6 Molecular and Crystal Structures of Polymorphic …
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(a) Y
(b) YO
(c) RO
(d) R
Fig. 6.11 Molecular geometries of the four polymorphs of the o-Br pyrazine dye viewed parallel
(upper) and perpendicular (lower) to the pyrazine ring: a Y-form (KELGEO02), b YO-form
(KELGEO03), c RO-form (KELGEO01) and d R-form (KELGEO)