Molybdenum is an element with an extremely rich and interesting chemistry having very versatile applications in various fields of human activity. It is used extensively in metallurgical applications. Because of their anti-wear properties, molybdenum compounds find wide applications as lubricants - particularly in extreme or hostile environmental situations. Many molybdates and heteropolymolybdates are white and therefore used as pigments. In addition, they are non-toxic and act as efficient corrosion inhibitors and smoke suppressants. Hydroprocessing of petroleum is one of the largest industries employing heterogeneous catalysts. Molybdenum catalysts have shown great promise in the liquefaction of coal and this may develop into one of its most important catalytic uses. The use of molybdenum compounds in homogeneous catalysis is also significant. Three important classes of molybdenum compounds in the solid state are reviewed, viz., oxides, sulphides and halides. The role of molybdenum in inorganic catalysis and enzymes receives prominent mention because of their impact on the progress of science and technology. Further biochemical and enzymic factors are discussed in separate chapters and their reaction to agriculture and animal husbandry. A new classification of covalent compounds which abandons the traditional oxidation state concept allows a powerful approach to the organisation of the complex and rich chemistry of molybdenum. Dramatic colour diagrams of abundances of molybdenum compounds provide broad insights into the important features and trends in the chemistry of molybdenum including reactivity and mechanism. The book is intended for use mainly as a research monograph by the many workers who may encounter molybdenum chemistry or who are looking for its application and potential uses in different technological fields. However, it will also serve as an advanced text for university lecturers and postgraduate students interested in inorganic, physical and industrial chemistry, chemical technology or biochemistry and biotechnology.

This volume 8 is the fourth in a series dealing with organomolybdenum compounds. An Empirical Formula Index and a Ligand Formula Index provide ready access to the compounds covered. Volume 5 describes mononuclear organomolybdenum compounds with isocyanide, 3 4 carbene, carbyne, alkynyl, alkene, alkyne, L, and L ligands with and without additional CO groups. Volume 6 starts the description of mononuclear organomolybdenum compounds with 5 one L Ligand, a Ligand bonded to molybdenum by five carbon atoms. The compounds contain either zero or one CO group bonded to the molybdenum atom. Volume 7 continues the 5 description of L-molybdenum compounds containing two CO groups, but no additional nl 5 ligands. This volume describes L-molybdenum compounds with two CO groups and additional 1 4 L to L ligands. Following the nomenclature used in this series of organomolybdenum com pounds, nl is an organic Ligand bonded by n C atoms to molybdenum, and mo is an electron 2 donor Ligand with m donor electrons. Thus 0 denotes a Ligand such as PR . 3 Many of the data, particular those in tables, are given in an abbreviated form without units; for explanations see p. X. Additional information, if necessary, is given before the individual table. Frankfurt am Main Manfred Winter November 1992 Wolfgang Petz X Remarks on Abbreviations and Dimensions Many compounds in this volume are presented in tables in which numerous abbreviations are used, the dimensions are omitted for the sake of conciseness. This necessitates the following clarifications.

In the first part of this volume the nitrogen-containing compounds of molybdenum are described. The Mo-N system shows that M0 N and MoN are the stable nitrides. MOlybdenum 2 metal dissolves nitrogen to some extent but only at high temperatures. To get better insight into the reactions between nitrogen and molybdenum, the solubility, diffusion, adsorption and desorption phenomena, and ion bombardment are included in the section of the Mo-N system. M0 N has a large range of homogeneity toward lower nitrogen concentrations. The black 2 hexagonal MoN has only a narrow range of homogeneity. In addition some molybdenum compounds containing nitrogen and oxygen are known. The second part contains a full description of the compounds of molybdenum with fluorine. The fluorides MoF n with n ~ 2 are metastable while those with n = 3 to 6 are stable and have been observed in the Mo-F system. Pure MoF can exist without traces of oxygen, in co nt rast 3 to earlier assumptions. MoF was unambigously prepared and characterized in 1957. Its crystal 4 structure is still unknown. MoF is often contaminated with the oxide fluoride MoOF and it is s 4 difficult to remove. Even sm all amounts affect the properties of MoF . MoF , which is liquid at s 6 room temperature and solidifies to a "plastic" crystal modification below ca. 17SC, is the most investigated of all the molybdenum fluorides.

Molybdenum and its compounds (oxides, sulphides, carbides, nitrides, selenides, molybdates and molybdenum complexes) have a number of applications in alloys, catalysts, electrochromics, sensors, capacitors, batteries, solar cells and so on. Promising works on their nanostructures have been reported as a means to enhance the performance of materials. The present book is an edited volume on molybdenum and its compounds in different applications. There are chapters concentrating on molybdenum and its alloys, molybdenum oxides, molybdenum sulphides, molybdenum carbides, molybdenum nitrides, molybdenum selenides, molybdenum blues, Keplerate-type molecular spheres, molybdenum complexes and molybdates.

This volume 8 is the fourth in a series dealing with organomolybdenum compounds. An Empirical Formula Index and a Ligand Formula Index provide ready access to the compounds covered. Volume 5 describes mononuclear organomolybdenum compounds with isocyanide, 3 4 carbene, carbyne, alkynyl, alkene, alkyne, L, and L ligands with and without additional CO groups. Volume 6 starts the description of mononuclear organomolybdenum compounds with 5 one L Ligand, a Ligand bonded to molybdenum by five carbon atoms. The compounds contain either zero or one CO group bonded to the molybdenum atom. Volume 7 continues the 5 description of L-molybdenum compounds containing two CO groups, but no additional nl 5 ligands. This volume describes L-molybdenum compounds with two CO groups and additional 1 4 L to L ligands. Following the nomenclature used in this series of organomolybdenum com pounds, nl is an organic Ligand bonded by n C atoms to molybdenum, and mo is an electron 2 donor Ligand with m donor electrons. Thus 0 denotes a Ligand such as PR . 3 Many of the data, particular those in tables, are given in an abbreviated form without units; for explanations see p. X. Additional information, if necessary, is given before the individual table. Frankfurt am Main Manfred Winter November 1992 Wolfgang Petz X Remarks on Abbreviations and Dimensions Many compounds in this volume are presented in tables in which numerous abbreviations are used, the dimensions are omitted for the sake of conciseness. This necessitates the following clarifications.

The Chemistry of Chromium, Molybdenum and Tungsten deals with the chemistry of chromium, molybdenum, and tungsten. The discovery and history, occurrence and distribution, and production of all three elements are discussed, along with their industrial uses, preparation, and allotropes; nuclear, physical, and chemical properties; biological activities; and analytical chemistry. Organized into three sections, this volume begins with an overview of the history, occurrence and distribution, and production of chromium, molybdenum, and tungsten, as well as their industrial uses, preparation, and allotropes; nuclear, physical, and chemical properties; biological activities; and analytical chemistry. The intermetallic phases in binary alloys of all three elements are also considered, along with their oxidation states and respective compounds including compounds with non-metallic elements; compounds of ?-acceptor ligands; organometallic complexes; and peroxy compounds such as peroxychromates, tetraperoxy molybdates, and peroxy tungstates. This book will be of interest to inorganic chemists as well as students and researchers in the field of inorganic chemistry.