Evan Freiberg
Published: 2001
Total Pages: 446
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Chapter 1. The chemistry of the metal-metal multiply bonded Tc2(II, II) core has been investigated with bis(diphenylphosphino)methane (dppm). The parent complex, Tc2Cl4(dppm)2, has been prepared from the reaction of Tc2C14(PEt3)4 with dppm. The reactivity of Tc2Cl4(dppm)2 with tert-butyl isocyanide has been studied and a neutral 1:1 adduct, Tc2Cl4(dppm)2CNBut, a cationic 1:2 adduct, [Tc2Cl3(dppm)4(CNBut)2](PF6), and a [mu]-iminyl complex, [Tc2Cl3(dppm)2(CNBut)2CNHBul(PF6), have been prepared. The parent compound and its reaction products have been characterized via a combination of spectroscopic techniques and single crystal X-ray crystallography. The metal-metal bonded ditechnetium bis(dppm) motif is retained in the reaction products. Chapter 2. The reduction of ammonium pertechnetate with bis(diphenylphosphino)methane (dppm), and with diphenyl-2-pyridyl phosphine (Ph2Ppy), has been investigated. The neutral Tc(II) complex, TcCl2(dppm)2, has been isolated from the reaction of (NH4)[TcO4] with excess dppm in refluxing EtOH/HCl. Chemical oxidation with ferricinium hexafluorophosphate results in formation of the cationic Tc(III) analogue, [TcCl2(dppm)2](PF6). The dppm ligands adopt the chelating bonding mode in both complexes, resulting in strained four member metallocycles. With excess PhPpy, the reduction of (NH4)[TcO4] in refluxing EtOH/HCl yields a complex with one chelating Ph2Ppy ligand and one unidentate Ph2Ppy ligand, TcCl3(Ph2Ppy-P, N)(Ph2Ppy-P).
