Divalent Germanium Compound with a Radical-Anionic Ligand:  Molecular Structures of (dpp-BIAN)^•-GeCl and Its Hydrochloration Products [(dpp-BIAN)(H)₂]^•+[GeCl₃]^- and [{(dpp-BIAN)(H)₂^•+}₂(Cl^-)]⁺[GeCl₃]^- (dpp-BIAN = 1,2-Bis{(2,6-diisopropylphenyl)imino}acenaphthene)

Abstract

The germanium(II) compound (dpp-BIAN)GeCl (1), which contains the radical anion of dpp-BIAN can be prepared either by reacting free dpp-BIAN ligand with 2 equiv of GeCl2(1,4-dioxane) in Et2O or by metathetical reaction of the sodium salt of dpp-BIAN with germanium dichloride in Et2O or benzene. The reaction of benzene solutions of 1 with 2 or 3 equiv of HCl led to protonation of the dpp-BIAN ligand affording [(dpp-BIAN)(H)2]*+[GeCl3]- (2) and [[(dpp-BIAN)(H)2*+]2(Cl-)]+ [GeCl3]- (3), which incorporate the radical cation of the protonated ligand. Compounds 1-3 have been characterized by elemental analysis, IR, UV-vis, and electron spin resonance (ESR) spectroscopy. Molecular structures of 1-3 were determined by single-crystal X-ray diffraction. In molecule 1, the Ge atom is positioned at the apex of the slightly distorted trigonal pyramid. The Ge-N bond lengths in 1 are 2.0058(19) and 2.004(2) A. The molecular structure of 2 consists of contact ions [(dpp-BIAN)(H)2]+ and [GeCl3]-. In the molecular structure of 3, two radical cations of [(dpp-BIAN)(H)2]+ are "coordinated" by the chlorine anion. The ESR signal of 1 indicates the presence of a dpp-BIAN radical anion and shows a hyperfine structure due to the coupling of an unpaired electron to 14N, 73Ge, 35Cl, 37Cl, and 1H nuclei (AN=0.48 (2 N), AGe=0.96, ACl=0.78 (35Cl), ACl=0.65 (37Cl), AH=0.11 (4 H) mT, g=2.0014). Both 2 and 3 reveal ESR signals of radical cation [(dpp-BIAN)(H)2]*+ (septet, AN=0.53, AH=0.48 mT, g=2.0031).

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

“…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. Herein we report on the synthesis and characterization by single-crystal X-ray analysis and ESR spectroscopy of the first zinc-zinc-bonded compound supported by radicalanionic ligands, [(dpp-bian)ZnÀZn(dpp-bian)] (4), as well as examination of its electronic structure by computation (DFT).…”

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

“…The second GeCl 2 effectively abstracts a chlorine atom leaving a monoimino germylene radical and generating a GeCl 3 radical. The GeCl 3 moiety probably dimerises to Ge 2 Cl 6 which has been suggested but not proven by the authors [25]. The germanium species is now Ge(III) with the unpaired electron on germanium.…”

“…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.…”

New Paramagnetic Derivatives of N-Heterocyclic Germylenes: An EPR Study

“…The EPR spectra of such complexes can provide rich information on their structures and mechanisms of transformation. The first compounds of this type have been recently reported [6][7][8]. The first crystalline paramagnetic germylene containing the radicalanion acenaphthenediimine ligand was obtained and isolated in [6].…”