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Tunable N‐substitution in Zwitterionic Benzoquinonemonoimine Derivatives: Metal Coordination, Tandemlike Synthesis of Zwitterionic Metal Complexes, and Supramolecular Structures
Author(s) -
Yang QingZheng,
Siri Olivier,
Braunstein Pierre
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.200500704
Subject(s) - chemistry , supramolecular chemistry , transamination , zwitterion , coordination complex , adduct , octahedron , stereochemistry , crystal structure , metal , medicinal chemistry , alkene , crystallography , molecule , catalysis , amino acid , organic chemistry , biochemistry
Full details on a very efficient transamination reaction for the synthesis of zwitterionic N,N ′‐dialkyl‐2‐amino‐5‐alcoholate‐1,4‐benzoquinonemonoiminium derivatives [C 6 H 2 ( ${^{\underline{}}}$ NHR) 2 ( ${^{\underline{}}}$ O) 2 ] 5 – 16 are reported. The molecular structures of zwitterions 5 (R=CH 3 ) in 5⋅ H 2 O, 13 (R=CH 2 CH 2 OMe), 15 (R=CH 2 CH 2 NMe 2 ), and of the parent, unsubstituted system [C 6 H 2 ( ${^{\underline{}}}$ NH 2 ) 2 ( ${^{\underline{}}}$ O) 2 ] 4 in 4⋅ H 2 O have been established by single‐crystal X‐ray diffraction. This one‐pot preparation can be carried out in water, MeOH, or EtOH and allows access to new zwitterions with N‐substituents bearing functionalities such as OMe ( 13 ), OH ( 9 – 12 ), NR 1 R 2 with R 1 = or ≠R 2 ( 14 – 16 ) or an alkene ( 8 ), leading to a rich coordination chemistry and allowing fine‐tuning of the supramolecular arrangements in the solid state. As previously described for 15 , which reacted with Zn(acac) 2 to afford the octahedral Zn II complex [Zn{C 6 H 2 (NCH 2 CH 2 NMe 2 )O(O)(NHCH 2 CH 2 NMe 2 )} 2 ] ( 20 ), ligands 13 and 16 with coordinating “arms” afforded with Zn(acac) 2 the 2:1 adducts [Zn{C 6 H 2 (NCH 2 CH 2 X)O(O)(NHCH 2 CH 2 NX)} 2 ] 19 (X=OMe) and 21 (X=NHEt), with N 2 O 4 and N 4 O 2 donor sets around the octahedral Zn II center, respectively. Furthermore, zwitterions 15 and 16 reacted with ZnCl 2 to give the stable, crystallographically characterized Zn II zwitterionic complexes [ZnCl 2 {C 6 H 2 (NCH 2 CH 2 NR 1 R 2 )O(O)(NHCH 2 CH 2 NHR 1 R 2 )}] 22 (R 1 =R 2 =Me) and 23 (R 1 =Et, R 2 =H) by means of an unprecedented, tandemlike synthesis in which 1) the two pendant amino groups of the organic benzoquinonemonoimine zwitterionic precursor favor metal coordination and proton transfer and 2) the saturated linker prevents π‐conjugation between the charges. The nature of the structural arrangements in the solid state for both inorganic ( 20 , 22 , 23 ) and organic ( 5 , 9 , 13 , and 15 ) molecules is determined by subtle variations in the nature of the N‐substituent on the zwitterion precursor.