Heteroallyl complexes

Transition metal complexes containing heteroallyl ligands, such as those in structures (7.79), have been less studied than metal allyl compounds. Complexes con- 

RP = CHPC1R with sodium tetracarbonylcobaltate( —I) gives the 1, 3-diphosphaallyl cobalt complex [equation (7.81)]. The C-P distances are 176.9(7) and 179.1(7) pm. 

Therefore, these distances are longer than for the P = C double bond and shorter than in the case of the P —C single bond. The compound has a square-pyramidal structure. The base contains two CO ligands and the phosphorus atoms while the third CO group is located at the pyramid vertex. The distances for Co-C(allyl), Co-P and Co-P are 203.4(7), 238.2(2), and 239.5(2) pm, respectively. 

Many complexes of transition metals possessing metallatriphosphatetrahedrane or metallatriarsenatetrahedrane structures were recently prepared and investigated [structures (7.82)]. Formally, these complexes are analogous to cyclopropenyl com- 

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In 2007, Smolensky and Eisen published a review entitled "Design of organometallic group IV heteroallylic complexes and their catalytic properties for polymerizations and olefin centered transformations.In this article a strong emphasis was placed on various synthetic and catalytic aspects of group IV metal amidinate complexes. It was clearly pointed out that such amidinate... 

In metal heteroallyl complexes the carbon atom is susceptible to attack by nucleophiles, resulting in replacement of Z or addition to the carbon atom.5 We do not deal with the ligands resulting from the latter reaction. 

Edelmann, F.T. Rare Earth Complexes with Heteroallylic Ligands. 179, 113-148 (1996). 

Scheme 3.23 Hetero-Cope (hetero-Claisen) rearrangement in vinylalkynyl ruthenium complexes formed by addition of heteroallyl compounds to C3 of complex 10.

Edelmann FT (1996) Rare Earth Complexes with Heteroallylic Ligands. 179 113-148 Edelmann FT (1996) Lanthanide Metdlocenes in Homogeneous Catalysis, 179 247-276 Ekhart CW, see de Raadt A (1997) 187 157-186... 

Edelmann FT (1996) Rare Earth Complexes with Heteroallylic Ligands. 179 113 -148 Edelmann FT (1996) Lanthanide Metallocenes in Homogeneous Catalysis. 179 247-276 Effenhauser CS (1998) Integrated Chip-Based Microcolumn Separation Systems. 194 51 - 82 Ehrfeld W, Hessel V, Lehr H (1998) Microreactors for Chemical Synthesis and Biotechnology -Current Developments and Future Applications. 194 233 - 252 Ekhart CW, see de Raadt A (1997) 187 157-186... 

Rare Earth Complexes with Heteroallylic Ligands... 

Table 1 shows the assignment of the various lanthanide elements in the numbering of the compounds in this article. As usual, scandium and yttrium have been included because of their chemical similarity with the lanthanides. Not included was the radioactive promethium for which no complex containing heteroallylic ligands has so far been reported. 

One of the most successful approaches towards alternative ligand sets for lanthanide complexes is the use of bulky heteroallylic ligands. These ligands have been shown to behave as steric cyclopentadienyl equivalents [24], i.e. their cone angle is very similar to that of C5H5 or C5Me5. Scheme 1 shows the heteroallylic anions which have been successfully employed. 

An interesting class of homoleptic lanthanide complexes has become available through the use of heteroallylic diphosphinomethanide ligands. The first member of the series was the lanthanum derivative, [CH(PPh2)2]3La (59c), which was characterized by X-ray crystallography (Fig. 19) [74]. The preparation of 59c involved treatment of anhydrous lanthanum trichloride with the potassium salt of the ligand ... 

Edelmann, F.T. Rare Earth Complexes with Heteroallylic Ligands. 179, 113-148 (1996). Edelmann, F.T. Lanthanide Metallocenes in Homogeneous Catalysis.179, 247-276(1996). El-Basil, S. Caterpillar (Gutman) Trees in Chemical Graph Theory. 153, 273-290 (1990). 

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