A stable free tetragermacyclobutadiene incorporating fused-ring bulky EMind groups

Abstract

The first free cyclobutadiene (CBD) germanium analogue was obtained as room-temperature stable dark red crystals via the reaction of the bulky EMind-substituted 1,2-dichlorodigermene with lithium naphthalenide. The cyclic 4π-electron antiaromaticity is essentially stabilized by the polar Jahn-Teller distortion in the germanium CBD producing a planar rhombic-shaped charge-separated structure.

New Types of Ge2 and Ge4 Assemblies Stabilized by a Carbanionic Dicarborandiyl-Silylene Ligand

“…The other Ge–Ge distances within the Ge 4 ring, ranging from 2.458(1) to 2.567(1) Å, are significantly shorter than the transannular Ge1A′–Ge2B length. It should be noted here that the somewhat related Ge 4 ring-containing Ge 4 [N­(Dipp)­( t Bu)] 4 [Ge–Ge distances ranging from 2.3621(8) to 2.6740(9) Å] and Ge 4 (Emind) 4 (Emind = 1,1,7,7-tetraethyl-3,3,5,5-tetramethyl- s -hydrindacen-4-yl, Ge–Ge = av 2.430 Å) were reported by Jones and Matsuo groups, respectively. However, the Ge atoms in the latter case are supported by four monoanionic substituents, while in 5 the Ge 4 ring is stabilized only by two monoanionic silylene ligands.…”

“…Small germanium clusters Ge n are of great interest and have been intensively studied both experimentally and theoretically, due to their technological importance, for instance, in catalytic processes and photolithography. − During the last few decades a novel class of germanium clusters with the general formula R m Ge n ( m ≤ n ) stabilized by bulky organic groups has emerged and gained growing research interest, in part since these species could serve as promising model compounds for bridging the gap between polynuclear Ge species in molecular, solid state and surface chemistry. − In Ge clusters with the formula R n Ge n , where each Ge atom features an organic substituent R, the Ge centers are in the oxidation state of 1. − Instead, in Ge compounds with the formula R m Ge n ( m < n ), the average oxidation state of the Ge atoms varies between 0 and 1 because of the presence of unsubstituted Ge atoms in the cluster cores. To date, except for Ge-containing Zintl anions and their derivatives, a considerable number of molecular small Ge clusters could be isolated and structurally characterized.…”

Synthesis and Reactivity Studies of Amido‐Substituted Germanium(I)/Tin(I) Dimers and Clusters

“…As was proposed for that compound, 9 can be formulated as being zwitterionic, with a lone pair of electrons at the pyramidal Ge center, and an empty p‐orbital at the trigonal planar germanium. Despite numerous germanium clusters that have appeared in the literature, such a structural motif is unknown for tetranuclear germanium(I) examples, the only other representatives of which are a tetragermatetrahedrane, a tetragermacyclobutadiene, and two zwitterionic, base‐stabilized tetragermacyclobutadienes…”

“…Selectedb ond lengths ()and angles (8)f or 8:Ge(1)ÀGe(2) 2.6022(10), Ge(1)ÀN(3) 1.886 (2),G e(2)ÀN(6) 1.889(3), N(3)ÀGe(1)ÀGe(2) 107.62 (8), N(6)ÀGe(2)ÀGe(1) 108.11 (8). ragermacyclobutadiene, [29] and two zwitterionic, base-stabilized tetragermacyclobutadienes. [30] Althoughc luster compound 9 hasa nu nsymmetrical structure in the solid state, itss olution-state 1 HNMR spectrum exhibits only one sharp set of ligand signals at room temperature.…”

“…All manipulations were carried out using standard Schlenk and glove box techniques under an atmosphere of high purity dinitro-gen. To luene, benzene, THF and hexane were distilled over molten potassium, while pentane and diethyl ether were distilled from Na-K (1:1) alloy. 1 H, 13 C{ 1 H}, 29 Si{ 1 H}, 11 B{ 1 H} and 119 Sn{ 1 H} NMR spectra were recorded on either Bruker DPX300, Avance III 400 or Varian Inova 500 spectrometers in deuterated solvents, and were referenced to the residual 1 Ho r 13 Cr esonances of the solvent used, SiMe 4 ,e xternal BF 3 COEt 2 or external SnMe 4 .M elting points were determined in sealed glass capillaries under dinitrogen, and are uncorrected. IR spectra were recorded as Nujol mulls, using an Agilent Cary 630 spectrometer operating in attenuated total reflectance (ATR) or transmission modes.…”