Coordination chemistry of the multi-funtionalized 3-(diphenylphosphino)-1-propylamine ligand with ruthenium(II)

Abstract

The reaction of RuCl₂(PPh₃)₃ with two molar equivalents of a multi-functionalized ligand, 3-diphenylphosphino-1-propylamine (DPPA) yields two mononuclear, low spin, diamagnetic, octahedral neutral complexes, [RuCl₂(η²-P,N-DPPA)₂] (<b style="">1</b>) and [RuCl₂(η²-P,N-DPPA)(PPh₃)₂] (<b style="">2</b>). The complexes have been characterized by conductivity measurements, FTIR, UV-vis, ¹H and variable temperature ³¹P{¹H} NMR, ESI(+)MS, TGA-DTG and cyclic voltammetry. The ESI(+) mass spectrogram of (<b style="">1)</b> shows molecular ion peak at <i style="">m/z</i> 658[M]⁺, indicating mononuclear nature of the complex . No fluxional behavior is observed from the variable temperature (200-300 K) ³¹P{¹H} NMR spectra. The complexes (<b style="">1) </b>and (<b style="">2) </b>upon treatment with CH₃CN in 1:1 molar ratio in the presence of NH₄PF₆ in dichloromethane solution afford the six-coordinate cationic complexes [RuCl(η²-P,N-DPPA)₂(CH₃CN)](PF₆) (<b style="">3</b>) and [RuCl(η²-P,N-DPPA)(CH₃CN)(PPh₃)₂](PF₆) (<b style="">4</b>), respectively. The complexes (<b style="">3)</b> and<b style=""> (4) </b>have also been characterized by FTIR, ESI(+)MS,¹H and ³¹P{¹H} NMR spectra at room temperature. The complexes (<b style="">1)</b> and (<b style="">2) </b>are found to<b style=""> </b>have high catalytic activity towards the oxidation of aromatic alcohols with H₂O₂/NaOCl as oxidant. Maximum conversion of 95% can be achieved under mild reaction conditions.