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Chalcogenide Derivatives of Imidotin Cage Complexes
Author(s) -
Eisler Dana J.,
Chivers Tristram
Publication year - 2005
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/chem.200500849
Subject(s) - chalcogen , chemistry , selenium , cubane , dimer , reagent , chalcogenide , stoichiometry , medicinal chemistry , crystallography , stereochemistry , crystal structure , organic chemistry
Reaction of the secocubane [Sn 3 (μ 2 ‐NH t Bu) 2 (μ 2 ‐N t Bu)(μ 3 ‐N t Bu)] ( 1 ) with dibutylmagnesium produces the heterobimetallic cubane [Sn 3 Mg(μ 3 ‐N t Bu) 4 ] ( 4 ) which forms the monochalcogenide complexes of general formula [ESn 3 Mg(μ 3 ‐N t Bu) 4 ] ( 5 a , E=Se; 5 b , E=Te) upon reaction with elemental chalcogens in THF. By contrast, the reaction of the anionic lithiated cubane [Sn 3 Li(μ 3 ‐N t Bu) 4 ] − with the appropriate quantity of selenium or tellurium leads to the sequential chalcogenation of each of the three Sn II centres. Pure samples of the mono‐ or dichalcogenides are, however, best obtained by stoichiometric redistribution reactions of [Sn 3 Li(μ 3 ‐N t Bu) 4 ] − and the trichalcogenides [E 3 Sn 3 Li(μ 3 ‐N t Bu) 4 ] − (E=Se, Te). These reactions are conveniently monitored by using 119 Sn NMR spectroscopy. The anion [Sn 3 Li(μ 3 ‐N t Bu) 4 ] − also acts as an effective chalcogen‐transfer reagent in reactions of selenium with the neutral cubane [{Snμ 3 ‐N(dipp)} 4 ] ( 8 ) (dipp=2,6‐diisopropylphenyl) to give the dimer [(thf)Sn{μ‐N(dipp)} 2 Sn(μ‐Se) 2 Sn{μ‐N(dipp)} 2 Sn(thf)] ( 9 ), a transformation that results in cleavage of the Sn 4 N 4 cubane into four‐membered Sn 2 N 2 rings. The X‐ray structures of 4 , 5 a , 5 b , [Sn 3 Li(thf)(μ 3 ‐N t Bu) 4 (μ 3 ‐Se)(μ 2 ‐Li)(thf)] 2 ( 6 a ), [TeSn 3 Li(μ 3 ‐N t Bu) 4 ][Li(thf) 4 ] ( 6 b ), [Te 2 Sn 3 Li(μ 3 ‐N t Bu) 4 ][Li([12]crown‐4) 2 ] ( 7 b′′ ) and 9 are presented. The fluxional behaviour of cubic imidotin chalcogenides and the correlation between NMR coupling constants and tin–chalcogen bond lengths are also discussed.