Inorganic chemistry 14624 225306223 2008-07-13T00:21:41Z Eagleal 4143438 Added [[sq:Kimia inorganike]] {{for|the journal|Inorganic Chemistry (journal)}} [[Image:Inorganic-montage.png|thumb|right|150px|'''Inorganic compounds show rich variety:'''<br> '''A:''' [[Diborane]] features [[Three-center two-electron bond|unusual bonding]]<br> '''B:''' [[Caesium chloride]] has an archetypal [[crystal structure]]<br> '''C:''' [[Cyclopentadienyliron dicarbonyl dimer|Fp<sub>2</sub>]] is an [[organometallic]] complex <br> '''D:''' [[Polydimethylsiloxane|Silicone]]'s uses range from [[breast implant]]s to [[Silly Putty]]<br> '''E:''' [[Grubbs' catalyst]] won the [[Nobel Prize in Chemistry|2005 Nobel Prize]] for [[Robert H. Grubbs|its discoverer]]<br> '''F:''' [[Zeolite]]s find extensive use as [[molecular sieve]]s<br> '''G:''' [[Copper(II) acetate]] surprised [[Theoretical chemistry|theoreticians]] with its [[diamagnetism]]]] '''Inorganic chemistry''' is the branch of [[chemistry]] concerned with the properties and behavior of [[inorganic compound]]s. This field covers all [[chemical compound]]s except the myriad [[organic compound]]s (compounds containing C-H bonds), which are the subjects of [[organic chemistry]]. The distinction between the two disciplines is far from absolute, and there is much overlap, most importantly in the sub-discipline of [[organometallic chemistry]]. ==Key concepts== [[Image:Potassium-oxide-3D-vdW.png|thumb|left|The structure of the ionic framework in [[potassium oxide]], K<sub>2</sub>O]] The bulk of [[inorganic compound]]s occur as [[salts]], the combination of [[cation]]s and [[anion]]s joined by [[ionic bond]]ing. Examples of cations are [[sodium]] Na<sup>+</sup>, and [[magnesium]] Mg<sup>2+</sup> and examples of anions are [[oxide]] O<sup>2−</sup> and [[chloride]] Cl<sup>−</sup>. As salts are neutrally charged, these ions form compounds such as [[sodium oxide]] Na<sub>2</sub>O or [[magnesium chloride]] MgCl<sub>2</sub>. The ions are described by their [[oxidation state]] and their ease of formation can be inferred from the [[ionization potential]] (for cations) or from the [[electron affinity]] (anions) of the parent elements. Important classes of inorganic compounds are the [[oxide]]s, the [[carbonate]]s, the [[sulfate]]s and the [[halide]]s. Many inorganic compounds are characterized by high [[melting point]]s. Inorganic salts typically are poor [[electrical conductivity|conductors]] in the solid state. Another important feature is their solubility in e.g. water (see: [[solubility chart]]), and ease of [[crystallization]]. Where some salts (e.g. [[Sodium chloride|NaCl]]) are very soluble in water, others (e.g. [[silicon dioxide|SiO<sub>2</sub>]]) are not. The simplest [[Inorganic chemical reaction|inorganic reaction]] is [[double displacement reaction|double displacement]] when in mixing of two salts the ions are swapped without a change in oxidation state. In [[redox reaction]]s one reactant, the ''oxidant'', lowers its oxidation state and another reactant, the ''reductant'', has its oxidation state increased. The net result is an exchange of [[electron]]s. Electron exchange can occur indirectly as well, e.g. in [[Battery (electricity)|batteries]], a key concept in [[electrochemistry]]. When one reactant contains hydrogen atoms, a reaction can take place by exchanging protons in [[Acid-base reaction theories|acid-base chemistry]]. In a more general definition, an acid can be any chemical species capable of binding to electron pairs is called a [[Lewis acid]]; conversely any molecule that tends to donate an electron pair is referred to as a [[Lewis base]]. As a refinement of acid-base interactions, the [[HSAB theory]] takes into account polarizability and size of ions. Inorganic compounds are found in nature as [[mineral]]s. Soil may contain iron sulfide as [[pyrite]] or calcium sulfate as [[gypsum]]. Inorganic compounds are also found multitasking as [[biomolecule]]s: as electrolytes ([[sodium chloride]]), in energy storage ([[Adenosine triphosphate|ATP]]) or in construction (the [[polyphosphate]] backbone in [[DNA]]). The first important man-made inorganic compound was [[ammonium nitrite]] for soil fertilization through the [[Haber process]]. Inorganic compounds are synthesized for use as [[catalyst]]s such as [[vanadium(V) oxide]] and [[titanium(III) chloride]], or as [[reagent]]s in [[organic chemistry]] such as [[lithium aluminium hydride]]. Subdivisions of inorganic chemistry are [[organometallic chemistry]], [[cluster chemistry]] and [[bioinorganic chemistry]]. These fields are active areas of research in inorganic chemistry, aimed toward new [[catalyst]]s, [[superconductor]]s, and [[medicine|therapies]]. ===Industrial inorganic chemistry=== Inorganic chemistry is a highly practical area of science. Traditionally, the scale of a nation's economy could be evaluated by their productivity of sulfuric acid. The top 20 inorganic chemicals manufactured in Canada, China, Europe, Japan, and the US (2005 data):<ref>"Facts & Figures Of The Chemical Industry” Chemical and Engineering News, July 10, 2006.</ref> [[aluminium sulfate]], [[ammonia]], [[ammonium nitrate]], [[ammonium sulfate]], [[carbon black]], [[chlorine]], [[hydrochloric acid]], [[hydrogen]], [[hydrogen peroxide]], [[nitric acid]], [[nitrogen]], [[oxygen]], [[phosphoric acid]], [[sodium carbonate]], [[sodium chlorate]], [[sodium hydroxide]], [[sodium silicate]], [[sodium sulfate]], [[sulfuric acid]], and [[titanium dioxide]]. The manufacturing of fertilisers is another practical application of industrial inorganic chemistry. ==Descriptive inorganic chemistry== Descriptive inorganic chemistry focuses on the classification of compounds based on their properties. Partly the classification focuses on the position in the periodic table of the heaviest element (the element with the highest atomic weight) in the compound, partly by grouping compounds by their structural similarities. When studying inorganic compounds, one often encounters parts of the different classes of inorganic chemistry (an organometallic compound is characterized by its coordination chemistry, and may show interesting solid state properties). Different classifications are: ===Coordination compounds=== [[Image:CoEDTA-anion-3D-balls.png|thumb|right|200px|[[EDTA]] [[chelation|chelates]] an octahedrally-coordinated [[cobalt|Co<sup>3+</sup>]] ion in [Co(EDTA)]<sup>−</sup>]] {{main|Coordination chemistry}} {{seealso|Werner-type complex}} Classical coordination compounds feature metals bound to "[[lone pair]]s" of electrons residing on the main group atoms of ligands such as H<sub>2</sub>O, NH<sub>3</sub>, [[chloride|Cl<sup>−</sup>]], and [[Cyanide|CN<sup>−</sup>]]. In modern coordination compounds almost all organic and inorganic compounds can be used as ligands. The "metal" usually is a metal from the groups 3-13, as well as the ''trans''-[[lanthanide]]s and ''trans''-[[actinide]]s, but from a certain perspective, all chemical compounds can be described as coordination complexes. The stereochemistry of coordination complexes can be quite rich, as hinted at by Werner's separation of two [[enantiomers]] of [[hexol|[Co((OH)<sub>2</sub>Co(NH<sub>3</sub>)<sub>4</sub>)<sub>3</sub>]<sup>6+</sup>]], an early demonstration that chirality is not inherent to organic compounds. A topical theme within this specialization is supramolecular coordination chemistry.<ref>Lehn, J. M., Supramolecular Chemistry: Concepts and Perspectives, VCH: Weinhiem, 1995</ref> *Examples: [Co([[EDTA]])]<sup>−</sup>, [[Cobalt(III) hexammine chloride|[Co(NH<sub>3</sub>)<sub>6</sub>]<sup>3+</sup>]], [[Titanium tetrachloride|TiCl<sub>4</sub>]]([[THF]])<sub>2</sub>. ===Main group compounds=== [[Image:Tetrasulfur-tetranitride-3D-vdW.png|thumb|right|200px|[[Tetrasulfur tetranitride]], S<sub>4</sub>N<sub>4</sub>, is a main group compound that continues to intrigue chemists]] These species feature elements from [[Periodic table group|groups]] 1, 2 and 13-18 (excluding hydrogen) of the periodic table. Due to their often similar reactivity, the elements in group 3 ([[Scandium|Sc]], [[Yttrium|Y]], and [[Lanthanum|La]]) and group 12 ([[Zinc|Zn]], [[Cadmium|Cd]], and [[Mercury (element)|Hg]]) are also generally included.<ref>Greenwood, N. N.; & Earnshaw, A. (1997). Chemistry of the Elements (2nd Edn.), Oxford:Butterworth-Heinemann. ISBN 0-7506-3365-4.</ref> Main group compounds have been known since the beginnings of chemistry, e.g. elemental [[sulfur]] and the distillable white [[phosphorus]]. Experiments on oxygen, [[oxygen|O<sub>2</sub>]], by [[Antoine Lavoisier|Lavoisier]] and [[Joseph Priestley|Priestley]] not only identified an important [[diatomic]] gas, but opened the way for describing compounds and reactions according to [[stoichiometry|stoichiometric]] ratios. The discovery of a practical synthesis of [[ammonia]] using iron catalysts by [[Carl Bosch]] and [[Fritz Haber]] in the early 1900’s deeply impacted mankind, demonstrating the significance of inorganic chemical synthesis. Typical main group compounds are SiO<sub>2</sub>, SnCl<sub>4</sub>, and N<sub>2</sub>O. Many main group compounds can also be classed as “organometallic”, as they contain organic groups, e.g. B([[methyl group|CH<sub>3</sub>]])<sub>3</sub>). Main group compounds also occur in nature, e.g. [[phosphate]] in [[DNA]], and therefore may be classed as bioinorganic. Conversely, organic compounds lacking (many) hydrogen ligands can be classed as “inorganic”, such as the fullerenes, [[Carbon nanotube|buckytube]]s and binary carbon oxides. *Examples: [[tetrasulfur tetranitride]] S<sub>4</sub>N<sub>4</sub>, [[diborane]] B<sub>2</sub>H<sub>6</sub>, [[silicone]]s, [[fullerene|buckminsterfullerene]] C<sub>60</sub>. ===Transition metal compounds=== [[Image:Copper-phthalocyanine-3D-vdW.png|thumb|right|150px|[[Phthalocyanine Blue BN|Copper phthalocyanine]] is a [[transition metal]] compound related to [[heme|haem]]]] Compounds containing metals from group 4 to 11 are considered transition metal compounds. Compounds with a metal from group 3 or 12 are sometimes also incorporated into this group, but also often classified as main group compounds. Transition metal compounds show a rich coordination chemistry, varying from tetrahedral for titanium (e.g. TiCl<sub>4</sub>) to square planar for some nickel complexes to octahedral for coordination complexes of cobalt. A range of transition metals can be found in biologically important compounds, such as iron in hemoglobin. *Examples: [[iron pentacarbonyl]], [[titanium tetrachloride]], [[cisplatin]] ===Organometallic compounds=== [[Image:N-butyllithium-tetramer-3D-balls.png|thumb|right|200px|[[Organolithium reagent]]s are most often found in polymeric form, such as [[N-butyllithium|''n''-butyllithium]] shown here]] {{Main|Organometallic chemistry}} Usually, organometallic compounds are considered to contain the M-C-H group.<ref>C. Elschenbroich, A. Salzer ”Organometallics : A Concise Introduction” (2nd Ed) (1992); Wiley-VCH: Weinheim. ISBN 3-527-28165-7</ref> The metal (M) in these species can either be a main group element or a transition metal. Operationally, the definition of an organometallic compound is more relaxed to include also highly [[lipophilic]] complexes such as [[metal carbonyl]]s and even metal [[alkoxide]]s. Organometallic compounds are mainly considered a special category because organic ligands are often sensitive to hydrolysis or oxidation, necessitating that organometallic chemistry employs more specialized preparative methods than was traditional in Werner-type complexes. Synthetic methodology, especially the ability to manipulate complexes in solvents of low coordinating power, enabled the exploration of very weakly coordinating ligands such as hydrocarbons, H<sub>2</sub>, and N<sub>2</sub>. Because the ligands are petrochemicals in some sense, the area of organometallic chemistry has greatly benefited from its relevance to industry. *Examples: [[Cyclopentadienyliron dicarbonyl dimer]] (C<sub>5</sub>H<sub>5</sub>)Fe(CO)<sub>2</sub>CH<sub>3</sub>, [[Ferrocene]] Fe(C<sub>5</sub>H<sub>5</sub>)<sub>2</sub>, [[Molybdenum hexacarbonyl]] Mo(CO)<sub>6</sub>, [[Diborane]] B<sub>2</sub>H<sub>6</sub>, [[Tetrakis(triphenylphosphine)palladium(0)]] Pd[P(C<sub>6</sub>H<sub>5</sub>)<sub>3</sub>]<sub>4</sub> ===Cluster compounds=== [[Image:Decaborane-3D-balls.png|thumb|left|200px|[[Decaborane]] is a powerfully toxic [[cluster compound]] of [[boron]]]] [[Image:Fe4S4-3D-vdW.png|thumb|right|200px|[[Iron-sulfur cluster]]s are central components of [[iron-sulfur protein]]s, essential for human [[metabolism]]]] {{main|Cluster compound}} Clusters can be found in all classes of [[chemical compounds]]. According to the commonly accepted definition, a cluster consists minimally of a triangular set of atoms that are directly bonded to each other. But metal-metal bonded dimetallic complexes are highly relevant to the area. Clusters occur in "pure" inorganic systems, organometallic chemistry, main group chemistry, and bioinorganic chemistry. The distinction between very large clusters and bulk solids is increasingly blurred. This interface is the chemical basis of nanoscience or [[nanotechnology]] and specifically arise from the study of [[quantum size effect]]s in [[cadmium selenide]] clusters. Thus, large clusters can be described as an array of bound atoms intermediate in character between a molecule and a solid. <br><br> *Examples: [[Triiron dodecacarbonyl|Fe<sub>3</sub>(CO)<sub>12</sub>]], [[Decaborane|B<sub>10</sub>H<sub>14</sub>]], [[Molybdenum(II) chloride|[Mo<sub>6</sub>Cl<sub>14</sub>]<sup>2−</sup>]], [[Iron-sulfur protein|4Fe-4S]] <br> ===Bioinorganic compounds=== [[Image:Vitamin-B12-Co-centre-3D-balls.png|thumb|right|200px|The octahedral [[cobalt]] centre of [[Cyanocobalamin|Vitamin B<sub>12</sub>]]]] {{Main|Bioinorganic chemistry}} See also [[Bioorganometallic chemistry]] By definition, these compounds occur in nature, but the subfield includes anthropogenic species, such as pollutants (e.g. [[methylmercury]]) and drugs (e.g. [[Cisplatin]]).<ref>S. J. Lippard, J. M. Berg “Principles of Bioinorganic Chemistry” University Science Books: Mill Valley, CA; 1994. ISBN 0-935702-73-3.</ref> The field, which incorporates many aspects of biochemistry, includes many kinds of compounds, e.g. the phosphates in DNA, and also metal complexes containing ligands that range from biological macromolecules, commonly [[peptide]]s, to ill-defined species such as [[humic acid]], and to [[water]] (e.g. coordinated to [[gadolinium]] complexes employed for [[MRI]]). Traditionally bioinorganic chemistry focuses on electron- and energy-transfer in proteins relevant to respiration. Medicinal inorganic chemistry includes the study of both non-essential and [[dietary mineral|essential element]]s with applications to diagnosis and therapies. *Examples: [[hemoglobin]], [[methylmercury]], [[carboxypeptidase]] ===Solid state compounds=== {{main|solid-state chemistry}} [[Image:YBCO-3D-balls.png|thumb|right|150px|[[Yttrium barium copper oxide|YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7</sub>]], or YBCO, is a high temperature [[superconductor]] able to [[Meissner effect|levitate]] above a magnet when colder than its [[critical temperature]] of about 90 K (−183°C)]] This important area focuses on [[Chemical structure|structure]],<ref>Wells, A.F. (1984). Structural Inorganic Chemistry, Oxford: Clarendon Press.</ref> bonding, and the physical properties of materials. In practice, solid state inorganic chemistry uses techniques such as [[crystallography]] to gain an understanding of the properties that result from collective interactions between the subunits of the solid. Included in solid state chemistry are metals and their [[alloys]] or intermetallic derivatives. Related fields are [[condensed matter physics]], [[mineralogy]], and [[materials science]]. *Examples: [[Semiconductor|silicon chips]], [[zeolites]], [[Yttrium barium copper oxide|YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7</sub>]] ==Theoretical inorganic chemistry== An alternative perspective on the area of inorganic chemistry begins with the [[Bohr model]] of the atom and, using the tools and models of [[theoretical chemistry]] and [[computational chemistry]], expands into bonding in simple and then more complex molecules. Precise quantum mechanical descriptions for multielectron species, the province of inorganic chemistry, is difficult. This challenge has spawned many semi-quantitative or semi-empirical approaches including [[molecular orbital theory]] and [[ligand field theory]], In parallel with these theoretical descriptions, approximate methodologies are employed, including [[density functional theory]]. Exceptions to theories, qualitative and quantitative, are extremely important in the development of the field. For example, [[Copper(II) acetate|Cu<sup>II</sup><sub>2</sub>(OAc)<sub>4</sub>(H<sub>2</sub>O)<sub>2</sub>]] is almost diamagnetic below room temperature whereas Crystal Field Theory predicts that the molecule would have two unpaired electrons. The disagreement between qualitative theory (paramagnetic) and observation (diamagnetic) led to the development of models for "magnetic coupling." These improved models led to the development of new magnetic materials and new technologies. ===Qualitative theories=== [[Image:Ferricyanide-3D.png|thumb|right|200px|[[Crystal field theory]] explains why [[Ferricyanide|[Fe<sup><small>III</small></sup>(CN)<sub>6</sub>]<sup>3−</sup>]] has only one unpaired electron]] Inorganic chemistry has greatly benefited from qualitative theories. Such theories are easier to learn as they require little background in quantum theory. Within main group compounds, [[VSEPR]] theory powerfully predicts, or at least rationalizes, the [[Chemical structure|structures]] of main group compounds, such as an explanation for why NH<sub>3</sub> is pyramidal whereas ClF<sub>3</sub> is T-shaped. For the transition metals, [[crystal field theory]] allows one to understand the magnetism of many simple complexes, such as why [[Ferricyanide|[Fe<sup><small>III</small></sup>(CN)<sub>6</sub>]<sup>3−</sup>]] has only one unpaired electron, whereas [Fe<sup><small>III</small></sup>(H<sub>2</sub>O)<sub>6</sub>]<sup>3+</sup> has five. A particularly powerful qualitative approach to assessing the structure and reactivity begins with classifying molecules according to [[electron counting]], focusing on the numbers of [[valence electron]]s, usually at the central atom in a molecule. ===Molecular Symmetry Group Theory=== [[Image:Nitrogen-dioxide-3D-vdW.png|thumb|right|200px|[[Nitrogen dioxide]], NO<sub>2</sub>, exhibits [[Symmetry group|''C<sub>2v</sub>'' symmetry]]]] A central construct in inorganic chemistry is the theory of [[molecular symmetry]].<ref>Cotton, F. A., Chemical Applications of Group Theory, John Wiley & Sons: New York, 1990</ref> Mathematical [[group theory]] provides the language to describe the shapes of molecules according to their "[[Molecular symmetry|point group symmetry]]". Group theory also enables factoring and simplification of theoretical calculations. Spectroscopic features are analyzed and described with respect to the symmetry properties of the, ''inter alia'', vibrational or electronic states. Knowledge of the symmetry properties of the ground and excited states allows one to predict the numbers and intensities of absorptions in vibrational and electronic spectra. A classic application of Group Theory is the prediction of the number of C-O vibrations in substituted metal carbonyl complexes. The most common applications of symmetry to spectroscopy involve vibrational and electronic spectra. As an instructional tool, Group Theory highlights commonalities and differences in the bonding of otherwise disparate species, such as [[Tungsten(VI) fluoride|WF<sub>6</sub>]] and [[Molybdenum hexacarbonyl|Mo(CO)<sub>6</sub>]] or [[Carbon dioxide|CO<sub>2</sub>]] and [[Nitrogen dioxide|NO<sub>2</sub>]]. ===Reaction pathways=== The theory of chemical reactions is more challenging than the theory for a static molecule. [[Marcus theory]] provides a powerful linkage between bonding, mechanism, and reactivity. The relative strengths of metal-ligand bonds, which can be calculated theoretically, anticipates the kinetically accessible pathways. ==Thermodynamics and inorganic chemistry== An alternative quantitative approach to inorganic chemistry focuses on energies of reactions. This approach is highly traditional and [[empirical]], but it is also useful. Broad concepts that are couched in thermodynamic terms include [[redox potential]], [[acidity]], [[phase (matter)|phase]] changes. A classic concept in inorganic thermodynamics is the [[Born-Haber cycle]], which is used for assessing the energies of elementary processes such as [[electron affinity]], some of which cannot be observed directly. ==Mechanistic inorganic chemistry== An important and increasingly popular aspect of inorganic chemistry focuses on reaction pathways. The mechanisms of reactions are discussed differently for different classes of compounds. ===Main group elements and lanthanides=== The mechanisms of main group compounds of groups 13-18 are usually discussed in the context of organic chemistry (organic compounds are main group compounds, after all). Elements heavier than C, N, O, and F often form compounds with more electrons than predicted by the [[octet rule]], as explained in the article on [[hypervalent]] molecules. The mechanisms of their reactions differ from organic compounds for this reason. Elements lighter than [[carbon]] ([[Boron|B]], [[Beryllium|Be]], [[Lithium|Li]]) as well as [[Aluminium|Al]] and [[Magnesium|Mg]] often form electron-deficient structures that are electronically akin to [[carbocation]]s. Such electron-deficient species tend to react via associative pathways. The chemistry of the lanthanides mirrors many aspects of chemistry seen for aluminium. ===Transition metal complexes=== Mechanisms for the reactions of transition metals are discussed differently from main group compounds.<ref>R. G. Wilkins "Kinetics and Mechanism of Reactions of Transition Metal Complexes" Wiley-VCH Verlag; 2nd, 1991) ISBN 3-527-28389-7</ref> The important role of d-orbitals in bonding strongly influences the pathways and rates of ligand substitution and dissociation. These themes are covered in articles on [[coordination chemistry]] and [[ligand]]. Both associative and dissociative pathways are observed. An overarching aspect of mechanistic transition metal chemistry is the kinetic lability of the complex illustrated by the exchange of free and bound water in the prototypical complexes [M(H<sub>2</sub>O)<sub>6</sub>]<sup>n+</sup>: :[M(H<sub>2</sub>O)<sub>6</sub>]<sup>n+</sup> + 6 H<sub>2</sub>O* → [M(H<sub>2</sub>O*)<sub>6</sub>]<sup>n+</sup> + 6 H<sub>2</sub>O :where H<sub>2</sub>O* denotes [[isotope|isotopically]] enriched water, e.g. H<sub>2</sub><sup>17</sup>O The rates of water exchange varies by 20 orders of magnitude across the periodic table, with lanthanide complexes at one extreme and Ir(III) species being the slowest. ====Redox reactions==== Redox reactions are prevalent for the transition elements. Two classes of redox reaction are considered: atom-transfer reactions, such as oxidative addition/reductive elimination, and [[electron transfer|electron-transfer]]. A fundamental redox reaction is "self-exchange", which involves the [[Degenerate energy level|degenerate]] reaction between an oxidant and a reductant. For example, [[permanganate]] and its one-electron reduced relative [[potassium manganate|manganate]] exchange one electron: :[MnO<sub>4</sub>]<sup>−</sup> + [Mn*O<sub>4</sub>]<sup>2−</sup> → [MnO<sub>4</sub>]<sup>2−</sup> + [Mn*O<sub>4</sub>]<sup>−</sup> ====Reactions at ligands==== Coordinated ligands display reactivity distinct from the free ligands. For example, the acidity of the ammonia ligands in [[Cobalt(III) hexammine chloride|[Co(NH<sub>3</sub>)<sub>6</sub>]<sup>3+</sup>]] is elevated relative to NH<sub>3</sub> itself. Alkenes bound to metal cations are reactive toward nucleophiles whereas alkenes normally are not. The large and industrially important area of [[catalysis]] hinges on the ability of metals to modify the reactivity of organic ligands. [[Homogeneous catalysis]] occurs in solution and [[heterogeneous catalysis]] occurs when [[gas]]eous or [[solution|dissolved]] substrates interact with surfaces of solids. Traditionally [[homogeneous catalysis]] is considered part of organometallic chemistry and [[heterogeneous catalysis]] is discussed in the context of [[Surface chemistry|surface science]], a subfield of solid state chemistry. But the basic inorganic chemical principles are the same. Transition metals, almost uniquely, react with small molecules such as CO, H<sub>2</sub>, O<sub>2</sub>, and C<sub>2</sub>H<sub>4</sub>. The industrial significance of these feedstocks drives the active area of catalysis. ==Characterization of inorganic compounds== Because of the diverse range of elements and the correspondingly diverse properties of the resulting derivatives, inorganic chemistry is closely associated with many methods of analysis. Older methods tended to examine bulk properties such as the electrical conductivity of solutions, [[melting point]]s, [[solubility]], and [[acidity]]. With the advent of [[Quantum mechanics|quantum theory]] and the corresponding expansion of electronic apparatus, new tools have been introduced to probe the electronic properties of inorganic molecules and solids. Often these measurements provide insights relevant to theoretical models. For example, measurements on the [[Ultra-violet photoelectron spectroscopy|photoelectron spectrum]] of [[methane]] demonstrated that describing the bonding by the two-center, two-electron bonds predicted between the carbon and hydrogen using [[Valence Bond Theory]] is not appropriate for describing ionisation processes in a simple way. Such insights led to the popularization of [[molecular orbital theory]] as fully delocalised orbitals are a more appropriate simple description of electron removal and electron excitation. Commonly encountered techniques are: * [[X-ray crystallography]]: This technique allows for the 3D determination of [[molecular structure]]s. * Various forms of [[spectroscopy]] ** [[Ultraviolet-visible spectroscopy]]: Historically, this has been an important tool, since many inorganic compounds are strongly colored ** [[NMR spectroscopy]]: Besides <sup>1</sup>[[Hydrogen|H]] and <sup>13</sup>[[Carbon|C]] many other "good" NMR nuclei (e.g. <sup>11</sup>[[Boron|B]], <sup>19</sup>[[Fluorine|F]], <sup>31</sup>[[Phosphorus|P]], and <sup>195</sup>[[Platinum|Pt]]) give important information on compound properties and structure. Also the NMR of paramagnetic species can result in important structural information. Proton NMR is also important because the light hydrogen nucleus is not easily detected by X-ray crystallography. ** [[Infrared spectroscopy]]: Mostly for absorptions from [[:category:carbonyl complexes|carbonyl ligands]] ** [[Electron-nuclear double resonance]] (ENDOR) spectroscopy **[[Mossbauer spectroscopy|Mössbauer spectroscopy]] ** [[Electron-spin resonance]]: ESR (or EPR) allows for the measurement of the environment of [[paramagnetic]] metal centres. * [[Electrochemical|Electrochemistry]]: [[Cyclic voltammetry]] and related techniques probe the redox characteristics of compounds. ==Synthetic inorganic chemistry== Although some inorganic species can be obtained in pure form from nature, most are synthesized in chemical plants and in the laboratory. Inorganic synthetic methods can be classified roughly according the volatility or solubility of the component reactants.<ref>Girolami, G. S.; Rauchfuss, T. B. and Angelici, R. J., Synthesis and Technique in Inorganic Chemistry, University Science Books: Mill Valley, CA, 1999</ref> Soluble inorganic compounds are prepared using methods of [[organic synthesis]]. For metal-containing compounds that are reactive toward air, [[Schlenk line]] and [[glove box]] techniques are followed. Volatile compounds and gases are manipulated in “vacuum manifolds” consisting of glass piping interconnected through valves, the entirety of which can be evacuated to 0.001 mm Hg or less. Compounds are condensed using [[liquid nitrogen]] (b.p. 78K) or other [[cryogen]]s. Solids are typically prepared using tube furnaces, the reactants and products being sealed in containers, often made of fused silica (amorphous SiO<sub>2</sub>) but sometimes more specialized materials such as welded Ta tubes or Pt “boats”. Products and reactants are transported between temperature zones to drive reactions. ==References== {{WVD}} <references/> ==See also== * [[List of important publications in chemistry#Inorganic chemistry|Important publications in inorganic chemistry]] * [[Non-life]] ==Links== Links to Online Inorganic Chemistry Journals[http://www.chemseer.com/journals/journals_inorganic.shtml] {{BranchesofChemistry}} [[Category:Inorganic chemistry| ]] [[Category:Chemistry]] {{Link FA|lmo}} [[af:Anorganiese chemie]] [[ar:كيمياء لاعضوية]] [[be:Неарганічная хімія]] [[bg:Неорганична химия]] [[ca:Química inorgànica]] [[cs:Anorganická chemie]] [[da:Uorganisk kemi]] [[de:Anorganische Chemie]] [[el:Ανόργανη χημεία]] [[es:Química inorgánica]] [[eo:Neorganika kemio]] [[fa:شیمی معدنی]] [[fo:Ólívrunnin evnafrøði]] [[fr:Chimie inorganique]] [[gl:Química inorgánica]] [[ko:무기화학]] [[id:Kimia anorganik]] [[it:Chimica inorganica]] [[he:כימיה אי-אורגנית]] [[la:Chemia Inorganica]] [[lv:Neorganiskā ķīmija]] [[lb:Anorganesch Chimie]] [[lt:Neorganinė chemija]] [[lmo:Chímica inurgànica]] [[hu:Szervetlen kémia]] [[ms:Kimia tak organik]] [[nl:Anorganische chemie]] [[ja:無機化学]] [[no:Uorganisk kjemi]] [[nn:Uorganisk kjemi]] [[nds:Anorgaansch Chemie]] [[pl:Chemia nieorganiczna]] [[pt:Química inorgânica]] [[ro:Chimie anorganică]] [[ru:Неорганическая химия]] [[sk:Anorganická chémia]] [[sq:Kimia inorganike]] [[sr:Неорганска хемија]] [[sh:Anorganska hemija]] [[su:Kimia anorganik]] [[fi:Epäorgaaninen kemia]] [[sv:Oorganisk kemi]] [[th:เคมีอนินทรีย์]] [[vi:Hóa vô cơ]] [[tr:İnorganik kimya]] [[uk:Неорганічна хімія]] [[zh:无机化学]]