The reactivities of phosphanylphosphinidene complexes [(DippN)(2)W(Cl)(eta(2)-P-PtBu2)](-) (1), [(pTol(3)P)(2)Pt(eta(2)-P=PtBu2)] (2), and Rdppe)Pt(eta(2)-P=PtBu2)] (3) toward dihaloalkanes and methyl iodide were investigated. The reactions of the anionic tungsten complex (1) with stochiometric Br(CH2)(n)Br (n = 3, 4, 6) led to the formation of neutral complexes with a tBu(2)PP(CH2)(3)Br ligand or neutral dinuclear complexes with unusual tetradentate tBu(2)PP(CH2)(n)PPtBu2 ligands (n = 4, 6). The methylation of platinum complexes 2 and 3 with Mel yielded neutral or cationic complexes bearing side-on coordinated tBu(2)P-P-Me moieties. The reaction of 2 with I(CH2)(2)I gave a platinum complex with a tBu(2)P-P-I ligand. When the same dihaloalkane was reacted with 3, the P-P bond in the phosphanylphosphinidene ligand was cleaved to yield tBu(2)PI, phosphorus polymers, [(dppe)PtI2] and C2H4. Furthermore, the reaction of 3 with Br(CH2)(2)Br yielded dinuclear complex bearing a tetraphosphorus tBu(2)PPPPtBu(2) ligand in the coordination sphere of the platinum. The molecular structures of the isolated products were established in the solid state and in solution by single-crystal X-ray diffraction and NMR spectroscopy. DFT studies indicated that the polyphosphorus ligands in the obtained complexes possess structures similar to free phosphenium cations tBu(2)P(+)=P-R (R = Me, I) or (tBu(2)P(+)=P)(2).