title: Crystal chemistry of trialkylsilyl-capped (3Z)-4-(methylthio)-3-penten-1-yne: polymorphism, twinning and ambiguity of order-disorder descriptions.
abstract: The crystallization behavior of trimethylsilyl-capped (3Z)-4-(methylthio)-3-penten-1-yne (1-TMS) and the triisopropylsilyl and tert-butyldimethylsilyl analogues (1-TIPS) and (1-TBDMS) was investigated. (1-TMS) crystallizes in the Sohncke space group P212121with Z' = 1. (1-TIPS) exists as two polymorphs, both crystallizing in P\overline 1 with Z' = 2 independent molecules. Polymorph (I) is an order-disorder (OD) twin. Two interpretations in terms of M = 1 or M = 2 kinds of OD layers are possible, with different degrees of idealization. Polymorph (II) is fully ordered (non-twinned). Its structure can be derived from polymorph (I) by inverting the orientation of every second molecule. (1-TBDMS) (P\overline1, Z' = 2) is an OD twin, where the OD description is unambiguously in M = 1 kinds of layers.
authors.affiliation: Institute of Applied Synthetic Chemistry, TU Wien, Vienna, Austria.
authors.forename: Daniel
authors.initials: D
authors.lastname: Lumpi
authors.affiliation: Institute of Applied Synthetic Chemistry, TU Wien, Vienna, Austria.
authors.forename: Paul
authors.initials: P
authors.lastname: Kautny
authors.affiliation: Institute of Chemical Technologies and Analytics, TU Wien, Vienna, Austria.
authors.forename: Berthold
authors.initials: B
authors.lastname: Stöger
authors.affiliation: Institute of Applied Synthetic Chemistry, TU Wien, Vienna, Austria.
authors.forename: Johannes
authors.initials: J
authors.lastname: Fröhlich
keywords: Hirshfeld fingerprint plots; desymmetrization; layer structures; order–disorder theory; polymorphism; twinning