The selenium centers of [Pt₂(μ-Se)₂(PPh₃)₄] are subject to electrophilic attack from various organic halides. Reactions with MeI, n-BuCl, α,α⁶-dichloro-p-xylene, and α,α⁶-dichloro-o-xylene give [Pt₂(μ-Se)(μ-SeMe)(PPh₃)₄]⁺, [Pt₂(μ-Se)(μ-SeBu)(PPh₃)₄]⁺, [Pt₂(μ-Se)(μ-SeCH₂C₆H₄CH₂Cl)(PPh₃)₄]⁺, and [Pt₂(μ-SeCH₂C₆H₄CH₂Se)(PPh₃)₄]²⁺, respectively, preserving the dinuclear core and giving rise to new selenium-derivatized ligand complexes. Reaction with oxalyl chloride gives [Pt(η²-Se₂C₂O₂-Se,Se⁶)(PPh₃)₂], leading to the disintegration of the core to a mononuclear complex supported by a new chelating selenium donor ligand. Reactions with malonyl chloride and succinyl chloride give [(COCH₂COCl)Se]₂ and [(COCH₂CH₂COCl)Se]₂ respectively, leading to complex disintegration and liberation of new selenium materials. The crystal structures of the aggregates [Pt₂(μ-Se)(μ-SeMe)(PPh₃)₄][PF₆], [Pt₂(μ₃-Se)₂(PPh₃)₄(CH₂C₆H₄CH₂)][PF₆]₁.₂₅[Cl]₀.₇₅, and [Pt(η²-Se₂C₂O₂-Se,Se⁶)(PPh₃)₂] are described. The potential of using [Pt₂(μ-Se)₂(PPh₃)₄] as a source for metal-assisted synthesis of new and unusual organoselenium compounds is discussed.