Cd-X bonds

The broken bonds (boldface = dissociated BDEs (boldface = recommended data reference in parentheses) Methods  

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Here f and f2 represent the bond strength of the Cd-X bond, dictated by bulk crystal structure, and that between the surface Cd and the probably adsorbed, polysulfide species from solution, resp. The larger fj, the more likely it is that the photogenerated hole,h+, will react with the polysulfide species, i.e. the lower the probability of self-oxidation. 

In chapter 6 (section 6.2.3.2) we have pointed out that the Cd—X bond energies (X = OOH or 00 ) are lower by ca. 3 kcal moF than the Cb—X BE in the phenyl species. This result is confirmed by the calculations done on the dibenzofuranyl system. Table 7.7 show that dibenzofuran hydroperoxide has the same DBF—OOH bond energy (87.56 kcal mol ) as phenyl-hydroperoxide with CeHs—OOH to be 86.93 kcal moF. The Cd—OOH bond energy of the vinyl hydroperoxide is lower at 84.5 kcal moF. The comparison among the peroxy radicals of the three systems shows the same tend DBF—00 (50.08 kcal moF ) and CbHs—00 (50.22 kcal moF ) bonds are identical, while CH2=C—00 bond is 47.28 kcal moF. ... 

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,... 

N-Acylhydrazine (L) derivatives of the stoichiometry MX2L2 (M = Zn or Cd X = NCS, NO2, NCO or iS04 L = formyl-, benzoyl- or nitrobenzoyl-hydrazine) have been prepared the ligand is N,0-chelate bonded in all cases.154"157... 

Crystal structures of the benzotriazole complexes [Zn(HL)Cl2] and [Zn2L4] (HL = benzotriazole 62) have been reported the former compound has the metal in a tetrahedral N2C12 environment (Zn—N, 2.014, 2.034 A Zn—Cl, 2.241, 2.235 A) and the latter is a polymeric species.441 The complex [H2L]2[ZnCU] (HL = 62) has also been described it is isostructural with the tetrachlorocobaltate(II) analogue, which has previously been structurally characterized.441 The synthesis and powder diffraction pattern for [ZnL Cy (L = 62) have also been reported.442 Complexes of the type MX2L2 (M - Zn, X = Cl, Br, I or SCN M = Cd, X = Cl L = allyl or 3,5-dimethylpyrazole) have been synthesized where L is 3,5-dimethylpyrazole, cadmium also forms the complexes (CdBr2L3 and CdI2L4. When L is allylpyrazole, alkene coordination is not observed thiocyanate is N-bonded.443,444... 

The complexes MX2L2 (M = Zn, X = Cl, Br or I M = Cd, X = Cl) and HgX2L (X = Q, Br, SCN, N03 or S04) have been isolated, where L is the sterically hindered ligand 2-imino-4-oxo-1,3-thiazolidine.880 All complexes are formulated as monomeric tetrahedral with Zn, ligand coordination is via the ring N atom, but in the Cd complexes coordination via sulfur is observed. The ligand is bound via both N and S in the Hg complexes. The SCN is unidentate and S-bonded nitrate is unidentate, whereas sulfate is bidentate. 

Probably we are dealing here with an intrinsic difference between these two structure types. Their solid state chemistry shows the wurtzite structure to be the more rigid one (in terms of substitution, for example). This could imply a difference in Cd-X (X=S,Se,Te) bond strengths. These bond strengths are, according to Pauling s ionicity concept, influenced by the... 

The four-coordinate 2,2 -bipyridyl and triazine adducts Me2Cd(bipy),3 (Me3SiCH2)2Cd(bipy), 5 and Me2Cd[(CH2 NMe)3]2 have been isolated, and the bipyridyl derivatives (4a) have been structurally characterized by X-ray diffraction. Notably, the coordination environments about the cadmium centers in both compounds deviate substantially from tetrahedral, with large C-Cd-C bond angles (Table 3). 

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