Quinquevalent Compounds

Kauffmann, J. Ennan, and K. Berghus, Tetrahedron Lett., 1984, 25. 1971. Syntheses and uses of PhAs(CH2CH2CpLl)2 and related compounds. 

Yambushev, G.I. Kokorev, and F.G. Khalitov, Zh. Obshch. Khlm., 1984, 84, 857. Preparation of ArEtAsCl from ArAsCl2 and Et4Pb. 

Ranjan, K. Slnghal, and R. Rastogl, Synth. React. Inorg. Met-Org. Chem. 1984, U, 269. Synthesis of Ar SbONCR R, Ar SbOCOR and Ph SbNRCOR.  

Burgert and R. Rewickl, Chem. Ber., 1984, 2409. Synthesis and spectra of 9-[l,2-(He02C)-2-Ph Sb-ethenyl]fluorenlde and arsenic analogue. 

Mesmeyanov, V.G. Kharitonov, S.T. Berman, P.V. Petrovskii and O.A. Reutov, Dokl. Akad. Nauk. SSSR. 1984, 274. 606 Izv. Akad. Mauk. SSSR, Ser. Khlm., 

SbOSb (iii) (Ph2SbBrO)2 from Ph2SbBr and Bu OOH planar Sb202 ring, and (iv) various spirocyclic arsoranes e.g. trigonal bipyramldal, Meijs7oaie CMe )2 and rectangular pyramidal (12). 

Tbe formation was reported of pentacoordlnate arslnimines, containing N-As coordination, e.g. (13) these compounds dimerize to dlarsadlazocyclobutanes.  

Thermolysis of PhgBi in CO2 provided Ph3BiOC(0)CgH - . An e.s.c.a./n.q.r. study of Me3SbCl2 SbCl3 (8) has been carried out the observed n.q.r. transitions were related to the known cross-linked chain structure of (8). Spectra ( Mflssbauer, H n.m.r. and C n.m.r.) of R3SbX2were interpreted as revealing that as the electronegativity of X increases, the electron cloud about Sb spreads towards X and also towards the plane perpendicular to the Sb-X axis. 

Preparations of R3ASF2 have been achieved (i) by low temperature direct fluorination of R3AS (R=CgFg) and (ii) by anodic oxidation of R3AS in the presence of CgH. iNH2 and pyH , BF4 . 

In contrast to covalently bonded (9), He3Sb(OSOR)2 (R=CF3 or CH2CH2OH) has an ionic structure (from vibrational spectra). From the n.m.r. and electronic spectra of R3 bQ2 (10) and R SbQX (11, X=C1 or Br) (Q=8-quinolinate), it has been deduced that Q has a greater chelating effect in (11) than in (10). 

Stable ylides, Ph sVcXY (e.g.X.Y=g-MeC(-H S02.PhC0.HeC0 XY=-C(0)(CH2)3C(0)-have been produced by the reactions of Ph3Sb and XYCN2 in the presence of Cu[CH(C0CF3)2]2- 

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If we admit the hypothesis 2 that the three quantum orbits of the second series may contain a maximum of 6, 6 instead of 4, 4 electrons, it follows that PC15 also, and other quinquevalent compounds, may be written with ordinary valencies or duplet bonds only, giving shells of 10 . If, however, 8 is the maximum possible (failing the completion of 12), then PC16 must be constituted either as NII4C1, or it must contribute two electrons to a pair of chlorine atoms, thus developing a mixed bond. In the first case... 

Wg= 2K/t = 1.85 0.01 mm/s. This puts an upper limit of AEg < 0.05 mm/s to the possible electric quadrupole. interaction at the gold sites in these quinquevalent compounds, which is in agreement with the observed octahedral symmetry of the AuF anion in the crystal structure XezFyAuF ... 

In the course of the tempestuous development of organophosphorus chemistry, interest has only recently been focused on compounds of formally quinquevalent phosphorus having coordination number 3, such as 1, 2, or 3, although one of the other species of this kind has long been postulated as reactive intermediate of solvolysis of phosphorylation reactions. Definite evidence of even proof of the existence of such coordinatively unsaturated phosphorus compounds, however, has been obtained only recently in mechanistic studies, by trapping reactions with suitable cycloaddends, or actually by direct isolation. 

The present survey is concerned exclusively with short-lived compounds of quinquevalent phosphorus with coordination number 3, which are not yet isolable in a classical sense with few exceptions they all possess at least one P/O double bond. Specifically, these are the metaphosphinates /, the metaphosphonates 2, and the metaphosphates 3. Studies of the methyleneoxophosphoranes 1 (X = O) and the monomeric metaphosphate ion 3 (Z = Oe, X = Y = O) have been especially thorough. 

In the case of 22b-e, the butadienes 24b-d and the hexatriene 24 e, respectively, are also obtained on trapping with cinnamaldehyde, the 1,3-diene 24a is even the sole reaction product. It is quite obvious that the olefins 24 are secondary products of the trapping reaction of 9 arising by photofragmentation of 22. The other product is phenyldioxophosphorane (23) which also numbers among the short-lived compounds of quinquevalent phosphorus with coordination number 3 (see Sect. 3.1). 

Because of the lack of information in the literature on the radical reactions of compounds of quinquevalent phosphorus, it is impossible to postulate a readily acceptable mechanism for the oxidation of zinc dialkyl dithiophosphates. Colclough and Cunneen (7) rejected immediately the possibility of hydrogen abstraction, but in view of the present results serious consideration has been given to this reaction. During this work it was shown (15) that abstraction of hydrogen from trialkyl phosphates, trialkyl phosphonates, and sodium dialkyl phosphates can occur at room temperature in an aqueous medium in the presence of hydroxy radicals. 

Compounds of the type KBr3 are usually supposed to contain a tervalent halogen the chlorates, bromates, and iodates, and compounds of the type Csl5, to contain quinquevalent halogens and the perchlorates and periodates and compounds of the type Csl7, to contain septivalent halogens. 

The compounds of phosphorus containing the quinquevalent element are generally the most stable but with antimony and bismuth those of the tervalent element are the most stable, in fact few compounds of quinquevalent bismuth are known. The difference in stability of the ter- and quinque-valent compounds of arsenic is not so marked. Evidence of arsenic existing as a quadrivalent element in certain organic compounds has been observed.1... 

The ammonium theory.—In the ammonium theory of H. Davy, A. M. Ampere, and J. J. Berzelius, it was assumed. that the ammonium compounds contain a metallic radicle, NH4 (4.31,38), which may replace potassium, sodium, etc., in different salts. When ammonia unites with hydrogen chloride, the NH4-radicle is formed which unites with chlorine to form ammonium chloride in the same way that potassium united with chlorine forms potassium chloride. The ammonium theory thus corresponds with the ethyl theory of J. J. Berzelius, and J. von Liebig. The nitrogen is assumed to be quinquevalent, and this is in harmony with the work of V. Meyer and M. T. Lecco, A. Ladenburg, and W. Lossen on the quaternary ammonium baseb, and with the isomorphism of the ammonium and the potassium salts. 

The analyses of H. Davy, and J. L. Gay Lussac and L. J. Thenard show that nitric oxide has the empirical composition NO. This formula agrees with the physical properties of the gas. Oxygen is bivalent, hence the nitrogen in nitric oxide also behaves as a bivalent element 0=N but nitrogen is usually ter-or quinque-valent, so that nitric oxide is usually considered to be an unsaturated compound. No evidence of the existence of 0=N—N=0 has been observed. C. Weltzien considers that the radicle NO is sometimes univalent, and sometimes bivalent. J. C. Thomlinson s calculations of the thermochemical eq. of nitrogen in nitric oxide favoured the assumption that the oxygen is quinquevalent. E. Muller discussed this subject and E. C. Stoner, and C. D. Niven, the electronic structure. 

There have been several calculations dealing with AH5 species where A is a second-row atom, S, Si, or P. PH5 is a hypothetical molecule and has been extensively studied as the prototype quinquevalent phosphorus compound. Earlier calculations by Rauk et al.2S1 found that -functions had a significant effect on the total energy, but primarily act to overcome deficiencies in the basis set used which was (12,9,1/5)->[6,4,1/2]. ... 

David NA, Anderson HH, Koch DA et al (1932) Comparative toxicity and protozoacidal action of acetarsone, carbarsone and certain related quinquevalent arsenical compounds. Proc Soc Exp Biol Med 29 125-128... 

The phosphorus probably is the central atom, possessing the coordination number 4, in all compounds which were considered formerly to contain quinquevalent phosphorus. The complete series between the quadrivalent hydride and oxide will appear as—... 

The acid which is produced finally by the oxidation of phosphorus in the presence of sufficient water and after heating has probably the constitutional formula OP(OH)s (see p. 59). The term ortho, in accordance with Graham s description, was applied to ordinary phosphoric acid. Later, on the hypothesis of the quinquevalent nature of phosphorus, it was considered that the hypothetical acid P(OH)5 would, strictly speaking, be the ortho acid. However, the present theories of valency do not indicate the possible existence of such an acid, but rather that OP(OH)3 should be the most highly hydroxylated compound. 

Phosphorus is almost exclusively tervalent in its organo-eompounds and lower halides, etc., and quinquevalent in the compounds PX5, phosphonium compounds and the phosphoric acids according to modem theory, however, this quinquevalency is really quadricovalency. Compounds showing other valencies are not common, and sometimes are of doubtful individuality. 

As may be noted, major advances in the development of preparative rentes for tetracoordinated quinquevalent organophosphoms compounds occurred in the late nineteenth and early twentieth centuries. In more recent times, owing to increased applications and potential applications for derivatives of phosphonic and phosphinic acids, including biomedical regnlation, pest control, flame retardation, and biochemical mechanistic exploration, among others, increased attention has been given to approaches for the preparation of such materials. 

Oxygen is bivalent in most of its compounds. Since oxygen combines with most of the elements, some of which form several different oxides, the common valences of the elements can be found by considering the formulas of their oxides. Thus sodium, with oxide Na, 0, is univalent calcium (oxide CaO) is bivalent aluminum (oxide ALO ) is tervalent phosphorus (oxides P2O3 and P2O,) is both tervalent and quinquevalent. 

The reaction of xenon with platinum hexafluoride yields at least two distinct quinquevalent platinum products, XePtF, and Xe(PtFj)j. A third compound XePtjFij which is diamagnetic, is produced by heating the former. During continuing investigations of the reaction between xenon, fluorine, and platinum pentafluoride, at least two different compounds have been detected. The better characterized compound is produced when 1 1 molar ratios of xenon and platinum pentafluoride are employed in admixture with 80 p.s.i. 

We have prepared material of empirical formula RhF, and have established the rhodium to be quinquevalent. The compound has been prepared by the action of gaseous fluorine, at 90 Ib./sq.in. on the trifluoride at 400°. It has also been identified, together with the hexafluoride and trifluoride, as a product of the combustion of rhodium wire in fluorine. The compound is a dark red solid, m.p. 

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