Oxyhalides

A number of oxyhalides of nitrogen are known including the types XNO nitrosyl halides) with X = F, Cl, or Br, and XN02 (nitryl halides) with X = F or Cl. All of these compounds are gases at room temperature. Nitrosyl halides can be prepared by the reactions of halogens with NO  

The oxyhalides are very reactive and generally function to halogenate other species. For example, they react to give produce halo complexes as illustrated by the equations 

These interesting compounds also undergo halogenation reactions. 

Much less is known about ruthenium oxyhalides than about the osmium compounds. The only compound definitely characterized [24] is RuOF4, synthesized by fluorination of Ru02, condensing the product at — 196°C. It loses oxygen slowly at room temperature, rapidly at 70°C. 

It gives the parent ion in the mass spectrum and has a simple IR spectrum (z/(Ru=0) 1040 cm-1 and (i/(Ru-F) 720 cm-1) similar to that of the vapour (1060, 710, 675 cm-1), implying a monomeric structure. Chlorides RuOCl2 and Ru2OClA (x = 5,6) have been claimed various oxo complexes Ru2OXjo are well defined. 

Although no OsF8 has been described, there are oxofluorides in the +8 state. 

It is thermally stable but instantly hydrolysed in air (like osmium oxyhalides in general) it has a simple vibrational spectrum ( (0s=0) 940 cm-1 KOs-F) 680, 590, 570 cm-1) (Table 1.2) and a ds-octahedral structure has been confirmed by an electron diffraction study (0s=0 1.674 A, Os—F 1.843-1.883 A). 

Several syntheses have been reported for orange-yellow diamagnetic 0s03F2 (m.p. 172-173°C) [26]  

It has also been made by passing RUF5 vapour down a hot glass tube RUF5 + Si02 --------------------------- RUOF4 + SiF4 

Although not binary compounds, a discussion of actinide oxyhalides is not out of place here. A number of these are formed by the earlier actinides, another difference between the 4f and 5f metals. 

Thorium forms ThOX2 (X = Cl, Br, I) but there is a greater variety with protactinium  

Of these, yellow PaOBrs has a cross-linked chain structure with seven-coordinate Pa (bound to 3 O and 4 Br). Yellow-green PaOCl2 has an important structure adopted by many 

Question 10.1 Discuss the halides formed by the actinides, commenting on the trends in oxidation state as the series is crossed. 

Answer 10.1 Early on in the series, as far as uranium, the maximum oxidation state corresponds to the total number of outer shell electrons. Uranium forms a hexachloride, in addition to the MEe also formed by Np and Pu. After uranium, neptunium forms the full range of tetrahalides, but, from plutonium onwards, the (-1-3) state dominates the chemistry of the binary halides, which strongly resemble those of the lanthanides. This may reflect decreased availability of 5f (and 6d ) electrons for bonding. As usual, F supports the highest oxidation states. 

El-Sharkawy and K. D. Warren, Inorg. Nuclear Chem. Letters, 1976,12, 643. 

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Oxygen solubility Oxygen tents Oxygen transfer Oxygen transfer rate Oxygen transport Oxyhalide Oxyhemoglobin... 

Niobium Halides and Oxyhalides. AH possible haUdes of pentavalent niobium are known and preparations of lower valent haUdes generally start with the pentahaUde. Ease of reduction decreases from iodide to fluoride. 

Vanadium Halides and Oxyhalides. Known haUdes and oxyhahdes of vanadium, their valences, and their colors are Hsted in Table 3. 

Halides and Oxyhalides. Vanadium(V) oxytrichloride is prepared by chloriaation of V20 mixed with charcoal at red heat. The tetrachloride (VCl is prepared by chlorinating cmde metal at 300°C and freeing the Hquid from dissolved chlorine by repeated freezing and evacuation. It now is made by chlorinating V20 or VOCl ia the presence of carbon at ca 800°C. Vanadium trichloride (VCl ) can be prepared by heating VCl ia a stream of CO2 or by reaction of vanadium metal with HCl. 

Oxyhalide Glasses. Many glasses contain both oxide and haUde anions. The introduction of haUdes into an oxide glass typically serves to reduce the glass-transition temperature, T, and to increase the coefficient of thermal expansion. Oxyfluorophosphates have been investigated as laser host... 

Because silver, gold and copper electrodes are easily activated for SERS by roughening by use of reduction-oxidation cycles, SERS has been widely applied in electrochemistry to monitor the adsorption, orientation, and reactions of molecules at those electrodes in-situ. Special cells for SERS spectroelectrochemistry have been manufactured from chemically resistant materials and with a working electrode accessible to the laser radiation. The versatility of such a cell has been demonstrated in electrochemical reactions of corrosive, moisture-sensitive materials such as oxyhalide electrolytes [4.299]. 

Antimony trioxide (SbaOj). It is produced from stibnite (antimony sulphide). Some typical properties are density 5.2-5.67 g/cm- pH of water suspension 2-6.5 particle size 0.2-3 p,m specific surface area 2-13 m-/g. Antimony trioxide has been the oxide universally employed as flame retardant, but recently antimony pentoxide (SbaOs) has also been used. Antimony oxides require the presence of a halogen compound to exert their fire-retardant effect. The flame-retarding action is produced in the vapour phase above the burning surface. The halogen and the antimony oxide in a vapour phase (above 315 C) react to form halides and oxyhalides which act as extinguishing moieties. Combination with zinc borate, zinc stannate and ammonium octamolybdate enhances the flame-retarding properties of antimony trioxide. 

Phosphenyl Chloride Phosphides Phosphorus nitride. Oxyhalides. 

The only significant difference between halide melts and oxyhalide melts is that oxyfluoride complexes have a tendency to dissociate at relatively high concentrations yielding polyanion groups. This phenomenon is related with the need to achieve coordination saturation. 

No complexes have at present been authenticated in oxidation states greater than +6, whereas oxyhalide complexes exist where the +8 state is known this parallels trends in the halides and oxyhalides. 

Diverse and sometimes contrasting types of kinetic behaviour have been described for the decompositions of salts in this class, which includes the metal carbonates, sulphates, nitrates and nitrites, phosphates, oxyhalides, permanganates and chromates (Sects. 3.1—3.7, respectively). It is con-... 

The high values of E generally characteristic of the decomposition reactions of metal oxyhalides are widely interpreted as evidence that the initial step in anion breakdown is the rupture of the X—O bond and that the energy barrier to this reaction is not very sensitive to the properties of the cation present. Information of use in the formulation of reaction mechanisms has been obtained from radiolytic studies of oxyhalogen salts [887-889],... 

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