Anionic Homoleptic Compounds

Anionic homoleptic thiolate compounds of the type [AufSR)2] have been obtained with SR = benzoxazole-2-thiolate (495),28 6 pyrimidine-2-thiolate,28 6 2,3,4,6-tetra-O-acetyl-l-thiolate-,3-D-glucopyranosate,2846 2-thiouracilate,2846 2,3-dihydro-benzimidole-2-thiolate,2846... 

Figure 2.8 Average radius Rav and effective or trispyrazole [22], oxygen atoms of the charge Zf resulting from the REC correction POM series LnW10 and LnW22, [23] and halo-of different homoleptic compounds nitro- genides F , Cl-, Br" anions [21]. genated ligands of the type bis-pyrazole...

In connection with investigations on the catalytic activity of organometallic compounds of the rare earths, anionic homoleptic allyl derivatives of Ce, Nd, Sm, Gd and Dy have been prepared according to eq. (47). Allyl lithium was generated in situ from Sn(C3Hj)4 and another lithium alkyl LiL. The compounds, isolated as their dioxane complexes after precipitation from ethereal solution by addition of dioxane, are described as containing fluxional allyl groups from their infrared and H NMR spectra (Mazzei, 1979) ... 

Additional bonds are thus donor bonds, and to accept electron pairs from neutral and anionic ligands, zinc uses the two remaining 4p orbitals to form sp2 and sp3 hybrids. In the absence of steric effects, discrete, homoleptic, anionic tri- and tetraorganozinc compounds (zincates) have almost always ideal trigonal-planar and tetrahedral geometries, respectively. 

A second problem is the widespread occurrence of compounds in which several different anionic elements bond to the metal (heteroleptic compounds). Most inorganic compounds have homoleptic coordination, i.e. the cation is bonded to only one kind of anion, making the determination of the bond valence parameters relatively simple (Appendix 1). Flomoleptic coordination is much less common among the transition-metal complexes. As described in Appendix 1, bond valence parameters for a variety of transition metals to O, N, C, Cl, S, and P have been determined using heteroleptic systems although the values obtained are often less reliable than those obtained from homoleptic systems. 

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