Five new lanthanide complexes displaying crotonato bridges have been prepared: [Gd₂(crot)₆(H₂O)₄] · 4(bpa) (1); [Ho₂(crot)₇]_n · (Hbpa) (2); [Gd₂(crot)₆(bipy)₂] (3); [Ho₂(crot)₆(bipy)₂] (4) and [Nd₂(crot)₆(H₂O)₃]_n (5), where bipy=2,2′bipyridine; bpa=di(2-pyridyl)amine; crot=crotonato. The compounds were characterized by magnetic susceptibility measurements and their crystal structures were determined by single crystal X-ray diffraction. These studies showed complexes 1, 3 and 4 to be dimers while structures 2 and 5 are polymeric in nature. Five lanthanide complexes displaying crotonates bridges were synthetized in the presence of aromatic diimines. The resulting compounds [Gd₂(crot)₆(H₂O)₄] · 4(bpa); [Ho₂(crot)₇]_n · (Hbpa); [Gd₂(crot)₆(bipy)₂]; [Ho₂(crot)₆(bipy)₂] and [Nd₂(crot)₆(H₂O)₃]_n; were characterized by magnetism and their crystal structure were determined by single crystal X-ray diffraction. The roll of the diimine is different in all of the complexes; sometimes being coordinated, uncoordinated or as external crystallization agent.