Premium
Templating and Selection in the Formation of Macrocycles Containing [{P( μ ‐N t Bu) 2 }( μ ‐NH)] n Frameworks: Observation of Halide Ion Coordination
Author(s) -
Bashall Alan,
Bond Andrew D.,
Doyle Emma L.,
García Felipe,
Kidd Sara,
Lawson Gavin T.,
Parry Mark C.,
McPartlin Mary,
Woods Anthony D.,
Wright Dominic S.
Publication year - 2002
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(20020802)8:15<3377::aid-chem3377>3.0.co;2-5
Subject(s) - chemistry , tetramer , dimer , halide , yield (engineering) , selectivity , crystallography , ion , solvent , stereochemistry , inorganic chemistry , organic chemistry , catalysis , materials science , metallurgy , enzyme
Amination of [ClP( μ ‐N t Bu)] 2 ( 1 ) using NH 3 in THF gives the cyclophospha( III )zane dimer [H 2 NP( μ ‐N t Bu)] 2 ( 2 ), in good yield. 31 P NMR spectroscopic studies of the reaction of 1 with 2 in THF/Et 3 N show that almost quantitative formation of the cyclic tetramer [{P( μ ‐N t Bu)} 2 ( μ ‐NH)] 4 ( 3 ) occurs. The remarkable selectivity of this reaction can (in part) be attributed to pre‐organisation of 1 and 2 , which prefer cis arrangements in the solid state and solution. The macrocycle 3 can be isolated in yields of 58–67 % using various reaction scales. The isolation of the major by‐product of the reaction (ca. 0.5–1 % of samples of 3 ), the pentameric, host–guest complex [{P( μ ‐N t Bu) 2 } 2 ( μ ‐NH)] 5 (HCl)⋅2 THF] ( 4 ⋅2 THF), gives a strong indication of the mechanism involved. In situ 31 P NMR spectroscopic studies support a stepwise condensation mechanism in which Cl − ions play an important role in templating and selection of 3 and 4 . Amplification of the pentameric arrangement occurs in the presence of excess LiX (X=Cl, Br, I). In addition, the cyclisation reaction is solvent‐ and anion‐dependent. The X‐ray structures of 2 and 4 ⋅2 THF are reported.