Organometallic and coordination chemistry on phosphazenes. III. Synthesis, characterization, and electrochemical behavior of transition metal-cinnamonitrile cyclophosphazene derivatives

摘要: Hexakist 4-formylphenoxy cyclophosphazene (1) reacts with six equivalents of cyanomethylenetriphenylphosphorane to give hexakist 4-cinnamonitrile cyclotriphosphazene bearing 12 functional groups tsix nitriles and olefins' able coordinate up metals. In this way a series polynuclear phosphazene metal derivatives (8–12) was prepared different transition metals in oxidation states. Pt(0), Pt(II) Rh(I). The analogous cinnamonitrile (3–7) were used as models for the characterization corresponding compounds. redox properties complexes3–5 and8–10 well free cinnamonitrile2 substituted cyclophosphazene1 have been investigated by cyclic voltammetry (CV) controlled potential electrolysis (CPE) aprotic media (THF, CH2Cl2, or NCMe 0.2M [NBu4][BF4]), at Pt electrodes. Cathodic processes detected only when unsaturated C=C bond group is uncoordinated: hence, compounds1. 4. and9. they are irreversible occur potentialsE p red ca. −1.3 −1.9V vs SCE which less cathodic than that exhibited (2:E −2.0 V SCE), believed be centered electron-acceptor emptyπ* (C=C) orbital each present molecule. Anodic displayed complexes3. 5. 8. and10 least one Pt(0) site: irreversible, conceivably such center, potentials (E bv 0.7 1.2 SCE) dependent on electronic effects ligands, particular strong electron-withdrawing ability group. Complex10 undergoes dissociation form9 possibly solvated [Pt(PPh3)2] species adsorb electrode surface. No evidence any process ring has found.