The first 4d/4f polyphosphides were obtained from reactions of the divalent metallocenes [Cp*2Ln(thf)2] (Ln = Sm, Yb) with [CpMo(CO)2}2(μ,η2:2-P2)] or [Cp*Mo(CO)2(η3-P3)]. New aggregation of the central phosphorus scaffold in combination with P–P bond formation within the coordination sphere of the transition metal was observed.