Complex, thermal decomposition

Reaction at 160°-170°C between the 76°C dimer and Fe(CO)5 (326) produces in addition to complex (129), the trinuclear complex (CiciHi6)Fe3(CO)9 (m.p. 170°C), the binuclear species (Ci,jHiR)Fe2(CO)(i (m.p. 191°C),and a small amount of another isomer of (Ci,jHiR)Fe(CO)3 melting at 175°-180°C. On the basis of its Mbssbauer spectrum and its temjierature-independent NMR spectrum, structure (132) has been assigned (523) to the trinuclear complex. Thermal decomposition of (Ci6Hi(i)Fe3(CO)j) yields two isomeric forms of (Ci(,Hig)Fe2(CO)o, one identical to that mentioned above and another possessing the same melting point. To these complexes the structures (133) and (134), respectively, based on NMR data, have been assigned. 

The deposition of platinum, rhodium and ruthenium acetylacetonates on titania takes place by reaction with the surface hydroxy groups to give a supported complex. Thermal decomposition of these supported complexes in vacuum gave highly dispersed titania supported metal catalysts having metal particles about 2 nm in diameter. ... 

In reality, the phenomena are complex. Thermal decomposition is superimposed on catalytic decomposition and, at the same time, both homolytic and heterolytic mechanisms occur. The fast equilibrium that is established between peracid and X peroxide also adds to the complexity of the system, viz. 

Kinetic Stability of Metal Formyl Complexes. Metal formyl complexes have approximately the same kinetic stability as the corresponding metal acetyl complexes. Thermal decomposition of (CH3CH2)4N [(C6-H50)3P] (CO)3FeCHO" in THF at 65°C gives a mixture of two metal hydrides in a 4 1 ratio (CO)4FeH , formed by loss of phosphite and... 

MX of >99% purity can be obtained with the MGCC process with <1% MX left in the raffinate by phase separation of hydrocarbon layer from the complex-HF layer. The latter undergoes thermal decomposition, which Hberates the components of the complex. 

Beryllium Hydride. BeryUium hydride [13597-97-2] is an amorphous, colorless, highly toxic polymeric soHd (H = 18.3%) that is stable to water but hydroly2ed by acid (8). It is insoluble in organic solvents but reacts with tertiary amines at 160°C to form stable adducts, eg, (R3N-BeH2 )2 (9). It is prepared by continuous thermal decomposition of a di-/-butylberylhum-ethyl ether complex in a boiling hydrocarbon (10). 

Rhenium Halides and Halide Complexes. Rhenium reacts with chlorine at ca 600°C to produce rheniumpentachloride [39368-69-9], Re2Cl2Q, a volatile species that is dimeric via bridging hahde groups. Rhenium reacts with elemental bromine in a similar fashion, but the metal is unreactive toward iodine. The compounds ReCl, ReBr [36753-03-4], and Rel [59301-47-2] can be prepared by careful evaporation of a solution of HReO and HX. Substantiation in a modem laboratory would be desirable. Lower oxidation state hahdes (Re X ) are also prepared from the pentavalent or tetravalent compounds by thermal decomposition or chemical reduction. 

The reaction of higher alkyl chlorides with tin metal at 235°C is not practical because of the thermal decomposition which occurs before the products can be removed from the reaction zone. The reaction temperature necessary for the formation of dimethyl tin dichloride can be lowered considerably by the use of certain catalysts. Quaternary ammonium and phosphonium iodides allow the reaction to proceed in good yield at 150—160°C (109). An improvement in the process involves the use of amine—stannic chloride complexes or mixtures of stannic chloride and a quaternary ammonium or phosphonium compound (110). Use of these catalysts is claimed to yield dimethyl tin dichloride containing less than 0.1 wt % trimethyl tin chloride. Catalyzed direct reactions under pressure are used commercially to manufacture dimethyl tin dichloride. 

Trichlorotitanium monoacylates form, dufing thermal decomposition of TiCl, ester complexes (128) ... 

Future Methods. A by-product stream containing 60—80% PEA can be obtained from the catalytic air oxidation of ethylbenzene [100-41-4] (100). Perfumery-grade material can be isolated from this stream by complexing the PEA with a metal haUde (such as CaCl2), separation of the adduct, and thermal decomposition followed by distillation. 

Pyrolysis Thermal decomposition of 1,1,1,2-tetrachloroethane produces tetrachloroethylene (by disproportionation), hydrogen chloride, and trichloroethylene via dehydrochlorination (111). The yield of the latter is increased in the presence of ferric chloride (112). Other catalytic materials include FeCl —KCl mixture (113), AlCl (6), the complex of AlCl with nitrobenzene (114), activated alumina (3), Ca(OH)2 (115,116), and NaCl (94). 

Chromia—alumina catalysts are prepared by impregnating T-alumina shapes with a solution of chromic acid, ammonium dichromate, or chromic nitrate, followed by gentie calciaation. Ziac and copper chromites are prepared by coprecipitation and ignition, or by thermal decomposition of ziac or copper chromates, or organic amine complexes thereof. Many catalysts have spiael-like stmctures (239—242). 

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