Synthesis and coordination of a ferrocenyl-substituted bicyclic phosphite

• Synthesis of a ferrocenyl-substituted bicyclic phosphite is reported.
• Optimization experiments led to isolation of an oxazoline side-product.
• The phosphite was used to prepare a bis(phosphite) tungsten–carbonyl complex.
• Electrochemical behaviour of the phosphite and its complex was studied.

{[Tris(hydroxymethyl)methylamino]carbonyl}ferrocene (1) reacts with phosphorus(III) chloride in the presence of pyridine or triethylamine to afford a ferrocenyl-substituted bicyclic phosphite, {[(2,6,7-trioxa-1-phosphabicyclo[2.2.2]oct-4-yl)amino]carbonyl}ferrocene (2), in a moderate yield. (4,5-Dihydro-4,4-bis(chloromethyl)-2-oxazolyl)ferrocene (3) is found to be formed in some experiments as a minor side-product, resulting presumably via halogenation of 1 and base-induced cyclization of an intermediate chloromethyl derivative. The reaction of 2 with [W(CO)4(cod)] (cod = cycloocta-1,5-diene) at elevated temperature produces bis-phosphite complex cis-[W(CO)4(2-κP)2] (4) as the major product. All newly prepared compounds have been characterized by spectroscopic methods (IR, NMR and mass spectrometry) and elemental analysis. The crystal structures of 2, 3·1/2H2O and 4·Me2CO·H2O were determined by single-crystal X-ray diffraction and the redox behaviour of phosphite 2 and the W(0) complex 4 was studied by cyclic voltammetry.

Treatment of {[tris(hydroxymethyl)methylamino]carbonyl}ferrocene with PCl3 and a base affords ferrocenyl-substituted bicyclic phosphite, {[(2,6,7-trioxa-1-phosphabicyclo[2.2.2]oct-4-yl)amino]carbonyl}ferrocene. When reacted with [W(CO)4(cod)] (cod = cycloocta-1,5-diene), this donor gives rise to bis-phosphite complex cis-[W(CO)4(2-κP)2] (4) as the major product. The phosphite and its W-complex are characterized by spectroscopic methods and further studied by voltammetric techniques.Figure optionsDownload as PowerPoint slide