Eight‐Coordinate Endohedral Rhenium, Osmium and Iridium Atoms in Rare‐Earth Halide Cluster Complexes

Abstract

Endohedral (interstitial) atoms are essential for almost all of the rare-earth halide cluster complexes. Most of these contain octahedral clusters, some are isolated, but the majority exhibits condensation by common edges to structures of higher dimensionality. Higher coordination numbers of the endohedral atoms are rare. Four examples of extended cluster complexes with eight-coordinate endohedral atoms of sixth-period elements (Re, Os, Ir) are presented. In the quasi-isostructural, non-isotypic halides {ReGd(4)}Br(4) and (OsSc(4))Cl(4), square antiprisms of gadolinium and scandium atoms, respectively, are connected by two common faces to chains, surrounded and loosely connected by halogenido ligands. The Re and Os atoms build a slightly bent chain with only little bonding interactions. Chemical bonding is dominated by endohedral atom-cluster atom and cluster atom-halide interactions. The same is true for the two scandium bromides and {Os(3)Sc(12)}Br(16)Sc, which contain chains of face-sharing square antiprisms and cubes in a ratio of 2:1. Metal metal bonding is attested by short distances between those endohedral Ir and Os atoms, respectively, which center the square antiprisms (283 pm and 290 pm, respectively). Magnetic and conductivity measurements on {Ir(3)Sc(12)}Br(16) reveal paramagnetism and a small-band-gap semiconductor. This is in accord with electronic structure calculations

A Topological Link between Lanthanide and Alkali‐Metal Clusters: Face‐Sharing Gadolinium Octahedra Centered by Endohedral Iridium Atoms in {Ir3Gd11}Br15

“…The {Ir 3 Gd 11 } clusters are surrounded by a total of 30 bromido ligands with Gd-Br distances ranging from 287.5 to 357.6 pm with an average of 310.1 pm, which is quite consistent with Gd-Br distances ranging from 297.1 to 313.8 pm with an average of 307.3 pm in {ReGd 4 }Br 4 . [12] All of the bromido ligands bridge to neighbouring cluster complexes, as attested by the formulation {Ir 3 Figure 2 exhibits how one cluster complex is connected to surrounding clusters. As {Ir 3 Gd 11 }Br 15 crystallizes in the hexagonal space group P6 3 /m, the crystal structure may also be classified as being built in the fashion of a hexagonal closest packing of {Ir 3 Gd 11 } clusters.…”

“…This will not be considered a bonding distance, in the sense of a two-center-two-electron bond, although it is close to the Ir-Ir distance of 283.28(11) pm in {Ir 3 Sc 12 }Br 16 , [12] which, in this special case, has been considered a two-electron bonding distance for the following reason: For {Ir 3 15 we count that same number of 45 electrons per formula unit, or 15 when scaled per endohedral iridium atom. All Ir-Gd distances are shorter than the Ir-Ir contacts (see Table 1) and much shorter than Gd-Gd distances, although these are all in the ranges usually observed in these clusters.…”

“…Face-sharing of octahedral rare-earth metal clusters is not known so far, in contrast to the increasing number of monocapped trigonal-prismatic or square-(anti-)prismatic endohedral iridium atoms form a triangle with Ir-Ir distances of 295.51 (11) clusters that share common faces resulting in chains, as in {RuPr 3 }Cl 3 [10] (seven-coordinate endohedral ruthenium atom) or in {OsY 4 }Br 4 [11] and the higher symmetric {ReGd 4 }Br 4 [12] as well as {Ir 3 Sc 12 }Br 16 , [12] all with eightcoordinate endohedral atoms (Re, Os, Ir).…”

Revealing Tendencies in the Electronic Structures of Polar Intermetallic Compounds

“…The transition-metal-centered rare-earth cluster chains observed for certain rare-earth transition-metal halides have also been determined to exist in the crystal structures for certain rare-earth transition-metal tellurides (an overview of the hitherto determined rare-earth transition-metal tellurides comprising groups 7-11 elements is provided in Table 3 [65,66]. Analyses of the nature of bonding in the telluride and the bromide indicated that the bonding in these materials is dominated by the heteroatomic interactions.…”

The First Lanthanide Telluride-Bromide: La3Te4Br, a Valence Compound

“…There is also a growing number of metal-rich lanthanide tellurides, see especially [18], of which Sc 2 Te [20] [22]. Both compounds contain the same extended cluster chain of square antiprisms and cubes of scandium atoms (in a 2:1 ratio) with endohedral eight-coordinate osmium atoms!…”