Bei der Einwirkung der Isothiocyanate R' -N = C = S (R' = CH,, C,H5, C6H5) auf die Dimanganacyclohexadiene [(OC),Mn -S = PR,], ( l a , b) [R = CH, (a), C6H5 (b)] erhalt man durch offnung einer Mn -S-Bindung unter CO-Eliminierung die neuartigen, tricyclischen Verbindungen k -P ( R 3 -M~( C O ) ; -S = P ( R~-M~( C O ) , -S -& = N R (~~X -~, bx-z), indenenalledrei Atome des Heterocumulens zusatzliche Bindungen eingegangen sind. 2ax -z, bxz sind gegeniiber erh6htem CO-Druck stabil. Nach einer Kristallstrukturbestimmung liegt 2az als Enantiomerengemisch vor und kristallisiert in der triklinen Raumgruppe P1 mit 2 = 2. I Preparation and Properties of, and Reactions with, Metal-Containing Heterocycles, XXXlI The Reactive Behaviour of [(OC),Mn -S = PR,], Towards Isothiocyanates By cleavage of an Mn -S bond and C O elimination the action of the isothiocyanates R'-N = C = S ( R = CH,, CzQ5, C6H5) on the dimanganacyclohexadienes [(OC),Mn -S = PR,], ( l a , b) [R = CH, (a), C6H5 (b)] results in the formation of the novel tricyclic compounds S -P(R3 -M k O ) , -S = P(R3 -Mn(CO), -k -C = NR' (2ax -z, bxz) in which all three atomsof the heterocumulene have entered into additional bonds. 2axz, bxz are stable towards elevated CO pressure. According t o an X-ray structural determination, 2az is present as an enantiomeric mixture and crystallizes in the triclinic space group P1 with 2 = 2.