10 Dq parameter

From a knowledge of the free-ion B values the ft parameters are readily derived. For most di configurations these represent /J35 quantities, but as explained before (7) for d3 and d8 systems respectively 55 and fizz parameters may also in principle be deduced. In the present work the (S values listed are always /S35 parameters unless otherwise stated, but for the 5d systems OsFe- and IrFij and the 5d2 system OsF6 the ft values are essentially 55 quantities since they are obtained predominantly from bands arising from the t t manifold. The and Dq parameters derived for the 4 d and 5 d hexafluorides are now given in Table 22. 

The Dt parameter is a measure of the difference between the equatorial and axial Dq parameters. In an elongated octahedron, the energy separations between pairs of 3d orbital energy levels are expressed by... 

Analogous expressions apply to crystal field states for electronic configurations involving these orbitals (cf. fig. 3.13). These energy separations are shown in fig. 3.21. All three parameters, Dq(eq)y Dt and Ds, may be determined experimentally provided that energies of three absorption bands originating from transition metal ions in tetragonally distorted octahedral sites occur in the crystal field spectra. Equation (3.15) yields the Dq( a) parameter, so that the mean Dq parameter, Dq(m) may be calculated from... 

Computation of the mean crystal field strength is also legitimate when the vi transition of an F term ion is split by a low symmetry component to the ligand field, but the V2 and vz transitions are not. It is likely, however, that the Dq parameter obtained in this case appertains to the excited state of the molecule and is not necessarily related to the ground state, crystal field, splitting energy. (See below.)... 

In those circumstances where it is possible to determine a value of Dt from analysis of the spectrum of a complex, a value for the difference in the equatorial and axial Dq parameters may be estimated. If the assumption is made that corresponds exactly with Dq in the MXe compounds, or if Dq can be observed directly, then the axial crystal field strength can be evaluated. 

Yatsimirskii considers that the ligand field effect is an important one in explaining the trends in the stability constants. He (37) has established a ligand series based on the change in the values of the Dq parameter for the light lanthanides ... 

Table 2. 10 Dq parameters of some 3d fluorides. Point charge calculations were carried out using Hartree-Fock (H.F.) or Staler functions...

Compounds in square brackets do not form regular octahedra. The experimental and calculated 10 Dq parameters axe based on the four Me—F distances in the x, y plane. 

Fig. 1. Electrostatic 10 Dq parameters of some octahedral MeFs-complexes, calculated by considering the spatial extension of the ligand electrons. Hartree-Fock functions have been used for both the Zd and F orbitals...

The hardness parameters for MM+ are the dissociation energies of the nonbonded interactions of two identical atoms divided by 1.125, 8=Dq/1.125. The values of Dq used are ... 

Parameters q and W are variables when filtration conditions are changed. Coefficient (rj, is a function of pressure (rj, = f(P). The exact relationship can be derived from experiments in a device called a compression-permeability cell. Once this relationship is defined, the integral of the right hand side of the above equation may be evaluated analytically. Or, if the relationship is in the form of a curve, the evaluation may be made graphically. The interrelation between W and P, is established by the pump characteristics, which define q = f(W) in the integral. Filtration time may then be determined from dq/dt = W, from which we may state ... 

The diffusivity Dq and equilibrium moisture content Wg are parameters which describe a specimen s moisture diffusion properties. 

Cobalt(III) complexes of the general formula [CoL2]BF4, have been prepared for 3a [179], 9 [137], 10 [139], 11 [140], and 12 [141] and their values of Dq are 2200-2500 cm and values of the covalency parameter, B, are 550-740 cm The strongest field and most covalent bonding is provided by 11, 2-acetylpyridine C-hexamethyleneiminethioemicarbazone, which has the largest alkyl function attached at N. 

Alternatively, proton double quantum (DQ) NMR, based on a combined DQ excitation and a reconversion block of the pulse sequence, has been utilized to gain direct access to residual DCCs for cross-linked systems.69,83-89 For this purpose, double-quantum buildup curves are obtained with use of a well-defined double-quantum Hamiltonian along with a specific normalization approach. Residual interactions are directly proportional to a dynamic order parameter Sb of the polymer backbone,87... 

From their spectrum Allen el al. derived the parameters Dq = 2500 cm-1, and B = 500 cm-1, assuming f - 1000 cm-1 and C/B = 4.75. A somewhat better fitting might have been possible if C and B had been allowed to vary independently but for reasons explained in Section 4.(i) this was not permitted. 

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