The Group V Elements P, As, Sb, Bi

The electronic structures and some other properties of the elements are listed in Table 13-1. The valence shells have a structure formally similar to that of nitrogen, but, beyond the stoichiometries of some of the simpler compounds—-NH3, PH3, NC13, BiCl3, for example—there is little resemblance between the characteristics of these elements and those of nitrogen. 

Electronic structure [Ne]3iJ3p3 [Ar]3d °4s24p3 [Kr]4d105s25p3 [Xe]4/ t5rf1°6j26p3 

Although oxidation states or oxidation numbers can be, and often are, assigned to these elements in their compounds, they are of rather limited utility except in the formalities of balancing equations. The important valence features concern the number of covalent bonds formed and the stereochemistries. The general types of compound and stereochemical possibilities are given in Table 13-2. 

5 Trigonal bipyramidal PFS, AsF5, SbCl5, Ph5P, Ph5As 

The differences between N and P in their chemistries, which are due to the same factors as are responsible for the C—Si and O—S differences, can be summarized as follows  

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Ammonium salts constitute only one type of a large class of compounds known as onium salts/ The monopositive cation of these salts consists of a central atom of an element from Periodic Group V(N,P,As,Sb,Bi), VI(0,S,Se,Te), or VII(Cl,Br,I), which is bonded covalently to hydrogen atoms, organic radicals, or a combination of these. Onium salts, in which oxygen is the central atom, are known as oxonium salts. Although Werner made a number of important experimental studies of oxonium salts, and even discovered several new types of such compounds 78,90), his theoretical views are of primary interest here. 

The binary compounds of the Group 13 metals with the elements of Group 15 (N, P, As, Sb, Bi) are stmcturally less diverse than the chalcogenides just considered but they have achieved considerable technological application as III-V semiconductors isoelectronic with Si and Ge (cf. BN isoelectronic with C, p. 207). Their stmctures are summarized in Table 7.10 all adopt the cubic ZnS stmcture except the nitrides of Al, Ga and In which are probably more ionic (less covalent or metallic) than the others. Thallium does not form simple compounds... 

A gradual increase is observable in the electropositiveness of the metals in the order V-—>-Nb—>Ta (increase in atomic weight), as in the ease of the elements of the B Subdivision of this group, N—j-P—> As—>-Sb—>Bi. It is also worthy of notice that, consistent with the usual rule, the A Subdivision on the whole is more strongly electropositive than the B Subdivision. The following observations show these facts clearly —... 

The compositions of the most numerous actinide compounds with elements of the group V of the periodic table (X = N, P, As, Sb, Bi) belong to the types AnX2, An3Xt, AnX. These pnictides can be synthesized in solid-gas-reactions with actinide hydride, or with metal powder obtained by thermal dissociation of hydrides. 

The reaction of (CH3XCF3)3PN(CH3)2 with CS2 proceeds with CS2 insertion into the P-N bond and formation of the (CH3XCF3)3F(Me2Dtc) compound (S90). Very little is known about the chemistry of the xanthate or dithioacid complexes of the Group V elements. The P(EtXant)3 has been reported (410). The IR spectrum of this molecule and those of the corresponding As(III) and Sb(III) compounds show a monotonic decrease of the C—O vibration around 1200 cm 1 (by 7 cm-1 intervals) from P to Bi (635). 

The perfluorophenyl derivatives of the elements of Group V (P, As, Sb. Bi) are elTectivc sources of the three perfluorophenyl groups bonded with the elements, under the conditions of catalysis by fluoride ion. 

To convert the formula of an open-chain, saturated hydrocarbon to a formula containing Group V elements (N, P, As, Sb, Bi), one additional hydrogen atom must be added to the molecular formula for each such Group V element present. In the following examples, each formula is correct for a two-carbon acyclic, saturated compound. 

The occurrence of homoatomic anions [En] of the elements of groups IV (C, Si, Ge, Sn, Pb) and V (P, As, Sb, Bi) as constituents of Zintl phases is well knownJ Despite numerous attempts, just a few of the En clusters have been isolated as uncharged molecules E Rx from the Zintl phases by reaction with suitable agents such as alkyl chlorides. 

The second area of activity is that of metallo-de-diazoniation, the reactions that are the subject of this section. This activity began in 1929 when Nesmeyanov (1929a, b) and McClure and Lowy (1929, 1931) independently found that phenylmercuric chloride is formed if mercury is vigorously agitated with an aqueous solution of ben-zenediazonium chloride (Scheme 10-86). Analogous compounds based on elements of groups V and Vb (P, As, Sb, and Bi) have also been found, some even before those of mercury. 

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