Group cyclopentadienyl complexes

Table 9.9. Properties of Titanium Group Cyclopentadienyl Complexes...

Beryllium forms a series of cyclopentadienyl complexes [Beftj -CsHiY] with Y = H, Cl, Br, Me, —C=CH and BH4, all of which show the expected C5, symmetry (Fig. 5.10a). If the pe/ifo/topfo-cyclopentadienyl group (p. 937) contributes 5 electrons to the bonding, then these are all 8-electron Be complexes consistent with the octet rule for elements of the first short... 

Cationic cyclopentadienyl complexes are not common in this group, but recent examples whose structures have been determined include [Nb ( j -C5H5)2Cl2]BF4< > and [Nb( j -C5H5)2L2](BF4)2 (L = CNMe and NCMe),< > which have pseudo-tetrahedral symmetry. 

Kopf-Maier P, Kopf H (1988) Transition and Main-Group Metal Cyclopentadienyl Complexes Preclinical Studies on a Series of Antitumor Agnets of Different Structural... 

Volume 1, Metal Complexes. Describes the organopalladium complexes containing Pd—C a bonds, hydrides, olefins and acetylenes, dienes, w-allylic groups, cyclopentadienyls, and benzenes. 

The rhodium cyclopentadienyl complex [T75-C5(CH3)5RhCl2]2, in the presence of base at 50 atm H2, also effects stereoselective catalytic hydrogenation of benzenes. Substrates with unprotected —OH or —C02H groups were not effectively hydrogenated, but aryl ethers, esters, and ketones and N,iV -dimethylaniline were all reduced, some-... 

Several mixed 7r-benzene-jr-cyclopentadienyl complexes have been investigated in UPS in order to compare the properties of these groups as ligands. The ds system Cr(cp)(bz) was investigated by Evans etal (57) together with the d6 complexes Cr(bz)2, Cr(tol)2, and Mn(cp)(bz). The spectmm of Cr(cp)(bz) shows in the region... 

Viewed as a group, aU of the lanthanide cyclopentadienyl complexes show the behavior expected if the metal-ring interaction were purely electrostatic in nature. 

The tetramethylethanediyl-bridged, f-butyl-substituted bis-cyclopentadienyl complex Me4C2(3-f-BuC5H3)2Mg(THF) (129) is present in the solid state as a me o-diastere-oisomer. It has a structure in which both cyclopentadienyl groups are /7 -bonded to magnesium while only one THF molecule is coordinated to magnesium (Figure 62) . 

Cyclopentadienyl-ligated complexes, with chromium, 5, 380 Cyclopentadienyl-like compounds, lanthanide and Group 3 complexes, 4, 105... 

Methoxycarbonyl)chroman-3-one, arylation, 9, 394—395 Methoxycarbonyl groups, Ru and Os complexes, 6, 837 2-Methoxyestradiol, via iridium cyclopentadienyl complexes,... 

Amongst the last group of complexes, compound 377 represents a special interest because its structure testifies that the carbon atom of the cyclopentadienyl fragment of ferrocene may participate in the coordination with the metal (Pt) [689] ... 

Two communications on propene polymerization by non-metallocene catalysts that include DFT/MM calculations have been recently published [60, 61]. They deal with group 4 bidentate non-cyclopentadienyl complexes. In the first communication [60], the topic addressed is the fact that a C2-symmetric precatalyst of titanium leads to a syndiotactic polymer, contrary to observations of metallocene catalysts. The chirality at the metal center is found to play a key role in the stereocontrol of the process. The second communication [61] addresses the fact that a C2-symmetric precatalyst of zirconium very similar to the previous one produces an isotactic polymer, finds out that it is due to a complicated concourse of synergic steric and electronic effects, and emphasizes the key role that serendipity still plays in the design of new catalysts. 

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