Tungston-183 NMR spectroscopy: 2Jw-w coupling. Structural application to 1-12 heteropolytungstates

Abstract

4589phosphorus bond distance in 1 is much shorter than the reported average values in ( C 6~5 P ) 5 [2.217 (6) All6 and (C6H5P)6 [2.237(3) All7 in spite of the strong steric hindrance in 1, indicating that the bond in the diphosphene has considerably double bond character. All intermolecular approaches correspond to the van der Waals interactions. Reaction of 1 in carbon tetrachloride with chlorine gas at room temperature gave (2,4,6-tri-tert-butylphenyl)phosphonic dichloride almost quantitatively after treatment with water. The same result was obtained in the presence of methanol.The compound 1 is the first isolated phosphobenzene with a localized P==P bond in contrast to [ (trifluoromethy1)phosphinidene] tributylpho~phorane'~ with a delocalized P=P bond.Compound 1 may serve as a good model for theoretical studies as well as studies in organic and inorganic chemistry. Further investigation of the chemical properties and reactions of 1 is now in progress.

Direct Bromination of Keggin Fragments To Give [PW9O28Br6]3−: A Polyoxotungstate with a Hexabrominated Face

“…[9] Another feature of this crystal structure also shown in Figure 1 is the acetonitrile solvate molecule situated with the N atom 1.19 above the mean plane of the six bromo ligands, with N´´´Br distances of 3.773 ± 4.053 . The formation of 1 from [NaPW 11 O 39 ] 6À and C 2 O 2 Br 2 is consistent with a degradation process in which initial electrophilic attack at the basic oxide surface is followed by excision of two WO 2 Br 2 fragments as the oxalato-bridged dinuclear complex 2. The formation of 1 from [NaPW 11 O 39 ] 6À and C 2 O 2 Br 2 is consistent with a degradation process in which initial electrophilic attack at the basic oxide surface is followed by excision of two WO 2 Br 2 fragments as the oxalato-bridged dinuclear complex 2.…”

“…The bromoanion [PW 9 O 28 Br 6 ] 3À (1) was initially obtained as one of the products from the reaction between (nBu 4 N) 6 -[NaPW 11 O 39 ] [5] and C 2 O 2 Br 2 in an attempt to attach oxalate groups to the surface of the PW 11 Keggin fragment. The acetonitrile solvate of (nBu 4 N) 3 -1 crystallized as yellow crystals along with colorless crystals of (nBu 4 N) 2 [W 2 O 4 -Br 4 (m-C 2 O 4 )] and both compounds were structurally characterized by single-crystal X-ray diffraction.…”

“…The 31 P NMR peak for 1 occurs at d P À 11.6, and in the 183 W NMR spectrum the brominated tungsten atoms WBr of 1 and WBr 2 of 2 have characteristic low-field chemical shifts with peaks at d W 189.1 and 281.6, respectively. [12] Bromination of (nBu 4 N) 6 [NaPW 11 O 39 ] with SOBr 2 also resulted in excision of two tungsten atoms and formation of (nBu 4 N) 3 -1 as the major phosphotungstate product (67 % of the total integrated intensity in the 31 P NMR spectrum). [8±11] The effect of bromination on d W can be seen by comparison with the 183 W NMR spectrum of [(PhSnOH) 3 (PW 9 O 34 ) 2 ] 12À , the only other structurally characterized example of a functionalized polyoxometalate containing the b,A-PW 9 fragment.…”

“…[1±8] Natural photoenzymes are very rare. [11] With their ability of transforming optical signals into chemical motion, photoenzymes might have important future applications in molecular-scale electronics in the areas of signal transformation, amplification, integration, and information storage. [11] With their ability of transforming optical signals into chemical motion, photoenzymes might have important future applications in molecular-scale electronics in the areas of signal transformation, amplification, integration, and information storage.…”

Synthesis, characterization and study of the chromogenic properties of the hybrid polyoxometalates [PW11O39(SiR)2O]3− (R=Et, (CH2)nCHCH2 (n=0, 1, 4), CH2CH2SiEt3, CH2CH2SiMe2Ph)

“…Coupling constants are around 10 Hz for edge-sharing octahedra and around 20 Hz for corner-sharing octahedra [27]. On this basis, we can establish the theoretical connectivity matrix valid for any monosubstituted Keggin polytungstate ( (1): conventional 1D spectrum (down) and 1D COSY spectrum (up).…”