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Transition metal oxofluorides comprising lone pair elements: Synthesis and Characterization
Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
2014 (engelsk)Doktoravhandling, med artikler (Annet vitenskapelig)
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.

sted, utgiver, år, opplag, sider
Stockholm: Department of Materials and Environmental Chemistry (MMK), Stockholm University , 2014. , s. 70
Emneord [en]
lone pairs, oxofluorides, low-dimensional compounds
HSV kategori
Forskningsprogram
oorganisk kemi
Identifikatorer
URN: urn:nbn:se:su:diva-103051ISBN: 978-91-7447-890-7 (tryckt)OAI: oai:DiVA.org:su-103051DiVA, id: diva2:714892
Disputas
2014-06-16, Magnélisalen, Kemiska övningslaboratoriet, Svante Arrhenius väg 16 B, Stockholm, 13:00 (engelsk)
Opponent
Veileder
Merknad

At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 4: Manuscript.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

Tilgjengelig fra: 2014-05-22 Laget: 2014-04-29 Sist oppdatert: 2014-08-29bibliografisk kontrollert
Delarbeid
1. Synthesis and crystal structure of two synthetic oxofluoride framework compounds - Co2TeO3F2 and Co2SeO3F2
Åpne denne publikasjonen i ny fane eller vindu >>Synthesis and crystal structure of two synthetic oxofluoride framework compounds - Co2TeO3F2 and Co2SeO3F2
2012 (engelsk)Inngår i: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 41, nr 41, s. 12786-12789Artikkel i tidsskrift (Fagfellevurdert) 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.

HSV kategori
Identifikatorer
urn:nbn:se:su:diva-82983 (URN)10.1039/c2dt31188g (DOI)000309545100020 ()
Forskningsfinansiär
Swedish Research Council
Merknad

AuthorCount:2;

Tilgjengelig fra: 2012-12-07 Laget: 2012-12-03 Sist oppdatert: 2017-12-07bibliografisk kontrollert
2. Synthesis and crystal structure of Fe6Ca2(SeO3)(9)Cl-4 - a porous oxohalide
Åpne denne publikasjonen i ny fane eller vindu >>Synthesis and crystal structure of Fe6Ca2(SeO3)(9)Cl-4 - a porous oxohalide
2013 (engelsk)Inngår i: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 42, nr 22, s. 7859-7862Artikkel i tidsskrift (Fagfellevurdert) 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.

HSV kategori
Identifikatorer
urn:nbn:se:su:diva-92278 (URN)10.1039/c3dt50952d (DOI)000318943400006 ()
Merknad

AuthorCount:2;

Tilgjengelig fra: 2013-07-25 Laget: 2013-07-25 Sist oppdatert: 2017-12-06bibliografisk kontrollert
3. Crystal Structure and Magnetic Properties of FeSeO3F: Alternating Antiferromagnetic S = 5/2 chains
Åpne denne publikasjonen i ny fane eller vindu >>Crystal Structure and Magnetic Properties of FeSeO3F: Alternating Antiferromagnetic S = 5/2 chains
Vise andre…
2014 (engelsk)Inngår i: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 53, nr 8, s. 4250-4256Artikkel i tidsskrift (Fagfellevurdert) 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.

HSV kategori
Identifikatorer
urn:nbn:se:su:diva-103472 (URN)10.1021/ic5003995 (DOI)000334902400037 ()
Tilgjengelig fra: 2014-05-19 Laget: 2014-05-19 Sist oppdatert: 2017-12-05bibliografisk kontrollert
4. Acentric Pseudo-Kagome Structures: The Solid Solution (Co1-xNix)3Sb4O6F6
Åpne denne publikasjonen i ny fane eller vindu >>Acentric Pseudo-Kagome Structures: The Solid Solution (Co1-xNix)3Sb4O6F6
Vise andre…
(engelsk)Manuskript (preprint) (Annet vitenskapelig)
HSV kategori
Identifikatorer
urn:nbn:se:su:diva-103475 (URN)
Tilgjengelig fra: 2014-05-19 Laget: 2014-05-19 Sist oppdatert: 2014-05-19bibliografisk kontrollert
5. Crystal Structure and Magnetic Properties of the S=1/2 Quantum Spin System Cu-7(TeO3)(6)F-2 with Mixed Dimensionality
Åpne denne publikasjonen i ny fane eller vindu >>Crystal Structure and Magnetic Properties of the S=1/2 Quantum Spin System Cu-7(TeO3)(6)F-2 with Mixed Dimensionality
Vise andre…
2014 (engelsk)Inngår i: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 53, nr 14, s. 7661-7667Artikkel i tidsskrift (Fagfellevurdert) 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).

HSV kategori
Forskningsprogram
oorganisk kemi
Identifikatorer
urn:nbn:se:su:diva-106923 (URN)10.1021/ic5009686 (DOI)000339472000066 ()
Merknad

AuthorCount:7;

Tilgjengelig fra: 2014-08-29 Laget: 2014-08-27 Sist oppdatert: 2017-12-05bibliografisk kontrollert

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