TY - JOUR
T1 - Facially coordinating cyclic triamines, Part 1
T2 - The coordination chemistry of cis-3,5-diaminopiperidine and substituted derivatives
AU - Pauly, Jörg W.
AU - Sander, Jürgen
AU - Kuppert, Dirk
AU - Winter, Manuela
AU - Reiss, Guido J.
AU - Zürcher, Fabio
AU - Hoffmann, Rudolf
AU - Fässler, Thomas F.
AU - Hegetschweiler, Kaspar
PY - 2000/8/4
Y1 - 2000/8/4
N2 - 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 CoII, CoIII, NiII, CuII, ZnII, and CdII 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 NiII (log β2 = 21.2, β2 = [M(dapi)2][M]-1 [dapi]-2, 25°C, μ = 0.1 moldm-3). Cyclic voltammetry established quasi-reversible formation of [Ni(dapi)2]3+ with a redox potential of 0.91 V (versus NHE) for the NiII/III couple. [Co(dapi)2]3+ was prepared by aerial oxidation of the corresponding CoII precursor. The two isomers trans-[Co(dapi)2]3+ (13+, 26%) and cis-[Co(dapi)2]3+ (23+, 74%), have been separated and isolated as solid Cl- and CF3SO3- salts. In a non-aqueous medium 13+ and 23+ reacted with paraformaldehyde and NEt3 to give the methylidene-imino derivatives 33+ and 43+, in which the two piperidine rings are bridged by two or one N-CH2-O-CH2-N bridges, respectively. Crystal structure analyses were performed for H3daPi[ZnCl4]Cl, 1Cl3·2H2O, 2Cl3·H2O, 3[ZnCl4]Cl, 4[ZnCl4]Cl, [Ni(dapi)2]Cl2· H2O, [Cu(dapi)2](NO3)2, [Cu(dapi)Cl2], [(dapi)ClCd-(μ2-Cl)2-CdCl(dapi)], and [Co(dapi)(NO2)(CO3)]. The stability of [MII(dapi)]2+ and [MII(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 NiII complexes of the pentadentate N3,N5-bis-(2-pyridinylmethyl)-cis-3,5-diaminopiperidine (py2dapi) and the hexadentate N3,N5,1-tris(2-pyridinylmethyl)-cis-3,5-diaminopiperidine (py3dapi) have been isolated as crystalline ClO4- salts [Ni-(py2dapi)Cl]ClO4 and [Ni(py3dapi)]-(C1O4)2·H2O and characterized by crystal structure analyses.
AB - 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 CoII, CoIII, NiII, CuII, ZnII, and CdII 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 NiII (log β2 = 21.2, β2 = [M(dapi)2][M]-1 [dapi]-2, 25°C, μ = 0.1 moldm-3). Cyclic voltammetry established quasi-reversible formation of [Ni(dapi)2]3+ with a redox potential of 0.91 V (versus NHE) for the NiII/III couple. [Co(dapi)2]3+ was prepared by aerial oxidation of the corresponding CoII precursor. The two isomers trans-[Co(dapi)2]3+ (13+, 26%) and cis-[Co(dapi)2]3+ (23+, 74%), have been separated and isolated as solid Cl- and CF3SO3- salts. In a non-aqueous medium 13+ and 23+ reacted with paraformaldehyde and NEt3 to give the methylidene-imino derivatives 33+ and 43+, in which the two piperidine rings are bridged by two or one N-CH2-O-CH2-N bridges, respectively. Crystal structure analyses were performed for H3daPi[ZnCl4]Cl, 1Cl3·2H2O, 2Cl3·H2O, 3[ZnCl4]Cl, 4[ZnCl4]Cl, [Ni(dapi)2]Cl2· H2O, [Cu(dapi)2](NO3)2, [Cu(dapi)Cl2], [(dapi)ClCd-(μ2-Cl)2-CdCl(dapi)], and [Co(dapi)(NO2)(CO3)]. The stability of [MII(dapi)]2+ and [MII(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 NiII complexes of the pentadentate N3,N5-bis-(2-pyridinylmethyl)-cis-3,5-diaminopiperidine (py2dapi) and the hexadentate N3,N5,1-tris(2-pyridinylmethyl)-cis-3,5-diaminopiperidine (py3dapi) have been isolated as crystalline ClO4- salts [Ni-(py2dapi)Cl]ClO4 and [Ni(py3dapi)]-(C1O4)2·H2O and characterized by crystal structure analyses.
KW - N ligands
KW - Polyamines
KW - Stability constants
KW - Structure elucidation
UR - http://www.scopus.com/inward/record.url?scp=85046528535&partnerID=8YFLogxK
U2 - 10.1002/1521-3765(20000804)6:15<2830::AID-CHEM2830>3.3.CO;2-O
DO - 10.1002/1521-3765(20000804)6:15<2830::AID-CHEM2830>3.3.CO;2-O
M3 - Article
AN - SCOPUS:85046528535
SN - 0947-6539
VL - 6
SP - 2830
EP - 2846
JO - Chemistry - A European Journal
JF - Chemistry - A European Journal
IS - 15
ER -