The Chalcogen, X, Is In A -c(=x)- Group Patents (Class 558/178)
- Plural -C(=X)X- groups attached indirectly to the phosphorus by acyclic nonionic bonding (Class 558/180)
- The carbon of the -C(=X)X- group is bonded directly to the phosphorus or to nitrogen which is bonded directly to the phosphorus (Class 558/181)
- Acyclic carbon chain containing carbon to carbon unsaturation attached directly or indirectly to the phosphorus by acyclic nonionic bonding (Class 558/182)