. 2013 Aug 29;139(8):084509. doi: 10.1063/1.4818731

Table 2.

Geometric data on NMA and ACEM. See Fig. 1 for the atom numbering.

	Drude	Gas¹	Crystal²	Crystal survey	MP2/6–31G*
NMA
C4-C5	1.545	1.520	1.515	1.529 ± 0.041	1.514
C5-N7	1.328	1.386	1.326	1.300 ± 0.032	1.365
C5=O6	1.228	1.224	1.246	1.248 ± 0.026	1.232
N7-H8	1.019	NA	1.026	0.945 ± 0.095	1.010
N7-C9	1.448	1.469	1.455	1.432 ± 0.039	1.448
C4-C5-N7	114.0	114.1	116.3	116.1 ± 3.2	115.0
C5-N7-H8	117.3	NA	118.8	118.9 ± 3.2	118.8
C5-N7-C9	122.7	119.6	121.3	123.1 ± 3.8	122.1
O6=C5-C4	118.0	124.1³	121.9	120.6 ± 1.9	122.0
ACEM
C4-C5	1.528	1.519	1.503	1.503 ± 0.006	1.515
C5-N7	1.318	1.380	1.325	1.323 ± 0.006	1.375
C5=O6	1.220	1.220	1.243	1.247 ± 0.004	1.228
N7-H8	1.015	1.022	0.862	0.891 ± 0.067	1.012
N7-H9	1.018	1.022	0.946	0.911 ± 0.083	1.010
C4-C5-N7	116.5	115.1	117.2	117.5 ± 0.7	114.6
C5-N7-Hc	122.0	NA⁴	116.3	121.2 ± 4.0	116.2
C5-N7-Ht	119.9	NA	117.7	119.8 ± 3.0	120.6
O6=C5-C4	120.0	123.0	120.6	120.6 ± 0.4	123.3

Gas electron diffraction experimental results from Refs. ⁸³, ⁸⁴, ⁸⁵.

Crystal phase results from Ref. 103 for NMA and Ref. 104 for ACEM.

Determined from the published values of the O6=C5-N7 and C4-C5-N7 angles, assuming the relation ∡O6=C5-C4 = 360° – (∡O6=C5-N7 + ∡C4-C5-N7).

⁴

NA: Not applicable.