Synthesis and chemistry of a molybdenum carbonyl phosphinite complex containing a ditopic macrocyclic ligand with chelating phosphorus-donor and crown ether characteristics

Article abstract of DOI:10.1021/om00042a050

The reaction of 1,3-bis(chlorophenylphosphino)propane with triethylene glycol in THF in the presence of NEt₃, using high-dilution conditions, gives a mixture of phosphinite products (as assessed by ³¹P{¹H} NMR), one of which is the hybrid phosphinite macrocycle meso-11,15-diphenyl-1,4,7,10-tetraoxa-11,15-diphosphacyclopentadecane, [15]P₂O₄. This ligand was isolated as its Mo(CO)₄P₂ complex by reacting the mixture of phosphinite products with Mo(CO)₄(norbornadiene) under high-dilution conditions. Chromatographic workup of the products gave the complex cis-Mo(CO)₄{[15]P₂O₄} in an overall yield of 15-20%. The structure of this complex has been determined by single-crystal X-ray diffraction analysis. Addition of RLi reagents (R = Me, Ph, ⁿBu, ^tBu, NEt₂, NⁱPr₂) to this complex gives products of the type fac-Mo(CO)₃(RCOLi){[15]P₂O₄} in which the Li⁺ ion is encapsulated by the five oxygens of the RCO and [15]P₂O₄ ligands. The structure of fac-Mo(CO)₃(MeCOLi){[15]P₂O₄} has been determined by single-crystal X-ray analysis. A comparison of the relative rate of hydrolysis of Mo(CO)₃(PhCOLi)P₂ in wet THF solution to give LiOH + C₆H₆ + cis-Mo(CO)₄P₂ {P₂ = [15]P₂O₄ and Ph₂P(OCH₂CH₂)₃OPPh₂} shows that the benzoylate complex in which Li⁺ is encapsulated by the [15]P₂O₄ ligand is the more inert. The structure of fac-[Mo(CO)₃Br{[15]P₂O₄}]Li is also reported.