Technetium complexes cyclopentadienyl

Keywords Technetium Carbonyl complexes Technetium cyclopentadienyl Vitamin B12 Molecular imaging... 

Bernard J, Ortner K, Spingler B, Pietzsch HJ, Alberto R (2003) Aqueous synthesis of derivatized cyclopentadienyl complexes of technetium and rhenium directed toward radiopharmaceutical application. Inorg Chem 42 1014-1022... 

Saidi M, Kothari K, Pillai MRA et al (2001) Cyclopentadienyl 99m-technetium tricarbonyl piperi-din conjugate biodistribution and imaging studies. J Labelled Cpd Radiopharm 44 603-618 Saidi M, Seifert S, Kretzschmar M et al (2004) Cyclopentadienyl tricarbonyl complexes of 99m-Tc for the in vivo imaging of the serotonin 5-HTia receptor in the brain. J Organomet Chem 689 4739-4744... 

Cyclopentadienyl (Cp) complexes (see Cyclopentadienyl) are known for almost all the metals of the periodic chart, including technetium. The compounds with transition metals usually possess covalent jt Cp M bonding. The nature of the metal Cp bond is multiple. The <7-bond is formed from the overlap of an empty d orbital of Tc with one of the frUed jt bonding molecular orbital on Cp with good symmetry. Back-donation is usually also present from the filled d orbitals of Tc to one of the empty n molecular orbitals on Cp. These molecules are usually called sandwich compounds (see Sandwich Compound), when there are two Cp ligands bonded to the metal, or half-sandwich complexes (see Half-sandwich Complexes) when only one Cp ligand is present. 

The formation of the hydrides may proceed via bis(jr-cyclopentadienyl)-metal halide complexes, since compounds such as (ir-CeH ReCU+CI-and (t-CjHOjWCU are known and are readily reduced to the neutral hydrides on treatment with lithium aluminum hydride 64) (Eq. 5). Treatment of technetium tetrachloride with sodium cyclopentadiene does not give a hydride analogous to that of rhenium. Molecular weight determina-... 

Bigott HM, Parent E, Luyt LG, Katzenellenbogen JA, Welch MJ (2005) Design and synthesis of functionalized cyclopentadienyl tricarbonylmetal complexes for technetium-94m PET imaging of estrogen receptors. Bioconjugate Chem 16 255-264... 

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