Titration Calorimetry for the Determination of Basicities of Transition Metal Complexes

摘要: When one thinks of Bronsted bases, ions or molecules that come to mind are those contain a non-metal atom with lone pair electrons is capable forming donor-acceptor bond proton (H+). Examples common bases OH− NH3, CH3CO2 −, CN−, Et2S, and Ph3P, among many others. In metal, the metal normally not considered basic. Yet, since 1930’s, transition complexes protonated at center have become quite common. Initially such basic were anionic carbonyl organometallic ligands, as Fe(CO)4 2− Re(CO)5 (η5-C5H5)W(CO)3 − Co(CO)4 −. However, it has increasingly obvious neutral complexes, W(CO)3(PMe3)3, (η5-C5H5)2ReH, Fe(H)2(Me2PCH2CH2PMe2)2, (η5-C5Me5)Ir(l,5-cyclooctadiene), can also be center. And there even few examples cationic Os(H)(CH3CN)(dppe)2 + Ir(CO)(dppe)2 +, where dppe = Ph2PCH2CH2PPh2, metal. all these acid-base reactions (eq 1), an electron on forms H+ give hydride complex (H-MLn +) whose $$:M{L_n} HA \rightleftharpoons H - M{L_n}^ {A^ }$$ (1) structure necessarily different than precursor base (:MLn). type in eq (1), :MLn inert gas configuration, i.e., obeys 18-electron rule, therefore will generally react anion (A−) acid (HA) by including A− ligand coordination sphere. As insoluble water, most protonation performed non-aqueous solvents.