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Ferro- and Antiferromagnetic Interactions in Oxalato-Centered Inverse Hexanuclear and Chain Copper(II) Complexes with Pyrazole Derivatives.
- Source :
- Molecules; May2021, Vol. 26 Issue 9, p2792-2792, 1p
- Publication Year :
- 2021
-
Abstract
- Two novel copper(II) complexes of formulas {[Cu(4-Hmpz)<subscript>4</subscript>][Cu(4-Hmpz)<subscript>2</subscript>(µ<subscript>3</subscript>-ox-κ<superscript>2</superscript>O<superscript>1</superscript>,O<superscript>2</superscript>:κO<superscript>2′</superscript>:κO<superscript>1′</superscript>)(ClO<subscript>4</subscript>)<subscript>2</subscript>]}<subscript>n</subscript> (1) and {[Cu(3,4,5-Htmpz)<subscript>4</subscript>]<subscript>2</subscript>[Cu(3,4,5-Htmpz)<subscript>2</subscript>(µ<subscript>3</subscript>-ox-κ<superscript>2</superscript>O<superscript>1</superscript>,O<superscript>2</superscript>:κO<superscript>2′</superscript>:κO<superscript>1′</superscript>)(H<subscript>2</subscript>O)(ClO<subscript>4</subscript>)]<subscript>2</subscript>[Cu<subscript>2</subscript>(3,4,5-Htmpz)<subscript>4</subscript>(µ-ox-κ<superscript>2</superscript>O<superscript>1</superscript>,O<superscript>2</superscript>:κ<superscript>2</superscript>O<superscript>2′</superscript>,O<superscript>1′</superscript>)]}(ClO<subscript>4</subscript>)<subscript>4</subscript>·6H<subscript>2</subscript>O (2) have been obtained by using 4-methyl-1H-pyrazole (4-Hmpz) and 3,4,5-trimethyl-1H-pyrazole (3,4,5-Htmpz) as terminal ligands and oxalate (ox) as the polyatomic inverse coordination center. The crystal structure of 1 consists of perchlorate counteranions and cationic copper(II) chains with alternating bis(pyrazole)(µ<subscript>3</subscript>-κ<superscript>2</superscript>O<superscript>1</superscript>,O<superscript>2</superscript>:κO<superscript>2′</superscript>:κO<superscript>1′</superscript>-oxalato)copper(II) and tetrakis(pyrazole)copper(II) fragments. The crystal structure of 2 is made up of perchlorate counteranions and cationic centrosymmetric hexanuclear complexes where an inner tetrakis(pyrazole)(µ-κ<superscript>2</superscript>O<superscript>1</superscript>,O<superscript>2</superscript>:κ<superscript>2</superscript>O<superscript>2′</superscript>,O<superscript>1′</superscript>-oxalato)dicopper(II) entity and two outer mononuclear tetrakis(pyrazole)copper(II) units are linked through two mononuclear aquabis(pyrazole)(µ<subscript>3</subscript>-κ<superscript>2</superscript>O<superscript>1</superscript>,O<superscript>2</superscript>:κO<superscript>2′</superscript>:κO<superscript>1′</superscript>-oxalato)copper(II) units. The magnetic properties of 1 and 2 were investigated in the temperature range 2.0–300 K. Very weak intrachain antiferromagnetic interactions between the copper(II) ions through the µ<subscript>3</subscript>-ox-κ<superscript>2</superscript>O<superscript>1</superscript>,O<superscript>2</superscript>:κO<superscript>2′</superscript>:κO<superscript>1′</superscript> center occur in 1 [J = −0.42(1) cm<superscript>−1</superscript>, the spin Hamiltonian being defined as H = −J∑S<subscript>1,i</subscript> · S<subscript>2,i+1</subscript>], whereas very weak intramolecular ferromagnetic [J = +0.28(2) cm<superscript>−1</superscript>] and strong antiferromagnetic [J' = −348(2) cm<superscript>−1</superscript>] couplings coexist in 2 which are mediated by the µ<subscript>3</subscript>-ox-κ<superscript>2</superscript>O<superscript>1</superscript>,O<superscript>2</superscript>:κO<superscript>2′</superscript>:κO<superscript>1′</superscript> and µ-ox-κ<superscript>2</superscript>O<superscript>1</superscript>,O<superscript>2</superscript>:κ<superscript>2</superscript>O<superscript>2′</superscript>,O<superscript>1′</superscript> centers, respectively. The variation in the nature and magnitude of the magnetic coupling for this pair of oxalato-centered inverse copper(II) complexes is discussed in the light of their different structural features, and a comparison with related oxalato-centered inverse copper(II)-pyrazole systems from the literature is carried out. [ABSTRACT FROM AUTHOR]
- Subjects :
- OXALATES
PYRAZOLE derivatives
COPPER
MAGNETIC properties
CRYSTAL structure
PYRAZOLES
Subjects
Details
- Language :
- English
- ISSN :
- 14203049
- Volume :
- 26
- Issue :
- 9
- Database :
- Complementary Index
- Journal :
- Molecules
- Publication Type :
- Academic Journal
- Accession number :
- 150373387
- Full Text :
- https://doi.org/10.3390/molecules26092792