Single decarbonylative addition reactions

In addition to substitution of the carbonyl groups, changes in the cyclopentadienyl ring have also been extensively studied. The use of pentamethylcyclopentadiene led to formation of some of the first organometallic multiply bonded complexes as discussed in Section 4.8. The tris(pyrazolyl)borate ion (Tp , see Tris(pyrazolyl)borates) is a Cp analog." It reacts with Mo(CO)6 to yield the TpMo(CO)3 anion. Oxidation yields the paramagnetic radical that shows no tendency to form a single metal-metal bond. Decarbonylation yields a triply bonded stracture. These reactions are summarized in equation (16). 

Mechanism. No single mechanism explains the action of all fire retardants, so they probably work through a combination of several mechanisms. The mechanisms of fire retardants in wood involve a complex series of simultaneous reactions whose products may affect subsequent reactions. Pyrolysis of cellulose involves dehydration, depolymerization, decarbonylation, decomposition of smaller compounds, condensation, and other reactions. These pyrolysis reactions occur both in the solid phase and vapor phase. Addition of fire retardants will alter the reactions however, this alteration will depend on the additives, the material, and the thermal-physical environment. The presence of oxygen adds subsequent and competitive oxidation reactions to the above series. These oxidative reactions can take place in both the solid and vapor phases. Evidence indicates that most fire retardants reduce combustible volatiles production and limit combustion to the solid phase. The best retardants also inhibit solid-phase oxidation to effectively remove the fuel from the fire. 

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