Complexes arsilidene—

Mass spectra of arsilidene complexes, [Cp Mn(CO)2]2AsR, 17-24 (Table 3), contain molecular ion peaks. The most common fragment ions correspond to elimination of 2CO, R and Cp Mn(CO)2. The abundances of these ions depend strongly on the R substituent at the As atom (Table 4). Substituents R such as F, I, OCS, NCS and N3 are easily eliminated directly from the molecular ion. Loss of Ph, however, occurs only after elimination of all carbonyl ligands, and R = H, R = c-Hex are not lost at all. Only compounds with R = Ph, H and c-Hex have mass spectra which display peaks corresponding to (M—2CO) and (M-4CO) ". The formation of (M — R — nCO) (n = 2,4) ions is characteristic of complexes containing R = I, OCS, NCS and N3. The complex having R = F is intermedi-... 

TABLE 4. The relative abundances of ions in the mass spectra of some arsilidene complexes Cp Mn(CO)jjj.AsR Mn(CO)2Cp ... 

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