New tricyclic hexacoordinated phosphoranes 1-6 with internal N-->P coordination containing ring sizes varying from five to eight membered have been synthesized by oxidative addition of a quinone or a diol to a cyclic phosphite. The bicyclic phosphorane (NC9H6O)P(O-2(3,5-t-Bu)(2)C6H2)((O-2,4-(t-Bu)(2)C6H2)(2)CH2). 1/2H(2)O (7 . 1/2H(2)O) has been synthesized by adding the 3,5-di-tert-butyl-o-benzoquinone to the cyclic phosphite. The compound (NC9H6O)P(2,2’-OC6H4C6H4O)(2) (6) results from a novel ring exchange reaction of a phosphorinane by a phosphepin in two ways : (a) by treating (OCH(2)CMe(2)CH(2)O)P((OC9H6N) with 2,2’-biphenol/N-chlorodiisopropylamine and (b) by treating (Et(2)N)P(OCH(2)CH(2)CMe(2)CH(2)O)(2,2’-OC6H4C6H4O) with 8-hydroxyquinoline. Treatment of the aminophosphorane (Et(2)N)P(OCH(2)CMe(2)CH(2)O)(O2C14H8) with 2,4,6-trimethylbenzoic acid led to the unique ester (OCH(2)CMe(2)CH(2)O)P(O){OC14H8(C(O)-2,4,6-Me(3)C(6)H(2))} (10). P-31 NMR data for the new compounds are discussed with respect to the differing ring sizes and coordination number on phosphorus. X-ray analysis shows hexacoordination in 2, 4, and 6 with an N-->P bond and pentacoordination in 7 without an N-->P bond. The coordinating nitrogen is trans to an oxygen of the six-membered ring in 2 and of the seven-membered ring in 4. The eight-membered ring in 7 spans a diequatorial position in a trigonal bipyramidal arrangement.