The structural architecture found in low-dimensional materials can lead to a number of interesting physical properties including anisotropic conductivity, magnetic frustration and non-linear optical properties. There is no standard synthesis concept described thus far to apply when searching for new low-dimensional compounds, and therefore control on the design of the new materials is of great importance.This thesis describes the synthesis, crystal structure and characterization of some new transition metal oxohalide compounds containing p-elements having a stereochemically active lone-pair. First row transition metal cations have been used in combination with SeIV, SbIII and TeIV ions as lone-pair elements and Cl- and Br- as halide ions. The lone-pairs do not participate in covalent bonding and are responsible for an asymmetric one-sided coordination. Lone-pair elements in combination with halide ions have shown to be powerful structural spacers that can confine transition metal building blocks into low-dimensional arrangements. The halide ions and lone-pairs reside in non-bonded crystal volumes where they interact through weak van der Waals forces. The transition metal atoms are most often arranged to form sheets, chains or small clusters; most commonly layered compounds are formed.To further explore the chemical system and to separate the transition metal entities even more the possibility to include tetrahedral building blocks such as phosphate-, silicate-, sulphate- and vanadate building blocks into this class of compounds has been investigated. Tetrahedral building blocks are well known for their ability of segmenting structural arrangements by corner sharing, which often leads to the formation of open framework structures. The inclusion of tetrahedral building blocks led to the discovery of interesting structural features such as complex hydrogen bonding, formation of unusual solid solutions or faulted stacking of layers.Compounds for which phase pure material could be synthesized have been characterized in terms of their magnetic properties. Most compounds were found to have antiferromagnetic spin interactions and indications of magnetic frustration could be observed in some of them. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 6: Manuscript. Paper 9: Manuscript. Paper 10: Manuscript.</p>

<p>This thesis is based upon synthesis and structure determination of new transition metal oxo-halide compounds, which includes p-element cations that have a stereochemically active lone pair. A synthesis concept has been developed, which uses several different structural features to increase the possibility to yield a low-dimensional arrangement of transition metal cations. A total of 17 new compounds has been synthesised and their structures have been determined <i>via</i> single-crystal X-ray diffraction. The halides and the stereochemically active lone-pairs will typically act as terminating species segregating into regions of non-bonding volumes, which may take the form of 2D layers, 1D channels or Euclidean spheres. The transition metals that have been used for this work are copper, cobalt and iron. The Hard-Soft-Acid-Base principle has been utilized to match strong Lewis acids to strong Lewis bases and weak acids to weak bases. All compounds show tendencies towards low-dimensionality; they all have sheets of transition metal cations arranged into layers, where the layers most often are connected via weak dispersion forces.</p>

This thesis is based upon synthesis and structure determination of new transition metal oxo-halide compounds, which includes p-element cations that have a stereochemically active lone pair. A synthesis concept has been developed, which uses several different structural features to increase the possibility to yield a low-dimensional arrangement of transition metal cations. A total of 17 new compounds has been synthesised and their structures have been determined via single-crystal X-ray diffraction. The halides and the stereochemically active lone-pairs will typically act as terminating species segregating into regions of non-bonding volumes, which may take the form of 2D layers, 1D channels or Euclidean spheres. The transition metals that have been used for this work are copper, cobalt and iron. The Hard-Soft-Acid-Base principle has been utilized to match strong Lewis acids to strong Lewis bases and weak acids to weak bases. All compounds show tendencies towards low-dimensionality; they all have sheets of transition metal cations arranged into layers, where the layers most often are connected via weak dispersion forces.

Rechargeable batteries have already conquered the market of portable electronics (i.e., mobile phones and laptops) and are set to further enable the large-scale deployment of electric vehicles and hybrid electric vehicles in a not too distant future. In this context, a deeper understanding of the fundamental processes governing the electrochemical behavior of electrode materials for batteries is required for further development of these applications. The aims of the work described in this thesis have been to investigate how electrochemical properties and structural properties of novel electrode materials relate to each other. In this sense, electrochemical characterization, structural analysis using XRD and their combined simultaneous use via in operando XRD experiments have played a crucial part. The investigations showed that: Two oxohalides, Ni3Sb4O6F6 and Mn2Sb3O6Cl, react with Li-ions in a complex manner involving different types of reaction mechanisms at low voltages in Li half cells. In operando XRD show that both of these materials are reduced in a conversion reaction via an in situ formation of nanocomposites, which proceed to react reversibly with Li-ions in a combination of alloying and conversion reactions. Carbon-coated Na2Mn2Si2O7 was synthesized and characterized as a possible positive electrode material for non-aqueous Na-ion batteries. DFT calculations point to a structural origin of the modest electrochemical behavior of this material. It is suggested that structural rearrangements upon desodiation are associated with large overpotentials. It is demonstrated via an in operando synchrotron XRD study that Fe(CN)6 vacancies in copper hexacyanoferrate (CuHCF) play an important role in the electrochemical behavior toward Zn2+ in an aqueous CuHCF/Zn cell. Furthermore, manganese hexacyanomanganate (MnHCM) is shown to react reversibly with Li+, Na+ and K+ in non-aqueous alkali metal half cells. In contrast to CuHCF, which is a zero-strain material, MnHCM undergoes a series of structural transitions (from monoclinic to cubic) during electrochemical cycling.