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Fig. 3.4: Sn 119 NMR spectra of (CsNa 4 [{Sn(CH 3 ) 2 } 3 O(H 2 O) 4 ( β-XW 9 O 33 )]·5H 2 O) [X = As (top)CsNa- 1, Sb(bottom)CsNa-2] calculations, which indicate that all terminal oxygen atoms bound to the tin atoms are diprotonated.[82] Close inspection of CsNa-1 and CsNa-2 indicates that the C-Sn-C bond angles are significantly smaller than ∼180 ◦ C indicating that the interior methyl groups experience still some degree of repulsion (see Figure 3.6). The C-Sn-C bond angles of the two equivalent organotin groups are very similar for 1a (149(1), 152(1)) and CsNa-2 (150(1), 151(1) ◦ ). However, the C-Sn-C bond angle of the unique organotin unit is distinctly larger in polyanion CsNa-1 (166(1) ◦ ) than in CsNa-2 (162(1) ◦ ). This seems to reflect (a) the smaller size of the As III atom compared to Sb III , (b) the shorter As III -O bond lengths compared to Sb III and (c) the smaller size of the As III lone pair compared to Sb III . It is known that the alpha to beta isomerization of [α-AsW 9 O 33 ] 9− and [α-SbW 9 O 33 ] 9− is facilitated in acidic, aqueous medium [69, 83]. This is in complete agreement with the synthetic conditions for CsNa-1 and CsNa-2, which were isolated at pH 3. The (β-AsW 9 O 33 ) fragment has so far only been observed in two different polyoxoanion structures [33, 83]. The large tungstoarsenate(III) [As 6 W 65 O 217 (H 2 O) 7 ] 26− is the only example of a polyanion that contains both isomers, (α-AsW 9 O 33 ) and (β-AsW 9 O 33 ), 31
Fig. 3.5: Left: combined polyhedral and ball/stick representation of the 2-D solid state structure of (CsNa 4 [{Sn(CH 3 ) 2 } 3 O(H 2 O) 4 (β-XW 9 O 33 )]·5H 2 O) ∞ (X = As, CsNa-1; Sb, CsNa-2). The WO 6 octahedra are purple and the balls represent tin (green), arsenic/antimony (blue), oxygen (red) and carbon (yellow). Hydrogen atoms are omitted for clarity (left),Right: Side view of the 2-D solid state structure of (CsNa 4 [{Sn(CH 3 ) 2 } 3 O(H 2 O) 4 (β-XW 9 O 33 )]·5H 2 O) ∞ (X = As, CsNa-1; Sb, CsNa-2). in the same structure [33]. The fact that no cations are involved in the exclusively covalent 2-D network of CsNa-1 and CsNa-2 requires it to possess a negative charge. Indeed the appropriate number of cations (1 Cs, 4 Na) for each polyanionic unit was found by X-ray diffraction and elemental analysis. Therefore CsNa-1 and CsNa-2 are best described as polymeric polyanion salts. This view is further supported by our observation that CsNa-1 and CsNa-2 are water-soluble upon heating. Clearly, in solution the polymeric structure of CsNa-1 and CsNa-2 has to decompose and we identified the likely sites: the very long Sn-O(W’) bonds in CsNa-1 (2.414 - 2.656 Å) and CsNa-2 (2.427 - 2.633 Å). The question arises in which form CsNa-1 and CsNa-2 are present in solution: oligomeric or monomeric. The latter option requires the existence of the hypothetical, monomeric polyanion [{Sn(CH 3 ) 2 (H 2 O) 2 } 3 (β-XW 9 O 33 )] 3− (X = As III 1, Sb III 2). Polyanion 1 consists of a (β-AsW 9 O 33 ) fragment which is stabilized by three dimethyltin fragments and polyanion 2 represents its antimony derivative (see Figures 3.6). The three dimethyltin groups of 1 and 2 are grafted onto the polyanion via two Sn- 32
Page 1 and 2: Hybrid Organic-Inorganic Polyoxomet
Page 3 and 4: Abstract Polyoxometalates (POMs) ar
Page 5 and 6: the cubic system (space group I m¯
Page 7 and 8: AsW 9 O 32 OH) 2 ]·36H 2 O (RbNa-1
Page 9 and 10: Paris-Sud, Orsay Cedex, France) for
Page 11 and 12: 2.2.9 Synthesis of K 12 [H 2 P 2 W
Page 13 and 14: Bibliography . . . . . . . . . . .
Page 15 and 16: 3.5 Left: combined polyhedral and b
Page 17 and 18: 3.33 Combined polyhedron and ball/s
Page 19 and 20: List of Tables 1.1 Selected M-M dis
Page 21 and 22: MO 6 octahedra surrounding a centra
Page 23 and 24: 1.1.1 The clathrate-like structure
Page 25 and 26: 7(MoO 4 ) 2− + 8H + → [Mo 7 O 2
Page 27 and 28: Fig. 1.4: Combined polyhedral/ball
Page 29 and 30: This planar structure was originall
Page 31 and 32: [X 2 M 18 O 62 ] 6− , the D 3h We
Page 33 and 34: [P 2 W 19 O 68 (HO)] 14− , [P 2 W
Page 35 and 36: Fig. 1.11: Monomeric (left) and dim
Page 37 and 38: Chapter 2 Experimental 2.0.1 Reagen
Page 39 and 40: 2.2 Preparation of starting materia
Page 41 and 42: as Cs 6 [P 2 W 5 O 23 ]·7H 2 O by
Page 43 and 44: was adjusted between 5-6 by additio
Page 45 and 46: Chapter 3 Results 3.1 The hybrid or
Page 47 and 48: Fig. 3.2: FTIR spectra of compound
Page 49: Fig. 3.3: W 183 NMR spectra of (CsN
Page 53 and 54: formed upon crystallization and bot
Page 55 and 56: X-ray Crystallography A crystal of
Page 57 and 58: the presence of the four (CH 3 ) 2
Page 59 and 60: Fig. 3.10: Cyclic voltammogram of 2
Page 61 and 62: as a function of electrolyte compos
Page 63 and 64: was observed that could be traced t
Page 65 and 66: electrochemical set-up was an EG &
Page 67 and 68: Fig. 3.14: The central core of Sn(C
Page 69 and 70: of these fragments [88, 90]. For co
Page 71 and 72: diffractometer using Mo K α radiat
Page 73 and 74: Fig. 3.18: Side view of [{Sn(CH 3 )
Page 75 and 76: host−guest systems with large cav
Page 77 and 78: X-ray Crystallography Single crysta
Page 79 and 80: 3.5.2 Results and discussions Polya
Page 81 and 82: Fig. 3.26: Ball and stick represent
Page 83 and 84: can distinguish between different m
Page 85 and 86: Fig. 3.28: STM pictures of {Sn(CH 3
Page 87 and 88: Fig. 3.31: Size distribution by int
Page 89 and 90: 3.6 The bis-phenyltin substituted,
Page 91 and 92: Table 3.7: Crystal Data and Structu
Page 93 and 94: tral belt in-between the two tin at
Page 95 and 96: Fig. 3.35: 183 W NMR spectra of com
Page 97 and 98: whereas they are five-coordinated (
Page 99 and 100: investigated by scanning tunneling
Page 101 and 102:
3.8 The di-titanium substituted, lo
Page 103 and 104:
Fig. 3.37: Ball/stick (left), polyh
Page 105 and 106:
[As 2 W 19 O 67 (H 2 O)] 14− , [A
Page 107 and 108:
3.9 The cyclic trimeric-titanium su
Page 109 and 110:
Table 3.9: Crystal Data and Structu
Page 111 and 112:
Fig. 3.40: FTIR spectra of compound
Page 113 and 114:
Fig. 3.42: Side-view of compound 11
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11 by 183 W-NMR (at 16.66 MHz on a
Page 117 and 118:
3.11 Structure and solution propert
Page 119 and 120:
472(w), 444(w) cm −1 . This proce
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MHz in 10 mm tubes and the 111 Cd N
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Fig. 3.47: 111 Cd NMR spectra of [C
Page 125 and 126:
in aqueous solution, so that the nu
Page 127 and 128:
of cadmium ions in 12 and 13 and it
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doubtedly 183 W-NMR, but the parama
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K): (relative intensities in parent
Page 133 and 134:
Fig. 3.49: Combined polyhedral/ball
Page 135 and 136:
Fig. 3.50: 183 W NMR spectrum of [I
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(17) are isostructural. They consis
Page 139 and 140:
Fig. 3.53: 183 W NMR spectrum of [I
Page 141 and 142:
3.12.4 Conclusion We have synthesiz
Page 143 and 144:
[37] D. Gatteschi, O. Kahn, J. Mill
Page 145 and 146:
94:226403, 2005. [123] R. J. Hamers
Page 147 and 148:
[206] I. Loose, E. Droste, M. Bösi
Page 149 and 150:
NMR Spectra Fig. 3.54: 13 C NMR spe
Page 151 and 152:
Fig. 3.56: 31 P NMR spectrum of pol
Page 153 and 154:
Fig. 3.58: 13 C NMR spectrum of pol
Page 155 and 156:
Fig. 3.60: 1 H NMR spectrum of poly
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Fig. 3.62: 119 Sn NMR spectrum of p
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Fig. 3.66: 1 H NMR spectrum of poly
Page 161 and 162:
Fig. 3.70: 13 C NMR spectrum of pol
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were applied and an absorption corr
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Fig. 3.75: Size distribution by num
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Table 3.16: Crystal Data and Struct
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Fig. 3.80: FTIR spectra of compound
Page 171 and 172:
FIRASAT HUSSAIN International Unive
Page 173 and 174:
Publications 1. Observation of a Ha
Page 175 and 176:
PAPERS IN CONFERENCE/ SYMPOSIA / WO
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