https://doi.org/10.1351/goldbook.P04548
The saturated hydrides of tervalent phosphorus having the general formula PnHn+2. Individual members having an unbranched phosphorus chain are named phosphane, diphosphane, triphosphane, etc. The name of a saturated hydride of phosphorus wherein one or more phosphorus atoms have a bonding number of 5 is formed by prefixing locants and λ5 symbols to the name of the corresponding phosphane. Hydrocarbyl derivatives of PH3 belong to the class phosphines.
Source:
PAC, 1995, 67, 1307. (Glossary of class names of organic compounds and reactivity intermediates based on structure (IUPAC Recommendations 1995)) on page 1357 [Terms] [Paper]