The prophosphatranes upon which this thesis focusses, P(NMeCH[subscript]2CH[subscript]2)[subscript]3N,P(NHCH[subscript]2CH[subscript]2)[subscript]3N, and P(NBnCH[subscript]2CH[subscript]2)[subscript]3N have been found to be at least 10[superscript]7times more basic than any known phosphine derivative. While the methyl analogue was reported from these laboratories prior to the present work, the other two prophosphatranes are new;The basicities of these species were compared to each other by spectroscopic means and by competitive deprotonation experiments, as discussed in Parts I and II. The unexpected basicity order, in which the hydrogen analogue was found to be more basic than the methyl analogue which was more basic than the benzyl analogue, could not be explained sufficiently by either steric or inductive arguments. However the observed trend may be explained by the extra stability found in electron delocalization;The unusually high basicities observed for the prophosphatranes has been postulated to be due to a combination of the formation of three chelate rings and the ability to form a three-center-four-electron molecular orbital system in the conjugate-acid phosphatranes. An attempt to separate these two effects is described in Part III. Thus in (Me[subscript]2N)[subscript]2P(NMeCH[subscript]2CH[subscript]2)NMe[subscript]2, there is the possibility of forming one chelate ring upon the formation of a 3-center-4-electron molecular orbital system with a Lewis acid such as a proton. If such a transannular interaction occurred in this compound, it did not offer enough stability in the conjugate acid to prevent the evolution of HNMe[subscript]2, giving the phosphenium cation, (Me[subscript]2N)[overline]P(NMeCH[subscript]2CH[subscript]2N[superscript]+Me[subscript]2), strongly indicating that chelate rings contribute substantially to the unusual stability of phosphatrane cations;Some metal chemistry of P(NMeCH[subscript]2CH[subscript]2)[subscript]3N is discussed in Part IV. This prophosphatrane (a) coordinates to Re(CO)[subscript]5Br, displacing a CO cis to the bromide; (b) causes disproportionation of ClHgMe to give HgMe[subscript]2 and Cl[subscript]2Hg (P(NMeCH[subscript]2CH[subscript]2)[subscript]3N) [subscript]2; (c) induces a redox reaction giving H[overline]P(NMeCH[subscript]2CH[subscript]2)[subscript]3N[superscript]+, Hg[superscript]0, and a peroxide; and (d) reduces mercury (II) to give the dioxaphosphetane dimer, (HMe[subscript]2NCH[subscript]2CH[subscript]2[overline]N(CH[subscript]2CH[subscript]2MeN)[subscript]2PO] [subscript]2(OTf)[subscript]4.;In an attempt to prepare 1,1,2,2-tetraethylcarboxylatocyclobutane, the heretofore unknown tetraester, tricyclo (4.2.1.1[superscript]2,5) -1,2,5,6-tetraethylcarboxylatodecane-9,10-dione, was synthesized. The ester was probably formed from the dimerization of 2,5-diethylestercyclopentanone;Synthetic and spectroscopic data are reported on all of the above compounds and crystallographic determinations for H[overline]P(NHCH[subscript]2CH[subscript]2)[subscript]3N[superscript]+Cl[superscript]-, (Me[subscript]2N)(:)[overline]PNMeCH[subscript]2CH[subscript]2NMe[subscript]2(BF[subscript]4), Cl[subscript]2Hg (P(NMeCH[subscript]2CH[subscript]2)[subscript]3N) [subscript]2, (HMe[subscript]2NCH[subscript]2CH[subscript]2[overline]N(CH[subscript]2CH[subscript]2MeN)[subscript]2PO] [subscript]2 (OTf)[subscript]4, cis-ReBr(CO)[subscript]4 (P(NMeCH[subscript]2CH[subscript]2)[subscript]3N), and tricyclo (4.2.1.1[superscript]2,5]-1,2,5,6-tetraethylcarboxylatodecane-9,10-dione are presented.