Complexes of group 6 Cr, Mo, W

Substance Generation / Matrix or Solvent/Method/r[K] g-Factor / a-Value [mT] Ref/ add. Ref 

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Interaction of metals with cyclopropenylidene to form stable complexes has been widely studied340 in the last two decades since the first reported synthesis of pentacarbonyl(2,3-diphenylcyclopropenylidene)chromium (see belowy4. Two groups of cyclopropenylidene metal derivatives may be distinguished neutral cyclopropenylidene complexes represented by two resonance forms, and the cationic cyclopropenylium transition metal complexes of groups 6 (Cr, Mo, W), 7 (Mn), 8 (Fe) and 10 (Pd, Pt), whereas the latter cationic cr-complexes are derived from both main group metals (Li, Mg) and group 10 (Pd, Pt) transition metals. 

Although many transition metals form carbene complexes, only Group 6 (Cr, Mo, W) heteroatom-stabilized Fischer carbenes of the type... 

The synthesis of cyclopropyl carbyne complexes follows the general Fischer synthesis of carbyne complexes from alkoxycarbene complexes typical of transition metals of group 6 (Cr, Mo, W). Thus, addition of cyclopropyllithium to chromium and tungsten hexacar-bonyl followed by alkylation of the acylmetallate intermediate with triethyloxonium fluo-roborate gave cyclopropyl ethoxycarbene complexes which, upon subsequent reaction with boron tribromide at -25 °C, afforded the corresponding /ra 5 -bromotetracarbonyl cyclopropylcarbyne complexes (equation 91). However, whereas the monotungsten... 

Zr, Hf), group 6 (Cr, Mo, W), and group 10 (Ni, Pd, Pt). (Note that CrH6 was optimized with MoH -like angular geometry to prevent formation of the Cr(H2)3 dihydrogen complex.)... 

Figure 4.103 Incremental CO binding energies, Eq. (4.129), for M(CO) complexes of group 6 metals Cr (circles), Mo (squares), and W (triangles). For n = 3, the quantity plotted is the average energy of dissociating all three carbonyls from M(CO)3.

The carbonyl complexes of group VI (Cr, W, Mo) as M(CO)j and Group VII (Mn2, Rc2, MnRe) as M2(CO),o were resolved by Li et al. [924] on a Cjg column. A 10-min group VI separation was achieved using a 70/30 acetonitrile/water mobile phase, whereas a 10-min Group VII separation required an 80/20 acetonitrile/water mobile phase. In the same paper, a series of alkylphosphines (< 2P-(CH)2) -Pacetonitrile/water mobile phase. 

Other heteronuclear complexes are those of the bis(diphenylphosphino)methanide and the group 6 metals, [M(C04) (PPh2)2CHAu(PPh3) ] (M = Cr, Mo, W).2641... 

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