Abstract
Three different types of copper(ii) complexes have been studied of the hexadentate Schiff base ligand N,N′-bis[2-((salicylidenimine)amino)ethyl] piperazine (H2L) having the piperazine backbone in the chair form and axial–axial (a, a) N-atom lone pairs in the free state. The structure of the products is influenced by the reaction conditions and by the exogenous ligands, affecting the conformation of the piperazine moiety (primary structure) and the topology and nuclearity of the resulting complexes (secondary structure). In [Cu2L(DMF)2]X2 (X = ClO4-, 1a; NO3-, 1b), the lone-pairs of chair-piperazine adopt the equatorial–equatorial (e, e) conformation. In the presence of NEt3 and NaN3, two types of [CuII 4] complexes [Cu4(L)2(OH)2(H2O)2]X2·nH2O (X = ClO4-, n = 1, 2a; X = NO3-, n = 4, 2b) and [Cu4(L)2(N3)2(H2O)2]X2·H2O (X = ClO4-, 3a; NO3-, 3b) are obtained where four copper(ii) ions are bridged by two hexadentate μ3-piperazine ligands, this time in chair–e, a conformation, and by two OH and N3 groups. In CH3CN, reactions of 1, 2 or 3 with NaN3 always produce the double end-to-end azido bridged 1D polymer [Cu2L(N3)2]n (4) having a chair-e, e piperazine backbone. All studied conformations of the piperazine bridge mediate antiferromagnetic interactions between the Cu(ii) ions, as revealed by bulk magnetization measurements. The striking difference in intensity of the coupling through trans-e, e piperazine observed for complexes 1a and 4 might be due to complementarily effects between the ligands involved.
| Original language | English |
|---|---|
| Pages (from-to) | 1352-1362 |
| Number of pages | 11 |
| Journal | Journal of the Chemical Society. Dalton Transactions |
| Issue number | 8 |
| DOIs | |
| Publication status | Published - Feb 10 2009 |
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ASJC Scopus subject areas
- Chemistry(all)
Cite this
Structure and dimensionality of coordination complexes correlated to piperazine conformation : From discrete [CuII 2] and [CuII 4] complexes to a μ1,3-N3- bridged [CuII 2]n chain. / Paital, Alok Ranjan; Mandal, Debashree; Huang, Xiaoying; Li, Jing; Aromí, Guillem; Ray, Debashis.
In: Journal of the Chemical Society. Dalton Transactions, No. 8, 10.02.2009, p. 1352-1362.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Structure and dimensionality of coordination complexes correlated to piperazine conformation
T2 - From discrete [CuII 2] and [CuII 4] complexes to a μ1,3-N3- bridged [CuII 2]n chain
AU - Paital, Alok Ranjan
AU - Mandal, Debashree
AU - Huang, Xiaoying
AU - Li, Jing
AU - Aromí, Guillem
AU - Ray, Debashis
PY - 2009/2/10
Y1 - 2009/2/10
N2 - Three different types of copper(ii) complexes have been studied of the hexadentate Schiff base ligand N,N′-bis[2-((salicylidenimine)amino)ethyl] piperazine (H2L) having the piperazine backbone in the chair form and axial–axial (a, a) N-atom lone pairs in the free state. The structure of the products is influenced by the reaction conditions and by the exogenous ligands, affecting the conformation of the piperazine moiety (primary structure) and the topology and nuclearity of the resulting complexes (secondary structure). In [Cu2L(DMF)2]X2 (X = ClO4-, 1a; NO3-, 1b), the lone-pairs of chair-piperazine adopt the equatorial–equatorial (e, e) conformation. In the presence of NEt3 and NaN3, two types of [CuII 4] complexes [Cu4(L)2(OH)2(H2O)2]X2·nH2O (X = ClO4-, n = 1, 2a; X = NO3-, n = 4, 2b) and [Cu4(L)2(N3)2(H2O)2]X2·H2O (X = ClO4-, 3a; NO3-, 3b) are obtained where four copper(ii) ions are bridged by two hexadentate μ3-piperazine ligands, this time in chair–e, a conformation, and by two OH and N3 groups. In CH3CN, reactions of 1, 2 or 3 with NaN3 always produce the double end-to-end azido bridged 1D polymer [Cu2L(N3)2]n (4) having a chair-e, e piperazine backbone. All studied conformations of the piperazine bridge mediate antiferromagnetic interactions between the Cu(ii) ions, as revealed by bulk magnetization measurements. The striking difference in intensity of the coupling through trans-e, e piperazine observed for complexes 1a and 4 might be due to complementarily effects between the ligands involved.
AB - Three different types of copper(ii) complexes have been studied of the hexadentate Schiff base ligand N,N′-bis[2-((salicylidenimine)amino)ethyl] piperazine (H2L) having the piperazine backbone in the chair form and axial–axial (a, a) N-atom lone pairs in the free state. The structure of the products is influenced by the reaction conditions and by the exogenous ligands, affecting the conformation of the piperazine moiety (primary structure) and the topology and nuclearity of the resulting complexes (secondary structure). In [Cu2L(DMF)2]X2 (X = ClO4-, 1a; NO3-, 1b), the lone-pairs of chair-piperazine adopt the equatorial–equatorial (e, e) conformation. In the presence of NEt3 and NaN3, two types of [CuII 4] complexes [Cu4(L)2(OH)2(H2O)2]X2·nH2O (X = ClO4-, n = 1, 2a; X = NO3-, n = 4, 2b) and [Cu4(L)2(N3)2(H2O)2]X2·H2O (X = ClO4-, 3a; NO3-, 3b) are obtained where four copper(ii) ions are bridged by two hexadentate μ3-piperazine ligands, this time in chair–e, a conformation, and by two OH and N3 groups. In CH3CN, reactions of 1, 2 or 3 with NaN3 always produce the double end-to-end azido bridged 1D polymer [Cu2L(N3)2]n (4) having a chair-e, e piperazine backbone. All studied conformations of the piperazine bridge mediate antiferromagnetic interactions between the Cu(ii) ions, as revealed by bulk magnetization measurements. The striking difference in intensity of the coupling through trans-e, e piperazine observed for complexes 1a and 4 might be due to complementarily effects between the ligands involved.
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U2 - 10.1039/b814681k
DO - 10.1039/b814681k
M3 - Article
SP - 1352
EP - 1362
JO - Dalton Transactions
JF - Dalton Transactions
SN - 1477-9226
IS - 8
ER -