Absorption of Methylene, Hydrohalogenocarbenes and Dihalogenocarbenes in the Ultraviolet Visible Range: Ab Initio and Density Functional Theory (DFT) Approaches

Alao Latifatou Laye; Diomande Sekou; Bede Affoue Lucie; Assoma Amon Benjamine; Kone Soleymane

doi:doi:10.11648/j.ajqcms.20261001.14

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Absorption of Methylene, Hydrohalogenocarbenes and Dihalogenocarbenes in the Ultraviolet Visible Range: Ab Initio and Density Functional Theory (DFT) Approaches

Alao Latifatou Laye^*

, Diomande Sekou

, Bede Affoue Lucie

, Assoma Amon Benjamine, Kone Soleymane

Published in American Journal of Quantum Chemistry and Molecular Spectroscopy (Volume 10, Issue 1)

Received: 12 May 2026 Accepted: 28 May 2026 Published: 10 June 2026

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Abstract

Carbenes are unstable biradical molecules with a longer lifetime in space than on Earth. This theoretical study focused on analyzing the spectroscopic properties of methylene and monohalogenated and dihalogenated derivatives in the ultraviolet-visible range. Structures of these compounds can exist in two electronic states depending on the orbitals containing the non-bonding electrons: singlet S₀ and triplet T₁. Three theoretical levels HF/6-311++G (d, p), MP2/6-311++G (d, p), and B3LYP/6-311++G (d, p) were used to perform this analysis. Absorption spectra were calculated for the optimized structures (S₀ and T₁) of methylene, three hydrohalogenocarbenes and two dihalogenocarbenes at each of the chosen theoretical levels. The calculations allowed us to study the behavior of these carbenes in ultraviolet-visible absorption. It was determined that, at maximum absorption, all of these carbenes in the singlet S₀ state absorb in the visible range. However, in the T₁ triplet state, they absorb in the ultraviolet range. Under maximum oscillation conditions, these carbenes absorb in the ultraviolet regardless of the electronic state of the structure. The calculated absorption wavelengths show that the transition from the ground state to their excited states of the studied carbenes is sometimes accompanied by a bathochromic effect and sometimes by a hypsochromic effect.

Published in	American Journal of Quantum Chemistry and Molecular Spectroscopy (Volume 10, Issue 1)
DOI	10.11648/j.ajqcms.20261001.14
Page(s)	35-41
Creative Commons	This is an Open Access article, distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution and reproduction in any medium or format, provided the original work is properly cited.
Copyright	Copyright © The Author(s), 2026. Published by Science Publishing Group

Keywords

Carbene, Theory Level, Spectroscopy, Wavelength, Bathochrome, Hypsochrome

1. Introduction

To date, approximately 200 polyatomic chemical species (molecules, free radicals, or ions) have been detected in interstellar space using spectroscopy. The first molecule detected in interstellar space, in 1937

[1]

, was the CH radical (methylidene). Methylene

[2]

was detected in 1995. This species is the simplest of the carbenes. It is the subject of this study.

The presence of methylene and free radicals in the interstellar medium shows that carbenes can be found in space. These molecular entities are very short-lived biradicals.

Carbene species are neutral organic species composed of a divalent carbon atom with six valence electrons: two electrons in each bond with neighboring atoms and two unbound electrons. They are produced by the photolysis of “Diazo” or “Diazirine” compounds. They are also characterized by two electrons not involved in bonds (Figure 1).

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Figure 1. carbene production by photolysis.

Carbene molecules can exist in two different forms depending on the orbitals occupied by the non-bonding electrons: the singlet form (S₀ and S₁) and the triplet form (T₁)

[3-7]

(Figure 2). In the singlet form, the two electrons are paired in one of the

sp

hybrid orbitals. However, the triplet form has two unpaired electrons. They are located, respectively, in one of the

{sp}^{2}

hybrid orbitals and in the vacant

p_{z}

orbital.

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Figure 2. Different electronic states of carbenes.

These electrons, not involved in bonds, make carbenes unstable. They are considered highly reactive transient species that are difficult to isolate. However, these molecules can be found in space, where they have a longer lifetime, whereas in the terrestrial environment, direct access to them is difficult, even impossible. Hence the interest in studying them using theoretical chemistry. Adéoti and al.

[8]

studied the stability and reactivity of carbenes using two semi-empirical methods, AM1 and MNDO. Their results showed low accuracy in analyzing the properties of carbenes and a recurring discrepancy between calculated and experimental values.

The aim of this work is to use absorption properties to identify carbenes (methylene and its analogs). This involves determining the ultraviolet absorption spectra and related properties of carbenes. Various theoretical approaches are used to perform these calculations, including ab initio methods and density functional theory.

2. Materials and Methods

2.1. Structures of the Molecules Studied

As well as methylene, three (03) hydrohalogenocarbenes and two (02) dihalogenocarbenes were studied in this work. Table 1 shows these molecules.

Table 1. Structures of methylene and five studied carbene derivatives Absorption wavelengths.

Methylene

Hydrohalogenocarbenes

Dihalogenocarbenes

X = F or Cl or Br

X1 = X2 = F or Cl

2.2. Computational Methods

The calculations for this study were performed in the gas phase using the Gaussian 09

[9]

software. Three Ab Initio methods were used: the Hartree-Fock method

[10, 11]

(HF) and two post-HF methods

[11]

: MP2 and CIS

[12]

. the Density Functional Theory (DFT) method was also employed using the B3LYP functional

[13, 14]

. Each of these methods involved optimizing the geometry of all the structures.

A single-point calculation is then made on each optimized structure using the CIS method in the RHF framework for the singlet state S₀ and in the UHF framework for the triplet state T₁. For each calculation, the 6-311++G (d, p) triple-zeta basis set is used in association with the chosen method. In particular, The CIS configuration interaction method was used to determine the absorption wavelength and the corresponding oscillation strength.

3. Results and Discussion

Absorption Properties of the Studied

For each of the seven carbenes studied, the singlet S₀ and triplet T₁ states were submitted to the calculations described in Section I.2. Thus, we determined the maximum absorption wavelength (

λ_{\max}

) and the corresponding oscillator strength (

f

). In addition, we considered the maximum value of this strength (

f_{\max}

) and the associated wavelength. For the analysis of the results, the difference

λ_{\max} (S_{0}) - λ_{\max} (T_{1})

is denoted by

{Δ λ}_{\max}

. For the maximum values of the oscillation strength of states S₀ and T₁, the difference between the corresponding wavelengths

λ (S_{0}) - λ (T_{1})

is denoted by

Δ λ

. When

{Δ λ}_{\max}

Δ λ

is positive, this is referred to as a bathochromic effect; otherwise, it is referred to as a hypsochromic effect.

3.1. Absorption of the Methylene

Table 2 and Table 3 show the results obtained for methylene, which were used to calculate Δλ and

{Δ λ}_{\max}

, respectively. These values were calculated using different levels of theory.

Table 2. Absorption wavelengths

λ (nm)

and shifts

Δλ (nm)

associated with the maximum oscillation force

f_{\max}

in the S₀ and T₁ electronic states of methylene; values calculated using the 6-311++G(d,p) basis set associated with different methods.

Calculation	$λ$		$f_{\max}$		$Δ λ$	$∆ f$
method	$S_{0}$	$T_{1}$	$S_{0}$	$T_{1}$	$λ (S_{0}) - λ (T_{1})$	$f (S_{0}) - f (T_{1})$
HF	125	126	0.20	0.08	-1	0.12
B3LYP	125	129	0.20	0.08	- 4	0.12
MP2	125	127	0.20	0.08	-2	0.12

The HF/6-311++G**, MP2/6-311++G**, and B3LYP/6-311++G** theory levels used for the calculations yield consistent results for the same electronic state S₀ or T₁ at maximum oscillation (

f_{\max}

). These calculations identify the T₁ state as the ground state of methylene

[15]

. The wavelengths associated with these electronic states all lie in the ultraviolet (UV) range. According to our calculations, the absorption wavelength of the singlet state (S₀) of methylene is 125 nm. The values obtained clearly show that the wavelength λ (nm) is higher in the T₁ state than in the S₀ state. The difference between the absorption bands of the excited S₀ state of methylene and its ground state T₁ is negative. It ranges from -1 nm to -4 nm. The transition of methylene from its ground state T₁ to the S₀state is accompanied by a hypsochromic effect.

The calculation methods used estimate that the maximum oscillation force (

f_{\max}

) higher in the excited electronic state S₀than in the ground state T₁. For a given electronic state, the value of the oscillation force is constant. It is 0.20 for the S₀ state and 0.08 for the T₁ state. This force is higher in the singlet S₀ state.

The values of the maximum absorption wavelengths and those of the corresponding oscillation forces, for these two electronic states of methylene are calculated and given in Table 3.

Table 3. Maximum absorption wavelengths (

λ_{\max} in nm

) and corresponding oscillation forces

f

in the electronic states S₀ and T₁ of methylene calculated with the HF, MP2 and B3LYP methods with the 6-311++G** function basis.

Calculation	$λ$		$f_{\max}$		$Δ λ$	$∆ f$
method	$S_{0}$	$T_{1}$	$S_{0}$	$T_{1}$	$λ (S_{0}) - λ (T_{1})$	$f (S_{0}) - f (T_{1})$
HF	790	172	0.009	0.040	619	-0.031
B3LYP	742	173	0.009	0.037	569	-0.028
MP2	749	172	0.009	0.039	577	-0.030

Data in Table 3 clearly show that under conditions of maximum absorption, the wavelengths are very different from those at maximum oscillation. These increase very significantly when absorption is maximal in both the S₀ and T₁ electronic states of methylene. According to the three levels of theory used, the maximum absorption of methylene T₁ (ground state) is observed in the UV range with an average wavelength

λ_{\max} = 172 nm

. However, methylene in the excited electronic state S₀absorbs most strongly in the visible range. The HF, B3LYP, and MP2 methods estimate

λ_{\max}

to be

790 nm, 742 nm and 749 nm

respectively. When absorption is at its maximum, the transition from the ground electronic state T₁ to the excited state S₀ of methylene is accompanied by a bathochromic effect. The gap between the absorption bands of the excited state S₀ of methylene and its ground state T₁ is positive and very large. It range from 569 nm to 619 nm.

When methylene absorption is at its maximum, the oscillation forces are higher in the triplet state T₁. This constant is opposite to that shown in Table 2, which was obtained when oscillation was at its maximum.

3.2. Absorption of Hydrohalogenocarbenes

The results of the calculations of the absorption wavelengths (

λ

) and oscillation forces of the hydrohalogenocarbenes are reported in Tables 4 and 5.

Table 4. Absorption wavelengths

λ (nm)

and shifts

Δλ (nm)

associated with the maximum oscillation force

f_{\max}

in the S₀ and T₁ electronic states of hydrohalogenocarbenes calculated with three methods.

Hydrohalo-genocarbenes	$λ$		$f_{\max}$		$Δ λ$	$∆ f_{\max}$
Hydrohalo-genocarbenes	$S_{0}$	$T_{1}$	$S_{0}$	$T_{1}$	$λ (T_{1}) - λ (S_{0})$	$f (T_{1}) - f (S_{0})$
HF/6-311++G(d,p)
CHF	104	123	0.262	0.063	19	0.2
CHCl	151	158	0.219	0.051	7	0.2
CHBr	142	155	0.268	0.047	14	0.2
B3LYP /6-311++G(d,p)
CHF	104	124	0.256	0.062	20	0.2
CHCl	152	157	0.208	0.051	6	0.2
CHBr	141	180	0.307	0.362	39	-0.1
MP2 /6-311++G(d,p)
CHF	104	124	0.259	0.061	20	0.2
CHCl	149	157	0.229	0.052	8	0.2
CHBr	142	155	0.232	0.069	14	0.2

Data in Table 4 indicate that these hydrohalogenocarbenes in the S₀ and T₁ states, when the oscillation force is at its maximum, absorb in the ultraviolet range. Calculations estimate that, for a given hydrohalogenocarbene in the same electronic state, the values of the absorption wavelengths are very close. Only one value of

λ

deviates from this observation. This is the value obtained (

λ = 180 nm

) at the B3LYP/6-311++G(d,p) level for hydrohalogenocarbene in its triplet stateT₁. For the three hydrohalogenocarbenes CHF, CHCl, and CHBr, calculations show that the absorption wavelength is shorter for CHF and longer for CHCl. Furthermore, for all three compounds, the wavelength is longer at state T₁ than at state S₀.

The singlet state S₀, more stable than the triplet state T₁ for hydrohalogenocarbenes, corresponds to the ground state of these compounds. For these compounds, the transition from the ground state to the excited state T₁ occurs by absorption with a bathochromic effect.

Data in Table 4 shows that the maximum oscillation force (

f_{\max}

) is higher in the ground state (S₀). Its value varies by the same amount (0.2) between the two electronic states S₀ and T₁ in the three hydrohalogenocarbenes.

The values of the maximum absorption wavelengths and those of the corresponding oscillation forces, for these two electronic states of the three hydrohalogenocarbenes, are also calculated and reported in Table 5.

Table 5. Maximum absorption wavelengths (

λ_{\max} in nm

) and corresponding oscillation forces

f

in the electronic states S₀ and T₁ of hydrohalogenocarbenes calculated with three methods.

Hydrohalo-genocarbenes	$λ$		$f_{\max}$		$Δ λ$	$∆ f_{\max}$
Hydrohalo-genocarbenes	$S_{0}$	$T_{1}$	$S_{0}$	$T_{1}$	$λ (T_{1}) - λ (S_{0})$	$f (T_{1}) - f (S_{0})$
HF/6-311++G(d,p)
CHF	479	174	0.017	0.032	-305	-0.01
CHCl	598	204	0.010	0.000	-394	0.01
CHBr	625	239	0.008	0.000	-386	0.01
B3LYP /6-311++G(d,p)
CHF	470	172	0.016	0.030	-298	-0.01
CHCl	580	202	0.010	0.000	-377	0.01
CHBr	601	236	0.008	0.000	-365	0.01
MP2 /6-311++G(d,p)
CHF	475	172	0.016	0.032	-303	-0.02
CHCl	593	201	0.009	0.001	-392	0.01
CHBr	613	234	0.008	0.000	-379	0.01

Data in this table clearly show that under maximum absorption conditions, the wavelengths are very different from those at maximum oscillation. They increase significantly when absorption is maximum in both the S₀ and T₁ electronic states of hydrohalogenocarbenes. Our calculations indicate that the absorption wavelength remains lower for the CHF compound and higher for the CHBr compound. Furthermore, for all three compounds, the wavelength is higher in the S₀ state than in the T₁ state. Between the ground states S₀ of hydrohalogenocarbenes

[15]

and their excited states T₁, there is a significant decrease in the maximum absorption wavelength. This transition is accompanied by a significant hypsochromic effect.

The three levels of calculations consistently indicate that these molecules, in their T₁ electronic states, absorb in the UV range. The maximum absorption lengths

λ_{\max}

vary between 174 and 236 nm. In the S₀ electronic state, the calculated maximum absorption lengths

λ_{\max}

vary between 475 and 625 nm. These absorptions are all located in the visible range.

With the exception of the CHF compound, the oscillation force associated with

λ_{\max}

is greater in the S₀ state. It is zero for the hydrohalogenocarbenes CHCl and CHBr in the T₁ state. In the CHX compounds (X = F, Cl, Br) in the S₀ state, it decreases as the atomic number increases.

3.3. Absorption of Dihalogenocarbenes

The results of the calculations of the absorption wavelengths (

λ

) and oscillation forces of the dihalogenocarbenes are reported in Tables 6 and 7.

Table 6. Absorption wavelengths

λ (nm)

and shifts

Δλ (nm)

associated with the maximum oscillation force

f_{\max}

in the S₀ and T₁ electronic states of dihalogenocarbenes calculated with three methods.

Dihalogeno-carbenes	$λ$		$f_{\max}$		$Δ λ$	$∆ f_{\max}$
Dihalogeno-carbenes	$S_{0}$	$T_{1}$	$S_{0}$	$T_{1}$	$λ (T_{1}) - λ (S_{0})$	$f (T_{1}) - f (S_{0})$
HF/6-311++G(d,p)
CF2	115	108	0.212	0.034	-7	0.18
CCl2	167	153	0.058	0.047	-14	0.01
B3LYP /6-311++G(d,p)
CF2	113	168	0.216	0.027	55	0.19
CCl2	138	153	0.120	0.045	15	0.07
MP2 /6-311++G(d,p)
CF2	125	111	0.179	0.028	-15	0.15
CCl2	136	152	0.191	0.050	16	0.14

Results in Table 6 reveal no general trend in the absorption wavelength of one electronic state compared to another. It is sometimes longer for the S₀ state and sometimes shorter for the S0 state. The DFT (B3LYP) and MP2 methods estimate that the absorption wavelength associated with

f_{\max}

is longer when the CCl₂ compound is in the T₁ state, contrary to the HF method. For the CF₂ compound, HF and MP2 calculations estimate that the absorption wavelength of the S₀ state is greater than that of the T₁ state. The DFT method predicts the opposite. All these results indicate that from the ground state S₀ to the T₁ state, the UV absorption of the CF₂ and CCl₂ compounds is sometimes accompanied by a bathochromic effect and sometimes by a hypsochromic effect. The results show that the dihalogenocarbenes CF₂ and CCl₂, in the S₀ or T₁ electronic state, absorb in the ultraviolet. In the T₁ state, the compound CCl₂ absorbs at 253 nm according to the three calculation methods.

The maximum oscillation force constant is higher when the compound is in the S₀ state. But for a given state, the maximum oscillation force decreases as the atomic number (Z) of the halogen increases.

The values of the maximum absorption wavelengths and those of the corresponding oscillation forces, for the two electronic states of the dihalogenocarbenes studied are also calculated and reported in Table 7.

Table 7. Maximum absorption wavelengths (

λ_{\max} in nm

) and corresponding oscillation forces

f

in the electronic states S₀ and T₁ of dihalogenocarbenes calculated with three methods.

Dihalogeno-carbenes	$λ$		$f_{\max}$		$Δ λ$	$∆ f_{\max}$
Dihalogeno-carbenes	$S_{0}$	$T_{1}$	$S_{0}$	$T_{1}$	$λ (T_{1}) - λ (S_{0})$	$f (T_{1}) - f (S_{0})$
HF/6-311++G(d,p)
CF2	232	170	0.075	0.028	-62	0.05
CCl2	469	236	0.009	0.001	-233	0.00
B3LYP /6-311++G(d,p)
CF2	237	168	0.071	0.027	-69	0.04
CCl2	462	240	0.009	0.001	-222	0.01
MP2 /6-311++G(d,p)
CF2	289	168	0.059	0.028	-121	0.03
CCl2	469	235	0.009	0.001	-234	0.01

Results in Table 7 illustrate that the maximum wavelength (

λ_{\max}

) of the studied dihalogenocarbenes is greatest in the ground state S₀

[15]

. According to the results of the three calculation methods, the CF₂ compound absorbs in the ultraviolet in both the ground state S₀ and the excited state T₁. As for the dichlorocarbene, it absorbs in the visible in the S₀ state and in the ultraviolet in the excited state T₁. For dihalogenocarbenes, the transition from the S₀ state to the T₁ state is accompanied by a decrease in the maximum absorption wavelength (hypsochromic effect). All calculations yield more consistent values for the maximum wavelength (

λ_{\max}

) for the T₁ state compared to the S₀ state.

Compared to hydrohalogenocarbenes, dihalogenocarbenes exhibit a significant decrease in the maximum absorption wavelengths of the S₀ state. This decrease is even more pronounced for compound CF₂. In the T₁ state, compounds CHF and CF₂ have very similar maximum absorption wavelengths (168 nm to 172 nm). Comparison of the maximum absorption wavelengths of CHCl and CCl₂compounds in the T₁ state shows an increase from 32 nm to 38 nm for CCl₂ according to the different calculation methods.

The oscillation force associated with

λ_{\max}

is estimated to be very low, particularly for dichlorocarbene (CCl₂). For difluorocarbene (CF₂), the value of this force is always lower in the T₁ electronic state.

4. Conclusion

This study demonstrated, using three levels of theory, that when the oscillation force of methylene is at its maximum (

f_{\max}

), both the electronic states T₁ (ground) and S₀ (excited) of methylene absorb in the ultraviolet. These calculations also reveal that the absorption accompanying the transition from the T₁ to the S₀ electronic state of methylene undergoes a wavelength decrease; hence, a hypsochromic effect. However, under the conditions of maximum absorption (

λ_{\max}

), the two states T₁ and S₀ of methylene absorb in two distinct spectroscopic ranges. In its ground state (T₁), methylene absorbs in the ultraviolet. When this carbene is in its excited state (S₀), it absorbs in the visible, according to all the levels of theory used.

Extending the calculations to hydrohalogenocarbenes, we found that the S₀ electronic state is the ground state of these carbenes. Both the S₀ and T₁ electronic states of the studied hydrohalogenocarbenes absorb in the ultraviolet when the oscillation forces are at their maximum. However, the absorption accompanying the transition from their S₀ to T₁ electronic states undergoes an increase in wavelength; hence, a bathochromic effect. When absorption is at its maximum, the studied hydrohalogenocarbenes, in their S₀ ground electronic state, absorb in the visible spectrum. In their excited T₁ state, they absorb in the ultraviolet.

Applied to the two dihalogenocarbenes CF₂ and CCl₂, the theoretical levels used show that both the ground electronic state S₀ and the excited electronic state T₁ absorb in the ultraviolet. When the oscillation forces are at their maximum, the transition from the S₀ to the T₁ electronic state for these compounds is sometimes accompanied by a bathochromic effect and sometimes by a hypsochromic effect. When absorption is at its maximum, only the S₀ electronic state of CCl₂ absorbs in the visible region. In its excited state T₁, this compound absorbs in the ultraviolet. Both the S₀ and T₁ states of the carbene CF₂ absorb in the ultraviolet.

Abbreviations

UV	Ultraviolet
S0 State	Singlet State
T1 State	Triplet State

Author Contributions

Alao Latifatou Laye: Conceptualization, Formal Analysis, Methodology, Resources, Software, Validation, Visualization, Writing – original draft, Writing – review & editing

Diomande Sekou: Data curation, Formal Analysis, Investigation, Validation, Visualization, Writing – review & editing

Bede Affoue Lucie: Data curation, Formal Analysis, Methodology, Writing – review & editing

Assoma Amon Benjamine: Data curation, Investigation, Writing – review & editing

Kone Soleymane: Conceptualization, Supervision, Visualization, Writing – review & editing

Conflicts of Interest

The authors declare no conflicts of interest.

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Laye, A. L., Sekou, D., Lucie, B. A., Benjamine, A. A., Soleymane, K. (2026). Absorption of Methylene, Hydrohalogenocarbenes and Dihalogenocarbenes in the Ultraviolet Visible Range: Ab Initio and Density Functional Theory (DFT) Approaches. American Journal of Quantum Chemistry and Molecular Spectroscopy, 10(1), 35-41. https://doi.org/10.11648/j.ajqcms.20261001.14

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Laye, A. L.; Sekou, D.; Lucie, B. A.; Benjamine, A. A.; Soleymane, K. Absorption of Methylene, Hydrohalogenocarbenes and Dihalogenocarbenes in the Ultraviolet Visible Range: Ab Initio and Density Functional Theory (DFT) Approaches. Am. J. Quantum Chem. Mol. Spectrosc. 2026, 10(1), 35-41. doi: 10.11648/j.ajqcms.20261001.14

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Laye AL, Sekou D, Lucie BA, Benjamine AA, Soleymane K. Absorption of Methylene, Hydrohalogenocarbenes and Dihalogenocarbenes in the Ultraviolet Visible Range: Ab Initio and Density Functional Theory (DFT) Approaches. Am J Quantum Chem Mol Spectrosc. 2026;10(1):35-41. doi: 10.11648/j.ajqcms.20261001.14

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@article{10.11648/j.ajqcms.20261001.14,
  author = {Alao Latifatou Laye and Diomande Sekou and Bede Affoue Lucie and Assoma Amon Benjamine and Kone Soleymane},
  title = {Absorption of Methylene, Hydrohalogenocarbenes and Dihalogenocarbenes in the Ultraviolet Visible Range: Ab Initio and Density Functional Theory (DFT) Approaches},
  journal = {American Journal of Quantum Chemistry and Molecular Spectroscopy},
  volume = {10},
  number = {1},
  pages = {35-41},
  doi = {10.11648/j.ajqcms.20261001.14},
  url = {https://doi.org/10.11648/j.ajqcms.20261001.14},
  eprint = {https://article.sciencepublishinggroup.com/pdf/10.11648.j.ajqcms.20261001.14},
  abstract = {Carbenes are unstable biradical molecules with a longer lifetime in space than on Earth. This theoretical study focused on analyzing the spectroscopic properties of methylene and monohalogenated and dihalogenated derivatives in the ultraviolet-visible range. Structures of these compounds can exist in two electronic states depending on the orbitals containing the non-bonding electrons: singlet S0 and triplet T1. Three theoretical levels HF/6-311++G (d, p), MP2/6-311++G (d, p), and B3LYP/6-311++G (d, p) were used to perform this analysis. Absorption spectra were calculated for the optimized structures (S0 and T1) of methylene, three hydrohalogenocarbenes and two dihalogenocarbenes at each of the chosen theoretical levels. The calculations allowed us to study the behavior of these carbenes in ultraviolet-visible absorption. It was determined that, at maximum absorption, all of these carbenes in the singlet S0 state absorb in the visible range. However, in the T1 triplet state, they absorb in the ultraviolet range. Under maximum oscillation conditions, these carbenes absorb in the ultraviolet regardless of the electronic state of the structure. The calculated absorption wavelengths show that the transition from the ground state to their excited states of the studied carbenes is sometimes accompanied by a bathochromic effect and sometimes by a hypsochromic effect.},
 year = {2026}
}

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TY  - JOUR
T1  - Absorption of Methylene, Hydrohalogenocarbenes and Dihalogenocarbenes in the Ultraviolet Visible Range: Ab Initio and Density Functional Theory (DFT) Approaches
AU  - Alao Latifatou Laye
AU  - Diomande Sekou
AU  - Bede Affoue Lucie
AU  - Assoma Amon Benjamine
AU  - Kone Soleymane
Y1  - 2026/06/10
PY  - 2026
N1  - https://doi.org/10.11648/j.ajqcms.20261001.14
DO  - 10.11648/j.ajqcms.20261001.14
T2  - American Journal of Quantum Chemistry and Molecular Spectroscopy
JF  - American Journal of Quantum Chemistry and Molecular Spectroscopy
JO  - American Journal of Quantum Chemistry and Molecular Spectroscopy
SP  - 35
EP  - 41
PB  - Science Publishing Group
SN  - 2994-7308
UR  - https://doi.org/10.11648/j.ajqcms.20261001.14
AB  - Carbenes are unstable biradical molecules with a longer lifetime in space than on Earth. This theoretical study focused on analyzing the spectroscopic properties of methylene and monohalogenated and dihalogenated derivatives in the ultraviolet-visible range. Structures of these compounds can exist in two electronic states depending on the orbitals containing the non-bonding electrons: singlet S0 and triplet T1. Three theoretical levels HF/6-311++G (d, p), MP2/6-311++G (d, p), and B3LYP/6-311++G (d, p) were used to perform this analysis. Absorption spectra were calculated for the optimized structures (S0 and T1) of methylene, three hydrohalogenocarbenes and two dihalogenocarbenes at each of the chosen theoretical levels. The calculations allowed us to study the behavior of these carbenes in ultraviolet-visible absorption. It was determined that, at maximum absorption, all of these carbenes in the singlet S0 state absorb in the visible range. However, in the T1 triplet state, they absorb in the ultraviolet range. Under maximum oscillation conditions, these carbenes absorb in the ultraviolet regardless of the electronic state of the structure. The calculated absorption wavelengths show that the transition from the ground state to their excited states of the studied carbenes is sometimes accompanied by a bathochromic effect and sometimes by a hypsochromic effect.
VL  - 10
IS  - 1
ER  -

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Author Information

Alao Latifatou Laye

Department of Science, Structures of Matter and Technology (SSMT), University of Felix Houphouët-Boigny, Abidjan, Ivory Coast

Contact Email

http://orcid.org/0009-0007-4222-9507
Diomande Sekou

Department of Agro-Industrial Sciences and Technologies (AIST), University of San Pedro, San Pedro, Ivory Coast

http://orcid.org/0009-0000-9938-3723
Bede Affoue Lucie

Department of Science, Structures of Matter and Technology (SSMT), University of Felix Houphouët-Boigny, Abidjan, Ivory Coast

http://orcid.org/0000-0002-2891-6171
Assoma Amon Benjamine

Department of Science, Structures of Matter and Technology (SSMT), University of Felix Houphouët-Boigny, Abidjan, Ivory Coast
Kone Soleymane

Department of Science, Structures of Matter and Technology (SSMT), University of Felix Houphouët-Boigny, Abidjan, Ivory Coast

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APA Style

Laye, A. L., Sekou, D., Lucie, B. A., Benjamine, A. A., Soleymane, K. (2026). Absorption of Methylene, Hydrohalogenocarbenes and Dihalogenocarbenes in the Ultraviolet Visible Range: Ab Initio and Density Functional Theory (DFT) Approaches. American Journal of Quantum Chemistry and Molecular Spectroscopy, 10(1), 35-41. https://doi.org/10.11648/j.ajqcms.20261001.14

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ACS Style

Laye, A. L.; Sekou, D.; Lucie, B. A.; Benjamine, A. A.; Soleymane, K. Absorption of Methylene, Hydrohalogenocarbenes and Dihalogenocarbenes in the Ultraviolet Visible Range: Ab Initio and Density Functional Theory (DFT) Approaches. Am. J. Quantum Chem. Mol. Spectrosc. 2026, 10(1), 35-41. doi: 10.11648/j.ajqcms.20261001.14

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AMA Style

Laye AL, Sekou D, Lucie BA, Benjamine AA, Soleymane K. Absorption of Methylene, Hydrohalogenocarbenes and Dihalogenocarbenes in the Ultraviolet Visible Range: Ab Initio and Density Functional Theory (DFT) Approaches. Am J Quantum Chem Mol Spectrosc. 2026;10(1):35-41. doi: 10.11648/j.ajqcms.20261001.14

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@article{10.11648/j.ajqcms.20261001.14,
  author = {Alao Latifatou Laye and Diomande Sekou and Bede Affoue Lucie and Assoma Amon Benjamine and Kone Soleymane},
  title = {Absorption of Methylene, Hydrohalogenocarbenes and Dihalogenocarbenes in the Ultraviolet Visible Range: Ab Initio and Density Functional Theory (DFT) Approaches},
  journal = {American Journal of Quantum Chemistry and Molecular Spectroscopy},
  volume = {10},
  number = {1},
  pages = {35-41},
  doi = {10.11648/j.ajqcms.20261001.14},
  url = {https://doi.org/10.11648/j.ajqcms.20261001.14},
  eprint = {https://article.sciencepublishinggroup.com/pdf/10.11648.j.ajqcms.20261001.14},
  abstract = {Carbenes are unstable biradical molecules with a longer lifetime in space than on Earth. This theoretical study focused on analyzing the spectroscopic properties of methylene and monohalogenated and dihalogenated derivatives in the ultraviolet-visible range. Structures of these compounds can exist in two electronic states depending on the orbitals containing the non-bonding electrons: singlet S0 and triplet T1. Three theoretical levels HF/6-311++G (d, p), MP2/6-311++G (d, p), and B3LYP/6-311++G (d, p) were used to perform this analysis. Absorption spectra were calculated for the optimized structures (S0 and T1) of methylene, three hydrohalogenocarbenes and two dihalogenocarbenes at each of the chosen theoretical levels. The calculations allowed us to study the behavior of these carbenes in ultraviolet-visible absorption. It was determined that, at maximum absorption, all of these carbenes in the singlet S0 state absorb in the visible range. However, in the T1 triplet state, they absorb in the ultraviolet range. Under maximum oscillation conditions, these carbenes absorb in the ultraviolet regardless of the electronic state of the structure. The calculated absorption wavelengths show that the transition from the ground state to their excited states of the studied carbenes is sometimes accompanied by a bathochromic effect and sometimes by a hypsochromic effect.},
 year = {2026}
}

Copy | Download

TY  - JOUR
T1  - Absorption of Methylene, Hydrohalogenocarbenes and Dihalogenocarbenes in the Ultraviolet Visible Range: Ab Initio and Density Functional Theory (DFT) Approaches
AU  - Alao Latifatou Laye
AU  - Diomande Sekou
AU  - Bede Affoue Lucie
AU  - Assoma Amon Benjamine
AU  - Kone Soleymane
Y1  - 2026/06/10
PY  - 2026
N1  - https://doi.org/10.11648/j.ajqcms.20261001.14
DO  - 10.11648/j.ajqcms.20261001.14
T2  - American Journal of Quantum Chemistry and Molecular Spectroscopy
JF  - American Journal of Quantum Chemistry and Molecular Spectroscopy
JO  - American Journal of Quantum Chemistry and Molecular Spectroscopy
SP  - 35
EP  - 41
PB  - Science Publishing Group
SN  - 2994-7308
UR  - https://doi.org/10.11648/j.ajqcms.20261001.14
AB  - Carbenes are unstable biradical molecules with a longer lifetime in space than on Earth. This theoretical study focused on analyzing the spectroscopic properties of methylene and monohalogenated and dihalogenated derivatives in the ultraviolet-visible range. Structures of these compounds can exist in two electronic states depending on the orbitals containing the non-bonding electrons: singlet S0 and triplet T1. Three theoretical levels HF/6-311++G (d, p), MP2/6-311++G (d, p), and B3LYP/6-311++G (d, p) were used to perform this analysis. Absorption spectra were calculated for the optimized structures (S0 and T1) of methylene, three hydrohalogenocarbenes and two dihalogenocarbenes at each of the chosen theoretical levels. The calculations allowed us to study the behavior of these carbenes in ultraviolet-visible absorption. It was determined that, at maximum absorption, all of these carbenes in the singlet S0 state absorb in the visible range. However, in the T1 triplet state, they absorb in the ultraviolet range. Under maximum oscillation conditions, these carbenes absorb in the ultraviolet regardless of the electronic state of the structure. The calculated absorption wavelengths show that the transition from the ground state to their excited states of the studied carbenes is sometimes accompanied by a bathochromic effect and sometimes by a hypsochromic effect.
VL  - 10
IS  - 1
ER  -

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