Reactions of RSe − (R = Me, Ph) Groups in [RSeFe(CO) 4 I and [RSeCr(CO) 5 − ]

The anionic [MeSeFe(CO) 4 ] and [MeSeCr(CO) 5 ] complexes were synthesized by reaction of [PPN][HFe(CO) 4 ] and [PPN][HCr(CO) 5 ] with MeSeSeMe respectively via nucleophilic cleavage of the Se‐Se bond. The ease of cleavage of the Se‐Se bond follows the nucleophilic strength of metal‐hydride complexes. Methylation of [RSeCr(CO) 5 − ] by the soft alkylating agent MeI resulted in the formation of neutral (MeSeMe)Cr(CO) 5 in THF at 0°C. In contrast, the [ICr(CO) 5 − ] was isolated at ambient temperature. Reaction of [MeSeFe(CO) 4 − ] or [MeSeCr(CO) 5 − ] with HBF 4 yielded (CO) 3 Fc(μ‐SeMe) 2 Fe(CO) 3 dimer and anionic [(CO ) 5 Cr (μ‐SeMe)Cr(CO) 5 − ] respectively, and no neutral (HSeMe)Fe(CO) 4 and (HSeMe)Cr(CO) 5 were detected spectrally (IR) even at low temperature. Reaction of NOBF 4 or [Ph 3 C][BF 4 ] and [MeSeCr(CO) 5 − ] resulted in the neutral monodentate (MeSeSeMe)Cr(CO) 5 complex. Addition of 1 equiv CpFe(CO) 2 I to 2 equiv [MeSeCr(CO) 5 − ] gave CpFe(CO) 2 (SeMe) and the anionic [(CO) 5 Cr(μ‐SeMe)Cr(CO) 5 − ] in THF at ambient temperature.