Table 2. Model Statistics for Bond Lengths a–d, Where Each Compound is Represented in the T1 and T2 Forms^a.

	bond	geometry	r2	q2	RMSEE
T2	a	most stable	0.863	0.860	0.456
		same conf (excl. 23)	0.988	0.987	0.137
	b	most stable	0.603	0.553	0.792
		same conf (excl. 23)	0.924	0.922	0.342
	c	most stable	0.583	0.540	0.812
		same conf (excl. 23)	0.989	0.989	0.130
	d	most stable	0.423	0.424	0.920
		same conf (excl. 23)	0.974	0.973	0.199
T1	a	most stable	0.906	0.898	0.377
		same conf	0.952	0.944	0.270
	b	most stable	0.608	0.599	0.769
		same conf	0.885	0.879	0.416
	c	most stable	0.803	0.781	0.545
		same conf	0.745	0.729	0.620
	d	most stable	0.463	0.456	0.900
		same conf	0.819	0.814	0.522

^a“Most stable” refers to the models formed with 2,6-di-ortho-compounds plus the more stable coplanar conformers of the mono-ortho-compounds. “Same conf” refers to models where mono-ortho-compounds are optimized from an orthogonal orientation of the two rings, so as to match that of the 2,6-di-ortho-substituted compounds (i.e., all compounds optimized from the same conformation). Compound 23 falls within the “most stable” set as it did not optimize to a local minimum with an orthogonal geometry. Corresponding plots are shown in Figures S1 and S2, whereas Tables S5 and S6 show bond lengths and angles D1 and D2.