Cyclopentadienyl --complexes preparation

Two other functionally substituted 17-cyclopentadienyl titanium dicarbonyl complexes prepared by Rausch and co-workers include the vinyl Cp compound (i7-C5H4CH=CH2)CpTi(CO)2 (81) and the carbomethoxy Cp compound (rj-C5H4C02Me)CpTi(C0)2 (82). Both were synthesized via the aluminum-induced reductive carbonylation of the corresponding dichloride derivatives. 

Organosilyl substituted 7)5-cyclopentadienyl complexes may be prepared by two main procedures (a) reactions of silylated cyclopenta-dienes or their alkali metal derivatives, with an appropriate transition metal compound (carbonyl or halide) with formation of ir-bonds (b) metalation of a preformed 7j5-cyclopentadienyl complex, followed by treatment with an organohalosilane. 

A very versatile preparation seems to be the elimination of organotin halides in the reaction of organostannyl-organosilylcyclopentadienes with metal carbonyl halides. This reaction is very selective and only Sn—C bonds are cleaved with formation of 7)5-cyclopentadienyl complexes (7) ... 

Bis(cyclooctene)—iridium(I) complexes, preparation, 7, 316 Bis(cyclopentadienyl) alkenes, with tantalum, 5, 157 Bis(cyclopentadienyl) alkyne niobium complexes, characteristics, 5, 81... 

Bis(cyclopentadienyl)titanium(II) dicarbonyl complexes, preparation and reactivity, 4, 250 Bis(cyclopentadienyl)titanium(II) dinitrogen complexes, preparation and reactivity, 4, 250 Bis(cyclopentadienyl)titanium halides ligand metathesis reactions, 4, 537 olefin polymerization, 4, 538 organic reactions, 4, 540 properties, 4, 530 reductions, 4, 532 synthesis, 4, 510... 

Deprotonation with aluminum alkys, 9, 272 mononuclear carbonyl iridium complexes, 7, 302 for palladium cyclopentadienyl complexes, 8, 390 in Ru and Os half-sandwich preparations, 6, 569 in silver carbene synthesis, 2, 206 Desulfurization... 

Iridium nanoparticles, preparation, 12, 82 Iridium(III) O-ligated complexes, preparation, 7, 315 Iridium polyhydrides, preparation and characteristics, 7, 405 Iridium pyrrolyl derivatives, reactivity, 7, 282 Iridium tetrahydrides, characteristics, 7, 407-408 Iridium trihydrides, preparation, 7, 405 Iridium vinylidenes, synthesis and characteristics, 7, 352 Iridium xyliphos complexes, properties, 7, 442 Iridoids, via Pauson-Khand reaction, 11, 360 Iron(arene) (cyclopentadienyl) cations, preparation and reactivity, 6, 166... 

Manganese carbenes, preparation, 5, 825 Manganese carbonyl complexes with 776-arene complexes, 5, 787 cyclopentadienyl complexes, 5, 783 with hydrocarbon ligands, complexes, 5, 776 synthesis and characteristics, 5, 761 Manganese carbonyl halides, applications and reactivity,... 

Polymetallic alkynes, with platinum heterobimetallic derivatives, 8, 647 homobimetallic complexes, 8, 645 polymetallic derivatives, 8, 648 Polymetallic cyclopentadienyl iridium complexes, preparation and characteristics, 7, 370... 

Furthermore, we could show that this reaction mechanism to produce Cp-complexes of "mTc is not limited to carboxylate derivatives of Cp but that also further functionalities can be conjugated to receive, e.g., amides (49 and 50) [125]. This reactivity implies that, comparable to the SAAC approach, Thiele s acid derivatives can be incorporated in, e.g., a peptide strand and directly be labeled with [99mTc(OH2)3(CO)3]+. The preparation of cyclopentadienyl complexes with a variety of functionalities attached to the cyclopentadienyl ring stands for a more routine introduction of this important tridentate ligand in radiopharmaceutical organometallic complexes. 

Another interesting cyclopentadienyl complex is Ti(CsH5)2Cl2, which is prepared by a reaction that is analogous to that shown in Eq. (21.63). The reaction can be shown as follows ... 

A second group of complexes that have received detailed attention are the (i73-allyl)nickel(i75-cyclopentadienyl) complexes, which may be prepared by reacting nickelocene with an allyl-Grignard reagent (69). Data for typical examples are shown in Table IX. In this particular case, a sufficiently large number of complexes have been studied that a series of chemical shift increments can be extracted from the data (shown in Table X) and have been used with considerable success in assigning structures to ij3-allyl nickel complexes of unknown structure. 

The tripyrazolylborate anion (RB(pz)3, 58) acts as a tridentate ligand, and frequently results in complexes which are analogous to cyclopentadienyl complexes. The first Rhin-RB(pz)3 complexes were prepared by the oxidative addition of I2 to [Rh2 RB(pz)3 (CO)3], and resulted in octahedral, monomeric complexes [Rh RB(pz)3 (CO)I2] (R = H, and, in low yield, for R = pz).892 For the tetrapyrazolyl species (R = pz) the NMR spectrum showed two, non-interconverting pyrazole environments in a 3/1 ratio, consistent with a tridentate configuration for the borate. The C—O stretch is very high (2090 cm-1), consistent with the formal Rhni designation.892... 

Transneptunium tris(cyclopentadienyl) complexes can be prepared on a microscale from the reaction of molten Cp2Be with the anhydrous trichlorides (equation 21). The products are isolated by fractional sublimation. X-ray powder diffraction indicates that these CpsAn complexes are... 

For the analogous cyclopentadiene(3 ee Cyclopentadienyl) derivative, prepared by a different route, the complex is unstable in solution and is believed to dissociate back to H2 and the Mo-Mo triple-bonded complex. In view of the fact that many catalytic cycles utilize hydrogen, these types of complexes are important models. Interactions of dihydrogen leading to cleavage of the metal-metal bond are discussed in Section 7.1.4. 

The compound Na[Tc3(CO)9(OMe)4] prepared by the incomplete carbonylation of sodium pertechnetate in methanol shows promises as an important reagent for the future. It has been used to prepare LTc(CO)3, Tc2(CO)io, and various arene and cyclopentadienyl complexes (see Arene Complexes and Cydopentadienyl). The reaction conditions for these syntheses are moderately mild. 

Considerable effort has been directed to the stereoselective synthesis of aimulated cyclopentadienyl complexes of the group 4 transition metals. Ci asymmetric and C2 synunetric aimulated cyclopentadienyl ligands have been used to prepare chiral organotitanium complexes, which are now being actively studied as catalysts for asymmetric synthesis and olefin polymerization see Asymmetric Synthesis by Homogeneous Catalysis). 

Addition of a substituent, such as an alkyl group or a fused ring, to the cyclopentadienyl group in ania-metallocenes leads to the possibility of racemic and meso complexes. For example, ethylenebis(l-indenyl) and ethylenebis(tetrahydro-1-indenyl) complexes prepared by Brintzinger and coworkers have been isolated in both the racemic form (31) and meso form... 

Sterically bulky vanadocene [C5(i-Pr) H5 ]2V is prepared by treatment of VCI3 or [V2Cl3]2[Zn2Cl6] with the corresponding K[C5(i-Pr) H5 ]. The dinuclear cyclopentadienyl complex is also accessible. The fulvalenediyl complex (16) is obtained from VCl2(THF)2 and CioH6Li2 as shown in Scheme 10. ... 

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