Polyanion [{Ce(H2O)2}2Mn2(B-α-GeW9O34)2]8- (1) constitutes the first example of a heterometallic 3d-4f cluster related to the Weakley-type dimeric structure, and it contains an unprecedented CeIII2MnIII2O20 rhomblike moiety displaying dominant CeIII-MnIII ferromagnetic interactions.
