Molybdenum(atomic no.42;atomic weight 95.94;mp.2610 deg C;bp.5560 deg C;electronic configuration Kr 4d~55s~1)a chemical element belonging to group 6 of periodic table is a silvery white metal,tough but malleable and softer than glass.Its main mineral ores are molybdenite,powellite and wulfenite.It exists in common oxidation states of -4,-2,0,+2,+4,+6.It is used to prepare a number of alloys because it imparts toughness,weldability and corrosion resistance and is capable of enduring high temperature e.g.,in the manufacture of parts of jet engines.Sodium molybdate is used in manufacture of paints.Mo compounds are also used as catalysts in various industrial processes.Mo is also present in enzymes of nitrogen fixing bacteria such as nitrate reductase and nitrogenase.Nitrogenase contains two proteins molybdoferredoxin and azoferridoxin.Molybdoferredoxin is a brown,air sensitive solid which contains two Mo atoms,24 to 36 Fe atoms and 24 to 36 S atoms together with a protein and has a molecular weight of about 22500.Recently there has been increased interest in various molybdenum compounds for uses in organic synthesis in the laboratory and in industry.Due to its variable oxidation states,there are many stable Mo compounds which have been employed recently in organic synthesis.The present review is a survey of the literature up to 2003 and covering various organic transformations reported with different molybdenum reagents so far.Many of these reagents are available commercially and others may be prepared in the laboratory.The review starts with reactions of Mo(CO)_6 which have been investigated in great details.Wherever available,the probable reaction paths have also been described.
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