T-shaped coordination

Fig. 15.4B Siereoview of ihe structure of the ](Ph3P)jKhp cation, showing the planar, approximately T-shaped coordination about the rhodium mom. Note the unusual manner in which the phenyl ring ai the lower right is drawn inward ihe rhodium atom. [From Yured, Y. W., Miles. S. L. Buu. R. Reed. C A. J. Am. Clwm. Sac 1977, 99.707f.-7()78 Reproduced with permission ...

A chloride-bridged structure has been proposed for the 1 1 adduct, [HgCl2(btaH)]2 (172). Mercury(II) benzotriazolate, Hg(bta)2, has been obtained from mercury(II) perchlorate, benzotriazole, and triethyl-amine in ethanol (172), and from mercuric oxide and benzotriazole (158). Mercuric acetate and chloride react with benzotriazole to form mixed mercury(II) salts, HgX(Ka) (X = MeC02 or Cl) (139). A dimeric structure (Fig. 13) with T-shaped coordination at mercury has been determined by X-ray diffraction methods (203) for the methyl derivative Hg(Me)(bta) (172). Cyclooctane-1,2-dione dihydrazide reacts with HgO... 

Figure 16 Schematic structure of T-shaped coordination of Cu1 by a tridentate pyrazole-type ligand89...

The presence of one or several nitrides is effective at modifying the metal cluster structure. Face bridging naked nitrides are not known but a nitrogen atom with a T-shaped coordination has been found in [Mo3(N )(0)(C0)4(C5H5)3]. Semi-exposed nitrides have been found in the species with four or five metal atoms they are invariably encapsulated into clusters of higher nuclearity. All the tetranuclear... 

The characteristic T-shaped coordination is found for compounds with one carbon and two heteroatom ligands. The simplest structure is that of phenyliodine(III) dichloride with I—Cl bond distances of 2.54 A and Cl—I—C angles of 86°. In general, in the other examples for which structures have been determined, the corresponding angles are less than 90°. Secondary bonding is important in the overall packing of these compounds and has been fully analyzed for two examples. ... 

A recent structure determination has shown that the compound I(OS02F)2l has the characteristic T-shaped coordination with the I" —I distance of 2.678 A in the equatorial position and two I—O axial distances of 2.09 and 2.26 A with O—I—angles of 91.0 and 85.3 . A secondary I O bond of 3.05 A completes a coordination similar to that in the [XeFs] ion described earlier. The only noble gas compound of this class is Xe(OTeF5)4, prepared from the interaction of Xep4 and B(OTeF5)3, for which the Raman spectrum supports the square planar arrangement. ... 

Montanari, DesMarteau and Pennington reported the X-ray structural analysis of a fluoroalkyliodine(III) dicarboxylate, l-[bis(trifluoroacetoxy)iodo]-2,2,2-trifluoroethane (54, Scheme 2.25) [68], Compound 54 has a T-shaped coordination similar to other known dicarboxylates, but forms a previously unknown tetrameric array of molecules due to strong intermolecular I---0 contacts. 

Fig. 4.1. The [Rh(PPh3)3) cation showing the planar approximately T-shaped coordination about rhodium(I). (From J. Am. Chem. Soc., 99,7076 (1977). Reproduc with permission).

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