The asymmetric unit of [2•(Na(crypt)] contains two solvent/ligand separated anions, which both feature quite different S-C-C angles of 177.5(3)° and 165.2(3)°. This indicates a shallow energy profile for the bending of the S-C-C angle, which can be easily influenced by subtle changes in the molecular environment such as by packing effects. Both angles are considerably larger than those reported for IIa and IIb, indicating a more pronounce ynolate character (B, Figure ). In contrast, the C-C bond lengths of the ketenyl moiety in the two anions are with approx 1.205(5) Å only slightly shorter than the C=C bonds of other ketenes and between those of IIa and IIb (Table ). Likewise, the C-O bonds are markedly shorter than in IIa and IIb, which corroborates with a C=O double bond as expected for the ketenyl anion structure A. This structure was expected due to the stronger electron-withdrawing ability of the tosyl group compared to the thiophosphoryl and phosphinoyl group, which reduces the shift of electron density from the former yldiide into the π* orbital of carbon monoxide (Int, Scheme 1). Consistently, the more acute S-C-C angle found for one of the two anions in the structure of [2•(Na(crypt)] is associated with the shorter C-O bond. Overall, this observation suggests that a more acute angle as well as a stronger electron-withdrawing substituent R favor the ketenyl anion form A over ynolate B.