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Transition metal oxofluorides comprising lone pair elements: Synthesis and Characterization
Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Within the family of transition metal oxochlorides/bromides containing lone pair elements, the transition metal cations often adopt a low-dimensional arrangement such as 2D layers, 1D chains or 0D clusters. The reduced dimensionality is attributed to the presence of stereochemically active lone pairs which are positioned in the non-bonding orbital and will not participate in bond formation and instead act as structural spacers that help to separate coordination polyhedra around transition metal cations from forming three dimensional networks. On the other hand, the chlorine and bromine ions also play an important role to open up the crystal structure because of their low coordination number. However, fluorine has been rarely used in this concept due to the difficulties in synthesis.

This thesis is focused on finding new compounds in the M-L-O-F system (M = transition metal cation, L= p-block lone pair elements such as Te4+, Se4+, or Sb3+) in order to study the structural character of fluorine. Hydrothermal reactions have been adopted instead of conventional chemical transport reactions that are commonly used for synthesizing compounds in the M-L-O-(Cl, Br) family. A total of 8 new transition metal oxofluorides containing lone pair elements have been synthesized and their structures have been determined via single crystal X-ray diffraction. Bond valence sum calculations are used to distinguish in between fluorine and oxygen due to their very similar X-ray scattering factors.

Place, publisher, year, edition, pages
Stockholm: Department of Materials and Environmental Chemistry (MMK), Stockholm University , 2014. , 70 p.
Keyword [en]
lone pairs, oxofluorides, low-dimensional compounds
National Category
Inorganic Chemistry
Research subject
Inorganic Chemistry
Identifiers
URN: urn:nbn:se:su:diva-103051ISBN: 978-91-7447-890-7 (print)OAI: oai:DiVA.org:su-103051DiVA: diva2:714892
Public defence
2014-06-16, Magnélisalen, Kemiska övningslaboratoriet, Svante Arrhenius väg 16 B, Stockholm, 13:00 (English)
Opponent
Supervisors
Note

At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 4: Manuscript. Paper 5: Manuscript.

Available from: 2014-05-22 Created: 2014-04-29 Last updated: 2014-08-29Bibliographically approved
List of papers
1. Synthesis and crystal structure of two synthetic oxofluoride framework compounds - Co2TeO3F2 and Co2SeO3F2
Open this publication in new window or tab >>Synthesis and crystal structure of two synthetic oxofluoride framework compounds - Co2TeO3F2 and Co2SeO3F2
2012 (English)In: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 41, no 41, 12786-12789 p.Article in journal (Refereed) Published
Abstract [en]

Two new isostructural Co2+ containing tellurium and selenium oxofluoride compounds Co2TeO3F2 and Co2SeO3F2 are synthesized and their structures determined by single crystal X-ray diffraction. They crystallize in the orthorhombic space group Pnma with the unit cell parameters a = 7.3810(5) angstrom, b = 10.1936(7) angstrom, c = 5.3013(3) angstrom and a = 7.2655(8) angstrom, b = 10.0013(13) angstrom, c = 5.3564(6) angstrom, respectively. The Co(II) ion has octahedral coordination [CoO3F3] and builds up a 3D framework by corner- and edge sharing. The Se(IV) and the Te(IV) ions have the coordinations [SeO3E] and [TeO3E] respectively where E is the lone-pair electrons. The Se(IV) and Te(IV) ions are isolated from each other and bond only to the [CoO3F3] polyhedra. The electronegative element fluorine takes the role of a network builder like oxygen and helps to form the 3D framework structure. This is a difference compared to many oxohalide compounds containing Cl and Br where the halide ions are terminating ions preventing a 3D network from being formed. Long range antiferromagnetic interactions dominate at temperatures < 20 K. The magnetic susceptibility follows the Curie-Weiss law above 25 K with the Curie constant C = 5.62 emu K mol(-1), the Weiss temperature theta = -56 K and the effective magnetic moment mu(eff) = 4.74 mu(B) per cobalt atom.

National Category
Inorganic Chemistry
Identifiers
urn:nbn:se:su:diva-82983 (URN)10.1039/c2dt31188g (DOI)000309545100020 ()
Funder
Swedish Research Council
Note

AuthorCount:2;

Available from: 2012-12-07 Created: 2012-12-03 Last updated: 2017-12-07Bibliographically approved
2. Synthesis and crystal structure of Fe6Ca2(SeO3)(9)Cl-4 - a porous oxohalide
Open this publication in new window or tab >>Synthesis and crystal structure of Fe6Ca2(SeO3)(9)Cl-4 - a porous oxohalide
2013 (English)In: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 42, no 22, 7859-7862 p.Article in journal (Refereed) Published
Abstract [en]

A porous oxohalide, Fe6Ca2(SeO3)(9)Cl-4, has been synthesized by solid state reactions using concentrated HCl as the Cl-source. It crystallizes in the hexagonal space group P6(3)/m with unit cell parameters a = 12.118(2) angstrom, c = 12.703(4) angstrom, Z = 2. The crystal structure is an open framework having one-dimensional channels extending along [001] that the chlorine atoms and lone pairs on Se4+ are facing. The channels in this framework structure are unusually large compared to other oxohalide compounds and also accessible to guest molecules. Water vapor sorption measurements show an uptake of 9 wt% at 293 K.

National Category
Inorganic Chemistry
Identifiers
urn:nbn:se:su:diva-92278 (URN)10.1039/c3dt50952d (DOI)000318943400006 ()
Note

AuthorCount:2;

Available from: 2013-07-25 Created: 2013-07-25 Last updated: 2017-12-06Bibliographically approved
3. Crystal Structure and Magnetic Properties of FeSeO3F: Alternating Antiferromagnetic S = 5/2 chains
Open this publication in new window or tab >>Crystal Structure and Magnetic Properties of FeSeO3F: Alternating Antiferromagnetic S = 5/2 chains
Show others...
2014 (English)In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 53, no 8, 4250-4256 p.Article in journal (Refereed) Published
Abstract [en]

The new oxofluoride FeSeO3F crystallizes in the space group P21/n and consists of [FeO3F]∞ zigzag chains with alternating Fe−F−Fe and Fe−O−Fe spin exchange paths. The magnetic susceptibility of FeSeO3F is largely described by an S = 5/2 Heisenberg antiferromagnetic chain with alternating antiferromagnetic spin exchanges, and FeSeO3F undergoes a long-range antiferromagnetic ordering below 45 K.

National Category
Inorganic Chemistry
Identifiers
urn:nbn:se:su:diva-103472 (URN)10.1021/ic5003995 (DOI)000334902400037 ()
Available from: 2014-05-19 Created: 2014-05-19 Last updated: 2017-12-05Bibliographically approved
4. Acentric Pseudo-Kagome Structures: The Solid Solution (Co1-xNix)3Sb4O6F6
Open this publication in new window or tab >>Acentric Pseudo-Kagome Structures: The Solid Solution (Co1-xNix)3Sb4O6F6
Show others...
(English)Manuscript (preprint) (Other academic)
National Category
Inorganic Chemistry
Identifiers
urn:nbn:se:su:diva-103475 (URN)
Available from: 2014-05-19 Created: 2014-05-19 Last updated: 2014-05-19Bibliographically approved
5. Crystal Structure and Magnetic Properties of the S=1/2 Quantum Spin System Cu-7(TeO3)(6)F-2 with Mixed Dimensionality
Open this publication in new window or tab >>Crystal Structure and Magnetic Properties of the S=1/2 Quantum Spin System Cu-7(TeO3)(6)F-2 with Mixed Dimensionality
Show others...
2014 (English)In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 53, no 14, 7661-7667 p.Article in journal (Refereed) Published
Abstract [en]

The new oxofluoride Cu-7(TeO3)(6)F-2 has been synthesized by hydrothermal synthesis. It crystallizes in the triclinic system, space group P (1) over bar. The crystal structure constitutes a Cu-O framework with channels extending along [001] where the F- ions and the stereochernically active lone-pairs on Te4+ are located. From magnetic susceptibility, specific heat, and Raman scattering measurements we find evidence that the magnetic degrees of freedom of the Cu-O-Cu segments in Cu-7(TeO3)(6)F-2 lead to a mixed dimensionality with single Cu S = 1/2 moments wealdy coupled to spin-chain fragments. Due to the weaker coupling of the single moments, strong fluctuations exist at elevated temperatures, and long-range magnetic ordering evolves at comparably low temperatures (T-N = 15 K).

National Category
Chemical Sciences
Research subject
Inorganic Chemistry
Identifiers
urn:nbn:se:su:diva-106923 (URN)10.1021/ic5009686 (DOI)000339472000066 ()
Note

AuthorCount:7;

Available from: 2014-08-29 Created: 2014-08-27 Last updated: 2017-12-05Bibliographically approved

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