An ab initioand AIM investigation into the hydration of 2-thioxanthine

BMC Chemistry

Table 1 Interaction energies including BSSE corrections (ΔE) of the seven 2TX^...H₂O complexes, BSSE, bond lengths of X--H (R_X--H), hydrogen bond distances (r_Y...H), selected change of X--H bond lengths (Δr_X-H), stretching vibrational frequency of monomer upon complex formation (Δν_X-H), and the corresponding calculated change of infrared intensities (ΔI_X-H) at the MP2/6-311G (d, p) level.

complexes	ΔE^a	BSSE^a	X--H^...Y	R _X-H ^b	r _Y ^... _H ^b	Δr_X-H^b	Δν_X-H^c	ΔI_X-H^d
I	-7.6^e	1.6^e	N(1)--H^...O_w^g	1.027	1.919	+0.013	--230	+436
	(--6.6)^f	(0.6)^f	O_w--H^...O(11)^h	0.967	2.019	+0.009	--112	+134
II	--12.7	1.9	N(7)--H^...O_w	1.031	1.796	+0.020	--344	+642
	(--11.7)	(0.6)	O_w--H^...O	0.971	1.912	+0.013	--194	+402
III	--8.6	1.6	N(3)--H^...O_w	1.024	1.924	+0.013	--216	+386
	(--6.8)	(0.6)	O_w--H^...N	0.967	2.086	+0.009	--124	+158
IV	--4.8	1.0	C--H^...O_w	1.080	2.510	-0.001	+10	+19
	(--3.6)	(0.4)	O_w--H^...N	0.964	2.129	+0.005	--73	+145
V	--8.2	1.8	N(1)--H^...O_w	1.031	1.838	+0.017	--313	+504
	(--7.0)	(0.6)	O_w--H^...S	0.976	2.453	+0.018	--131	+152
VI	--9.3	1.8	N(3)--H^...O_w	1.037	1.800	+0.016	--366	+591
	(--8.2)	(0.6)	O_w--H^...S	0.968	2.452	+0.010	--225	+436
VII	--3.3	1.8	C--H^...O_w	1.083	2.179	+0.002	--31	+133
	(--2.6)	(0.4)

^a kcal mol^-1;^b Å;^ccm^-1; ^d km mol^-1; ^ecalculated at the MP2/6-311++G(2d, 2p)//MP2/6-311G(d, p) level; ^fcalculated at the B3LYP/6-311++G(2d,2p)//B3LYP/6-311G(d, p) level; ^gO_w represents the oxygen atom of water.^hchange in the O--H symmetrical stretch frequencies of water, the change in asymmetric stretch is small and not given here.

ISSN: 2661-801X