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

Abstract

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.