bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nickel: Organometallic ChemistryBased in part on the article Nickel: Organometallic Chemistry by Clifford P. Kubiak which appeared in the
Encyclopedia of Inorganic Chemistry, First Edition
.
Authors: Zargarian Davit 
Published: December 2011

Abstract
The organometallic chemistry of nickel has experienced rapid growth over the past decade. A number of exciting new areas have emerged, such as the reactivities of Ni(0)‐carbene complexes and the polymerization of olefins catalyzed by nickel complexes of nitrogen‐based ligands. In addition, the traditionally rich area of Ni‐catalyzed organic transformations has undergone major developments that have expanded the scope of their applications. These are the subjects of the present chapter.
Among the topics that will be discussed are the preparation, characterization, and reactivity studies of nickel complexes of allyl, cyclopentadienly, indenyl, and tris(pyrazolyl)borate ligands. The main structural and bonding properties of these complexes are presented and their major reactivities are outlined. Another topic of importance is the chemistry of the nickel complexes of hydride, alkyl, alkenyl, and silyl ligands. Hydrido and alkyl complexes of nickel are often involved in many catalytic processes of commercial importance, and so an in‐depth understanding of the fundamental reactivities of these complexes is crucial to expanding their practical applications. Silyl complexes are involved in the transformations of organosilicon compounds, and for this reason their basic reactivities and structural properties are of interest.
Zerovalent nickel complexes are also very important in the catalytic organic transformations. One of the most exciting developments in this area is the recent introduction of N‐heterocyclic carbene ligands. Ni complexes of these ligands have been shown to be important catalysts and reagents for a number of important organic transformations. Some of the practical methods for preparing Ni‐carbene complexes will be outlined, and the recently reported catalytic reactions promoted by these complexes will be described.

One of the most important areas of growth for the chemistry of nickel has been the polymerization and copolymerization of olefins. Thus, this chapter will describe the discovery of a family of diimine complexes that catalyze the polymerization of aliphatic olefins. A series of new and highly efficient catalysts were introduced in rapid progression, a great deal of new chemistry has been discovered, and a number of industrial processes have been developed on the basis of these nickel complexes. We will also discuss the emergence of new strategies for the efficient cross‐coupling of alkyl halides with organozinc and Grignard reagents, as well as the coupling of dienes with CO
2
.
Niobium & Tantalum: Inorganic & Coordination Chemistry
Authors: Hubert‐Pfalzgraf Liliane G. 
Published: December 2011

Abstract

The chemistry of niobium and tantalum ranges from oxidation states +V to −III with no species of oxidation state −II known so far. The chemistry of those oxophilic metals is dominated by their highest oxidation states, V and IV. Pentahalides especially chlorides are the most usual starting material. They form numerous complexes especially with hard donors and are used for access not only to pentavalent metal alkoxides, amides, thiolates, and so on but also to most molecular species in lower oxidation states. Oxo species are formed quite easily by O‐donor abstraction reactions or adventitious hydrolysis. Pentavalent alkoxides are active in various catalytic processes and are useful precursors for access to oxide ceramics such as ferroelectrics via the formation of heterometallic species. The most relevant results in organometallic chemistry of Nb and Ta have been obtained with ancillary, bulky aryloxide or siloxide ligands. Niobium is more prone to reduction than tantalum. Chalcogenides and chalcogenohalides are often one–dimensional solids and display a rich structural and synthetic chemistry. Numerous trispyrazolylborate derivatives of Nb and Ta have been reported for oxidation states V to I. The development of the nonaqueous chemistry of those elements in intermediate oxidation states has become an active and fruitful area. Species based on MM or MM multiple bonds, the latter especially for Nb, have been characterized. The NbNb triple bond (2.20 Å) is much shorter than the MM distance in the metal. Tri‐ or divalent species are able to promote CE (E = O, S, N) cleavage and thus to generate novel ligands because of the trend of Nb and Ta to form multiple ME bonds and attain their highest oxidation states. CC coupling reactions are observed with unsaturated ligands (alkynes, nitriles, etc.). M
III
η
2
‐alkyne complexes have a metallocyclopropene character; they can react with unsaturated organic molecules via stoichiometric reactions. The reservoir of electrons of the MM bond is also of interest for activation of small molecules such as N
2
, H
2
, CO, and so on. Tri or tetradentate N,N; N,P; or N,O ligands have been used to stabilize dimeric dia or paramagnetic dinitrogen complexes. The bridging, highly activate N
2
ligand is amenable to functionalization in some cases, and cleavage into nitrides has been observed. The chemistry of reduced Nb and Ta halides is rich in clusters with nonintegral oxidation states (between III and I). Hexanuclear clusters dominate the aqueous chemistry for these oxidation states. One of their potential applications could be their use as contrasting agents. The species in the lowest oxidation states are essentially based on carbonyl ligands.
Nitrogen: Inorganic ChemistryBased in part on the article Nitrogen: Inorganic Chemistry by Harry H. Sisler which appeared in theEncyclopedia of Inorganic Chemistry, First Edition.
Authors: Hammerl Anton , Klapötke Thomas M. 
Published: December 2011

AbstractThe chemistry of nitrogen and its compounds with hydrogen, oxygen, and halogens is discussed in this article. The high stability of the nitrogen–nitrogen triple bond in dinitrogen in comparison with nitrogen–nitrogen single or double bonds makes polynitrogen compounds promising, highly energetic materials. Recently, several new polynitrogen species have been detected experimentally and salts of the polynitrogen cation N5+have been isolated in bulk. Salts of the azide anion N3−are already used as highly energetic materials.Binary compounds of nitrogen and hydrogen include ammonia, hydrazine, and several metastable species with nitrogen–nitrogen bonds. Ammonia, which is the starting material for all industrially produced nitrogen compounds, is probably the most important industrial chemical. Most of the ammonia produced is used as fertilizer, whereas hydrazine is used as an energetic material.The monomeric nitrogen oxides are among the most simple odd‐electron molecules and play an important role in the chemistry of the atmosphere. In combustion engines, huge amounts of nitric oxide are formed, which influence the ozone cycle both in the troposphere and in the stratosphere. Nitric oxide is a chemical messenger in biological systems and it helps to regulate a diverse array of physiological processes, such as neurotransmission, blood pressure and blood clot prevention.Oxoacids of nitrogen include hydroxylamine, nitrous acid, and nitric acid. Nitric acid is a major industrial chemical, which is primarily used for nitrate fertilizer production. Hydroxylamine is a starting material for the production of polyamide synthetics.Chlorine, bromine, and iodine halogen nitrogen compounds include halogensubstituted derivatives of ammonia, hydrazine, and diimine. They are unstable species that decompose to molecules in excited states. Nitrogen fluorides are thermodynamically more stable than the other nitrogen halides.Ternary compounds of nitrogen, oxygen, and halogens include nitrosyl‐ and nitrylhalides as well as the halogen nitrates. The stability of these compounds decreases from fluorine to iodine.
Oligomerization & Polymerization by Homogeneous Catalysis
Authors: Hlatky Gregory G. 
Published: December 2011

AbstractThe metal‐catalyzed oligomerization and polymerization of alkenes by homogeneous metal complexes has not only provided extraordinary insights into the chain‐growth process, it has also become of increasing commercial importance in delivering products of greater purity or improved properties. Novel materials not accessible using conventional heterogeneous catalysts can now be synthesized. Metals are no longer constrained to certain functions (titanium for polymerization, nickel for oligomerization) but span the range of molecular weights and polymer structures. This review discusses the fundamentals of chain‐growth polymerization catalyzed by homogeneous complexes and new developments in the field.
Osmium: Inorganic & Coordination Chemistry
Authors: Collinson Simon R. , Schröder Martin 
Published: December 2011

AbstractThe general features and coordination chemistry of Os are discussed in the context of the use of different ligand types to stabilize complexes of OsVIIIthrough to Os−II. The complexation chemistry with cyanide, N‐, P‐, O‐, S‐, and halide‐donor ligands is detailed. The asymmetric dihydroxylation and aminohydroxylation of alkenes, general coordination chemistry with macrocyclic and open chain ligands, porphyrin complexes, photophysical properties and electrochemistry of OsIIcomplexes of heterocyclic ligands and comparisons to their RuIIanalogues, and electron transfer in heterobimetallic and dendrimer complexes of OsIIare all highlighted.
Oxidation Catalysis by Transition Metal Complexes
Authors: Crabtree Robert H. 
Published: December 2011

AbstractOxidation catalysis is reviewed with emphasis on radical versus nonradical pathways, autoxidation, and mechanistic studies. Bioinorganic model catalysts are discussed, including the distinction between monooxygenase and dioxygenase pathways. Some organic synthetic applications as well as applications to green chemistry are discussed. Finally some organometallic oxidation catalysts are discussed.
Oxygen: Inorganic ChemistryBased in part on the article Oxygen: Inorganic Chemistry by Donald T. Sawyer which appeared in theEncyclopedia of Inorganic Chemistry, First Edition.
Authors: Bharara Mohan S. , Atwood David A. 
Published: December 2011

AbstractThe present review will provide a systematic and complete coverage of the formation, chemical properties, and reactivity of a wide range of common oxygen‐containing species. These include dioxygen, ozone, hydrogen peroxide, oxide, superoxide, and hydroxide, as well as the radical forms of most of these species.
P‐Donor LigandsBased in part on the article P‐Donor Ligands by Charles A. McAuliffe & Anthony G. Mackie which appeared in theEncyclopedia of Inorganic Chemistry, First Edition.
Authors: Schier Annette , Schmidbaur Hubert 
Published: December 2011

AbstractOrganophosphorus compounds of various types are among the most important classes of ligands in the coordination chemistry of the transition elements. This is particularly true for the tertiary phosphines R3P, which are known to stabilize complexes of metals in low oxidation states, while secondary and primary phosphines, R2HP and RPH2, are less common. The donor properties and the stereochemistry can be tuned by using carefully designed substitution patterns. More recently, organophosphorus compounds with low‐coordinate phosphorus atoms have also been employed as ligands in metal complexes. These include mainly phosphaalkenes and phosphaalkynes, phosphinidenes, diphosphenes, phosphinines, phosphonium cations, and even elemental phosphorus.
Palladium: Organometallic Chemistry
Authors: William Suggs J. 
Published: December 2011

Abstract

Four oxidation states of palladium are encountered in organometallic chemistry. In order of importance, they are Pd
II
, Pd
0
, Pd
IV
, and Pd
I
. With the reduction of palladium from Pd
II
to Pd
0
, the metal changes its reactivity from electrophile to nucleophile. Ligands π‐bound to Pd
II
, such as π‐allyl, alkene, and alkyne, show enhanced reactivity toward nucleophiles, particularly less basic nucleophiles such as malonates. Pd
0
species, such as (PR
3
)

n

Pd, are powerful nucleophiles. They undergo oxidative addition to alkyl, aryl, and vinyl halides to produce LnPd
II
‐R species. If the R group is an alkyl group with β‐hydrogens, a beta‐elimination of H usually takes place, giving a palladium hydride and an alkene. If the R group is aryl or vinyl, the species does not undergo beta‐elimination. Instead, if a second R′ group is bonded to the palladium center, reductive elimination can take place, forming R–R′. Alternatively, the PdR bond can add across an unsaturated group, such as an alkene, forming a new carbon–carbon bond. New carbon–palladium bonds can also form through transmetalation. Organotin, organoboron, organosilicon (and other main group and transition metal organometallic reagents) will react with Pd
II
halides to give new Pd
II
‐R bonds and R
3
SnX (or analogous) species. Because Pd
II
‐C bonds are neither very strong nor very weak (on the order of 160 kJ mol
−1
), palladium can catalyze many organic reactions. For example, in the Suzuki reaction, an aryl boronic acid (ArB(OH)
2
) and an aryl halide (Ar′X) are coupled to form a biaryl, Ar–Ar′. The mechanism involves a Pd
0
species undergoing oxidative addition to the Ar′X, forming L

n

Pd
II
Ar′(X), then transmetalation giving a L
n
Pd
II
Ar(Ar′) and, finally, reductive elimination forming Ar–Ar′ and regenerating L

n

Pd
0
. Palladium‐catalyzed reactions are increasingly being used in the synthesis of high value‐added chemicals such as pharmaceuticals. With basic, hindered phosphine ligands, such as P(
t
‐Bu)
3
, Pd
0
reagents undergo oxidative addition even with aryl chlorides, and new reactions, such as the arylation of amines (ArX + HNR
2
giving ArNR
2
) are possible.
Paramagnetic Organometallic Complexes
Authors: Leznoff Daniel B. , Mund Garry 
Published: December 2011

AbstractThe synthesis, characterization, and reactivity of paramagnetic (or open‐shell) organometallic species are described. Many stable complexes featuring transition metals, lanthanides, and actinides have been reported. These systems, which are exceptions to the 18‐electron rule (or 16‐electron rule), are increasingly being used in the catalytic realm, and also have different reactivity patterns compared to their diamagnetic counterparts due to the presence of the unpaired electrons. The formation and subsequent stability of paramagnetic organometallic complexes in violation of the 18‐electron rule can be explained via molecular orbital theory in terms of (1) the use of π‐donor ligands (as opposed to the ubiquitous π‐acceptor ligands usually found in organometallic chemistry); (2) kinetic stabilization with sterically demanding ligands; (3) partially filled molecular orbitals being nonbonding or slightly antibonding/bonding. Although metallocene‐based complexes are probably the most well studied of all paramagnetic organometallic complexes, homoleptic σ‐alkyl complexes and other non‐Cp systems have also been explored. Such non‐Cp ancillary ligands include amido‐, alkoxo‐, and thiolato‐ligands, β‐diketiminate ligands, and tris(pyrazolylborate) ligands. f‐electron organometallic systems also utilize a similar range of ligands, but due to their larger size, they can accommodate more sterically congested coordination spheres; for example, Cp*3M complexes can be prepared, and they show unusual reactivity pathways.Open‐shell organometallic molecules are known to span a range of electron counts from 8–20. Nineteen‐electron organometallic complexes are of particular interest with respect to the location of the extra electron residing primarily on the metal or on the ligand (in this case, the complex is referred to as an 18 + δ system).The discussion of short‐lived paramagnetic organometallic systems revolves around 17‐ and 19‐electron radicals, and their use in catalytic processes and as ‘super reducing agents.’ Many reactivity pathways for such organometallic radicals (or ‘metalloradicals’) have been identified.Characterization tools for paramagnetic organometallic complexes, such as NMR and ESR spectroscopy, DFT calculations, and magnetic measurements are presented. Variable temperature NMR studies and2H NMR can be of significant use in interpreting paramagnetic NMR spectra. Solid‐state NMR spectroscopy of paramagnetic organometallic systems is still in its infancy. The applications of paramagnetic organometallic complexes span many areas including catalysis (e.g. olefin polymerization), synthetic organic chemistry, and the development of molecule‐based magnetic materials.
Phosphorus–Nitrogen CompoundsBased in part on the article Phosphorus–Nitrogen Compounds by Robert H. Neilson which appeared in theEncyclopedia of Inorganic Chemistry, First Edition.
Authors: Haiduc Ionel 
Published: December 2011

AbstractPhosphorus displays several oxidation states (+II,+III, +IV, and+V) and coordination numbers (from one to six), and with nitrogen (also two‐, three‐, and four‐coordinate) can form a broad variety of compounds (purely inorganic or organo‐N‐ or ‐P‐substituted). In addition to mononuclear PN compounds, many short‐chain, polymeric, and cyclic compounds based on molecular skeletons formed by PN alternation are known. There are numerous classes of phosphorus–nitrogen compounds, and this article makes an attempt to introduce the most important ones in the limited space available by selecting what seem to be the most illustrative examples from a very rich chapter of chemistry.
Phosphorus: Organophosphorus Chemistry
Authors: Engel Robert , Cohen JaimeLee Iolani 
Published: December 2011

AbstractThe chemistry associated with compounds bearing at least one carbon–phosphorus bond has been surveyed. This survey has been organized on the basis of the coordination about the phosphorus center, beginning with monocoordinated phosphorus and continuing through hexacoordinated phosphorus. Preparations, stereochemistry, and reactivity are principal topics considered.
Photochemistry of Transition Metal Complexes: TheoryBased in part on the article Photochemistry of Transition Metal Complexes: Theory by Jeffrey I. Zink which appeared in the
Encyclopedia of Inorganic Chemistry, First Edition
.
Authors: Daniel Chantal 
Published: December 2011

Abstract
The most significant developments in quantum chemistry and wave packet dynamics that provide the theoretical tools to study the electronic spectroscopy and photoreactivity of transition metal complexes are presented. The difficulties inherent to this class of molecules as well as the degree of maturity of the theoretical approaches are discussed. Recent applications in the chemistry of transition metal complexes are selected to outline and to illustrate the necessity for a strong interplay between theory and experiments.
Platinum: Inorganic & Coordination Chemistry
Authors: Crabtree Robert H. , Torrens Hugo 
Published: December 2011

AbstractThe articlePlatinum: Inorganic & Coordination Chemistryincludes some historical highlights related to this metal as well as some properties and uses of platinum. Its inorganic and coordination chemistry is illustrated briefly through some specific chemical compounds and reactions. Binary compounds with halides, chalcogen, and related ligands are described. Platinum oxidation states 0 to IV are deal with on separated headings: compounds of Pt(0) predominantly with phosphine ligands; complexes of ‘monovalent’ platinum with PtPt bonds; Pt(II) with a large range of ligands; ‘trivalent’ platinum compounds and finally Pt(IV) bound to a variety of donor atoms. Nearly 70 references help the reader to follow specific topics.
Platinum: Organometallic ChemistryBased in part on the article Platinum: Organometallic Chemistry by Charles M. Lukehart which appeared in the
Encyclopedia of Inorganic Chemistry, First Edition
.
Authors: Chen Jwu‐Ting 
Published: December 2011

Abstract
This article aims to describe the prominent advances of organoplatinum chemistry in the latest decade. Recent development in this field has been much advanced with the design of new ancillary ligands as well as new organic ligands. For the former, the polydentate cyclometallated ligands, tridentate pincer ligands, nitrogen‐donor ligands, and aminocarbenes are discussed. For the latter, in addition to the synthesis and structure of new organoplatinum compounds, a noteworthy growth is to exploit some of these compounds for luminescent materials. The content in this regard is brief since it has been covered as an independent article of this volume. Organoplatinum species with unprecedented bonding modes or new organometallic functionalities are discussed separately. The progress of nano sciences prompts the conceptual revolution in the whole frontier line of chemical research. Organoplatinum chemistry has been contributing in a profound way to construction of the new substances of large skeletons. Exploration starting from clusters and molecular assemblies to organometallic polymers, particularly with rational design, is addressed. Reactions involving the SiH, SiSi, CH, and CC bond formation or cleavage are crucial to hydrosilylation and alkane functionalization respectively. Platinum‐silylene chemistry accounts for a major breakthrough in synthetic chemistry. As to platinum‐hydrides that are mainly concerned in Pt(IV)‐state and are key intermediates in alkane activation, their syntheses and structures are discussed in Section 5. Platinum(IV)‐alkyls are the theme of Section 6. The reaction mechanisms of Pt(II)/Pt(IV) involving aqueous CH activation and other reactions or catalysis involving organoplatinum are summarized at the end.
Polynuclear Organometallic Cluster Complexes
Authors: Keister Jerome B. 
Published: December 2011

Abstract
The title refers to molecular compounds containing three or more transition metal atoms and hydrocarbyl ligands as a part of the metal–carbon cluster core. Because the chemistry of trimetallic clusters is the most well developed, these examples are to be stressed. Selected examples are presented to illustrate the principles of structure and bonding of organometallic clusters, synthetic approaches, and chemical reactions, including ligand substitution, oxidative addition, intramolecular insertion, protonation of metal–metal bonds and coordinated ligands, nucleophilic attack on coordinated ligands, and ligand fluxionality. The chemistry of these clusters is exemplified by trimetallic clusters containing hydrocarbon fragments of one, two, or three carbon atoms. While, many of the features of cluster chemistry are common with those of organometallic complexes containing a single metal atom, there are notable differences in structures and reactivities owing to the tendencies of ligands to bridge between two or more metal atoms and for ligands bound to only a single metal atom to undergo facile intramolecular migrations between metal atoms. These distinctions give rise to the ‘metal‐cluster‐metal surface analogy’ in which structural and spectroscopic features of organometallic clusters are used as models for hydrocarbons chemisorbed on metal surfaces.