Tricapped trigonal prismatic complexes

The final example is a nine-coordinate tricapped trigonal prismatic complex. From either CSED or molecular orbital analysis, all the nine valence orbitals on the metal center (1 (n-l-l)s, 3 (n-l-l)p, 5 nd) are used to form bonds with the ligands, and no nonbonding orbitals are present, again consistent with the valency counting result. 

In contrast to the monoclinic tris-malonato complexes, M2(OOCCH2COO)s 8 H2O (M=Nd) which contain nonacoordinated lanthanide ions in a monocapped square antiprismatic polyhedron, the orthorhombic tris-malonates Pnma) have a tricapped trigonal prismatic geometry for the coordination polyhedron. A rep-... 

Fig. 33. The tricapped trigonal prismatic coordination polyhedron around Eu(III) in Eu(OHCH2COO)s complex...

Cationic deltahedral Pn clusters are known for Pn=Bi. [Bis], [Big], and [Bi9], which have been structurally characterized with complex counterions such as AlCLt, AsFg, and HfCle , can be obtained either by molten salt routes or by using so-called super acidic systems [205-209]. According to Wade s formalism, [Bis] " " and [Big] correspond to 12 ske closo and 22 ske arachno structures, respectively, and the latter adopts the shape of a square antiprism. [Bi9] " which is expected to form a 22 ske nido-cluster in analogy to Fig. 2d, rather adopts a distorted tricapped trigonal prismatic topology (Fig. 2c). 

Fig. 5. Plots of (a) S rl / Sz)j vs Cj/ Sz)j (eq. (48)) and (b) Sf /Cj vs (Sz)j/Cj (eq. (49)) for the carboxylate carbons in simulated nine-coordinate tricapped trigonal prismatic KtOOCCHhtOPEh] complexes (redrawn from Peters (1986)).

Both Tc04 and ReOj can be reduced by Na or K in ethanol to give the only transition metal homoleptic hydrido complexes, [MH9]2 , which have been isolated as the Na, K, and (for ReH only) Ba salts.47 In the solid state the H atoms adopt a tricapped trigonal prismatic arrangement around M, but H and "Tc nmr show that in solution the TcH ion is lluxional with the two types of hydrogen atoms undergoing rapid exchange. 

This complex has tricapped trigonal prismatic nine coordination of Pa, whilst MPaFe has dodecahedral 8 coordination and NasPaFg the very rare cubic 8 coordination. Other halide complexes can be made by appropriate methods ... 

Unlike the exclusively 6-coordinate iron(iii) siderophore complexes, higher coordination numbers are possible with plutonium the complex of Pu" with desferrioxamine E (DEE a hexadentate iron-binding siderophore ligand) has shown it to contain 9-coordinate [Pu(dfe)(H20)3]+ ions with a tricapped trigonal prismatic geometry (Figure 11.13). 

Mononuclear Complexes. They show at least 10 different geometries that are represented in Table 20. They range from tricapped trigonal prismatic (e.g. [ReH9] ), pentagonal bipyramidal (e.g. [OsH7] ), octahedral (e.g. 

Unusually, chloride is foimd in the first coordination sphere of lanthanum as well as nitrate in the serendipitously discovered mixed anion complexes [EaCl2(N03)(12-crown-4)]2 and [LaCl2(N03)(18-crown-6)]. A few complexes have been reported with other halides, such as [Sml3(dibenzo-18-crown-6)] (tricapped trigonal prismatic) and [LaBr3(12-crown-4)(acetone)] (distorted square antiprismatic). Lanthanide thiocyanate complexes of crown ethers are now starting to be studied. Several thiocyanate complexes of the... 

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