Cationic complexes molybdenum

Molybdenum and tungsten hexacarbonyls are able to form anionic complexes (AsPli4)2[(OC)4M( -pz)2M(CO)4] upon reaction with sodium pyrazolate and PluAsCl (72CB3203). The cationic complexes [(rj -Cp)2Mo(/Lt-pz)2Mo(rj -Cp)2] " (n = 2, 3) are known as well (74HCA1988). The other representatives of the complexes containing an exobidentate ligand (26) are derived from 4//-pyrazoles [70ZAAC(379)169]. 

Oxidation of trans-[Mo(N2)2(dppe)2] with I2 in methanol allows isolation of the unstable cationic complex frans-[Mo(N2)2(dppe)2]I3.6 This cation has also been prepared electrochemi-cally and the rate of its decomposition by loss of N2 studied.6 A range of dinitrogen complexes shows reversible one-electron oxidation in solution, but in general the monocations are too unstable to be isolated for molybdenum.6... 

A closely related formation of >/3-cydopropenyl molybdenum complex Cp P(OMe)3)2Mo( 3-C3Ph2Me), possibly involving an interamolecular ligand cycloaddition within a carbyne-acetylene intermediate complex, has been accomplished by treating the acetylenic cation complex [Cp f P(OMe)3 2Mo( 2-PhC=CPh)]BF4 with vinylmagne-sium bromide in THF (equation 253)321. 

To what extent can the example of a solid exoskeleton be replicated in the laboratory Going against most contemporary examples of flexible artificial cells, Muller and Rehder published an example of a complex molybdenum oxide that spontaneously forms discrete nanospheres [23], The hollow spheres were porous and allowed lithium cations to pass through the exoskeleton. While this a perhaps an extreme example of what may be considered an artificial cell, the authors assert that the presence of ion selective channels through the encapsulating oxide is directly analogous to natural ion channels in organic cells. 

There is no ending modification to the metal name in neutral or cationic complexes. However, in anionic complexes the name of the metal is modified to an -ate ending (e.g. molybdenum to molybdate, or zinc to zincate), as a signal that the complex unit is anionic. 

Controlled polyfunctionalization of cycloheptene can be achieved via nucleophilic addition and subsequent decomplexation of cyclo-heptadiene molybdenum cationic complexes (Scheme 16). ... 

The NMR characterisation of fBA adducts formed in the reaction of tungsten and molybdenum seven-coordinate compounds leaves little doubt concerning their formulation. However, we were unable to separate such compounds and to prepare a crystalline sample. To obtain a more stable terminal alkyne compound, we introduced two phosphine ligands into the coordination sphere of tungsten(II). In this way a cationic complex of tungsten(II), [WCl(CO)( BuC=CH)(NCMe)(PPh3)2]2[SnCl6], was prepared [45]. The crystal structure of this compound consists of two independent cations and a... 

At higher temperatures the effect of melt composition on the stability of Mo(V) solutions essentially disappears. At 750 °C the rate with which the concentration of Mo(V) ions in the melt decreased was essentially the same in NaCl-CsCI, NaCl-KCl and LiCl-KCl melts (Figure 6.11.7). It is possible that, at such temperatures, the destabilising effect of the melt cations on molybdenum(V) complexes is negligible compared to the thermal instability of MoClg" species caused by the high volatility of M0CI5. 

The iron-mediated synthesis of 2-oxygenated carbazoles is limited. On the other hand, a molybdenum-mediated approach works as a complementary route (Scheme 23.24) [31]. Similar to iron-coordinated cation 55, molybdenum-coordinated cations 61 react with electron-rich anilines 62 to give (if-cyclohexenyl)molybdenum complex 63. Then the oxidative cyclization of 63 followed by the subsequent aromatiza-tion and demetallation using activated manganese dioxide afforded the corresponding... 

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