New Germanium Complexes Containing Ligands Based on 4,6‐Di‐tert‐butyl‐N‐(2,6‐diisopropylphenyl)‐o‐iminobenzoquinone in Different Redox States

Abstract

The exchange reaction of lithium o‐amidophenolate, (AP)Li2, derived from the reaction of 4,6‐di‐tert‐butyl‐N‐(2,6‐diisopropylphenyl)‐o‐iminobenzoquinone (imQ) with GeCl4 in hexane or thf leads to (AP)2Ge (1) (AP is a dianion of imQ). The latter was also obtained by the interaction of GeCl2·dioxane and (ISQ)Li in toluene (ISQ is a radical anion of imQ). The reaction of (AP)Li2 with GeCl2·dioxane in thf results in the formation of germylene 2, [(AP)Ge (2)], which reduces neutral imQ to give compound 1. The exposure of 1 in thf to anhydrous HCl in a 1:1 molar ratio leads to its o‐aminophenolato derivative, (AP)(APH)GeCl (3). Free imQ inserts into the Ge–H bond of (C6F5)3GeH in thf to give (C6F5)3Ge(APH) (4). It is another way of obtaining complexes with protonated ligands such as APH. Compound 3 can be easily oxidized by air to form the stable paramagnetic complex (AP)(ISQ)GeCl (5). Complexes 1 and 3–5 were structurally investigated by using single‐crystal X‐ray diffraction.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

The Reduction of Sterically Hindered o‐Quinone and o‐Iminoquinone with Gallium and “GaI”

“…The use of amalgamated gallium in the reaction with imQ in THF allows one to obtain only the mixed-ligand derivative of Ga III (4) in which the first imQ ligand has a radical-anionic and the second one a dianionic nature (Scheme 4, path a). The similar delocalization of unpaired electron was reported for related five-coordinate tin [2f] and germanium [17] complexes that contain two differently charged o-iminoquinonate ligands. The hyperfine structure of the EPR spectrum of 4 in THF arises from hyperfine coupling (HFC) of unpaired electron with magnetic nuclei 69 Ga (60.1 %, I = 3/2, μ N = 2.01659), [15] 71 Ga (30.9 %, I = 3/2, μ N = 2.56227), [15] two equivalent protons 1 H (99.98 %, I = 1/2, μ N = 2.7928), [15] and two equivalent nitrogen atoms 14 N (99.63 %, I = 1, μ N = 0.4037) [15] of both o-iminoquinonate ligands.…”

New tin(IV) complexes with sterically hindered o‐iminobenzoquinone ligand: Synthesis and structure

“…The Sn (1) ligands reflects a charge delocalization over the whole molecule. The similar situation was observed recently for a germanium complex (iSQ)Ge(AP)Cl [6]. The electronic structure of complex 1 was examined by DFT calculations.…”

“…Such transitions are usual for mixedvalence metal complexes containing o-quinoid ligands in different redox states [1,10]. The role of the solvent was clarified by our steric calculations [6] of (AP) 2 Sn (hypothetical complex), (AP) 2 Sn(THF) [7a], and complex 1. The shielding of central metal (G-parameter) is 79.9(2)% and 93.7(2)% for (AP) 2 Sn (without THF molecule) and (AP) 2 Sn(THF) complexes, respectively.…”

“…Our calculations are confirmed by the EPR data. The radical separation estimated from the anisotropic EPR spectra (4.95Å) does not comply with "centroid(C(1)-C (6), N(1), O(1)) to centroid (C(1A)-C(6A), N(1A), O(1A))" distance between two o-iminoquinonato ligands in complex 1 obtained from X-ray structure (5.84Å). However, it is in rather good agreement with centroid-to-centroid distance (5.06Å) when the second centroid (C(1A)-C(6A), N(1A), O(1A), C(1B)-C(6B), N(1B), O(1B)) was calculated on the basis of another two ligands.…”

“…Recently, the synthesis of germanium [6], tin [5c, 7], and antimony [5a,b] complexes on the basis of imQ containing one or two o-iminoquinone ligands was reported. In this paper, we present a tin derivative containing three imQ moieties and its oxidation by molecular oxygen.…”