WCl6, 1, reacted with two equivalents of HC(O)NR2 (R = Me, Et) in CH2Cl2 to afford the W(VI) oxo-derivatives WOCl4(OCHNR2) (R = Me, 2a; R = Et, 2b) as main products. The hexachlorotungstate(V) salts [{OC–N(Me)CH2CH2CH2}2(μ-H)][WCl6], 3, and [PhNHC(Me)N(Ph)C(O)Me][WCl6], 4, were isolated in moderate yields from the 1 : 2 molar reactions of 1 with N-methyl-2-pyrrolidone (in CH2Cl2) and acetanilide (in CDCl3), respectively. The additions of two equivalents of ketones/aldehydes to 1/CH2Cl2 yielded the complexes WOCl4[OC(R)(R′)] (R = Me, R′ = Ph, 5a; R = R′ = Ph, 5b; R = R′ = Me, 5c; R = R′ = Et, 5d; R = H, R′ = 2-Me-C6H4, 5e) and equimolar amounts of C(R)(R′)Cl2. Analogously, WOCl3[κ2-{1,2-C6H4(O)(CHO)}], 5f, and 1,2-C6H4(OH)(CHCl2) were obtained from 1 and salicylaldehyde. The 1 : 1 reaction of 1 with acetone in CH2Cl2 resulted in the clean formation of WOCl4 and 2,2-dichloropropane. Compounds 5a,b,f were isolated as crystalline solids, whereas 5c,d,e could be detected by solution NMR only. The interaction of 1/CH2Cl2 with isatin, in a 1 : 1 molar ratio, revealed to be a new, convenient route for the synthesis of 3,3-dichloro-2,3-dihydro-1H-indol-2-one, 6. The 1 : 1 reactions of 1 with R′OCH(R)CO2Me (R = H, R′ = Me; R = Me, R′ = H) in a chlorinated solvent afforded the tungsten(V) adducts WCl4[κ2-OCH(R)CO2Me] (R = H, 7a; R = Me, 7b). 1/CH2Cl2 reacted sluggishly with equimolar quantities of trans-(CO2Et)CHCH(CO2Et) and CH2(CO2Me)2 to give, respectively, the W(IV) derivatives WCl4[κ2-CH2(CO2Me)2], 8a, and [WCl4-κ2-{trans-(CO2Et)CHCH (CO2Et)}]n, 8b, in about 70% yields. The molecular structures of 2a, 3, 4, 5a, 5f, 7a and 7b were ascertained by X-ray diffraction studies.

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A crystallographic and spectroscopic study on the reactions of WCl6 with carbonyl compounds.

Lacunary polyoxometalates (POMs) are useful rigid multidentate inorganic ligands to construct multinuclear metal oxo clusters and inorganic-organic hybrid materials. However, the use of multivacant lacunary POMs often suffers from their undesired condensation reactions at the highly reactive vacant sites. Herein, the introduction of alkoxy protecting groups into the vacant sites of lacunary POMs in organic media is reported for the first time. By reacting organic solvent-soluble trivacant lacunary Keggin-type POMs with methanol, six methoxy groups were successfully introduced into the vacant sites, resulting in the formation of the alkoxides TBA4 [A-α-XW9 O28 (OCH3 )6 ] (Ix -OMe; X=Si, Ge). These methoxy groups could protect the reactive vacant sites and suppress the undesired dimerization reaction into the corresponding α-Dawson-type POMs. Since the introduced monodentate methoxy groups could easily be dissociated by hydrolysis, ISi -OMe could be utilized as the precursor for the synthesis of metal-substituted POMs. In addition, by using pentaerythritol as the multidentate alkoxy ligand, the monomeric alkoxide TBA4 [A-α-SiW9 O28 {(OCH2 )2 C(CH2 OH)2 }3 ] (ISi -PE) was successfully synthesized. In particular, these multidentate alkoxy groups showed high resistance against hydrolysis. Moreover, by reacting ISi -PE with trivacant lacunary Keggin-type POMs, the dimeric inorganic-organic-inorganic hybrid structures TBAn H8-n [(A-α-SiW9 O28 ){(OCH2 )2 C(CH2 O)2 }3 (A-α-XW9 O28 )] (IISiX -PE; X=Si, Ge) with the same or different heteroatoms (Si and Ge) were successfully synthesized.

Alkoxides of Trivacant Lacunary Polyoxometalates

Sterically Demanding Fluorinated Substituents and Metal Fluorides with Bulky Ligands

Substituted tungsten fluorides

The monomeric tungsten oxo-fluoroalkoxide W(O)(CH2CF3)4 (1) was synthesized from W(O)Cl4 and CF3CH2OH in the presence of ammonia. It was used in atmospheric pressure chemical vapour deposition experiments to deposit non-stoichiometric WO2.9 when used as a single-source precursor or stoichiometric WO3 when O2 was used as co-reagent. Copyright © 2008 John Wiley & Sons, Ltd.

M. Nieger

Papers

Preparation and structural investigations of fluorinated tungsten(vi) alkoxides

1,8‐Diphosphatricyclo[6.2.2.02,7]dodeca‐2(7),3,5‐triene

1,8-Diphosphatricyclo(6.2.2.02,7)dodeca-2(7),3,5-triene

Preparation and Structural Investigations of Fluorinated Tungsten(IV) Alkoxides.