Molybdenum dihalides

The cluster cores Mo6E8 (E = S, Se, ) are very similar to those of molybdenum dihalides MoX2 (X = Cl, Br, I), and their derivatives... 

The dihalides react with alcohols leading to the formation of an enormous range of alkoxides and even aryloxides [Mo(NO)(Me2pzb)X(OR)] as detailed in Table 7, The crystal structure of [Mo(NO)(Me2pzb)a(OPr1)] has been determined,125 and the molybdenum shows normal octahedral six-coordination, albeit with a very short Mo-O bond. 

The same configuration has been reported also for molybdenum pentachloride,7 MoCl , antimony pentachloride,80 SbCli, and the tri-methylstibine dihalides,81 (CH ) 3bX. Molybdenum pentachloride... 

Also some six-coordinate derivatives of molybdenum dinitrosyl dihalides have been reported, e.g., Mo(NO)2(phen)Br2 (154). 

Whereas these reactions of dihalides with proton-active compounds seem reasonably simple, [Mo(NO)(Me2pzb)l2] reacts with Mc2CO, MeEtCO or diacetone alcohol in complex fashion, affording some [Mo(NO)(M pzb)I(OEt)J but also some [ Mo(NO)(Me2pzb)I 20], presumably via a reduced species such as the paramagnetic Mo(NO)(Me2pzb)I. The possible reaction course has been discussed, and it has been established that the dinuclear species has a slightly bent MoOMo system [171.0(15)°], with linear ZMoNO (176(3), mean). Mo—N = 1.74(3) and N—0 = 1.21(4) A (mean values). The two molybdenum coordination shells are eclipsed with respect to each other. 

A convenient preparatory method is to form the tertiary phosphine molybdenum hexafluoride complex in methylene chloride at -60°C. On heating such complexes, R3PF2-type compounds are liberated (6.510). Hydrogen fluoride adds to alkylphosphonous dihalides (6.511). Fluorophosphoranes are also obtained from diphosphines (6.538 below), or by halogenation of R2NPF2 -type compounds (7.107). 

Reviews with relevance material include those on organochromium complexes 3 and cyclopentadienyl molybdenum and tungsten dihalides. 1 ... 

Metal carbonyl complexes readily displace halogen atoms of organic halides, producing reactive species which are useful in organic synthesis. Certain ge/w-dihalides are reduced with iron pentacarbonyl (Coffey, 1961) or dicobalt octacarbonyl (Seyferth and Millar, 1972) or molybdenum hexa-carbonyl (Alper and Des Roches, 1976) to form dimeric olefin products. Ordinary monohalides are much less reactive, however. 

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