Magnetic Behavior of Odd- and Even-Electron Metal Carbonyl Clusters: The Case Study of [Co₈Pt₄C₂(CO)₂₄]^<i>n</i>− (<i>n</i> = 1, 2) Carbide Cluster

The reaction of [Co6C(CO)15]2− with 2 equiv of PtCl2(Et2S)2 affords the new heterobimetallic [Co8Pt4C2(CO)24]2−, [1]2−, carbonyl cluster. [1]2− undergoes reversible chemical and electrochemical oxidation and reduction processes disclosing a complete series of [1]n− (n = 1−4) clusters. The mono- and dianion of [1]n− have been isolated as their tetra-substituted ammonium salts and fully characterized by means of IR, 13C NMR, ESI-MS, and X-ray crystallography. Variable-temperature (VT) solid-state EPR studies on pure crystalline samples indicate that both [1]2− and [1]−• are paramagnetic, due to a doublet state of the latter and a triplet state of [1]2−. This conclusion is supported by SQUID measurements on the same crystalline sample of [1]2−. The present study indisputably demonstrates that even-electron transition metal carbonyl clusters (TMCC) can be magnetic.