The study of molybdenum chalcogenides and oxides exhibiting unique electronic or structural features

Barry Dale Davis, Purdue University

Abstract

Part I. Attempts to cleave $\rm Mo\sb3Se\sb3$ units from the $(\rm MO\sb3Se\sb3)\sb\infty$ strands in $\rm In\sb2(Mo\sb6Se\sb6),$ $\rm Li\sb{x}(Mo\sb6Se\sb6),$ and $\rm (Mo\sb6Se\sb6)$ suggest the chemical reactivity of these compounds is limited to intercalation/deintercalation or to destructive oxidation. The structure of a related phase, $\alpha$-$\rm Mo\sb{15}Se\sb{19},$ has been determined (space group P6$\sb3$/m (No. 176), Z = 2, a = 9.450(2)A, c = 19.600(2)A, R = 0.050 and R$\sb{\rm w}$ = 0.070). $\rm Mo\sb{15}Se\sb{19}$ is a binary compound containing two cluster units, $\rm Mo\sb6Se\sb8$ and $\rm Mo\sb9Se\sb{11}.$ Part II. (Ph$\sb4$As) $\sb2$($\rm Se\sb2Mo\sb{13}O\sb{40}$), (space group C2/c (No. 15), Z = 4, a = 28.403(6), b = 15.630(3), c = 22.400(4), $\beta$ = 135.42(1), R = 0.048, R$\sb{\rm w}$ = 0.064), is a minor product from the reaction of $(\rm Mo\sb3Se\sb3)\infty$ with (Ph$\sb4$As) Cl$\cdot$2H$\sb2$O. The compound contains an anion with an unprecedented structure which contains selenium cations coordinatively perturbing a reduced 13-molybdate. The anion contains external selenium atoms similar to the arsenate groups of (TBA)$\sb2$(NH$\sb4)\sb2$($\rm V\sb{10}O\sb{24}(O\sb3AsC\sb6H\sb4$-4-NH$\sb2)\sb3$) while exhibiting a cage structure identical to ($\rm Co\sp\Pi W\sb{12}O\sb{40}$) $\sp{6-}.$ Part III. Molybdenum heteropolyanions have been examined as building blocks for the formation of solids with size and shape selectivity. (Co(NH$\sb3)\sb6$) ($\rm PMo\sb{12}O\sb{40}$) $\cdot$4DMSO$\cdot$4H$\sb2$O crystallizes with Z = 2 in space group P 1 (No. 2) with cell dimensions a = 12.022(2), b = 15.771(2), c = 20.686(3), $\alpha$ = 80.78(1), $\beta$ = 76.66(1), $\gamma$ = 89.60(1) and residuals R = 0.076, R$\sb{\rm w}$ = 0.112. Partial structural solutions were obtained for the disordered systems (CO(NH$\sb3)\sb4$(NO$\sb2)\sb2$) $\sb3$ (PMo$\rm\sb{12}O\sb{40}$) $\cdot$xDMSO (space group P1 (No. 1), Z = 1, a = 12.037, b = 12.960, c = 14.844, $\alpha$ = 75.05, $\beta$ = 71.68, $\gamma$ = 63.95, R = 0.093, R$\sb{\rm w}$ = 0.172) and (CO(en)$\sb2$(NO$\sb2)\sb2$) $\sb3$ ($\rm PMo\sb{12}O\sb{40}$) $\cdot$xDMSO (space group P 1 (No. 2), Z = 1, a = 12.955, b = 13.390, c = 15.276, $\alpha$ = 76.58, $\beta$ = 76.13, $\gamma$ = 70.37, R = 0.235, R$\sb{\rm w}$ = 0.305). Powder patterns of (Co(en)$\sb3$) ($\rm PMo\sb{12}O\sb{40}$) and (Co(phen)$\sb3$) ($\rm PMo\sb{12}O\sb{40}$) indicate that solvent may be exchanged without change to the structure of these solids. Selective solvent exchange in these systems has been followed by CP-MAS NMR. The syntheses of (Co(bipy)$\sb3$) ($\rm PMo\sb{12}O\sb{40}$), (Ph$\sb3$MeP) $\sb3$ ($\rm PMo\sb{12}O\sb{40}$) $\cdot$EtOH$\cdot$H$\sb2$O, and (Fe(CP)$\sb2$) $\sb{\rm x}$ ($\rm PMo\sb{12}O\sb{40}$) are also reported. (Abstract shortened by UMI.)

Degree

Ph.D.

Advisors

Robinson, Purdue University.

Subject Area

Chemistry

COinS