Monocapped square antiprism

Tricapped Trigonal Prism, TTP Monocapped Square Antiprism, CSAP... 

Pr2(imda )(imda2 )Cl2 7 H20 9 Distorted monocapped square antiprism 372... 

The nonacoordination is fairly common for the lanthanide and the actinide complexes. Two (Fig. 27) idealized geometries have been proposed 93) for nonacoordinated polyhedra (i) the monocapped square antiprism (C41,) and (ii) the s-tricapped trigonal prism (Hs ). Out of these two geometries, the symmetrically tricapped trigonal prism is more common than the monocapped square antiprism and it was not imtil early 1970 s that this C v) geometry has been positively identified in lanthanide complexes. However, Hoard et al. 209) may have observed this geometry in [Ln(EDTA) (OH2) 3] complex but were unable to recognize it. 

As is common with the higher coordination geometries, the interconversion of Dzh Cav niay be easily achieved. The monocapped square antiprism (C4 ) can be generated from the s-tricapped trigonal prism by raising the points a and b (Fig. 27) and lowering the two caps c and d so that the four form the basal plane of the square antiprism. 

Th(C7H502)4(DMF)] C7H602 = tropolone Monocapped square antiprism t... 

The coordination geometry in the Me2SO complex of thorium 8-hydroxyquinolinate, Th(C9H6NO)4-2Me2SO, is a monocapped square antiprism in which only one Me2SO molecule is coordinated to the metal.130... 

Nine-metal arrays in conventional coordination clusters are the confacial bioctahedron and two M4 cubanes linked through a non-cluster metal atom among naked metal clusters the M9 polyhedron is the tricapped trigonal prism or the monocapped square antiprism, and in gold clusters the metal array is the centred cube, the centred crown, or a fragment of the centred icosahedron. 

Polymetallic anions, prepared by dissolution of alloys of the alkali and post-transition metals in amine solvents (often with a complexand for the alkali metal cation), have been characterized in crystalline and solution phases. Clusters TlSng3, Ge92 (with 20 skeletal bonding electrons), Sn93- (21 skeletal e) and Bi95+ (22 skeletal e) possess a tricapped trigonal prismatic structure, symmetry D3A, with variations of dimensional detail which correlate with the electron population.291 292 This structure is a ctoso-deltahedron, and with 20 (2h + 2) skeletal electrons can be construed to be three-dimensionally aromatic.292 The 22e clusters M94 (M = Ge, Sn, Pb) occur as the C4v monocapped square antiprism, a nido polyhedron. 

In [Pr2(H20)4(C4H6N04)2(C4H5N04)]Cl2,3H20, each hydrogen-iminodiacetate and iminodiacetate group was co-ordinated34 to four Pr3 + ions, thereby giving a three-dimensional network structure. The co-ordination polyhedron around each Pr atom is described as a distorted monocapped square antiprism made up of seven carboxylato O atoms and two water molecules. 

In these complexes anion coordination must be present with the exception of perchlorate. Lanthanide contraction may also be an influencing factor. The molecular structure [ 189] of Eu(TMU)3(N03)3 shows the presence of bidentate nitrates with a coordination number of nine. The coordination polyhedron is neither the tricapped trigonal prism nor the monocapped square antiprism which may be due to the small bite of nitrate ligand. The dimethyl acetamide (DMA) complexes behave similarly as those of tetramethyl urea (TMU) with less steric requirements as evidenced by the synthesis of [180-182] La(DMA)8(C104)3, La = La-Nd La(DMA)7(C104)3, La=Sm-Er La(DMA)6(C104)3, La = Tm-Lu. 

TCTP, symmetrically tricapped trigonal prism CSA, monocapped square antiprism IDA, iminodiacetato ODA, oxydiacetato T, tropolonato NTA, nitrilotriacetato PDC, pyridine-2,6-dicarboxylato(dipicolinato) Ox, 8-quinollinato terpy, terpyridyl DMSO, dimethylsulphoxide DMF, W,W-dimethyl formamide. 

Rh9(CO)2iP]2+ monocapped square antiprism with interstitial P Fe3(CO)9C2BFl3, octahedral Co3(CO)9Bi, tetrahedron HRu3Fe(CO)i2N, butterfly with interstitial N or trigonal bipyramid depending on the butterfly deltahedral angle Fe3(CO)i2(CH)As, trigonal bipyramid. 

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