Rare-earth-metal iodide clusters centered by transition metals: synthesis, structure, and bonding of R7I12M compounds (R = Sc, Y, Pr, Gd; M = Mn, Fe, Co, Ni)
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The compounds R7I12M (M = Co, Ni for R = Sc; M = Fe, Co for R = Y; M = Mn, Fe, Co for R = Gd; M = Mn, Fe, Co, Ni for R = Pr) have been synthesized by reactions of RI3, MI2, and R metals at 750-950 C in sealed Nb or Ta containers. These compounds all adopt the Sc(Sc6Cl12B) structure (space group R3, Z = ) with a transition metal at the cluster center (in place of boron). The seventh isolated R3+ ion can be substituted by Ca2+ in several of the Pr and Gd cases. The structural details of Sc7I12Co, Y7I12Fe, and (Ca0.65Pr0.35)(Pr6I12Co) were determined by single-crystal X-ray diffraction methods (a = 14.800, 15.351, 15.777 ; c = 10.202, 10.661, 10.925 ; R = 3.3, 3.8, 3.4%; Rw = 6.7, 3.3, 3.5%, respectively). The last of these presented twinning difficulties endemic to this structure type, but these were overcome satisfactorily by an approximate separation procedure. R-M distances in the clusters are short; Pr-Co = 2.770, Y-Fe = 2.621, and Sc-Co = 2.431 . While MO theory provides some useful guides to these compounds' stability, the true breadth of the chemistry possible remains to be explored. 1988, American Chemical Society. All rights reserved.
author list (cited authors)
Hughbanks, T., & Corbett, J. D.
complete list of authors
Hughbanks, Timothy||Corbett, John D