A 5-carbaphosphatrane and a 6-carbaphosphatrane were synthesized by utilizing triarylmethyl-type tetradentate ligands. Their structures were determined by X-ray crystallographic analysis to reveal that they have nealy ideal trigonal bipyramidal structures with a perfectly anti-apicophilic arrangement. (1)J(PH) and (1)J(PC) values of carbaphosphatranes were shown to be extraordinarily large as an apical coupling constant. The reactivities of carbaphosphatranes based on the tautomerization with their corresponding phosphonites were demonstrated in some reactions.