Phosphorus and Other Group VB Elements

and symmetry depending on the position of a selenium atom in the ring, and 

According to the electron diffraction study, A-cyanoimidosulfurous difluoride, (NC)—N=Sp2, takes a syn conformation in which the C=N group is syn with respect to the bisector of the SF2 angle symmetry). The IR and Raman spectra were assigned on the basis of normal coordinate analysis and DFT calculations [1701]. 

Group frequency charts in Appendix VIII indicate the regions for v(PH), v(PO), and v(PX) (X a halogen). 

The Raman frequencies of the tetrahedral P4 cluster are given in Sec. 2.5.1. The Raman spectrum of the Ag(P4)2 ion indicates that two P4 ligands coordinate to the 

Ag ion in D2/ symmetry [1706]. The P5 ion takes a planar ring structure of D5/, symmetry, and the medium-intensity Raman (polarized) band at 463 cm and the strong IR band at 815 cm have been assigned to the A l and E species, respectively [1707]. The P ion takes a planar ring structure of symmetry, and exhibits three Raman bands at 356 (Ai ), 507 ( 2 ), and 202 ( 2 ) cm [1708]. In the crystalline state, its symmetry is lowered to )2h- The IR and Raman spectra of the Pg ion in Ca5[Pg] were assigned on the basis of C2h symmetry [1709]. The Pff ion takes a cage structure of D3 symmetry, and its 27 (3 x 11 — 6) vibrations are classified into 5Ai (R)-h 4A2 (IR)+ 9E (IR, R). Complete band assignments have been based on normal coordinate analysis of this ion [1710]. 

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Other elements with which iron forms binary compounds, especially at higher temperatures, are boron, carbon, nitrogen, silicon, and phosphorus, l.ike FeO, these compounds often depart slightly or even considerably from daltonide composition, frequently being interstitial compounds, and in higher elements of groups VB and VIB, merging into the interstitial compound-solid solution picture which iron exhibits with the transition metals. 

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