Tellurium coordination geometries

Zr(CH=CH2)2(C5Me5)2] and elemental tellurium. The complex is assumed to contain tellurium atoms in a bent, two-coordinate geometry, which is common for this element in its divalent state. 

The molecular structure of Te(S2COEt)(S2CNEt2) (262) is shown in Fig. 163 and it becomes immediately evident that the coordination geometry is the same as that found for the binary tellurium xanthates described above. The xanthate ligand forms Te—SI and Te—S bond distances of 2.535(2) and 2.911(3) A, respectively, and these are longer than the corresponding distances formed by the dithiocarbamate ligand of 2.489(3) and 2.801(3) A, respectively. This key... 

Table 16.3 Coordination geometries of selenium, tellurium and polonium...

Coordination geometries of tellurium in tellurium subhalides clearly follow from a consideration of the structural units presented in Fig. 19. Even if the conditions of chemical bonding in these units are not quite clear at first sight, they are easily integrated into accepted conc ts using the common valence rules in connection with Gillespie-Nyhohn rules and taking into account the different coordination... 

The ionic cluster compound 63 contains six TePh ligands, the tellurium atoms of which define an octahedron. In contrast to 64 (see below), all tellurolato ligands act as m2-bridges. There are two distinct coordination geometries around the copper, and two of the metal centers are located inside the cluster below Tc3 faces. The others are coordinated by three tellurium atoms above Te3 faces and are also each ligated by one phosphine ligand each. 

Homoleptic dithiocarbamate complexes of both teUurium(II) (215, 293, 294, 296, 302-311) and tellurium(lV) (293, 294, 296, 302, 304-306, 309, 310, 312-315) are well known. The molecular structures of the bis(dithiocarbamate)tel-lurium(II) compounds, [Te(S2CNR2)2], are analogous to those of the corresponding Se compounds The Te atom exhibits a planar trapezoidal coordination geometry, with the two dithiocarbamate ligands bound in an anisobidentate fashion [Te—S(ave) = 2.52 (short) and 2.83 A (long)]. Tellurium(II) has a tendency for pentacoordination and, with the exception of [Te(S2CNCy2)2], which is monomeric (311), there is a short intermolecular Te-- S contact (av... 

The chemistry of 1,3-diketone complexes of nonmetallic elements (B, Si, Ge, Sb, Te) has been reviewed.68 Condensation of acetylacetone with TeCl4 yields Te(CH2COCH2COCH2)Cl2 (8a), which may be reduced to Te(CH2COCH2COCFI2) (8b). The crystal structures of these compounds demonstrate an unusual coordination of tellurium to the terminal carbons of the diketonate.61 72 In the dichloride complex, Teiv exhibits a distorted trigonal bipyramidal geometry with a stereochemi-cally active lone electron pair in the equatorial plane. In S2(MeCOCHCOMe)2 the acetylacetonate methine carbons are bonded to a disulfur unit.73... 

The tellurium atom is coordinated to eight sulfur atoms in the crystalline tellurium tetrakis[dithiocarbamates], The geometry is best described as a distorted dodecahedron3- 6. 

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