Iodine bromide molecule

The iodine bromide molecule, IBr, is an iiiterhalogeii compound. Assume that the molecular orbitals of IBr are analogous to the homonuclear diatomic molecule F2. (a) Which valence atomic orbitals of I and of Br are used to construct the MOs of IBr (b) What is the bond order of the IBr molecule (c) One of the valence MOs of IBr is sketched here. Why arc the atomic orbital contributions to this MO different in size (d) What is the label for the MO (e) For the IBr molecule, hovr many electrons occupy the MO ... 

To determine molecular motions in real time necessitates the application of a time-ordered sequence of (at least) two ultrafast laser pulses to a molecular sample the first pulse provides the starting trigger to initiate a particular process, the break-up of a molecule, for example whilst the second pulse, time-delayed with respect to the first, probes the molecular evolution as a function of time. For isolated molecules in the gas phase, this approach was pioneered by the 1999 Nobel Laureate, A. H. Zewail of the California Institute of Technology. The nature of what is involved is most readily appreciated through an application, illustrated here for the photofragmentation of iodine bromide (IBr). 

Figure 1.3. Real-time femtosecond spectroscopy of molecules can be described in terms of optical transitions excited by ultrafast laser pulses between potential energy curves which indicate how different energy states of a molecule vary with interatomic distances. The example shown here is for the dissociation of iodine bromide (IBr). An initial pump laser excites a vertical transition from the potential curve of the lowest (ground) electronic state Vg to an excited state Vj. The fragmentation of IBr to form I + Br is described by quantum theory in terms of a wavepacket which either oscillates between the extremes of or crosses over onto the steeply repulsive potential V[ leading to dissociation, as indicated by the two arrows. These motions are monitored in the time domain by simultaneous absorption of two probe-pulse photons which, in this case, ionise the dissociating molecule.

From l,l,-/)i.v-(3-methyl-4-imidazoline-2-selone)methane with iodine bromide, a solid compound containing disordered molecules with T-shaped CSeI2 and Br-Se(C)-I functions in the same crystal was isolated from 1,2-fe-(3-methyl-4-imidazoline-2-selone)ethane with iodine bromide, a solid... 

J. J. van Laar has shown how the form of the vap. press, curves of a liquid mixture can furnish an indication, not a precise computation, of the degree of dissociation of any compound which maybe formed, on the assumption that the different kind of molecules in the liquid—12, Br2, and IBr—possess partial press, each of which is equal to the product of the vap. press, of a given component in the unmixed state and its fractional molecular concentration in the liquid. It is assumed that in the liquid, there is a balanced reaction 2IBr I2-)-Br2, to which the law of mass action applies, where K is the equilibrium constant, and Clt C2, and C respectively denote the concentration of the free iodine, free bromine, and iodine bromide. From this, P. C. E. M. Terwogt infers that at 50 2°, K for the liquid is 7j and that for iodine monobromide about 20 per cent, of the liquid and about 80 per cent, of the vapour is dissociated. That the vapour of iodine monobromide is not quite dissociated into its elements is evident from its absorption spectrum, which shows some fine red orange and yellow lines in addition to those which characterize iodine and bromine. In thin layers, the colour of the vapour is copper red. 0. Ruff29 could uot prove the formation of a compound by the measurements of the light absorption of soln. of iodine and bromine in carbon tetrachloride. 

In the following method a slight excess of an alcoholic solution of bromine is added to an alcoholic solution of the tautomeric mixture the excess of bromine is immediately removed by the addition of a few drops of alcoholic /3-naphthoI solution potassium iodide solution is next added, and the hydrogen iodide formed by interaction with the hydrogen bromide present reduces the bromo-ketone with liberation of free iodine, which is estimated by titration with standard thiosulphate (in absence of starch). One molecule of iodine = one molecule of enolic compound. For criticism of this method, see Ann. Rep., 1930, 100. 

As indicated by Equation 1, a standard procedure for ozone recommends the addition of iodide ions and the titration of the liberated iodine. There is a serious problem in interpreting the results of the iodide reaction The quantity of iodine liberated is pH dependent. Inglis (6) reported that acid solutions gave more than one molecule of iodine per molecule of ozone. He tried bromide in normal nitric acid but obtained decreasing amounts of bromine from aliquots of the original ozone solution with time, while the iodine liberated from iodide remained constant. He concluded that the bromide-bromine reaction was unsatisfactory. Alder and Hill (1) found that ozone decomposes, according to its ultraviolet spectrum, faster than the decreasing ability of the same solution to liberate iodine from iodide. They concluded that a decomposition product of ozone, the hydroperoxyl ion, liberates iodine from iodide in the absence of ozone. 

Solution (a) Because IBr (iodine bromide) is diatomic, it has a linear geometry. Bromine is more electronegative than iodine (see Figure 3.9), so IBr is a polar molecule with bromine at the negative end. 

Of the several syntheses available for the phenothiazine ring system, perhaps the simplest is the sulfuration reaction. This consists of treating the corresponding diphenylamine with a mixture of sulfur and iodine to afford directly the desired heterocycle. Since the proton on the nitrogen of the resultant molecule is but weakly acidic, strong bases are required to form the corresponding anion in order to carry out subsequent alkylation reactions. In practice such diverse bases as ethylmagnesium bromide, sodium amide, and sodium hydride have all been used. Alkylation with (chloroethyl)diethylamine affords diethazine (1), a compound that exhibits both antihista-minic and antiParkinsonian activity. Substitution of w-(2-chloroethyl)pyrrolidine in this sequence leads to pyrathiazine (2), an antihistamine of moderate potency. 

Copper 11 halides are formed with chlorine, bromine and iodine, the chloride and bromide by reduction of the coppertll) halides with copper powder, and the iodide by reduction of coppertll) sulfate. CuSOj solulion with potassium iodide. The fluoride appears never to have been made, despite reports to the contrary. All are insoluble in H20. CoppertUl fluoride, CuF may be made from CuO and hydrofluoric acid at 400°C. coppertll) chloride. CuCl by dissolving the oxide or carbonate in HCI, and coppertll) bromide. CuBr from copper and bromine water coppertll) iodide. Cub, is unstable at room temperature with respect to decomposition intu Cul and iodine. The chloride and bromide are water-soluble, and ionic. The fluoride is only slightly water-soluble. Anhydrous copper(U) chloride. Cud , is monoclinic and its structure contains infinite-chain molecules formed by CuCLi groups that share opposite edges. CuBr. has a similar structure. 

The reaction of RSi(NH2)3 (R = 2,6-Pr 2C6H3NSiMe2Pr ) with InRs (R = Me, Et) leads to Si-NH-In cage molecules, which may be regarded as a model system for In metal-containing iminosilicates. Further functionalization without cleavage of the cage molecule is achieved by reaction with elemental bromide and iodine. ... 

---