Nine coordination

LaFs P3cl 7,185 7.351 irregular tricapped trigonal 106, 106a) 

U2F9 I43m 8.471 capped trig prism , forming (113) 

KU2F9 Pnam 8.70 7.035 11.48 capped trig, prism, sharing (114, 21) 

Underlined compounds are structure types, determined by single crystal techniques. 

BkFs and CfFa occur in the YFs structure type and are described in Table 5. 

---

Bismuth Trifluoride. Bismuth(III) duoride is a white to grey-white powder, density 8.3 g/mL, that is essentially isomorphous with orthorhombic YF, requiring nine-coordination about the bismuth (11). It has been suggested that BiF is best considered an eight-coordinate stmcture with the deviation from the YF stmcture resulting from stereochemical activity of the bismuth lone-pair electrons. In accord with its stmcture, the compound is the most ionic of the bismuth haUdes. It is almost insoluble in water (5.03 0.05 x 10 M at pH 1.15) and dissolves only to the extent of 0.010 g per 100 g of anhydrous HF at 12.4°C. 

The 15 trivalent lanthanide, or/ -block, ions La3+, Ce3+, Pr3+, Nd3+, Pm3+, Sm3+, Eu3+, Gd3+, Tb3+, Dy3+, Ho3+, Er3+, Tm3+, Yb3+, and Lu3+, which may be collectively denoted Ln3+, represent the most extended series of chemically similar metal ions. The progressive filling of the 4/orbitals from La3 + to Lu3 + is accompanied by a smooth decrease in rM with increase in atomic number as a consequence of the increasingly strong nuclear attraction for the electrons in the diffuse / orbitals (the lanthanide contraction). Thus, the nine-coordinate rM decrease from 121.6 to 103.2 pm from La3+ to Lu3+, and the eight-coordinate ionic radii decrease from 116.0 to 97.7 pm from La3+ to Lu3+ (2). Ligand field effects are small by comparison with those observed for the first-... 

Possible stereochemistries for eight-coordinate [Ln(H20)8]3+ are the dodecahedron, the square antiprism, and the cube, although the last seems less likely (295). The proposed nine-coordinate [Ln(H20)9]3+ tri-capped trigonal prism transition state is similar to the [Ln(H20)9]3+ structures observed in the solid state. Thus, the possible water exchange... 

As in aqueous solution, the lanthanide contraction favors a change from nine-coordination for the light lanthanides to eight-coordination for the light lanthanides such that [Ln(DMF)8]3+ is the major species when Ln3+ = Ce3+-Nd3+, and that this becomes the only detected species when Ln3+ = Tb3+-Lu3+ in dimethylformamide perchlorate solution (11, 92, 93, 321-323). Thus, Nd3+ is characterized by AH° = -14.9 kJ mol-1, AS0 = -69.1 J K"1 mol-1, and AV° = - 9.8 cm3 mol-1 for the equilibrium shown in Eq. (25) (93). The molar volume of DMF is 72 cm3 mol- and it therefore appears that the substantially smaller magnitude of AV° is a consequence of significant... 

Vikram L, Sivasankar BN (2008) New nine coordinated hydrated heavier lanthanide ethyl-diamine tetraacetates containing hydrazinium cation Crystal structure of N2H5[Dy(EDTA) (H20)3(H20)5. Ind J Chem 47A 25-31... 

Furthermore, a similar Dy4 complex (22, Figure 3.15) fixed by p4-C) atom was reported by our group [34]. Here, all Dy sites are nine-coordinate sites and exhibit... 

Obridgmg 2.78(1) A], but also effect a bridge in the homoleptic anion. The cation predictably involves bridging thiourea sulfur atoms [Bi-S 2.909(5) and 3.132(5) A] as well as two terminal thiourea ligands [Bi-S 2.677(5) and 3.152(6) A], In contrast, Bi(CH3COO]3(tu)3 is molecular in the solid state with bismuth in a nine-coordinate environment composed of three bidentate acetate groups [avg. Bi-0 2.509(4) A] and three thiourea sulfur atoms [avg. Bi-S 3.061(2) A] in a fac arrangement. 

Bi-0 2.54(l)-2.68(2) A], In contrast, the nine-coordinate capped square antiprism geometry for bismuth in [Bi(N03)3(H20)3] (18-crown-6) does not involve the expected multidentate ether coordination to bismuth, but rather a hydrogen-bonded interaction of the crown ether with the hydrated bismuth center chelated by bidentate nitrate groups [Bi-0 2.38(2)—2.56(2) A] 32, implying that the hexado-... 

Solid-state structures of two bismuth tartrate complexes reveal a similar asymmetric unit composed of two tartrate ligands on a bismuth center and are distinguished by replacement of a proton in Bi(H3tar)(H2tar) 3H20 (160) with by an ammomium ion in NH4[Bi (H2tar)2(H20)] H20 (161). The nine-coordinate bismuth environments in each structure are very similar, as illustrated in 48, respectively,... 

Figure 7.20 Nine-coordinate TTP (A) and CSAP (B) geometries exhibited by gadolinium (III) imaging agents. (Adapted with permission from Figure 1 of Caravan, R Ellison, J. J. McMurry, T. J. Lauffer, R. B. Chem. Rev., 1999, 99(9), 2293-2352. Copyright 1999, American Chemical Society.)...

---