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STRUCTURAL ASPECTS OF POLYOXOMOLYBDATE AND RHODIUM HYDRIDE METAL CLUSTERS
Abstract
Structural aspects of three polyoxomolybdate complexes, {(n-C(,4)H(,9))(,4)N}(,2) Mo(,2)O(,7), (alpha)-{(C(,6)H(,5))(,3)(n-C(,3)H(,7))P}(,4) Mo(,8)O(,26)(.)CH(,3)CN(.)H(,2)O, and (beta)-{(n-C(,3)H(,7))(,4)N}(,3)NaMo(,8)O(,26)(.)H(,2)O are discussed. Crystals of all three compounds belong to the monoclinic space group C(,2/c). Cell constants for {(n-C(,4)H(,9))(,4)N}(,2) Mo(,2)O(,7) are a = 19.724 (+OR-) 0.002 A, b = 14.000 (+OR-) 0.001 A, c = 17.131 (+OR-) 0.002 A, (beta) = 120.966 (+OR-) 0.007(DEGREES). Cell constants for (alpha)-{(C(,6)H(,5))(,3)(n-C(,3)H(,7))P}(,4) Mo(,8)O(,26)(.)CH(,3)CN(.)H(,2)O and (beta)-{(n-C(,3)H(,7))(,4)N}(,3)NaMo(,8)O(,26)(.)H(,2)O are a = 28.096 (+OR-) 0.006 A, b = 14.313 (+OR-) 0.002 A, c = 27.116 (+OR-) 0.005 A, (beta) = 121.32 (+OR-) 0.01(DEGREES) and a = 22.918 (+OR-) 0.002 A, b = 17.240 (+OR-) 0.002 A, c = 16.915 (+OR-) 0.002 A, (beta) = 111.947 (+OR-) 0.008(DEGREES) respectively. The Mo(,2)O(,7)('2-) anion is composed of two MoO(,4) tetrahedra sharing a vertex. The anion possesses rigorous crystallographic C(,2) symmetry. The (alpha)-Mo(,8)O(,26)('4-) anion consists of six octahedrally coordinated molybdenum atoms lying in a plane and forming a regular hexagon. Neighboring octahedra share edges. Two tetrahedrally coordinated molybdenum atoms lie above and below the center of the six molybdenum plane. The anion possesses near D(,3d) symmetry. The (beta)-Mo(,8)O(,26)('4-) anion is composed of eight octahedrally coordinated molybdenum atoms arranged in two layers. Metal atoms occupy the corners of a square comprising each layer. The two layers are staggered by approximately one half the diagonal distance along one of the squares' diagonals. The anion possesses near C(,2h) symmetry. Additionally two rhodium clusters, {HRh{P(O-i-C(,3)H(,7))(,3)}(,2)}(,2) and {HRh{P(OCH(,3))(,3)}(,2)}(,3), are discussed. Crystals of {HRh{P(O-i-C(,3)H(,7))(,3)}(,2)}(,2) belong to the triclinic space group P1(' )with unit cell dimensions of a = 12.270 (+OR-) 0.002 A, b = 9.869 (+OR-) 0.002 A, c = 23.893 (+OR-) 0.004 A, (alpha) = 119.18 (+OR-) 0.01(DEGREES), (beta) = 124.48 (+OR-) 0.01(DEGREES), (gamma) = 105.09 (+OR-) 0.01(DEGREES). The dimer has crystallographic C(,1) symmetry and is based on two square-planar P(,2)RhH(,2) units that share an edge. The Rh-Rh separation is 2.652(2)A. Crystals of {HRh{P(OCH(,3))(,3)}(,2)}(,3) belong to the monoclinic space group P2(,1) with unit cell dimensions of a = 10.803 (+OR-) 0.002 A, b = 13.852 (+OR-) 0.003 A, c = 13.658 (+OR-) 0.001 A, (beta) = 92.37 (+OR-) 0.01(DEGREES). Although the molecule possesses no crystallographic symmetry there is an axis of near twofold symmetry. The cluster has a near equilateral triangular form with a mean Rh-Rh separation of 2.823(1,13,20,3)A.
Subject Area
Chemistry
Recommended Citation
FREDRICH, MICHAEL FRANK, "STRUCTURAL ASPECTS OF POLYOXOMOLYBDATE AND RHODIUM HYDRIDE METAL CLUSTERS" (1981). ETD collection for University of Nebraska-Lincoln. AAI8124511.
https://digitalcommons.unl.edu/dissertations/AAI8124511