Theoretical descriptions of novel triplet germylenes M1-Ge-M2-M3 (M1 = H, Li, Na, K; M2 = Be, Mg, Ca; M3 = H, F, Cl, Br)

Abstract

In a quest to identify new ground-state triplet germylenes, the stabilities (singlet-triplet energy differences, ΔE) of 96 singlet (s) and triplet (t) M-Ge-M-M species were compared and contrasted at the B3LYP/6-311++G**, QCISD(T)/6-311++G**, and CCSD(T)/6-311++G** levels of theory (M = H, Li, Na, K; M = Be, Mg, Ca; M = H, F, Cl, Br). Interestingly, F-substituent triplet germylenes (M = F) appear to be more stable and linear than the corresponding Cl- or Br-substituent triplet germylenes (M = Cl or Br). Triplets with M = K (i.e., the K-Ge-M-M series) seem to be more stable than the corresponding triplets with M = H, Li, or Na. This can be attributed to the higher electropositivity of potassium. Triplet species with M = Cl behave similarly to those with M = Br. Conversely, triplets with M = H show similar stabilities and linearities to those with M = F. Singlet species of formulae K-Ge-Ca-Cl and K-Ge-Ca-Br form unexpected cyclic structures. Finally, the triplet germylenes M-Ge-M-M become more stable as the electropositivities of the α-substituents (M and M) and the electronegativity of the β-substituent (M) increase.

Estimating the stability and reactivity of novel bicyclic germylenes at density functional theory

“…[19] In order to characterize the stationary points as minima and to evaluate zero-point vibrational energy, harmonic vibrational frequencies are computed for restricted singlet and (unrestricted triplet) germylenes at (U)B3LYP/6-311++G**. [18,19] The nucleophilicity index (N) is calculated as N = E HOMO (Nu) − E HOMO (TCNE) , where tetracyanoethylene (TCNE) is chosen as the reference. [36,37] The global electrophilicity (ω) [38] is computed as ω = (μ 2 /2η), where μ is the chemical potential (μ ≈ (E HOMO + E LUMO )/2) and η is the chemical hardness (η = E LUMO − E HOMO ).…”

“…[10][11][12][13][14][15][16][17] Also, they are applied as precursors in the lowtemperature synthesis of Ge-rich semiconductors via chemical vapor deposition during the production of components of nanomaterials. [18] In contrast to carbenes, germylenes have mainly singlet ground states. [19][20][21] In fact, the lone pair electrons on -G̈e-increase s atomic orbital character with increasing atomic size.…”

Substituent effects of fused Hammick germylenes: Estimating the stability and reactivity using density functional theory

“…[3] Also, NHGes are applied as precursors in the low-temperature synthesis of Ge-rich semiconductors via chemical vapor deposition during the production of components of nanomaterials. [4] In 1987, Veith succeeded to synthesize the first NHGe (I) with a four-membered structure stabilized by two nearby nitrogen atoms (Scheme 1). [5] In contrast to normal carbenes, NHGes have mainly singlet ground states.…”

Novel tetrazol‐5‐germavinylidenes with triplet monomeric, normal, and abnormal forms studied using DFT method

“…In 1991, Arduengo and coworkers synthesized colorless crystals of 1,3‐di‐l‐adamantylimidazol‐2‐ylidene, which was the first stable NHC. After several years, theoretical researchers found that triplet N‐heterocyclic silylenes and germylenes could also be stable . In fact, due to the importance of triplet ground‐state silylenes and germylenes in chemical semiconductor manufacturing, vapor deposition and the aerospace and photonics industries, the preparation, and theoretical calculation of these isomers have become one of the most important topics in modern organosilicon and germanium chemistry.…”

“…In fact, due to the importance of triplet ground‐state silylenes and germylenes in chemical semiconductor manufacturing, vapor deposition and the aerospace and photonics industries, the preparation, and theoretical calculation of these isomers have become one of the most important topics in modern organosilicon and germanium chemistry. Recently, some studies indicated that the EPR spectrum and X‐ray crystallography provide unambiguous evidence for silylene and germylene triplet ground state . In 2011, Momeni et al researched at triplet NH‐vinylidene silylenes with (NRCH 2 ‐CH 2 NR)Si═Si and (NRCHCHNR)Si═Si structures …”