Phosphorus selenides are a relatively obscure group of compounds. There have been some studies of the phosphorus - selenium phase diagram and the glassy amorphous phases are reported. The compounds that have been reported are shown below. While some of phosphorus selenides are similar to their
sulfide analogues, there are some new forms, molecular P2Se5 and the polymeric catena-[P4Se4x. There is also some doubt about the existence of molecular P4Se10.
Crystallographically confirmed compounds
P2Se5
Molecular P2Se5 has a
norbornane like structure with two phosphorus atoms with oxidation state +3 bridged by two
diselenide units (−Se−Se−, analogous to
disulfide) and one selenide unit (−Se−).[1] It was isolated by solvent (
CS2) extraction from a P2Se5 amorphous phase made from the elements.[2]
P4Se3
P4Se3 has been characterised crystallographically and has the same structure as the low temperature form of P4S3.[3] It can be prepared from the elements. One preparation is to extract and recrystallise using
tetralin.
P4Se5
The P4Se5 molecule has the same structure as
P4S5.[4] It was prepared by reacting P4Se3 with
bromine in
CS2.
catena-[P4Se4x
This compound consists of polymeric chains of
norbornane-like units joined by Se atoms.[5] As each P atom in the repeat unit is bonded to another P atom and to two Se atoms, each P atom has a formal oxidation state of +2.
Compounds confirmed spectroscopically
P4Se4
P4Se4 has two crystalline forms α-P4Se4 with the same molecular structure as
α-P4S4 and β-P4Se4 with same molecular structure as
β-P4S4.[6] A fully characterised compound (CuI)3P4Se4 contains P4Se4 with a β-P4S4 structure.[7]
P4Se7
This has been reported to have the same structure as
P4S7.[8][9] One well-known textbook does not mention it at all.[10]
P4Se10
Molecular P4Se10 has been reported to share the same structure as
P4S10 and
P4O10,[8][9][11] but one well-known textbook does not mention it at all.[10] A review (2001) examining P-Se amorphous phases did not confirm the presence of molecular P4Se10.[12] The isoelectronic anion [Ge4Se104− which has the
adamantane like P4O10 structure is known, an example is the sodium salt Na4[Ge4Se10.[13]
Other compounds
P4Se6, P14Se, P4Se, P4Se2, P2Se, have been reported.[8]
Phosphorus - selenium glasses
Phosphorus - selenium glasses have been examined using
31P-NMR and Raman spectroscopy. Glasses are formed in PxSe1−x over the range of compositions 0 < x < 0.8 with a small window around 0.52 – 0.60 centred on 0.57 (corresponding to the compound P4Se3) where there is a tendency to crystallise. For x < 0.47 the glasses contain Sen chain fragments, pyramidal P units (P
oxidation state +3), quasi-tetrahedral P units (P oxidation state +5, with P=Se
double bond) and P2 units (P in formal oxidation state +4). There is no evidence for an
amorphous phase containing molecular P4Se10.[12]
^Blachnik, Roger; Lönnecke, Peter (1992). "From P4Se3I2via P3Se4I to P2Se5". Phosphorus, Sulfur, and Silicon and the Related Elements. 65 (1–4): 103–106.
doi:
10.1080/10426509208055329.
ISSN1042-6507.
^Penney, G. J.; Sheldrick, G. M. (1971). "Crystal and molecular structure of tetraphosphorus pentaselenide". Journal of the Chemical Society A: Inorganic, Physical, Theoretical: 245.
doi:
10.1039/j19710000245.
ISSN0022-4944.
^Ruck, Michael (1994). "Darstellung und Kristallstruktur des ersten polymeren Phosphorselenidscatena-(P4Se4)x". Zeitschrift für Anorganische und Allgemeine Chemie. 620 (10): 1832–1836.
doi:
10.1002/zaac.19946201028.
ISSN0044-2313.
^Blachnik, R.; Lönnecke, P.; Nuß, J. (1994). "Neues vom P4Se4". Zeitschrift für Anorganische und Allgemeine Chemie. 620 (1): 160–166.
doi:
10.1002/zaac.19946200126.
ISSN0044-2313.
^
abcCorbridge, D.E.C (2013). Phosphorus: Chemistry, Biochemistry and Technology. CRC Press, Taylor Francis Group. p. 808.
ISBN978-1-4398-4088-7.
^
abDevillanova, Francesco, ed. (2007). Handbook of Chalcogen Chemistry –New Perspectives in Sulfur, Selenium and Tellurium. Royal Society of Chemistry.
ISBN9780854043668.
^
abHolleman, Arnold Frederik; Wiberg, Egon (2001), Wiberg, Nils (ed.), Inorganic Chemistry, translated by Eagleson, Mary; Brewer, William, San Diego/Berlin: Academic Press/De Gruyter,
ISBN0-12-352651-5
^Housecroft, Catherine E; Sharpe, Alan G (2005). Inorganic Chemistry (2d ed.). Pearson education. p. 427.
ISBN978-0-13-039913-7.
^
abGeorgiev, D.; Mitkova, M.; Boolchand, P.; Brunklaus, G.; Eckert, H.; Micoulaut, M. (2001). "Molecular structure, glass transition temperature variation, agglomeration theory, and network connectivity of binary P-Se glasses". Physical Review B. 64 (13): 134204.
Bibcode:
2001PhRvB..64m4204G.
doi:
10.1103/PhysRevB.64.134204.
ISSN0163-1829.