Infrared and Raman Spectra of C₄H₄Se and C₄D₄Se Isotopomers: A DFT-PT2 Anharmonic Study

Table 2

Vibrational harmonic, ω, and anharmonic, 𝜈, wavenumbers (cm⁻¹), infrared intensities, 𝐼_IR (km/mol), and Raman activities 𝐴_Raman (Å⁴/amu) of C₄H₄Se.

		Description^a	B3LYP6-311G**					exp.^b
			𝐼IR	𝐴Raman	𝜔	ω ^c	𝜈	𝜈
A1	1	νC–H	1.9	253.1	3244	3137	3119	3100
	2	νC–H	7.8	180.4	3194	3088	3072	3063
	3	νC=C + νC–C + δC–H	18.3	38.0	1463	1415	1424	1419
	4	νring + δC–H	2.4	4.1	1373	1328	1347	1341
	5	δC–H	2.9	6.3	1103	1066	1090	1080
	6	Ring breathing + δC–H	2.4	11.8	1033	999	1016	1010
	7	δring	21.5	16.2	765	740	753	758
	8	δC–Se–C	0.2	7.2	460	445	454	456
A2	9	γC–H	0.0	1.0	923	892	911	905
	10	γC–H	0.0	1.5	685	662	681	685
	11	𝜏ring	0.0	0.0	552	534	547	541
B1	12	νC–H	1.1	1.3	3242	3135	3116	3100
	13	νC–H	4.6	106.9	3180	3075	3058	3054
	14	νC=C + δC–H	0.2	0.0	1565	1513	1530	1515
	15	δC–H	22.1	0.8	1268	1226	1241	1243
	16	δC–H	1.2	5.7	1105	1068	1091	1080
	17	δring	1.2	0.2	839	811	829	820
	18	νC–Se	0.8	5.3	621	600	609	623
B2	19	𝛾C–H	0.0	0.1	885	856	875	870
	20	γC–H	131.5	0.5	707	684	703	700
	21	τring	2.4	1.8	401	388	397	394
		rms deviation^d			63	18	9
		rms deviation^e			23	14	8
		rms deviation^f			136	30	13

^a𝜈: stretching; 𝛿: in-plane bending, 𝛾: out-of-plane bending, 𝜏: torsion.
^bReference [21].
^cScaled harmonic wavenumbers. The scaling factor of 0.9669 was taken from Irikura et al. [36].
^dAll the vibrational modes.
^eAll the vibrational modes excluding the 𝜈C–H modes.
^f𝜈C–H modes.