Reaction of (isopropyl)diphenylstannylbis(3,5-dimethylpyrazol-1-yl)methane [(i-Pr)Ph2SnCH(3,5-Me2Pz)2] and tricyclohexylstannylbis(3,5-dimethylpyrazol-1-yl)methane [Cy3SnCH(3,5-Me2Pz)2] with W(CO)5THF in refluxing THF yields heterobimetallic complexes (i-Pr)Ph2SnCH(3,5-Me2Pz)2W(CO)4 and Cy3SnCH(3,5-Me2Pz)2W(CO)4, respectively. Treatment of these heterobimetallic complexes, R3SnCH(3,5-Me2Pz)2W(CO)4 (R3 = (i-Pr)Ph2, Cy3, Et3), with I2 results in the formation of a novel η1-bis(pyrazol-1-yl)acyl complex CHC(O)(3,5-Me2Pz)2W(CO)3I, with the loss of the organotin group from the methine carbon. In addition, the reaction of R3SnCH(3,5-Me2Pz)2W(CO)4 with SnCl4 in a 1:1 molar ratio gives heterotrimetallic complexes R3SnCH(3,5-Me2Pz)2W(Cl)(CO)3SnCl3 (R = Cy, Et). It is unexpected that these heterotrimetallic complexes are also reactive in solution. They change to a novel four-membered heterometallacyclic complex CH(3,5-Me2Pz)2W(CO)3Cl in dichloromethane solution at room temperature. Furthermore, this complex can also be obtained by the selective cleavage of the W−Sn bond in complexes CH(3,5-Me2Pz)2W(CO)3SnAr3 with SnCl4.