Preparation, properties, and reactions of metal-containing heterocycles: Part CVI. Three-dimensional water-soluble platinacyclophanes

Abstract

Trifunctional primary phosphines of the type 1,3,5-[PH 2(CH 2) n ] 3C 6H 3 ( 3b– d) were obtained via an Arbusov reaction between the 1,3,5-tris(bromoalkyl)benzenes 1b– d and P(OEt) 3 followed by a reaction of the trisphosphonates 1,3,5-[(EtO) 2P(O)(CH 2) n ] 3C 6H 3 ( 2b– d) with LiAlH 4. A straightforward conversion of these sensitive key phosphines 3b– d to the corresponding water-soluble ligands 1,3,5-tris[bis(hydroxymethyl)phosphinylalkyl]benzenes 4b– d and 1,3,5-tris[bis(2′-diethylphosphonatoethyl)phophinylalkyl]benzenes 5b– d was achieved by formylation with formaldehyde and hydrophosphonation with diethyl vinylphosphonate, respectively. A five component self-assembly consisting of three equivalents of the platinum(II) complex Cl 2Pt(NCPh) 2 and two equivalents of the ligands 5b– d under high dilution conditions resulted in the formation of the nanoscaled, water-soluble triplatinacyclophanes 6b– d in high yields. However, comparable reactions with the ligands 4b– d led only to polymeric materials, which are insoluble in all organic solvents and water. The structures of the metallacyclophanes 6b– d were elucidated by 31P{ 1H}-, 13C{ 1H}-, and 195Pt{ 1H}-NMR spectroscopic investigations.