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A systematic study of the influence of ligand field on the slow magnetic dynamics of Co()-diimine compounds
Herein we report heteroleptic Co( ii ) diimine complexes [Co(H 2 bip) 2 Cl 2 ] ( 1 ), [Co(H 2 bip) 2 Br 2 ] ( 2 ), [Co(H 2 bip) 3 ]Br 2 ·1MeOH ( 3 ) and [Co(H 2 bip) 2 (Me 2 bpy)]Br 2 ·(MeCN) 0.5 ·(H 2 O) 0.25 ( 4 ) (H 2 bip = 2,2′-bi-1,4,5,6-tetrahydropyrimidine, bpy = 2,2′-dipyridyl, Me 2 bpy = 4,...
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| Published in: | Dalton transactions : an international journal of inorganic chemistry 2021-08, Vol.5 (31), p.1737-1748 |
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| cites | cdi_FETCH-LOGICAL-c314t-17c2e965b8872b0e1ceb145c7dc7b4c93c948c83f7423cd06b04e1b2ebd8cf6d3 |
| container_end_page | 1748 |
| container_issue | 31 |
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| container_title | Dalton transactions : an international journal of inorganic chemistry |
| container_volume | 5 |
| creator | Bhowmick, Indrani Newell, Brian S Shores, Matthew P |
| description | Herein we report heteroleptic Co(
ii
) diimine complexes [Co(H
2
bip)
2
Cl
2
] (
1
), [Co(H
2
bip)
2
Br
2
] (
2
), [Co(H
2
bip)
3
]Br
2
·1MeOH (
3
) and [Co(H
2
bip)
2
(Me
2
bpy)]Br
2
·(MeCN)
0.5
·(H
2
O)
0.25
(
4
) (H
2
bip = 2,2′-bi-1,4,5,6-tetrahydropyrimidine, bpy = 2,2′-dipyridyl, Me
2
bpy = 4,4′-Me-2,2′-dipyridyl), purposefully prepared to enable a systematic study of magnetic property changes arising from the increase of overall ligand field from σ/π-donor chlorido (
1
) to π-acceptor 4,4′Me-2,2′bpy (
4
). The presence of axial and rhombic anisotropy (
D
and
E
) of these compounds is sufficient to allow
1-4
to show field-induced slow relaxation of magnetization. Interestingly, we found as the effective ligand field is increased in the series, rhombicity (
E
/
D
) decreases, and the magnetic relaxation profile changes significantly, where relaxation of magnetization at a specific temperature becomes gradually faster. We performed mechanistic analyses of the temperature dependence of magnetic relaxation times considering Orbach relaxation processes, Raman-like relaxation and quantum tunnelling of magnetization (QTM). The effective energy barrier of the Orbach relaxation process (
U
eff
) is largest in compound
1
(19.2 cm
−1
) and gradually decreases in the order
1
>
2
>
3
>
4
giving a minimum value in compound
4
(8.3 cm
−1
), where the Raman-like mechanism showed the possibility of different types of phonon activity below and above ∼2.5 K. As a precursor of
1
, the tetrahedral complex [Co(H
2
bip)Cl
2
] (
1a
) was also synthesized and structurally and magnetically characterized: this compound exhibits slow relaxation of magnetization under an applied dc field (1800 Oe) with a record slow relaxation time of 3.39 s at 1.8 K.
A systematic study of four structurally-related hexacoordinate Co(
ii
) diimine complexes demonstrates links between ligand donor (σ/π) characteristics and slow magnetic dynamics and spin-lattice relaxation times. |
| doi_str_mv | 10.1039/d0dt01597k |
| format | article |
| fullrecord | <record><control><sourceid>proquest_cross</sourceid><recordid>TN_cdi_crossref_primary_10_1039_D0DT01597K</recordid><sourceformat>XML</sourceformat><sourcesystem>PC</sourcesystem><sourcerecordid>2559621231</sourcerecordid><originalsourceid>FETCH-LOGICAL-c314t-17c2e965b8872b0e1ceb145c7dc7b4c93c948c83f7423cd06b04e1b2ebd8cf6d3</originalsourceid><addsrcrecordid>eNpd0UtLw0AQAOAgCtbqxbuw4KUK0X3lsUdpfWHBSz2HZHZSt012azZB8u9tWqngaYbhm2GYCYJLRu8YFepeU91SFqlkfRSMmEySUHEhjw85j0-DM-9XlHJOIz4K1g_E977FOm8NEN92uieuJO0nEmPLqkMLOBQqs8ytJqXBShNnd8BX7pvU-dLi0Kt7m9cG_KCnbnITamNqY5GAqzeus9qfBydlXnm8-I3j4OPpcTF9Cefvz6_Th3kIgsk2ZAlwVHFUpGnCC4oMsGAygkRDUkhQApRMIRVlIrkATeOCSmQFx0KnUMZajIPJfu6mcV8d-jarjQesqtyi63zGo4grJQSNt_T6H125rrHb7QalYs64YFt1u1fQOO8bLLNNY-q86TNGs-Hu2YzOFru7v23x1R43Hg7u7y_iB2eVf3I</addsrcrecordid><sourcetype>Aggregation Database</sourcetype><iscdi>true</iscdi><recordtype>article</recordtype><pqid>2559621231</pqid></control><display><type>article</type><title>A systematic study of the influence of ligand field on the slow magnetic dynamics of Co()-diimine compounds</title><source>Royal Society of Chemistry</source><creator>Bhowmick, Indrani ; Newell, Brian S ; Shores, Matthew P</creator><creatorcontrib>Bhowmick, Indrani ; Newell, Brian S ; Shores, Matthew P</creatorcontrib><description>Herein we report heteroleptic Co(
ii
) diimine complexes [Co(H
2
bip)
2
Cl
2
] (
1
), [Co(H
2
bip)
2
Br
2
] (
2
), [Co(H
2
bip)
3
]Br
2
·1MeOH (
3
) and [Co(H
2
bip)
2
(Me
2
bpy)]Br
2
·(MeCN)
0.5
·(H
2
O)
0.25
(
4
) (H
2
bip = 2,2′-bi-1,4,5,6-tetrahydropyrimidine, bpy = 2,2′-dipyridyl, Me
2
bpy = 4,4′-Me-2,2′-dipyridyl), purposefully prepared to enable a systematic study of magnetic property changes arising from the increase of overall ligand field from σ/π-donor chlorido (
1
) to π-acceptor 4,4′Me-2,2′bpy (
4
). The presence of axial and rhombic anisotropy (
D
and
E
) of these compounds is sufficient to allow
1-4
to show field-induced slow relaxation of magnetization. Interestingly, we found as the effective ligand field is increased in the series, rhombicity (
E
/
D
) decreases, and the magnetic relaxation profile changes significantly, where relaxation of magnetization at a specific temperature becomes gradually faster. We performed mechanistic analyses of the temperature dependence of magnetic relaxation times considering Orbach relaxation processes, Raman-like relaxation and quantum tunnelling of magnetization (QTM). The effective energy barrier of the Orbach relaxation process (
U
eff
) is largest in compound
1
(19.2 cm
−1
) and gradually decreases in the order
1
>
2
>
3
>
4
giving a minimum value in compound
4
(8.3 cm
−1
), where the Raman-like mechanism showed the possibility of different types of phonon activity below and above ∼2.5 K. As a precursor of
1
, the tetrahedral complex [Co(H
2
bip)Cl
2
] (
1a
) was also synthesized and structurally and magnetically characterized: this compound exhibits slow relaxation of magnetization under an applied dc field (1800 Oe) with a record slow relaxation time of 3.39 s at 1.8 K.
A systematic study of four structurally-related hexacoordinate Co(
ii
) diimine complexes demonstrates links between ligand donor (σ/π) characteristics and slow magnetic dynamics and spin-lattice relaxation times.</description><identifier>ISSN: 1477-9226</identifier><identifier>EISSN: 1477-9234</identifier><identifier>DOI: 10.1039/d0dt01597k</identifier><language>eng</language><publisher>Cambridge: Royal Society of Chemistry</publisher><subject>Anisotropy ; Crystallography ; Diimide ; Ligands ; Magnetic induction ; Magnetic properties ; Magnetic relaxation ; Magnetization ; Quantum tunnelling ; Relaxation time ; Temperature dependence</subject><ispartof>Dalton transactions : an international journal of inorganic chemistry, 2021-08, Vol.5 (31), p.1737-1748</ispartof><rights>Copyright Royal Society of Chemistry 2021</rights><lds50>peer_reviewed</lds50><woscitedreferencessubscribed>false</woscitedreferencessubscribed><citedby>FETCH-LOGICAL-c314t-17c2e965b8872b0e1ceb145c7dc7b4c93c948c83f7423cd06b04e1b2ebd8cf6d3</citedby><cites>FETCH-LOGICAL-c314t-17c2e965b8872b0e1ceb145c7dc7b4c93c948c83f7423cd06b04e1b2ebd8cf6d3</cites><orcidid>0000-0002-3479-4959 ; 0000-0002-6310-1242 ; 0000-0002-9751-0490</orcidid></display><links><openurl>$$Topenurl_article</openurl><openurlfulltext>$$Topenurlfull_article</openurlfulltext><thumbnail>$$Tsyndetics_thumb_exl</thumbnail><link.rule.ids>314,780,784,27924,27925</link.rule.ids></links><search><creatorcontrib>Bhowmick, Indrani</creatorcontrib><creatorcontrib>Newell, Brian S</creatorcontrib><creatorcontrib>Shores, Matthew P</creatorcontrib><title>A systematic study of the influence of ligand field on the slow magnetic dynamics of Co()-diimine compounds</title><title>Dalton transactions : an international journal of inorganic chemistry</title><description>Herein we report heteroleptic Co(
ii
) diimine complexes [Co(H
2
bip)
2
Cl
2
] (
1
), [Co(H
2
bip)
2
Br
2
] (
2
), [Co(H
2
bip)
3
]Br
2
·1MeOH (
3
) and [Co(H
2
bip)
2
(Me
2
bpy)]Br
2
·(MeCN)
0.5
·(H
2
O)
0.25
(
4
) (H
2
bip = 2,2′-bi-1,4,5,6-tetrahydropyrimidine, bpy = 2,2′-dipyridyl, Me
2
bpy = 4,4′-Me-2,2′-dipyridyl), purposefully prepared to enable a systematic study of magnetic property changes arising from the increase of overall ligand field from σ/π-donor chlorido (
1
) to π-acceptor 4,4′Me-2,2′bpy (
4
). The presence of axial and rhombic anisotropy (
D
and
E
) of these compounds is sufficient to allow
1-4
to show field-induced slow relaxation of magnetization. Interestingly, we found as the effective ligand field is increased in the series, rhombicity (
E
/
D
) decreases, and the magnetic relaxation profile changes significantly, where relaxation of magnetization at a specific temperature becomes gradually faster. We performed mechanistic analyses of the temperature dependence of magnetic relaxation times considering Orbach relaxation processes, Raman-like relaxation and quantum tunnelling of magnetization (QTM). The effective energy barrier of the Orbach relaxation process (
U
eff
) is largest in compound
1
(19.2 cm
−1
) and gradually decreases in the order
1
>
2
>
3
>
4
giving a minimum value in compound
4
(8.3 cm
−1
), where the Raman-like mechanism showed the possibility of different types of phonon activity below and above ∼2.5 K. As a precursor of
1
, the tetrahedral complex [Co(H
2
bip)Cl
2
] (
1a
) was also synthesized and structurally and magnetically characterized: this compound exhibits slow relaxation of magnetization under an applied dc field (1800 Oe) with a record slow relaxation time of 3.39 s at 1.8 K.
A systematic study of four structurally-related hexacoordinate Co(
ii
) diimine complexes demonstrates links between ligand donor (σ/π) characteristics and slow magnetic dynamics and spin-lattice relaxation times.</description><subject>Anisotropy</subject><subject>Crystallography</subject><subject>Diimide</subject><subject>Ligands</subject><subject>Magnetic induction</subject><subject>Magnetic properties</subject><subject>Magnetic relaxation</subject><subject>Magnetization</subject><subject>Quantum tunnelling</subject><subject>Relaxation time</subject><subject>Temperature dependence</subject><issn>1477-9226</issn><issn>1477-9234</issn><fulltext>true</fulltext><rsrctype>article</rsrctype><creationdate>2021</creationdate><recordtype>article</recordtype><recordid>eNpd0UtLw0AQAOAgCtbqxbuw4KUK0X3lsUdpfWHBSz2HZHZSt012azZB8u9tWqngaYbhm2GYCYJLRu8YFepeU91SFqlkfRSMmEySUHEhjw85j0-DM-9XlHJOIz4K1g_E977FOm8NEN92uieuJO0nEmPLqkMLOBQqs8ytJqXBShNnd8BX7pvU-dLi0Kt7m9cG_KCnbnITamNqY5GAqzeus9qfBydlXnm8-I3j4OPpcTF9Cefvz6_Th3kIgsk2ZAlwVHFUpGnCC4oMsGAygkRDUkhQApRMIRVlIrkATeOCSmQFx0KnUMZajIPJfu6mcV8d-jarjQesqtyi63zGo4grJQSNt_T6H125rrHb7QalYs64YFt1u1fQOO8bLLNNY-q86TNGs-Hu2YzOFru7v23x1R43Hg7u7y_iB2eVf3I</recordid><startdate>20210821</startdate><enddate>20210821</enddate><creator>Bhowmick, Indrani</creator><creator>Newell, Brian S</creator><creator>Shores, Matthew P</creator><general>Royal Society of Chemistry</general><scope>AAYXX</scope><scope>CITATION</scope><scope>7SR</scope><scope>7U5</scope><scope>8BQ</scope><scope>8FD</scope><scope>JG9</scope><scope>L7M</scope><scope>7X8</scope><orcidid>https://orcid.org/0000-0002-3479-4959</orcidid><orcidid>https://orcid.org/0000-0002-6310-1242</orcidid><orcidid>https://orcid.org/0000-0002-9751-0490</orcidid></search><sort><creationdate>20210821</creationdate><title>A systematic study of the influence of ligand field on the slow magnetic dynamics of Co()-diimine compounds</title><author>Bhowmick, Indrani ; Newell, Brian S ; Shores, Matthew P</author></sort><facets><frbrtype>5</frbrtype><frbrgroupid>cdi_FETCH-LOGICAL-c314t-17c2e965b8872b0e1ceb145c7dc7b4c93c948c83f7423cd06b04e1b2ebd8cf6d3</frbrgroupid><rsrctype>articles</rsrctype><prefilter>articles</prefilter><language>eng</language><creationdate>2021</creationdate><topic>Anisotropy</topic><topic>Crystallography</topic><topic>Diimide</topic><topic>Ligands</topic><topic>Magnetic induction</topic><topic>Magnetic properties</topic><topic>Magnetic relaxation</topic><topic>Magnetization</topic><topic>Quantum tunnelling</topic><topic>Relaxation time</topic><topic>Temperature dependence</topic><toplevel>peer_reviewed</toplevel><toplevel>online_resources</toplevel><creatorcontrib>Bhowmick, Indrani</creatorcontrib><creatorcontrib>Newell, Brian S</creatorcontrib><creatorcontrib>Shores, Matthew P</creatorcontrib><collection>CrossRef</collection><collection>Engineered Materials Abstracts</collection><collection>Solid State and Superconductivity Abstracts</collection><collection>METADEX</collection><collection>Technology Research Database</collection><collection>Materials Research Database</collection><collection>Advanced Technologies Database with Aerospace</collection><collection>MEDLINE - Academic</collection><jtitle>Dalton transactions : an international journal of inorganic chemistry</jtitle></facets><delivery><delcategory>Remote Search Resource</delcategory><fulltext>fulltext</fulltext></delivery><addata><au>Bhowmick, Indrani</au><au>Newell, Brian S</au><au>Shores, Matthew P</au><format>journal</format><genre>article</genre><ristype>JOUR</ristype><atitle>A systematic study of the influence of ligand field on the slow magnetic dynamics of Co()-diimine compounds</atitle><jtitle>Dalton transactions : an international journal of inorganic chemistry</jtitle><date>2021-08-21</date><risdate>2021</risdate><volume>5</volume><issue>31</issue><spage>1737</spage><epage>1748</epage><pages>1737-1748</pages><issn>1477-9226</issn><eissn>1477-9234</eissn><abstract>Herein we report heteroleptic Co(
ii
) diimine complexes [Co(H
2
bip)
2
Cl
2
] (
1
), [Co(H
2
bip)
2
Br
2
] (
2
), [Co(H
2
bip)
3
]Br
2
·1MeOH (
3
) and [Co(H
2
bip)
2
(Me
2
bpy)]Br
2
·(MeCN)
0.5
·(H
2
O)
0.25
(
4
) (H
2
bip = 2,2′-bi-1,4,5,6-tetrahydropyrimidine, bpy = 2,2′-dipyridyl, Me
2
bpy = 4,4′-Me-2,2′-dipyridyl), purposefully prepared to enable a systematic study of magnetic property changes arising from the increase of overall ligand field from σ/π-donor chlorido (
1
) to π-acceptor 4,4′Me-2,2′bpy (
4
). The presence of axial and rhombic anisotropy (
D
and
E
) of these compounds is sufficient to allow
1-4
to show field-induced slow relaxation of magnetization. Interestingly, we found as the effective ligand field is increased in the series, rhombicity (
E
/
D
) decreases, and the magnetic relaxation profile changes significantly, where relaxation of magnetization at a specific temperature becomes gradually faster. We performed mechanistic analyses of the temperature dependence of magnetic relaxation times considering Orbach relaxation processes, Raman-like relaxation and quantum tunnelling of magnetization (QTM). The effective energy barrier of the Orbach relaxation process (
U
eff
) is largest in compound
1
(19.2 cm
−1
) and gradually decreases in the order
1
>
2
>
3
>
4
giving a minimum value in compound
4
(8.3 cm
−1
), where the Raman-like mechanism showed the possibility of different types of phonon activity below and above ∼2.5 K. As a precursor of
1
, the tetrahedral complex [Co(H
2
bip)Cl
2
] (
1a
) was also synthesized and structurally and magnetically characterized: this compound exhibits slow relaxation of magnetization under an applied dc field (1800 Oe) with a record slow relaxation time of 3.39 s at 1.8 K.
A systematic study of four structurally-related hexacoordinate Co(
ii
) diimine complexes demonstrates links between ligand donor (σ/π) characteristics and slow magnetic dynamics and spin-lattice relaxation times.</abstract><cop>Cambridge</cop><pub>Royal Society of Chemistry</pub><doi>10.1039/d0dt01597k</doi><tpages>12</tpages><orcidid>https://orcid.org/0000-0002-3479-4959</orcidid><orcidid>https://orcid.org/0000-0002-6310-1242</orcidid><orcidid>https://orcid.org/0000-0002-9751-0490</orcidid></addata></record> |
| fulltext | fulltext |
| identifier | ISSN: 1477-9226 |
| ispartof | Dalton transactions : an international journal of inorganic chemistry, 2021-08, Vol.5 (31), p.1737-1748 |
| issn | 1477-9226 1477-9234 |
| language | eng |
| recordid | cdi_crossref_primary_10_1039_D0DT01597K |
| source | Royal Society of Chemistry |
| subjects | Anisotropy Crystallography Diimide Ligands Magnetic induction Magnetic properties Magnetic relaxation Magnetization Quantum tunnelling Relaxation time Temperature dependence |
| title | A systematic study of the influence of ligand field on the slow magnetic dynamics of Co()-diimine compounds |
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