Spectroscopic and Quantum Chemical Study of the Novel Compound Cyclopropylmethylselenol

Abstract

An investigation into the properties of the novel compound cyclopropylmethylselenol has been undertaken by use of Stark-modulation microwave spectroscopy and high-level quantum chemical calculations. Ground-state spectra belonging to six isotopomers of a single conformer of the molecule were recorded and assigned. This conformer, predicted to be the lowest in energy by a series of quantum chemical calculations, possesses a synclinal arrangement of the H-C-C-Se atoms. In addition to the assignment of these ground-state spectra, transitions attributable to vibrationally excited states of the 78Se- and 80Se-containing isotopomers were identified. A tentative assignment of these excited-state spectra to specific vibrational modes has been made with the assistance of a density functional theory calculation at the B3LYP/6-311++G(3df,2pd) level of theory. Close agreement was found between experimental ground-state rotational constants and ab initio equilibrium values calculated at the MP2/aug-cc-pVTZ level of theory. Good agreement was also noted between certain r(s) principal axis coordinates of atoms in the molecule and the corresponding ab initio r(e) values. Limited evidence in favor of the formation of a weak intramolecular hydrogen bond between the H atom of the selenol group and electron density associated with the cyclopropyl ring is discussed.

Microwave and Quantum Chemical Study of the Hydrazino Group as Proton Donor in Intramolecular Hydrogen Bonding of (2-Fluoroethyl)hydrazine (FCH2CH2NHNH2)

“…The MP2 vibrational frequency is 100 cm −1 for this mode, while the B3LYP values of α B = −5.32 and α C = −2.76 MHz (Table S16). The equivalent experimental values obtained from the entries in Table 7 are α B = −7.88 (12) and α C = −4.13 (12) MHz.…”

“…Much of our work has focused on weak proton donor groups. Recently, we reported gas-phase studies of alcohols, − carboxylic acids, thiols, − thiolcarboxylic acids, selenols, − amines, − amides, , and phosphines, − where the said groups are proton donors in internal H bonds with acceptors such as the fluorine atom, ,,, the chlorine atom, ,,, π-electrons of triple bonds, − ,,,, π-electrons of double bonds, ,,,, and Walsh pseudo-π electrons. ,, References of many of our earlier works are found in the cited literature as well as in reviews. − …”

“…Recently, we reported gas-phase studies of alcohols, 1−5 carboxylic acids, 6 thiols, 7−10 thiolcarboxylic acids, 11 selenols, 12−15 amines, 16−18 amides, 19,20 and phosphines, 21−24 where the said groups are proton donors in internal H bonds with acceptors such as the fluorine atom, 1,6,9,11 the chlorine atom, 17,19,23,24 π-electrons of triple bonds, [3][4][5]7,13,15,18 π-electrons of double bonds, 2,8,10,14,21 and Walsh 25 pseudo-π electrons. 12,20,22 References of many of our earlier works are found in the cited literature as well as in reviews. 26−29 No gas-phase studies of hydrazines (R−NHNH 2 ), where the hydrazino group (−NHNH 2 ) acts as a proton donor, appear to have been reported.…”

Rotational spectrum and intramolecular hydrogen bonding in 1,2-butanedithiol

“…To date, rotationally resolved investigations of thiols and related sulfides have included mostly small alkyl derivatives like ethanethiol [8], ethanedithiol [9], propanethiol [10], propanedithiol [11], 3-butene-1-thiol [12], 3-butyne-1-thiol [13], cyclopropanemethanethiol [14], mercaptoacetonitrile [15], furfuryl mercaptane [7], diethyldisulfide [16], diallyldisulfide [17] and diphenyldisulfide [18]. For selenols, the 2-propene [19], 3-butene [20], 3-butyne [21], cyclopropylmethyl [22] and propargyl [23] derivatives have been studied. In presence of several polar groups some of these compounds offer the possibility of structurally analyzing thiol or selenol intramolecular hydrogen bonding, like (S/Se)-H•••(S/Se) [9,11] or (S/Se)-H•••p [12][13][14][19][20][21][22][23].…”

“…For selenols, the 2-propene [19], 3-butene [20], 3-butyne [21], cyclopropylmethyl [22] and propargyl [23] derivatives have been studied. In presence of several polar groups some of these compounds offer the possibility of structurally analyzing thiol or selenol intramolecular hydrogen bonding, like (S/Se)-H•••(S/Se) [9,11] or (S/Se)-H•••p [12][13][14][19][20][21][22][23]. When thiol/selenol groups are present in adjacent atoms intramolecular hydrogen bonds may contribute significantly to molecular stabilization, as in diols [24,25,26].…”