Coordination Chemistry of ADPO

The hypervalent phosphorus compound, 3,7-di-t-butyl-5-aza-2,8-dioxa-1-phosphabicyclo-[3.3.0]octa-2,4,6-triene (ADPO) forms adducts with chromium, tungsten, nickel and palladium metal centers. All four new adducts contain tetrahedral phosphorus atoms as a result of folding of the ADPO unit. This folding of the planar 10-P-3 ADPO molecule to provide an 8-P-3 center for coordination to the transition metal center is the result of the close energy balance between 10-P-3 ADPO and 8-P-3 ADPO and the strength of the phosphorus-metal interaction. In the case of a homoleptic palladium(II) complex, dimerizati on of the coordinated ADPO unit was observed.