Chapter 4 - Jacobs University

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<strong>Chapter</strong> 5 Organoruthenium POM The molecular structure of 3 reveals that the novel polyanion has four {Ru(p-cymene)(H 2 O)} 2+ groups covalently attached to the cavity of the cyclic P 8 W 48 , resulting in an assembly with C i symmetry (Figure 5.3 and 5.4). Each organoruthenium group is bound to P 8 W 48 via two Ru– O(W) bonds involving a belt oxygen of each of two adjacent, hexalacunary “P 2 W 12 ” building blocks. The inner coordination sphere of each Ru center is completed by a p-cymene ligand and a water molecule (Ru–OH 2 = 2.142(15) and 2.230(19) Å; Ru–O(W) = 2.043(14), 2.057(13), 2.039(14), and 2.076(14) Å). In our recently reported [{Ru(C 6 H 6 )(H 2 O)}{Ru(C 6 H 6 )}(g- XW 10 O 36 )] 4− (X=Si,Ge) one of the two {Ru(benzene)} 2+ groups exhibits the same binding motif. 14e In this respect, our [Ru(dmso) 3 (H 2 O)XW 11 O 39 ] 6− (X = Si,Ge) should also be mentioned as the {Ru(dmso) 3 } 2+ unit is similarly bound to the monolacunary Keggin fragment. 14b O9T O15T O13A O8T O12A O25C O17T O3A O89 O912 O25B O135 O137 O157 O21T W9 O20T W12 W13 O5T W8 O123 W15 O201 O812 W17 O35 O170 O78 O39 O9R O15R O151 W25 O134 W21 W3 W5 O58 O21A O178 W20 O2P2 O112 O4P2 O25D O204 O15 O3T O2P3 O4P3 O25A O1P3 O214 O24T O1T O13 O2P1 O711 W11 W14 O56 O1P2 O1P4 O67 O148 O189 O190 W1 O4P1 P2 P3 O2P4 W24 W7 O114 O14T W18 W6 O11T O18T O24A P1 O7T O710 O3P2 O3P3 P4 W19 O234 O1A O146 O12 O26 O1P1 O168 O4P4 O101 O193 O6T O3P4 O19T O3P1 W10 O16T W16 W2 O192 W23 O46 O10T O410 O162 W4 O10A C17 W22 O1A O24A O24 O16A O223 O23T O2T O1WR C11 O22T O4T C16 O4A Ru1 O22A C2 C7 C12 O3T O21A Ru2 C3 C1 C13 C10 C4 C6 C14 C15 O2WR C8 C5 C18 C19 C9 C20 Figure 5.4 ORTEP view of the asymmetric unit of the centrosymmetric polyanion 3 with atom labeling (50% probability displacement ellipsoids; H atoms have been omitted for clarity). 97
<strong>Chapter</strong> 5 Organoruthenium POM The four organoruthenium units in 3 are grafted near the rim of the central cavity of P 8 W 48 with the hydrophobic p-cymene groups protruding away from the hydrophilic polyanion (Figure 5.5). This allows for a potassium ion to be accommodated in each of the two opposite hinge-areas of 3. Interestingly, two of the waters coordinated to Ru point toward the inside of the cavity of 3 and the other two point toward the outside of the cyclic polyanion. The ruthenium centers in 3 bind to what appear to be the most reactive and sterically accessible oxygens of P 8 W 48 . Also in our Cu 2+ containing derivative [Cu 20 Cl(OH) 24 (H 2 O) 12 (P 8 W 48 O 184 )] 25− the central {Cu 20 (OH) 24 } 16+ cluster interacts with the same type of polyanion oxygens, but with all 16 equivalent sites on the inner surface of P 8 W 48 at the same time. At first sight, it seems that steric constraints allow only four rather than the expected eight bulky organoruthenium groups to be accommodated in the cavity of P 8 W 48 . Interestingly, those four groups are all in the same plane, bound on opposite sides of the inner cavity, which indicates that binding cooperativity is at work during formation of 3 (vide infra). The remaining four binding sites in 3 are occupied by two potassium ions and, very unexpectedly, also by two additional tungsten atoms (Figure 5.3 and 5.4).However, these inversion symmetry related potassium and tungsten sites exhibit only 50% occupancy, indicating crystallographic disorder. This means that in a given polyanion 3 only two of the four positions are actually occupied. There are no geometrical or steric constraints, therefore allowing for all three possible occupancy scenarios The presence of one extra equivalent of tungsten in 3 is important, as it leads to the first example of a P 8 W 49 framework. Furthermore, the coordination environment of this additional 98
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Synthesis, Structure and Properties
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"The greatest book of philosophy, w
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system, space group I4/m, unit cell
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Acknowledgements The accomplishment
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teaching, and Professor Maravanji S
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2.1.2 Single crystal X-ray diffract
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5.5 Conclusion…………………
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9.1.6.1 Results and discussion…
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9.3.5 Synthesis of K 12 [Hf 4 (µ 2
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Crespo………………………
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Figure 5.4 ORTEP view of the asymme
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Figure 9.6 31 P NMR of 7a in H 2 O/
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Figure 9.34 TGA spectrum of 17a…
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Figure 9.62 FTIR spectrum of 23a…
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Table 9.6 Crystal data and structur
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Chapter 1 Introduction heteropolyan
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Chapter 1 Introduction 1.3 Structur
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Chapter 1 Introduction C) Keggin a-
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Chapter 1 Introduction shows no suc
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Chapter 1 Introduction α-[P 2 W 18
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Chapter 1 Introduction Figure 1.7 B
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Chapter 1 Introduction [P 2 W 18 O
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Curriculum Vitae SIB SANKAR MAL Dep
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EDUCATION PhD Jacobs University (20
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POSTER, ORAL PRESENTATION 1. Poster
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6. “Two Iron-Containing Tungstoge
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Appendix
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Appendix
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