Cd-S bond

Pyridine derivatives with additional donor functions and sterically demanding substituents have been used with the intention of producing complexes of Cd (and of other metals) with low coordination number one of these ligands is the tridentate, planar-bonding 2,6-bis[(2,6-dimethyl-phenylimino)methyl] pyridine (pydim a Schiff base derived from 2,6-pyridine dialdehyde), which with Cd(BF4)2 and thiocyanate gives a dinuclear complex [(pydim)Cd(/x-NCS-S,N)]2(BF4)2 with N-dominated coordination sphere.191 As centrosymmetric Plijc, Z= 2), the complex has an antiparallel /x-1,3 NCS double bridge with Cd—N and Cd—S bonds (224.6 pm and 255.5 pm, respectively) the Cd—N(py) bond is clearly shorter than the Cd—N(imino) bonds (225.6 pm and 245.0 pm,... 

Other than the mutually photosensitive components, coupling between one photosensitive and another nonsensitive (e.g., very wide bandgap) semiconductor may also have positive effects on the photocatalytic performance of the sensitive one. For example, Kisch and Weiss (Weiss et al. 2001 Kisch and Weiss 2002) studied the Si02-supported CdS photoelectrode in an organic addition reaction, and found that the enhanced photocatalytic activity was related to the changes in bandgap and flat-band potential of CdS, which originates from an electronic semiconductor-support interaction mediated by [SiJ-O-Cd-S bonds. 

Dialkylcadmium compounds are also reactive towards H2S. For example, (Me3SiCH2)2Cd reacts immediately with H2S to give CdS (equation 19). Other organocadmium compounds with Cd S bonds include the thiocyanate derivatives RCdSCN that are obtained by the reaction of R2Cd with (SCN)2 (equation 20). ... 

The metal-peptide stoichiometry of the dimeric Cd peptide was studied by UV-Vis spectroscopy (77) as an absorption band at 238 nm is observed upon addition of Cd(II) to the peptide which is assigned to the ligand-to-metal charge-transfer (LMCT) transition of the newly formed Cd-S bonds. A Job plot demonstrated that the complex consists of 2 peptides and 1 metal ion. These results were supported by spectrophotometric titrations analyzed according to the following equilibrium (1) to yield n = 2 and IQ = 0.65 0.08 pM. 

Figure 36 The filigree of Cd-S bonds and the linked large cycles in the crystal structure of [Cd7(SC6H4-2-Me),4(DMF)J. Reproduced with permission from Inorg. Chem., 29, 1571 (1990)...

As an example of the capabilities of EXAFS spectroscopy, the mean Cd-S distances as a function of the diameters of a series of CdS nanocrystals are depicted in Figure 3.15 [163]. These data are gained from a thorough temperature-depen-dent study of the size dependence of various structural and dynamic properties of CdS nanoparticles ranging in size from 1.3 to 12.0 nm. The properties studied include the static and the dynamic mean-square relative displacement, the asymmetry of the interatomic Cd-S pair potential, with conclusions drawn as to the crystal structure of the nanoparticles, the Debye temperatures, and the Cd-S bond lengths. As seen from Figure 3.15, the thiol-stabilized particles (samples 1-7) show an expansion of the mean Cd-S distance, whereas the phosphate-stabilized particles (samples 8-10) are slightly contracted with respect to the CdS bulk values. 

In the preparation of zeolite-entrapped CdS, considerable attention has been paid to the ncd/nj ratio. A marked non-stoichiometry of zeolite-hosted metal sulfide particles has been found for CdS nanoparticles by X-ray photoelectron spectroscopy [345]. After sulfidation of a zeolite X sample that is partially ion-exchanged with Cd ions, the binding energies of Cd 3ds/2 electrons decrease by about 0.3 - 0.5 eV in dependence on the diameter of the CdS nanoparticles formed. The shift originates from the replacement of ionic interactions between the Cd + ions and the zeolitic framework oxygen by more covalent (Cd -S ) bonds. However, due to the larger effective masses of the electrons and holes in CdS (m, eff = 0.42 nie, mn, eff = 0.18 m ) [339], the absorption of CdS clusters in the pores of zeohtes is less affected by the zeoUte framework than that of PbS clusters. However, the effect of the zeolite framework on the excited-state relaxation processes, i. e., the luminescence behavior of the CdS clusters, can be very large. 

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