Stable Germylenes Derived from 1,2-Bis(arylimino)acenaphthenes

Abstract

Metal exchange reactions of the magnesium complexes (dpp-BIAN)Mg(THF) n , (dtb-BIAN)Mg(THF) n , and (bph-BIAN)Mg(THF) n with GeCl2(dioxane) afford the stable germylenes (dpp-BIAN)Ge (1), (dtb-BIAN)Ge(Et2O) (2), and (bph-BIAN)Ge (3), respectively (dpp-BIAN = 1,2-[(2,6-iPr2C6H3)N]2C12H6, dtb-BIAN = 1,2-[(2,5-tBu2C6H3)N]2C12H6, bph-BIAN = 1,2-[(2-PhC6H4)N]2C12H6). Compound 1 is also obtained from (dpp-BIAN)Na4 and GeCl4 in Et2O. The germylenes 1−3 were characterized by elemental analyses, 1H NMR, 13C NMR, and IR spectroscopy, and X-ray crystal structure analyses. In the monomeric molecules the two imino nitrogen atoms coordinate the germanium atom. The aryl(N) groups are arranged rather orthogonal to the acenaphthenediimine plane. Compound 3 shows an anti geometry with the ortho phenyl substituents of both N-phenyl rings positioned on opposite sides of the acenaphthenediimine plane. The bite angles N−Ge−N are 85.2° (1) and 85.0° (3), respectively. The Ge−N bond distances in 1−3 range from 1.878 to 1.915 Å.

[(dpp‐bian)ZnZn(dpp‐bian)]: A Zinc–Zinc‐Bonded Compound Supported by Radical‐Anionic Ligands

“…[5] Aggregation of alkaline-earth or aluminum complexes of [dpp-bian] nÀ (n = 1, 2) is prevented by two factors: the rigidity of the diimine fragment and the bulkiness of 2,6-iPr 2 C 6 H 3 substituents. Also the dpp-bian is able to stabilize the low oxidation state of germanium, thus providing twoand three-coordinate Ge II species with the dianionic and radical-anionic dpp-bian ligand, [(dpp-bian)Ge] [6] and [(dppbian)GeCl]. [7] Being inspired by the development of the ZnÀ Zn chemistry and to get more insight in solution behavior of zinc-zinc-bonded species we have attempted the synthesis of a Zn À Zn compound stabilized with the radical-anionic dppbian.…”

Molecular Structures and NMR Studies of Lithium and Germanium(II) Complexes of a New Chelating Amido–Imino Ligand Obtained by Addition of nBuLi to 1,2‐Bis(arylimino)acenaphthene

“…However, in contrast to compound 4, . [16] The Ge-Cl distance [2.3500(7) Å] is noticeably longer than the corresponding distance in the threecoordinate Ge II compound [(dpp-bian)GeCl] [2.2693(8) Å], which contains dpp-bian as a radical-anionic ligand. …”

“…[14] Alkylaluminum complexes with dppbian as a radical-anionic as well as a dianionic ligand are obtained by treating (dpp-bian)Na with R 2 AlX (R = Me, Et, iBu; X = Cl, Br). [15] Similarly, the metal-exchange reactions of (dpp-bian)Na 2 or (dpp-bian)Na with GeCl 2 give the germanium() derivatives [(dpp-bian)Ge] [16] and [(dpp-bian)-GeCl], [17] respectively. The variability of the oxidation state of the dpp-bian ligand is impressively demonstrated by the decomposition of [(dpp-bian)Mg(iPr)(Et 2 O)], which occurs with elimination of iPr radicals and simultaneous reduction of the dpp-bian radical anion to the dianion.…”

Can N-heterocyclic germylenes behave as Lewis acids - is there another side to Meller germylenes?

“…a redox reaction where Ge(II) is oxidised to Ge(IV) and the carbon backbone of the ligand is reduced. Interestingly, an analogous reaction using 1,2-bis{(2,6-diisopropylphenyl)-imino}acenaphthene 3 as the diimine produces a neutral radical species with a monoimino germylene structure 4 (see Scheme 5) [24,25]. If one peruses the available experimental data [23][24][25][26] carefully, one forms the opinion that in both cases the initial product might very well be similar and derived from simple addition of the diimine to GeCl 2 thus forming the Ge(IV) dichloride.…”

“…In the ESR spectra of these radical germylenes a hyperfine structure is observed, which is due to the hyperfine coupling of the unpaired electron with hydrogen and nitrogen atoms of the ligand as well as germanium and halogen [24][25][26][27][28]. The original authors assigned the structure given in Scheme 7, but a canonical form with the unpaired electron on the halogen must exist.…”