Ge2H2: a germanium-containing molecule with a low-lying monobridged equilibrium geometry

Abstract

Recent experimental and theoretical studies reporting remarkable monobridged structures for Si2H2, A12H2, and Ga2H2 have motivated us to re-investigate the singlet potential energy surface of Ge2H2 using the self-consistentfield (SCF), single and double excitation configuration interaction (CISD), and single and double excitation coupled cluster (CCSD) methods in conjunction with a double-£ plus polarization basis set (DZP). In addition to the dibridged (or butterfly) ground state and the low-lying vinylidene-like minimum reported earlier by Grev and DeLeeuw, our study predicts the existence of a monobridged isomer, which is characterized as a minimum by means of harmonic vibrational frequency analyses. Relative energies of the above structures were also predicted with use of the coupled cluster single, double, and (perturbative) triple excitation method (CCSD(T)), which employed a triple-£ plus polarization basis set augmented with a set of f functions on the germanium atoms (TZP+f). Final energetic predictions suggest that the monobridged structure is the second most stable isomer of Ge2H2, lying 8.9 kcal mol-1 above the butterfly ground state and 2.1 kcal mol-1 below the branched (vinylidene-like) minimum.

Gas Phase Preparation of the Elusive Monobridged Ge(μ‐H)GeH Molecule through Nonadiabatic Reaction Dynamics

“…On the singlet surface, the dibridged di‐ μ ‐hydrodigermanium butterfly molecule ( p1 , −105±7 kJ mol −1 , Ge( μ ‐H 2 )Ge, C 2ν , X 1 A 1 ) represents the thermodynamically most stable isomer followed by a monobridged isomer ( p2 , −70±7 kJ mol −1 , Ge( μ ‐H)GeH, C s , X 1 A′), digermenylidene ( p3 , −61±7 kJ mol −1 , H 2 GeGe, C 2ν , X 1 A 1 ), and singlet trans ‐bent digermyne ( p4 , −39±7 kJ mol −1 , HGeGeH, C 2h , X 1 A g ). The computed relative energies of these products agree very well with the previous results [2a,b,6b] . The triplet structures are consistently higher in energy than their singlet counterparts: triplet digermenylidene ( 3 p3 , −17±7 kJ mol −1 , H 2 GeGe, C 2ν , a 3 A 2 ), triplet trans ‐bent digermyne ( trans ‐ 3 p4 , −11±7 kJ mol −1 , HGeGeH, C 2h , a 3 A u ), triplet cis digermyne ( cis ‐ 3 p4 , 17±7 kJ mol −1 , HGeGeH, C s , a 3 A′′), triplet monobridged isomer ( 3 p2 , 22±7 kJ mol −1 , Ge( μ ‐H)GeH, C 1 , a 3 A), and triplet dibridged butterfly molecule ( 3 p1 , 64±7 kJ mol −1 , Ge( μ ‐H 2 )Ge, C s , a 3 A′′).…”

Directed Gas-Phase Formation of the Germaniumsilylene Butterfly Molecule (Ge(μ-H2)Si)

“…For one century, Langmuir’s concept of isoelectronicity has been influential in expanding novel synthetic chemistry, in rationalizing the reactivity of isoelectronic systems, in developing modern concepts of chemical bonding, and in understanding basic concepts of molecular structure . For the last decades, particular attention has been devoted to comparing the germanium and silicon chemistries with the analogous carbon chemistry. − Residing in main group XIV, carbon, silicon, and germanium each have four valence electrons and hence are isovalent . Yet, their chemical bonding can be quite distinct, as demonstrated by the linear tricarbon molecule [C 3 ; (1) ] strongly differing from the cyclic silicon dicarbide molecule [SiC 2 ; (2) ] and the bent disilicon carbide [Si 2 C; ( 3 )] and trisilicon [Si 3 ; (4) ] molecules (Figure ).…”

Combined Crossed Molecular Beams and Ab Initio Study of the Bimolecular Reaction of Ground State Atomic Silicon (Si; 3P) with Germane (GeH4; X1A1)

“…[1] Notable attention has been given on elucidating the similarities and disparities of the chemistries of germanium and silicon with analogous carbon compounds. [2][3][4][5] Carbon, silicon, and germanium belong to main group 14 and hence are isovalent with four valence electrons each. According to Langmuir's concept, one can expect a planar D 2h symmetric structure as a global minimum on the Si 2 H 4 and Ge 2 H 4 potential energy surfaces (PESs) similar to the ethylene molecule (C 2 H 4 , (1)).…”

“…For more than a century, Langmuir's concept of isovalency has been exploited to establish concepts of chemical bonding and to interpret the molecular structures of isovalent molecules [1] . Notable attention has been given on elucidating the similarities and disparities of the chemistries of germanium and silicon with analogous carbon compounds [2–5] . Carbon, silicon, and germanium belong to main group 14 and hence are isovalent with four valence electrons each.…”