Structural Analysis of Cubane-Type Iron Clusters.
The generalized cluster type [M4(μ3-Q)4Ln]xcontains the cubane-type [M4Q4]zcore unit that can approach, but typically deviates from, perfectTdsymmetry. The geometric properties of this structure have been analyzed with reference toTdsymmetry by a new protocol. Using coordinates of M and Q atoms, expressions have been derived for interatomic separations, bond angles, and volumes of tetrahedral core units (M4, Q4) and the total [M4Q4] core (as a tetracapped M4tetrahedron). Values for structural parameters have been calculated from observed average values for a given cluster type. Comparison of calculated and observed values measures the extent of deviation of a given parameter from that required in an exact tetrahedral structure. The procedure has been applied to the structures of over 130 clusters containing [Fe4Q4] (Q = S2-, Se2-, Te2-, [NPR3]-, [NR]2-) units, of which synthetic and biological sulfide-bridged clusters constitute the largest subset. General structural features and trends in structural parameters are identified and summarized. An extensive database of structural properties (distances, angles, volumes) has been compiled in Supporting Information.
Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L3G1, Canada.
Lay Ling
LL
Tan
R H
RH
Holm
Sonny C
SC
Lee
cubane-type clusters; idealized Td symmetry; molecular volumes; structural analysis