Synthesis and Characterization of Cu(II) and Mixed-Valence Cu(I)Cu(II) Clusters Supported by Pyridylamide Ligands

Joseph D. Schneider; Brett A. Smith; Grant A. Williams; Douglas R. Powell; Felio Perez; Gerard T. Rowe; Lei Yang

doi:10.1021/acs.inorgchem.0c00008

Synthesis and Characterization of Cu(II) and Mixed-Valence Cu(I)Cu(II) Clusters Supported by Pyridylamide Ligands

Joseph D. Schneider, Brett A. Smith, Grant A. Williams, Douglas R. Powell, Felio Perez, Gerard T. Rowe, Lei Yang

Chemical Sciences Division

Research output: Contribution to journal › Article › peer-review

42 Scopus citations

Abstract

A group of copper complexes supported by polydentate pyridylamide ligands H₂bpda and H₂ppda were synthesized and characterized. The two Cu(II) dimers [Cu^II ₂(Hbpda)₂(ClO₄)₂] (1) and [Cu^II ₂(ppda)₂(DMF)₂] (2) were constructed by using neutral ligands to react with Cu(II) salts. Although the dimers showed similar structural features, the second-sphere interactions affect the structures differently. With the application of Et₃N, the tetranuclear cluster (HNEt₃)[Cu^II ₄(bpda)₂(μ₃-OH)₂(ClO₄)(DMF)₃](ClO₄)₂ (3) and hexanuclear cluster (HNEt₃)₂[Cu^II ₆(ppda)₆(H₂O)₂(CH₃OH)₂](ClO₄)₂ (4) were prepared under similar reaction conditions. The symmetrical and unsymmetrical arrangement of the ligand donors in ligands H₂bpda and H₂ppda led to the dramatic conformation difference of the two Cu(II) complexes. As part of our effort to explore mixed-valence copper chemistry, the triple-decker pentanuclear cluster [Cu^II ₃Cu^I ₂(bpda)₃(μ₃-O)] (5) was prepared. XPS examination demonstrated the localized mixed-valence properties of complex 5. Magnetic studies of the clusters with EPR evidence showed either weak ferromagnetic or antiferromagnetic interactions among copper centers. Due to the trigonal-planar conformation of the trinuclear Cu(II) motif with the μ₃-O center, complex 5 exhibits geometric spin frustration and engages in antisymmetric exchange interactions. DFT calculations were also performed to better interpret spectroscopic evidence and understand the electronic structures, especially the mixed-valence nature of complex 5.

Original language	English
Pages (from-to)	5433-5446
Number of pages	14
Journal	Inorganic Chemistry
Volume	59
Issue number	8
DOIs	https://doi.org/10.1021/acs.inorgchem.0c00008
State	Published - Apr 20 2020

Funding

This work was supported by the College of Natural Sciences and Mathematics (CNSM) and University Research Council (URC) from the University of Central Arkansas, Arkansas Science & Technology Authority (ASTA) from the State of Arkansas, and the NSF (RUI Grant 1856438). We thank INBRE of Arkansas for the purchase of an EPR instrument and the NSF (Grant CCLI 0125711) for the purchase of a glovebox. We also thank Dr. Nan Xu at Penn State University—Altoona for collecting the electrochemistry data of complex 4 .

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10.1021/acs.inorgchem.0c00008

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@article{417b0f42641d40b595ace57fa1954bab,

title = "Synthesis and Characterization of Cu(II) and Mixed-Valence Cu(I)Cu(II) Clusters Supported by Pyridylamide Ligands",

abstract = "A group of copper complexes supported by polydentate pyridylamide ligands H2bpda and H2ppda were synthesized and characterized. The two Cu(II) dimers [CuII 2(Hbpda)2(ClO4)2] (1) and [CuII 2(ppda)2(DMF)2] (2) were constructed by using neutral ligands to react with Cu(II) salts. Although the dimers showed similar structural features, the second-sphere interactions affect the structures differently. With the application of Et3N, the tetranuclear cluster (HNEt3)[CuII 4(bpda)2(μ3-OH)2(ClO4)(DMF)3](ClO4)2 (3) and hexanuclear cluster (HNEt3)2[CuII 6(ppda)6(H2O)2(CH3OH)2](ClO4)2 (4) were prepared under similar reaction conditions. The symmetrical and unsymmetrical arrangement of the ligand donors in ligands H2bpda and H2ppda led to the dramatic conformation difference of the two Cu(II) complexes. As part of our effort to explore mixed-valence copper chemistry, the triple-decker pentanuclear cluster [CuII 3CuI 2(bpda)3(μ3-O)] (5) was prepared. XPS examination demonstrated the localized mixed-valence properties of complex 5. Magnetic studies of the clusters with EPR evidence showed either weak ferromagnetic or antiferromagnetic interactions among copper centers. Due to the trigonal-planar conformation of the trinuclear Cu(II) motif with the μ3-O center, complex 5 exhibits geometric spin frustration and engages in antisymmetric exchange interactions. DFT calculations were also performed to better interpret spectroscopic evidence and understand the electronic structures, especially the mixed-valence nature of complex 5.",

author = "Schneider, {Joseph D.} and Smith, {Brett A.} and Williams, {Grant A.} and Powell, {Douglas R.} and Felio Perez and Rowe, {Gerard T.} and Lei Yang",

note = "Publisher Copyright: {\textcopyright} 2020 American Chemical Society.",

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doi = "10.1021/acs.inorgchem.0c00008",

language = "English",

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T1 - Synthesis and Characterization of Cu(II) and Mixed-Valence Cu(I)Cu(II) Clusters Supported by Pyridylamide Ligands

AU - Schneider, Joseph D.

AU - Smith, Brett A.

AU - Williams, Grant A.

AU - Powell, Douglas R.

AU - Perez, Felio

AU - Rowe, Gerard T.

AU - Yang, Lei

PY - 2020/4/20

Y1 - 2020/4/20

N2 - A group of copper complexes supported by polydentate pyridylamide ligands H2bpda and H2ppda were synthesized and characterized. The two Cu(II) dimers [CuII 2(Hbpda)2(ClO4)2] (1) and [CuII 2(ppda)2(DMF)2] (2) were constructed by using neutral ligands to react with Cu(II) salts. Although the dimers showed similar structural features, the second-sphere interactions affect the structures differently. With the application of Et3N, the tetranuclear cluster (HNEt3)[CuII 4(bpda)2(μ3-OH)2(ClO4)(DMF)3](ClO4)2 (3) and hexanuclear cluster (HNEt3)2[CuII 6(ppda)6(H2O)2(CH3OH)2](ClO4)2 (4) were prepared under similar reaction conditions. The symmetrical and unsymmetrical arrangement of the ligand donors in ligands H2bpda and H2ppda led to the dramatic conformation difference of the two Cu(II) complexes. As part of our effort to explore mixed-valence copper chemistry, the triple-decker pentanuclear cluster [CuII 3CuI 2(bpda)3(μ3-O)] (5) was prepared. XPS examination demonstrated the localized mixed-valence properties of complex 5. Magnetic studies of the clusters with EPR evidence showed either weak ferromagnetic or antiferromagnetic interactions among copper centers. Due to the trigonal-planar conformation of the trinuclear Cu(II) motif with the μ3-O center, complex 5 exhibits geometric spin frustration and engages in antisymmetric exchange interactions. DFT calculations were also performed to better interpret spectroscopic evidence and understand the electronic structures, especially the mixed-valence nature of complex 5.

AB - A group of copper complexes supported by polydentate pyridylamide ligands H2bpda and H2ppda were synthesized and characterized. The two Cu(II) dimers [CuII 2(Hbpda)2(ClO4)2] (1) and [CuII 2(ppda)2(DMF)2] (2) were constructed by using neutral ligands to react with Cu(II) salts. Although the dimers showed similar structural features, the second-sphere interactions affect the structures differently. With the application of Et3N, the tetranuclear cluster (HNEt3)[CuII 4(bpda)2(μ3-OH)2(ClO4)(DMF)3](ClO4)2 (3) and hexanuclear cluster (HNEt3)2[CuII 6(ppda)6(H2O)2(CH3OH)2](ClO4)2 (4) were prepared under similar reaction conditions. The symmetrical and unsymmetrical arrangement of the ligand donors in ligands H2bpda and H2ppda led to the dramatic conformation difference of the two Cu(II) complexes. As part of our effort to explore mixed-valence copper chemistry, the triple-decker pentanuclear cluster [CuII 3CuI 2(bpda)3(μ3-O)] (5) was prepared. XPS examination demonstrated the localized mixed-valence properties of complex 5. Magnetic studies of the clusters with EPR evidence showed either weak ferromagnetic or antiferromagnetic interactions among copper centers. Due to the trigonal-planar conformation of the trinuclear Cu(II) motif with the μ3-O center, complex 5 exhibits geometric spin frustration and engages in antisymmetric exchange interactions. DFT calculations were also performed to better interpret spectroscopic evidence and understand the electronic structures, especially the mixed-valence nature of complex 5.

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U2 - 10.1021/acs.inorgchem.0c00008

DO - 10.1021/acs.inorgchem.0c00008

M3 - Article

C2 - 32237741

AN - SCOPUS:85082847212

SN - 0020-1669

VL - 59

SP - 5433

EP - 5446

JO - Inorganic Chemistry

JF - Inorganic Chemistry

IS - 8

ER -

Synthesis and Characterization of Cu(II) and Mixed-Valence Cu(I)Cu(II) Clusters Supported by Pyridylamide Ligands

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