) and Sn(I) radical anions, with 2‐Sn being the first structurally characterized Sn(I) radical of any kind. At first glance, the structures of 2‐Ge and 2‐Sn appear to be very similar to those of their tetrylene precursor complexes 1‐Ge and 1‐Sn , [17] but with the obvious addition of a [Na(THF) 6 ] cation in the lattice in both cases. The presence of this cation suggests that an electron has successfully been transferred onto the ( NON )E: unit, generating a solvent separated ion pair in both cases.…”

“…The Ge−N bond lengths in 2‐Ge for example, are pprox.. 0.1 Å longer than those in 1‐Ge (2.089(5)/2.072(6) Å in 2‐Ge cf. 1.983(3)/1.973(3) Å in 1‐Ge ) [17] and the Ge⋅⋅⋅O distance in 2‐Ge , a significant 0.4 Å longer than that in 1‐Ge (2.641(4) Å in 2‐Ge cf. 2.213(2) Å in 1‐Ge ) [17] .…”

“…1.983(3)/1.973(3) Å in 1‐Ge ) [17] and the Ge⋅⋅⋅O distance in 2‐Ge , a significant 0.4 Å longer than that in 1‐Ge (2.641(4) Å in 2‐Ge cf. 2.213(2) Å in 1‐Ge ) [17] . In contrast, the N−E−N angle in both radical anions does not change significantly from that in their precursor complexes (N−Ge−N 117.65(2)° 1‐Ge cf.…”

“…In addition, the neutral E(II) tetrylene complexes ( NON )E: (E=Ge, 1‐Ge ; Sn, 1‐Sn , Pb, 1‐Pb ) bearing the NON ligand have recently been reported by Breher, [17] which could be envisioned to serve as precursors to the radical anions, with the LUMO being the p z orbital located on the Group 14 center (see Supporting Information). The neutral tetrylene complexes used in this work were synthesized via a modified procedure to that reported, [17] via simple one‐pot salt metathesis reactions between the dilithium salt of the ligand, Li 2 ( NON ), and the corresponding Group 14 dihalide salt. These reactions led to three tetrylene complexes 1‐Ge , 1 ‐ Sn and 1‐Pb ) being isolated in high crystalline yields (68—86 %, see Supporting Information for further details).…”

“…2.213(2) Å in 1-Ge). [17] In contrast, the NÀ EÀ N angle in both radical anions does not change significantly from that in their precursor complexes (NÀ GeÀ N 117.65(2)°1-Ge cf. 117.2(2)°in 2-Ge; NÀ SnÀ N 115.83(10)°1-Sn cf.…”