Table 1. Data-collection statistics.

Values in parentheses are for the highest resolution shell.

	Form II	Form III
Resolution (Å)	15.0–1.8 (1.94–1.80)	15.0–1.9 (1.97–1.90)
Completeness (%)	99.9	93.8
〈I/σ(I)〉	12.7 (4.0)	12.5 (3.5)
No. of measured reflections	103726 (9670)	89162 (3792)
No. of unique reflections	21626 (2149)	17171 (998)
No. of reflections >3σ	15617 (906)	12961 (354)
Rmerge†	0.075 (0.524)	0.096 (0.442)

^† R _merge = .