N, P, As, Sb or Bi

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 

M X the explosive black nitride T1 3N is known, and the azides T1 N3 and T1 [T1 (N3)4] the phosphides TI3P, TIP3 and TIP5 have been reported but are not well characterized. With As, Sb and Bi thallium forms alloys and intermetallic compounds TI3X, Tl7Bi2 and TlBi2. 

The III-V semiconductors can all be made by direct reaction of the elements at high temperature and under high pressure when necessary. Some properties of the Al compounds are in Table 7.11 from which it is clear that there are trends to lower mp and energy band-gap Eg with increasing atomic number. 

Analogous compounds of Ga and In are grey or semi-metallic in appearance and show similar trends (Table 7.12). These data should be compared with those for Si, Ge, Sn and Pb on p. 373 and for the isoelectronic II-VI semiconductors of Zn, Cd and Hg with S, Se and Te (p. 1210). In addition, GaN is obtained by reacting Ga and NH3 at 1050° and InN by reducing and nitriding In203 with NH3 at 630°. The 

Other compounds containing Al-N or Ga-N bonds, including heterocyclic compounds and cluster organometallic compounds, are considered in section 7.3.6. 

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Numerous other binary compounds are obtained by direct interaction at elevated temperatures examples are the semi-conducting sulfides,20 M2S3, which can also be made by reaction of MC13 with H2S at 1100°. Group V compounds, MX, where X = N, P, As, Sb or Bi, which have the NaCl structure borides, MB4, MB6 and carbides, MC2 and M2C3 (pages 290 and 1075). 

Tc = Curie temperature Tn = Neel temperature Vc - crystal-field potential W = scale factor for the crystal-field splitting of the J ground-state energies X = symbol for an anion, N, P, As, Sb or Bi... 

Hirsch and co-workers calculated NICS values for tetrahedral clusters of N, P, As, Sb, and Bi, as well as for the corresponding tetra-anions composed of Si, Ge, Sn, or Pb atoms, finding diatropic values for 2,n(n 1) jr-systems.296a b It was postulated by Hirsch, Schleyer, and their co-workers that for icosahedral fullerenes and their hetero-analogues the Hiickel rule, involving 4/2+2 //-electrons, should be replaced by the 2(/2+l)2 electron rule.296... 

Interestingly, all of the elements in group 15 in the periodic table (N, P, As, Sb and Bi) are directly or indirectly related to the maintenance of human life as either essential elements (e.g., N and P) or therapeutic/toxic elements (e.g.. As, Sb and Bi). Currently antimony compounds (e.g., sodium stibogluconate, Pentostam ) are used clinically for the treatment of leishmaniasis and bismuth compounds (e.g., bismuth subsalicylate (BSS), colloidal bismuth subcitrate (CBS) and ranitidine bismuth citrate (RBC)) are widely used for the treatment of ulcer and Helicobacter pylori infection [l-3c,10,132,133]. Recently, clinical... 

Ylides in which the heteroatom is N, P, As, S, or Se are well known. Other ylides containing Sb, Bi, O, Te, I, or Br are also known, but they are rarely used as ligands since they are very unstable, and they will not be treated here. The synthesis of the ylides is achieved through several preparative methods, most of which have been comprehensively reviewed [2-11]. The most relevant of these requires two steps, and involves the reaction of a halide with an EZ nucleophile (NR3, PR3, ASR3, SR2, etc.) and subsequent dehydrohalogenation of the onium salt (method a) as represented in Scheme 2 [2-6]. This process has been reported in a wide variety of experimental conditions, using virtually all kinds of solvents and bases (provided that they are compatible). The desilylation of some a-SiMe3 onium salts (method b)... 

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. 

A Japanese patent describes the treatment of metal surfaces with amorphous layers of second metals having a thickness of 0.2-2.5 pm. The metal component includes one, or more, of the following V, Nb, Ta, N, P, As, Sb, Bi, Cr, Mo, W, S, Se, Te, and Po. The introdnction of snch a snrface coating is claimed to improve wear and burning resistance of the metal. Also, the coating serves to increase the retention of oil films by the metal surface thus improving lubrication properties. 

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. 

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