Other Types of Compounds

Many compounds do not belong to any of the types discussed in the preceding sections. For these, the reader should consult Spectroso)pic Properties of Inorganic and OrganometaUic Compounds, (1968-present), published by the Chemical Society, l.ondon, and other reference hooks cited at the end of Part 1. Here, the references are given for some representative compounds which are relatively simple and for which complete band assignments are available. 

Several review articles are available on the vibrational spectra of boron compounds. Lehmann and Shapiro reviewed r(BH), 5(BH2), KBC), (BB), etc. of alkylboranes, and Bellamy et al. discussed r(BN), (BH), (BX), i/(BC), etc. Meller lists (BN), t fBH), i (BX), and r(BC) of a number of organoboron-nitrogen compounds. For vibrational spectra of boron compounds containing the B-P bond, see a review by Verkade. The group frequency charts shown in Appendix VI include t lBH), (BO), and r(BX). 

As stated in Sec. II-6(A), Muller and co-workers reviewed the vibrational spectra of thio and seleno compounds of transition-metal ions. The group frequency chart of sulfur compounds shown in Fig. 11-22 is based on the literature appearing in this book. For individual compounds, only references are cited [S ] (n = 3 6) (939), (940), S7 (941), S (942), H2S3.4 (943), 

Herzberg, Moiecutar Spectra and Maleadar Smwture, Vol. I Spectra of Diatondc Molecules, Van Nosirand, Princeton, N.J., 1950 K. P. Huber and G Hcrzberg, Molecular Spectra and Molecular Structure, Vol. IV Constants of Diatomic Molecules, Van Nosirand, Princeton, N.J., 1979. 

Clarke and O- Mamaniov, inorg. NucL Cfiem. Lett., 7,993 (1971). 

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In Table I we give the irreducible representations, in Mulliken s notation, contained in the central and attached orbitals for compounds of other types of symmetry. When 3 or 4 atoms are trigonally or tetragonally attached, we have supposed that the plane of these atoms is a plane of symmetry, as in (N03) or Ni(CN)4 When there is no such symmetry plane, as in NHg, the distinctions between u and g, or between primes and double primes, are to be aholished,9 and the symmetries degenerate to Csv, Civ instead of DSh, D h- When 6 atoms are attached in the scheme Z>3, or 8 in % they are arranged respectively at the corners of a trigonal and a square prism. 

A few cases of emission have been reported for compounds of other types of ligands, which also deserve mention. The emission of K4[Ru(CN)f,] at 77 K211,212) has been characterized as a d-d transition. Vogler and Kunkely have made a rare observation of CT emission from the ruthenium(III) compound, K3[Ru(CN)6]213). 

The free valence number therefore provides a good guide to reactivity in alternant hydrocarbons unfortunately this approach cannot easily be extended to compounds of other types. It can be used only when the contribution to 6E due to changes in the qt is the same for different aromatic systems and this is so only if coulomb integrals a, are the same for all the atoms present. Equation (33) shows that this is not so for molecules containing heteroatoms the ionization potential Wt is different for different atoms. Equation (33) shows that non-alternant hydrocarbons such as azulene must also be excluded here the... 

Thiocyanogen reacts also with compounds of other types it can replace a hydrogen atom attached to sulfur or nitrogen, it can replace the heavy-metal atom of certain organometallic compounds, and it can add to the triaryl derivatives of arsenic, antimony, and bismuth. 

Aromatic nitro-compounds (but some compounds of other types behave similarly). 

CH = C = CH— are called allenes after the simplest member of the series. They are said to have cumulated double bonds. They react in most cases normally, that is, each double bond is unaffected by the proximity of the other they are converted by heating into the isomeric acetylenes. Compounds of the type... 

Section 7 16 Atoms other than carbon can be chirality centers Examples include those based on tetracoordmate silicon and Incoordinate sulfur as the chirality center In principle Incoordinate nitrogen can be a chirality center m compounds of the type N(x y z) where x y and z are different but inversion of the nitrogen pyramid is so fast that racemization occurs vrr tually instantly at room temperature... 

Try making a model of a hydrocarbon that contains three carbons only one of which is sp hybridized What is its molecular formula Is it an alkyne" What must be the hybridization state of the other two carbons (You will learn more about compounds of this type in Chapter 10 )... 

Carboxylic acid anhydrides compounds of the type RCOCR can also serve as sources of acyl cations and m the presence of aluminum chloride acylate benzene One acyl unit of an acid anhydride becomes attached to the benzene ring and the other becomes part of a carboxylic acid... 

Essential oils (Section 26 7) Pleasant smelling oils of plants consisting of mixtures of terpenes esters alcohols and other volatile organic substances Ester (Sections 4 1 and 20 1) Compound of the type... 

Organophosphorus Derivatives. Neopentyl glycol treated with pyridine and phosphorus trichloride in anhydrous dioxane yields the cycHc hydrogen phosphite, 5,5-dimethyl-l,3-dioxaphosphorinane 2-oxide (2) (32,33). Compounds of this type maybe useful as flameproofing plasticizers, stabilizers, synthetic lubricants, oil additives, pesticides, or intermediates for the preparation of other organophosphoms compounds (see Flame retardants Phosphorus compounds). 

Phosphoms forms weU-defined halogen compounds of the types PX, PX, POX, and PSX, all of which except the pentaiodide and the oxy- and sulfoiodides are known. In addition to the binary haUdes, a few of the many possible mixed haUdes, eg, PX2Y and PX2Y2, have been prepared. The commercially important phosphoms haUdes are phosphoms trichloride [7719-12-2] phosphoms oxychloride [10025-87-3] phosphoms pentachloride [10026-13-8] and phosphoms sulfochloride [3982-91-0]. A few other phosphoms haUdes, eg, PI, PR13) marketed as reagent... 

A number of compounds of the types RSbY2 and R2SbY, where Y is an anionic group other than halogen, have been prepared by the reaction of dihalo- or halostibines with lithium, sodium, or ammonium alkoxides (118,119), amides (120), azides (121), carboxylates (122), dithiocarbamates (123), mercaptides (124,125), or phenoxides (118). Dihalo- and halostibines can also be converted to compounds in which an antimony is linked to a main group (126) or transition metal (127). 

Other tri alkyl and triaryl compounds of the type R2SbY2, where Y is a pseudohaUde or a group such as NO, CIO, or S SO, have been prepared. They are usually obtained from the dihahdes by metathesis with a silver salt, eg ... 

In addition to the tri alkyl- and triaryldihaloarsoranes there are a number of compounds of the type R2ASY2, where Y is a pseudohalide, nitrate, carboxy, or other negative group. They are usually prepared from tri alkyl- or triaryldibromo- or dichloroarsoranes by metathesis. Thus dia2idotrimethyiarsorane [21121-84-6], C H AsN, has been prepared in the following manner (151) ... 

Detectors. The function of the gc detector is to sense the presence of a constituent of the sample at the outlet of the column. Selectivity is the property that allows the detector to discriminate between constituents. Thus a detector selective to a particular compound type responds especially weU to compounds of that type, but not to other chemical species. The response is the signal strength generated by a given quantity of material. Sensitivity is a measure of the abiHty of the detector to register the presence of the component of interest. It is usually given as the quantity of material that can be detected having a response at twice the noise level of the detector. 

The simplest chain compounds of the type RS NyR are the sulfur diimides RNSNR (Section 10.4) The other known thiazyl chains are summarized in Table 14.1. They can be conveniently classified as sulfur-rich, nitrogen-rich or even-chain species. 

Intramolecular chalcogen interactions may also stabilize reactive functional groups enabling the isolation of otherwise unstable species or their use as transient intermediates, especially in the case of selenium and tellurium. For example, tellurium(II) compounds of the type ArTeCl are unstable with respect to disproportionation in the absence of such interactions. The diazene derivative 15.23 is stabilized by a Te N interaction. Presumably, intramolecular coordination hinders the disproportionation process. Other derivatives of the type RTeX that are stabilized by a Te N interaction include 8-(dimethylamino)-l-(naphthyl)tellurium bromide, 2-(bromotelluro)-A-(p-tolyl)benzylamine, and 2-[(dimethylammo)methyl]phenyltellunum iodide. Intramolecular donation from a nitrogen donor can also be used to stabilize the Se-I functionality in related compounds." ... 

Numerous carbonyl halides, of which the best known are octahedral compounds of the type [M(C0)4X2] are obtained by the action of halogen on Fe(CO)5, or CO on MX3 (M = Ru, Os). Stepwise substitution of the remaining CO groups is possible by X or other ligands such as N, P and As donors. 

The principal compounds in this category are the monochalacogenides, which are formed by all three metals. It is a notable indication of the stability of tetrahedral coordination for the elements of Group 12 that, of the 12 compounds of this type, only CdO, HgO and HgS adopt a structure other than wurtzite or zinc blende (both of which involve tetrahedral coordination of the cation — see below). CdO adopts the 6-coordinate rock-salt structure HgO features zigzag chains of almost linear O-Hg-0 units and HgS exists in both a zinc-blende form and in a rock-salt form. 

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