The phosphinoborane adduct H3P center dot B(C6F5)(3) can be deprotonated using LiN(SiMe3)(2) to give the phosphidoborate salt Li[H2PB(C6F5)(3)], which was converted to the phosphidodiborates Li[H2P{B(C6F5)(3)}(2)] and Li[H2P{B(C6F5)(3)}{BH3}] by treatment with an equivalent of B(C6F5)(3) or Me2S center dot BH3, respectively. A series of anions of the form [RR'P{M(C6F5)(3)}{BH3}](-), where R = R' = Ph or R= Bu-t, R' = H, and M = B or Al, were prepared (through treatment of salts Li[RR'P(BH3)] with the corresponding Lewis acid) and characterized using multinuclear NMR elemental analysis and X-ray crystallography. The solid state structures of [Li(Et2O)(x)][Ph2P{M(C6F5)(3)}{BH3}] exhibit eta(2)-bonding of the BH3 group to the cationic lithium center. The attempted preparation of an analogous series with amide cores of the form [R2N{B(C6F5)(3)}{BH3}](-) proved unsuccessful; among the competing reaction pathways hydride abstraction occurred preferentially to yield Li[HB(C6F5)(3)] and dimers or higher oligorners with the composition (R2NBH2)(n).