Structural and Magnetic Diversity in Alkali-Metal Manganate Chemistry: Evaluating Donor and Alkali-Metal Effects in Co-complexation Processes

Marina Uzelac; Ivana Borilovic; Marco Amores; Thomas Cadenbach; Alan R. Kennedy; Guillem Aromí; Eva Hevia

doi:10.1002/chem.201504956

Structural and Magnetic Diversity in Alkali-Metal Manganate Chemistry: Evaluating Donor and Alkali-Metal Effects in Co-complexation Processes

Marina Uzelac, Ivana Borilovic, Marco Amores, Thomas Cadenbach, Alan R. Kennedy, Guillem Aromí, Eva Hevia

Department of Chemistry

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

15 Citations (SciVal)

Abstract

By exploring co-complexation reactions between the manganese alkyl Mn(CH₂SiMe₃)₂ and the heavier alkali-metal alkyls M(CH₂SiMe₃) (M=Na, K) in a benzene/hexane solvent mixture and in some cases adding Lewis donors (bidentate TMEDA, 1,4-dioxane, and 1,4-diazabicyclo[2,2,2] octane (DABCO)) has produced a new family of alkali-metal tris(alkyl) manganates. The influences that the alkali metal and the donor solvent impose on the structures and magnetic properties of these ates have been assessed by a combination of X-ray, SQUID magnetization measurements, and EPR spectroscopy. These studies uncover a diverse structural chemistry ranging from discrete monomers [(TMEDA)₂MMn(CH₂SiMe₃)₃] (M=Na, 3; M=K, 4) to dimers [{KMn(CH₂SiMe₃)₃C₆H₆}₂] (2) and [{NaMn(CH₂SiMe₃)₃}₂(dioxane)₇] (5); and to more complex supramolecular networks [{NaMn(CH₂SiMe₃)₃}_∞] (1) and [{Na₂Mn₂(CH₂SiMe₃)₆(DABCO)₂}_∞] (7)). Interestingly, the identity of the alkali metal exerts a significant effect in the reactions of 1 and 2 with 1,4-dioxane, as 1 produces coordination adduct 5, while 2 forms heteroleptic [{(dioxane)₆K₂Mn₂(CH₂SiMe₃)₄(O(CH₂)₂OCH=CH₂)₂}_∞] (6) containing two alkoxide-vinyl anions resulting from α-metalation and ring opening of dioxane. Compounds 6 and 7, containing two spin carriers, exhibit antiferromagnetic coupling of their S=5/2 moments with varying intensity depending on the nature of the exchange pathways.

Original language	English
Pages (from-to)	4843-4854
Number of pages	12
Journal	Chemistry - A European Journal
Volume	22
Issue number	14
DOIs	https://doi.org/10.1002/chem.201504956
Publication status	Published - 24 Mar 2016

Bibliographical note

Funding Information:
We thank the EPSRC, the Royal Society, and the European Research Council (ERC) for their generous sponsorship of this research. We also thank Professor Robert E. Mulvey for his insightful comments and Alexander Clunie for his assistance in the CHN analysis of highly air- A nd moisture-sensitive compounds.

Funding

We thank the EPSRC, the Royal Society, and the European Research Council (ERC) for their generous sponsorship of this research. We also thank Professor Robert E. Mulvey for his insightful comments and Alexander Clunie for his assistance in the CHN analysis of highly air- A nd moisture-sensitive compounds.

Keywords

alkali metals
cooperativity
Lewis bases
magnetism
manganese

ASJC Scopus subject areas

Catalysis
Organic Chemistry

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10.1002/chem.201504956

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@article{e117f11c16d2418db6f36e4f999dfeb6,

title = "Structural and Magnetic Diversity in Alkali-Metal Manganate Chemistry: Evaluating Donor and Alkali-Metal Effects in Co-complexation Processes",

abstract = "By exploring co-complexation reactions between the manganese alkyl Mn(CH2SiMe3)2 and the heavier alkali-metal alkyls M(CH2SiMe3) (M=Na, K) in a benzene/hexane solvent mixture and in some cases adding Lewis donors (bidentate TMEDA, 1,4-dioxane, and 1,4-diazabicyclo[2,2,2] octane (DABCO)) has produced a new family of alkali-metal tris(alkyl) manganates. The influences that the alkali metal and the donor solvent impose on the structures and magnetic properties of these ates have been assessed by a combination of X-ray, SQUID magnetization measurements, and EPR spectroscopy. These studies uncover a diverse structural chemistry ranging from discrete monomers [(TMEDA)2MMn(CH2SiMe3)3] (M=Na, 3; M=K, 4) to dimers [{KMn(CH2SiMe3)3C6H6}2] (2) and [{NaMn(CH2SiMe3)3}2(dioxane)7] (5); and to more complex supramolecular networks [{NaMn(CH2SiMe3)3}∞] (1) and [{Na2Mn2(CH2SiMe3)6(DABCO)2}∞] (7)). Interestingly, the identity of the alkali metal exerts a significant effect in the reactions of 1 and 2 with 1,4-dioxane, as 1 produces coordination adduct 5, while 2 forms heteroleptic [{(dioxane)6K2Mn2(CH2SiMe3)4(O(CH2)2OCH=CH2)2}∞] (6) containing two alkoxide-vinyl anions resulting from α-metalation and ring opening of dioxane. Compounds 6 and 7, containing two spin carriers, exhibit antiferromagnetic coupling of their S=5/2 moments with varying intensity depending on the nature of the exchange pathways.",

keywords = "alkali metals, cooperativity, Lewis bases, magnetism, manganese",

author = "Marina Uzelac and Ivana Borilovic and Marco Amores and Thomas Cadenbach and Kennedy, {Alan R.} and Guillem Arom{\'i} and Eva Hevia",

note = "Funding Information: We thank the EPSRC, the Royal Society, and the European Research Council (ERC) for their generous sponsorship of this research. We also thank Professor Robert E. Mulvey for his insightful comments and Alexander Clunie for his assistance in the CHN analysis of highly air- A nd moisture-sensitive compounds. ",

year = "2016",

month = mar,

day = "24",

doi = "10.1002/chem.201504956",

language = "English",

volume = "22",

pages = "4843--4854",

journal = "Chemistry - A European Journal",

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T1 - Structural and Magnetic Diversity in Alkali-Metal Manganate Chemistry

T2 - Evaluating Donor and Alkali-Metal Effects in Co-complexation Processes

AU - Uzelac, Marina

AU - Borilovic, Ivana

AU - Amores, Marco

AU - Cadenbach, Thomas

AU - Kennedy, Alan R.

AU - Aromí, Guillem

AU - Hevia, Eva

N1 - Funding Information: We thank the EPSRC, the Royal Society, and the European Research Council (ERC) for their generous sponsorship of this research. We also thank Professor Robert E. Mulvey for his insightful comments and Alexander Clunie for his assistance in the CHN analysis of highly air- A nd moisture-sensitive compounds.

PY - 2016/3/24

Y1 - 2016/3/24

N2 - By exploring co-complexation reactions between the manganese alkyl Mn(CH2SiMe3)2 and the heavier alkali-metal alkyls M(CH2SiMe3) (M=Na, K) in a benzene/hexane solvent mixture and in some cases adding Lewis donors (bidentate TMEDA, 1,4-dioxane, and 1,4-diazabicyclo[2,2,2] octane (DABCO)) has produced a new family of alkali-metal tris(alkyl) manganates. The influences that the alkali metal and the donor solvent impose on the structures and magnetic properties of these ates have been assessed by a combination of X-ray, SQUID magnetization measurements, and EPR spectroscopy. These studies uncover a diverse structural chemistry ranging from discrete monomers [(TMEDA)2MMn(CH2SiMe3)3] (M=Na, 3; M=K, 4) to dimers [{KMn(CH2SiMe3)3C6H6}2] (2) and [{NaMn(CH2SiMe3)3}2(dioxane)7] (5); and to more complex supramolecular networks [{NaMn(CH2SiMe3)3}∞] (1) and [{Na2Mn2(CH2SiMe3)6(DABCO)2}∞] (7)). Interestingly, the identity of the alkali metal exerts a significant effect in the reactions of 1 and 2 with 1,4-dioxane, as 1 produces coordination adduct 5, while 2 forms heteroleptic [{(dioxane)6K2Mn2(CH2SiMe3)4(O(CH2)2OCH=CH2)2}∞] (6) containing two alkoxide-vinyl anions resulting from α-metalation and ring opening of dioxane. Compounds 6 and 7, containing two spin carriers, exhibit antiferromagnetic coupling of their S=5/2 moments with varying intensity depending on the nature of the exchange pathways.

AB - By exploring co-complexation reactions between the manganese alkyl Mn(CH2SiMe3)2 and the heavier alkali-metal alkyls M(CH2SiMe3) (M=Na, K) in a benzene/hexane solvent mixture and in some cases adding Lewis donors (bidentate TMEDA, 1,4-dioxane, and 1,4-diazabicyclo[2,2,2] octane (DABCO)) has produced a new family of alkali-metal tris(alkyl) manganates. The influences that the alkali metal and the donor solvent impose on the structures and magnetic properties of these ates have been assessed by a combination of X-ray, SQUID magnetization measurements, and EPR spectroscopy. These studies uncover a diverse structural chemistry ranging from discrete monomers [(TMEDA)2MMn(CH2SiMe3)3] (M=Na, 3; M=K, 4) to dimers [{KMn(CH2SiMe3)3C6H6}2] (2) and [{NaMn(CH2SiMe3)3}2(dioxane)7] (5); and to more complex supramolecular networks [{NaMn(CH2SiMe3)3}∞] (1) and [{Na2Mn2(CH2SiMe3)6(DABCO)2}∞] (7)). Interestingly, the identity of the alkali metal exerts a significant effect in the reactions of 1 and 2 with 1,4-dioxane, as 1 produces coordination adduct 5, while 2 forms heteroleptic [{(dioxane)6K2Mn2(CH2SiMe3)4(O(CH2)2OCH=CH2)2}∞] (6) containing two alkoxide-vinyl anions resulting from α-metalation and ring opening of dioxane. Compounds 6 and 7, containing two spin carriers, exhibit antiferromagnetic coupling of their S=5/2 moments with varying intensity depending on the nature of the exchange pathways.

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KW - cooperativity

KW - Lewis bases

KW - magnetism

KW - manganese

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Structural and Magnetic Diversity in Alkali-Metal Manganate Chemistry: Evaluating Donor and Alkali-Metal Effects in Co-complexation Processes

Abstract

Bibliographical note

Funding

Keywords

ASJC Scopus subject areas

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