The coordination chemistry of the tri- and tetradentate chelating phosphines (2-PPh₂C₆H₄)₂P(O)Ph (P³O) and (2-PPh₂C₆H₄)₃P (P⁴) with respect to d¹⁰ copper subgroup metal ions has been investigated. Depolymerization of (MC₂R)_n (M = Cu, Ag) with P⁴ affords the series of mono- and trinuclear complexes (P⁴)CuC₂Ph (1), (P⁴)Cu₃(C₂Ph)₃ (2), (P⁴)Ag₃(C₂Ph) (Hal)₂ (Hal = Cl (3), Br (4), I (5)). Reactions of the M⁺ (M = Cu, Ag) ions with (M′C₂R)_n (M′ = Cu, Ag, Au) acetylides in the presence of P⁴ yield the family of dinuclear species [(P⁴)MM′(C₂R)]⁺ (6-12), which comprise the Cu₂/Ag₂ (6, 7; R = Ph), AuCu (8-10; R = Ph, C(OH)Me₂, C(OH)Ph₂), and AuAg (11, 12; R = Ph, C(OH)Ph₂) metal cores. A related triphosphine, (2-PPh₂C₆H₄)₂PPh (P³), applied in a similar protocol undergoes partial oxidation and leads to the heterotrimetallic clusters [{(P³O)M}₂Au(C₂R)₂]⁺ (M = Cu, R = C(OH)Ph₂, 13; M = Ag, R = C(OH)Ph₂, 14; M = Ag, R = Ph, 15), which can be prepared more efficiently starting from the oxidized ligand P³O. The structures of the complexes 1-4 and 6-15 were established by single-crystal X-ray crystallography. According to the variable-temperature ¹H and ³¹P{¹H} NMR experiments, compounds 1-12 demonstrate fluxional behavior in solution. The title complexes do not show appreciable luminescence in solution at 298 K, and the photophysical properties of 1-15 were studied in the solid state. The observed phosphorescence (_em up to 0.46, λ_em from 440 to 635 nm) is assigned to cluster-centered transitions mixed with some MLCT d →π^∗(alkynyl) character.