SYNTHESIS AND CHEMISTRY OF A MOLYBDENUM CARBONYL PHOSPHINITE COMPLEX CONTAINING A DITOPIC MACROCYCLIC LIGAND WITH CHELATING PHOSPHORUS-DONOR AND CROWN-ETHER CHARACTERISTICS

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 P-31{H-1} 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, (n)Bu, (t)Bu, 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)PO2 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.