Calcium monophosphide

Calcium monophosphide
Names
	Other names Calcium phosphide
Identifiers
CAS Number	39373-03-0 ;
3D model (JSmol)	Interactive image;
ECHA InfoCard	100.049.465
EC Number	254-431-6;
	InChI InChI=1S/2Ca.P2/c;;1-2/q2*+1;-2 Key: ZNARFUPPJCLHKN-UHFFFAOYSA-N;
	SMILES [Ca][P];
Properties
Chemical formula	CaP (Ca2P2)
Appearance	black solid
Solubility in water	decomposes
Hazards
	GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H260, H300, H311, H318, H330, H400
Precautionary statements	P223, P231+P232, P260, P264, P270, P271, P273, P280, P284, P301+P310, P302+P352, P304+P340, P305+P351+P338, P310, P312, P320, P321, P322, P330, P335+P334, P361, P363, P370+P378, P391, P402+P404, P403+P233, P405, P501
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
	(what is ?)
	Infobox references

Calcium monophosphide is the inorganic compound with the formula CaP. It is sometimes also known as "calcium phosphide", which also describes a different compound with composition Ca₃P₂. Calcium monophosphide is a black solid.

Structure and properties[]

The structures of CaP and sodium peroxide (Na₂O₂) are very similar.^[1] The solid is described as a salt: (Ca²⁺)₂P₂⁴⁻, or Ca₂P₂. Since the bonding is ionic, the diphosphide centers carry negative charge and are easily protonated. Upon hydrolysis this material releases diphosphine (P₂H₄):^[2]

Ca₂P₂ + 4 H₂O → 2 Ca(OH)₂ + P₂H₄

The hydrolyses of CaP and calcium carbide (CaC₂) are similar, except that diphosphine spontaneously ignites in air. Thus, CaP must be protected from air.

CaP decomposes to Ca₃P₂ at about 600 °C.

3 CaP → Ca₃P₂ + 1/4 P₄

References[]

^ Iandelli, A. and Franceschi, E., "On the crystal structure of the compounds CaP, SrP, CaAs, SrAs and EuAs", Journal of the Less Common Metals, 1973, volume 30, pp. 211-216. doi:10.1016/0022-5088(73)90107-0
^ Marianne Baudler, Klaus Glinka (1993). "Monocyclic and polycyclic phosphines". Chem. Rev. 93 (4): 1623–1667. doi:10.1021/cr00020a010.

[1] Iandelli, A. and Franceschi, E., "On the crystal structure of the compounds CaP, SrP, CaAs, SrAs and EuAs", Journal of the Less Common Metals, 1973, volume 30, pp. 211-216. doi:10.1016/0022-5088(73)90107-0

[2] Marianne Baudler, Klaus Glinka (1993). "Monocyclic and polycyclic phosphines". Chem. Rev. 93 (4): 1623–1667. doi:10.1021/cr00020a010.

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