Premium
The Coordination Chemistry of cis ‐3, 5‐Diaminopiperidine and Substituted Derivatives
Author(s) -
Pauly Jörg W.,
Sander Jürgen,
Kuppert Dirk,
Winter Manuela,
Reiss Guido J.,
Zürcher Fabio,
Hoffmann Rudolf,
Fässler Thomas F.,
Hegetschweiler Kaspar
Publication year - 2000
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(20000804)6:15<2830::aid-chem2830>3.0.co;2-x
Subject(s) - dapi , chemistry , aqueous solution , ligand (biochemistry) , crystallography , medicinal chemistry , organic chemistry , receptor , apoptosis , biochemistry
Abstract An efficient and convenient method for the preparation of cis ‐3,5‐diaminopiperidine (dapi) has been established and the coordination chemistry of this ligand with Co II , Co III , Ni II , Cu II , Zn II , and Cd II has been investigated in the solid state and in aqueous solution. Potentiometric measurements revealed a generally high stability for the bis complexes of the divalent cations with maximum stability for Ni II (log β 2 =21.2, β 2 =[M(dapi) 2 ][M] −1 [dapi] −2 , 25 °C, μ =0.1 mol dm −3 ). Cyclic voltammetry established quasi‐reversible formation of [Ni(dapi) 2 ] 3+ with a redox potential of 0.91 V (versus NHE) for the Ni II/III couple. [Co(dapi) 2 ] 3+ was prepared by aerial oxidation of the corresponding Co II precursor. The two isomers trans ‐[Co(dapi) 2 ] 3+ ( 1 3+ , 26 %) and cis ‐[Co(dapi) 2 ] 3+ ( 2 3+ , 74 %), have been separated and isolated as solid Cl − and CF 3 SO 3 − salts. In a non‐aqueous medium 1 3+ and 2 3+ reacted with paraformaldehyde and NEt 3 to give the methylidene‐imino derivatives 3 3+ and 4 3+ , in which the two piperidine rings are bridged by two or one N‐CH 2 ‐OCH 2 ‐N bridges, respectively. Crystal structure analyses were performed for H 3 dapi[ZnCl 4 ]Cl, 1 Cl 3 ⋅2 H 2 O, 2 Cl 3 ⋅H 2 O, 3 [ZnCl 4 ]Cl, 4 [ZnCl 4 ]Cl, [Ni(dapi) 2 ]Cl 2 ⋅H 2 O, [Cu(dapi) 2 ](NO 3 ) 2 , [Cu(dapi)Cl 2 ], [(dapi)ClCd‐( μ 2 ‐Cl) 2 ‐CdCl(dapi)], and [Co(dapi)(NO 2 )(CO 3 )]. The stability of [M II (dapi)] 2+ and [M II (dapi) 2 ] 2+ complexes in aqueous solution, particularly the remarkably high tendency of [M(dapi)] 2+ to undergo coordinative disproportionation is discussed in terms of the specific steric requirements of this ligand. Molecular mechanics calculations have been performed to analyze the different types of strain in these complexes. A variety of alkylated derivatives of dapi have been prepared by reductive alkylation with formaldehyde, benzaldehyde, salicylaldehyde, and pyridine‐2‐carbaldehyde. The Ni II complexes of the pentadentate N 3 , N 5 ‐bis(2‐pyridinylmethyl)‐ cis ‐3,5‐diaminopiperidine (py 2 dapi) and the hexadentate N 3 , N 5 ,1‐tris(2‐pyridinylmethyl)‐ cis ‐3,5‐diaminopiperidine (py 3 dapi) have been isolated as crystalline ClO 4 − salts [Ni(py 2 dapi)Cl]ClO 4 and [Ni(py 3 dapi)](ClO 4 ) 2 ⋅H 2 O and characterized by crystal structure analyses.