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Complexation of Triorganotin Derivatives of [18]Crown‐6‐ and [15]Crown‐5‐(benzo‐4‐carboxylate) with Alkali Thiocyanates
Author(s) -
Kemmer Martine,
Biesemans Monique,
Gielen Marcel,
Martins José C.,
Gramlich Volker,
Willem Rudolph
Publication year - 2001
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/1521-3765(20011105)7:21<4686::aid-chem4686>3.0.co;2-7
Subject(s) - chemistry , carboxylate , intramolecular force , crystallography , alkali metal , acetone , medicinal chemistry , intermolecular force , molecule , crystal structure , stereochemistry , inorganic chemistry , organic chemistry
Investigations of the simultaneous complexation of tri‐ n ‐butyltin and triphenyltin derivatives of [18]crown‐6‐ or [15]crown‐5‐(benzo‐4‐carboxylate) by the anion and cation from NaSCN or KSCN are reported. The crystal structure of [Na + ⊂[15]crown‐5‐{C 6 H 3 ‐4‐COOSn(C 6 H 5 ) 3 NCS} − ], 4 ⋅NaSCN, displays an unusual zwitterionic nature with one intramolecular charge separation characterized by an Na−Sn distance of 9.29(1) Å, and several intermolecular charge separations, the shortest being 5.48(1) Å. Similar distances (9.70(2), 9.28(2), intramolecular; 5.40(2) and 5.41(2) Å, shortest intermolecular) are observed in the more complicated structure of the corresponding [18]crown‐6‐(benzo‐4‐carboxylate) derivative, 3 ⋅NaSCN, with two independent molecules in the asymmetric unit. For the tri‐ n ‐butyltin analogues 1 and 2 , complex equilibria were observed in acetone and unraveled by variable temperature 13 C, 117 Sn, and 23 Na NMR studies. Their complexes with KSCN and NaSCN undergo decomposition in acetone solution, as evidenced by the transformation of [K + ⊂[18]crown‐6‐{C 6 H 3 ‐4‐COOSn( n Bu) 3 NCS} − ], into tri‐ n ‐butyltin isothiocyanate and a novel dimeric potassium [18]crown‐6‐(benzo‐4‐carboxylate), the structure of which was elucidated by X‐ray diffraction analysis.