Molybdenum dichloride

Clusters of six molybdenum, niobium, or tantalum atoms have been known for muny years, predating the work with rhenium. There two types In the first, an octahedron of six metal atoms is coordinated by eight chloride ligands, one on each face of the octahedron (Fig. 16.64a). This is found in molybdenum dichloride, MoftCI,2. better formulated as [MoftCIg]CI4. Each Mo(II) atom can use its four electrons to form four bonds with adjacent molybdenum atoms and can receive dative bonds from the four chloride ligands 164... 

Molybdenum dichloride, that is, the chloracid HMo3Cl,.4H20, dissolves in aqueous alkali hydroxides forming yellow solutions which, on boiling, deposit the black dihydroxide Mo(OH)2. The alcoholic solution conducts electricity, the molecular conductivity increasing on dilution hydrogen, the oxychloride Mo3Cl4(OH )2, and sometimes molybdenum are liberated at the cathode, w hilst acetaldehyde and ethyl chloride are formed at the anode. 

The hydroxychlorides Mo3Cl4(OH)2.2H20 and Mo3Cl4(OH)2.8H20, or [Mo3Cl4.2H20](OH)2.6H20 (see p. 124), are obtained by precipitation with acetic acid, before or after saturation with carbon dioxide respectively, of a solution of molybdenum dichloride in potassium hydroxide. 

In electroanalysis, electrodes of millimeter dimensions are termed millielec-trodes, while the more recently developed very small area electrodes of micron dimensions are termed microelectrodes there are differences in properties beyond simply the change of dimension. Thus in millielectrode-scale experiments the enhancement of the diffusion-limited current plateau has been observed by a number of other workers—for example, in the reduction of methylviologen in aqueous acetonitrile [32], in the oxidation of bis(cyclopentadienyl) molybdenum dichloride in acetonitrile [33], as well as in several other studies on the aqueous ferrocyanide/ferricyanide couple using wire or disc millielectrodes to study diffu-sional phenomena [34—36], Typical values of the diffusion layer thickness of approximately 5 pm are found under ultrasound [35] in contrast to the normal value of approximately 500 pm in silent conditions. 

Similar results at microelectrodes have been reported for oxidations of bis(cy-clopentadienyl) molybdenum dichloride [33] and chromium hexacarbonyl [41], both at platinum in acetonitrile. In the former instance, ultrasound also promoted the overall conversion of the substrate to the two-electron product and with greater efficiency at a potential where a one-electron process normally occurs, by inducing a follow-up disproportionation reaction. This provided a means to distinguish... 

Molybdenum dichloride. The commonest dichloride is in fact the yellow cluster compound Mo6C112 discussed below. The action of dry HC1 on Mo2(OCOCH3)4 at ca. 300° or better, the reaction sequence Mo(CO)6 cl2(1) > Mo(CO)4Cl2 Hc- >MoCla... 

MnAs MANGANESE ARSENIDE 1035 Mo02CI2 MOLYBDENUM DICHLORIDE DIOXIDE 1074... 

Mn3(As04)2 MANGANESE ARSENATE 1035 Mo02CI2[g] MOLYBDENUM DICHLORIDE DIOX. (GAS) 1074... 

The oxidation of bis(cyclopentadienyl)molybdenum dichloride in acetonitrile via a "DISP" mechanism undergoes enhancement of the subsequent chemical disproportionation step under insonation, while the reduction of ferricyanide... 

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