f-Element heavy pnictogen chemistry

Abstract

In this review, the molecular chemistry of the f-elements with heavy pnictogen ligands from phosphorus to bismuth is described.

Discovery and Characterization of Antiferromagnetic UFe5As3

“…From the difference Fourier map, first, an additional maximum was observed (12.19 e Å −2 ) close to the Fe5 position (0.64 Å). Nevertheless, independent refinement of the occupancy parameters for both split positions assuming occupation by iron reduced further residuals (R1 = 0.0332, wR2 = 0.0880) revealed a practically negligible defect at the Fe5 site of 0.979 (5), which is equal to one within 3 esd, but strong overoccupancy of the second split position of 0.072 (6), resulting in a nonphysical total occupation of 1.04 for both positions. A subsequent attempt to occupy the second split site by As did not change the residuals but slightly reduced the total occupancy for both split sites to 1.032.…”

“…In the crystal structure of UFe 5 As 3 (Figure 3), all atoms are located on two mirror planes at y = 1 / 4 and 3 / 4 . In a large family of compounds with a metal to metalloid ratio of 2:1, 24−27,35−45 atoms form a tessellation of slightly distorted hexagonal [Fe 6 As 6 ], pentagonal [Fe 6 As 4 ], tetragonal [U 2 Fe 4 As 2 ], and trigonal [U 2 Fe 4 ] prisms.…”

“…Also, while the f-element-based iron–arsenic compounds are not likely to be high- T c superconductors, we can observe what happens when more electronically complex f-electrons are placed inside crystal structures that show unconventional behavior − and use their small energy scales for easy tuning from one ground state to another. Indeed, it has been noted previously that the chemistry of f-elements with arsenic is quite diverse, , with several lanthanide-iron-arsenic ternaries examined during the search for new compounds with peculiar chemical and physical features. Surprisingly, only a handful of stoichiometries have been discovered so far: RFeAs (R = La, Ce, Pr, and Nd), RFe 2 As 2 (R = Eu), R 12 Fe 57.5 As 41 (R = La and Ce), RFe 4 As 12 (R = Ce, Pr, Nd, Sm, Gd, Tb − ), and R 6 Fe 13 As (R = Pr and Nd).…”

f-Element Zintl Chemistry: Actinide-Mediated Dehydrocoupling of H2Sb1– Affords the Trithorium and Triuranium Undeca-Antimontriide Zintl Clusters [{An(TrenTIPS)}3(μ3-Sb11)] (An = Th, U; TrenTIPS = {N(CH2CH2NSiiPr3)3}3–)

“…Although the chemistry of actinide (An)−nitrogen bonds can be considered to be fairly mature, 1−10 heavier group 15 analogs are less well developed. 11 Indeed, the numbers of An−P, −As, −Sb, and −Bi bonds falls away rapidly as group 15 is descended, and An−Sb and −Bi derivatives are particularly rare. 12−17 To address this situation we have been exploring the chemistry of An−Sb bonds.…”

“…Although the chemistry of actinide (An)–nitrogen bonds can be considered to be fairly mature, − heavier group 15 analogs are less well developed . Indeed, the numbers of An–P, −As, −Sb, and −Bi bonds falls away rapidly as group 15 is descended, and An–Sb and −Bi derivatives are particularly rare. − To address this situation we have been exploring the chemistry of An–Sb bonds. ,, After initial investigations involving (Me 3 Si) 2 Sb 1– and (Me 3 Si) 2 C(H)Sb(H) 1– , , the latter of which enabled access to a new molecular Zintl (Sb 3 Li 4 Sb 3 ) 2– dianion, we turned our attention to the parent antimonide H 2 Sb 1– to examine whether other An–Sb linkages and Zintl clusters might be accessible since up to Sb 8 4– has been stabilized by lanthanides .…”