New reactions and new products derived from α-deprotonated Fischer-type carbene complexes

Anionic Fischer-type aminocarbene complexes, [(CO)5MC(NMe2)CH2]Li (M = Cr or W), react with Ph2PCl and [Me2(MeS)S]BF4] - a source of SMe+ - to afford acyclic complexes (CO)5MC(NMe2)CH2X (X = PPh2, SMe2) and (CO)5MC(NMe2)CHX2 X = SMe), the chelates and , and the bridged compounds (CO)5MC(NMe2)CH2XM(CO)5 (X = PPh2, SMe). Cyclisation occurs much faster for Cr than for W. Crystal structures illustrate the bonding behaviour in the new complexes and especially characterise carbene-phosphine and carbene-thioether four-membered chelates for the first time. The sulfur-donor in the tetracarbonyl complexes , and shows an exceptionally weak trans influence.