화학공학소재연구정보센터
Inorganic Chemistry, Vol.34, No.24, 6130-6140, 1995
Synthesis and Characterization of K3Mo14O22, K1.66Pb1.34Mo14O22, and K1.29Sn1.71Mo14O22 - Oligomeric Clusters with 3 Trans Edge-Shared Mo Octahedra
The preparation and structural characterization of three new M(3)Mo(14)O(22) members in the series M(n)Mo(4n+2)P(6n+4) with n = 3 have afforded an experimental picture of the relationship between structure and bonding and the number of electrons available for metal-metal bonding. The three compounds, K3Mo14O22, K1.66Pb1.34Mo14O22, and K1.29Sn1.71Mo14O22, were synthesized from the appropriate quantities of metals, metal oxides, and potassium molybdate fired at 1200-1500 degrees C for 4-9 days. They were all structured in the space group P2(1)/a (No. 14) with Z = 2 and a = 9.916(2), 9.917(1), and 9.929(2) Angstrom; b = 9.325(2), 9.276(1), and 9.294(1) Angstrom; c = 10.439(2), 10.3560(9), and 10.338(2) Angstrom; beta = 103.96(1)degrees, 103.827(7)degrees. and 104.13(2)degrees; and R/R(w) (%) = 3.14/3.69, 6.00/4.81, and 2.45/2.99; using observed reflections/parameters of 1060/176, 1830/135, and 1015/182, respectively. The materials have condensed clusters with strong metal-metal bonding that are constructed of three trans edge-shared molybdenum octahedra with all edges bridged by oxygen atoms. The important differences among the clusters in these compounds are in the arrangement of the intercluster and apical-apical molybdenum bonding. The trimeric cluster units are interconnected via Mo-O bonding in a stair-step fashion along the c direction. In the a-b plane, Mo-O intercluster bonding creates a pocket in which the cations reside. The changes in bonding are correlated to the increasing number of electrons available for metal-metal bonding, based upon Mo-Mo bond order and Mo-O bond valence sums. Magnetic susceptibility and electrical resistivity results are discussed with respect to the structure and bonding.