Ariel E. Fenster

The infrared spectra of isotopically substituted metal carbonyls : II. Some 13Co- and C18O-substituted π-cyclopentadienylmetal carbonyl complexes

Abstract All of the IR-active CO stretching absorptions present during the reactions of CpMn(CO) 3 , CpMn(CO) 2 (C 8 H 14 ), CpMn(CO) 2 CS, CpMn(CO)(CS)(C 8 H 14 ), CpV(CO) 4 , and CpCo(CO) 2 with 13 C- and/or 18 O-enriched CO in n-hexane solution have been assigned to modes of the all- 12 C 16 O molecules and the various isotopically enriched species produced in the reactions. The proposed vibrational assignments are supported by force constant calculations for the energy factored CO stretching blocks of the (FG) matrices. The chief product of the reaction of CpMn(CO) 2 (C 8 H 14 ) with 90% 18 O-enriched CO is CpMn(CO) 2 (C 18 O); the relative intensities of the three CO stretching absorptions for this species are approximately in the ratio 1/1/1, in agreement with a previous theoretical prediction. The CS group in CpMn(CO) 2 CS is not replaced by carbon monoxide whereas both CO groups are exchanged. This observation suggests that CS is more strongly bonded to the manganese atom than are the CO groups.

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Cyclopentadienylmanganese dicarbonyl thiocarbonyl

The thiocarbonyl complex, C5H5Mn(CO)2(CS), has been isolated from the reaction of C5H5Mn(CO)2-(cis-cyclo-octene) with carbon disulphide.