Molecular Structures of the Digermanes Me₂XGeGeXMe₂ (X = Me, Cl, and H): An Ab Initio Study Combined with Experimental Investigation by Raman Spectroscopy and Gas Electron Diffraction

Abstract

Ab initio calculations were carried out to investigate the potential-energy surface for internal rotation of the methylated digermanes hexamethyldigermane Me(3)GeGeMe(3) ( 1), dichlorotetramethyldigermane Me(2)ClGeGeClMe(2) ( 2), and tetramethyldigermane Me(2)HGeGeHMe(2) ( 3). Different basis sets [6-31+G(d), SDD, aug-cc-pVTZ] were employed at the DFT and MP2 levels of theory to optimize structures and to calculate energies and vibrational frequencies. For 1, one minimum representing a staggered structure was located on the potential-energy surface. For 2 and 3, antiperiplanar conformations with C 2 symmetry were found to be the global minima. Additionally, synclinal minima were located for 2 and 3 when certain basis sets were employed. Determination of structural parameters in the gas phase by gas electron diffraction confirmed the computed predictions for all three compounds. For 2 and 3, the ratios of antiperiplanar to synclinal conformer were detected to be 90:10 (328 K) and 72:28 (293 K), respectively, by gas electron diffraction. The experimentally determined GeGe bond lengths in 1, 2, and 3 in the gas phase are 241.4(1), 242.7(2) (averaged for antiperiplanar and synclinal), and 241.7(1) pm (equal for antiperiplanar and synclinal). Only averaged structures were observed, using Raman spectroscopy, for 2 and 3 because the wavenumber differences are small between conformers and there is only a small contribution from the second conformer in each case. For 2, the crystal structure was also determined by X-ray diffraction. An anticlinal structure (with Cl atoms eclipsing the C atoms) was found with a GeGe bond length of 242.1 pm.

“Donor–Acceptor” Oligogermanes: Synthesis, Structure, and Electronic Properties

“…In the solid state, molecule 5 adopts a very unusual eclipsed conformation with a torsion angle C(1)–Ge(1)–Ge(2)–C(11) of −0.87(17)°. Similar to the case for molecule 9 , the eclipsed aryl rings in 5 have reciprocal orientations with the shortest C F ···C H distance of 3.285(6) Å.…”

“…The Ge− Ge bond in 5 is also longer than that in another unsymmetrical digermane, (C 6 F 5 ) 3 GeGeEt 3 (2.436 Å). 55 In the solid state, molecule 5 adopts a very unusual eclipsed conformation 54 The molecular structure of [(p-Tol) 3 Ge] 2 Ge(C 6 F 5 ) 2 ( 6) is highly symmetric (Figure 5). The coordination environments of all Ge atoms in 6 are distorted tetrahedra.…”

Reaction of germanes and digermanes with triflic acid: The route to novel organooligogermanes

“…The white solid was filtered off, washed with hot toluene and water. The purification was performed by extraction with CHCl 3 in Soxlett apparatus for 40 h. Hexaphenyldigermane (5) was isolated as a white powder. Yield 5.20 g (69%).…”

Quantum Mechanical Modeling for the GeX2/GeHX + GeH4 Reactions (X = H, F, Cl, and Br)

“…The theoretical exploration of the electronic structures of germanium compounds, with complementary experiments, has made spectacular advances over the past few years. − Distinctive reactions involving divalent germylenes are of practical importance, for example, leading to the chemical vapor deposition (CVD) of electronically effective materials …”

“…The theoretical exploration of the electronic structures of germanium compounds, with complementary experiments, has made spectacular advances over the past few years. [1][2][3][4][5][6][7][8][9][10][11][12][13] Distinctive reactions involving divalent germylenes are of practical importance, for example, leading to the chemical vapor deposition (CVD) of electronically effective materials. 14 Bauschlicher et al 15 were the first to apply ab initio methods to the study of the potential energy surface (PES) for the concerted nonleast-motion for the insertion reaction of singlet methylene into molecular hydrogen, CH 2 + H 2 f CH 4 .…”