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Article

Ether Complexes of Tungsten with Two Different Binding Modes: An O-Bound Ether and an η²-(CC) Vinyl Ether. Evidence for CH···O Hydrogen Bonding of Vinylic CH Groups

Supporting Info

Jeong-Sup Song,^† David J. Szalda,^‡ and R. Morris Bullock*

Contribution from the Chemistry Department, Brookhaven National Laboratory, Upton, New York 11973-5000

J. Am. Chem. Soc., 1996, 118 (45), pp 11134–11141

DOI: 10.1021/ja962193p

Publication Date (Web): November 13, 1996

†

Present address: Department of Chemistry, Sun Moon University, Asan City, Chungnam, South Korea, 336-840.

‡

Research Collaborator at Brookhaven National Laboratory. Permanent address: Department of Natural Sciences, Baruch College, New York, NY 10010.

In papers with more than one author, the asterisk indicates the name of the author to whom inquiries about the paper should be addressed.

Abstract

The reaction of PhCH(OCH₃)₂ with Cp(CO)₃WH and HOTf gives [Cp(CO)₃W(PhCH₂OCH₃)]⁺OTf^-. The structure of this benzyl methyl ether complex was determined by single crystal X-ray diffraction and was shown to have the ether bonded to tungsten through the oxygen. This compound was isolated as a kinetic product of the reaction; it decomposes in solution by releasing free PhCH₂OCH₃ and forming Cp(CO)₃WOTf. An analog with the BAr‘₄^- counterion [Ar‘ = 3,5-bis(trifluoromethyl)phenyl] is more stable. The reaction of the vinyl acetal CH₂CHCH(OEt)₂ with Cp(CO)₃WH and HOTf produces [Cp(CO)₃W(η²-EtOCHCHCH₃)]⁺OTf^-, in which the ether is bonded to tungsten through the CC bond of the vinyl ether. The crystal structure of this compound shows that the WC(OEt) distance (2.69(3) Å) is significantly longer than the WC(CH₃) distance (2.37(3) Å). There are weak CH···O hydrogen bonds between both vinyl CH's and oxygens of triflate counterions. Evidence is presented that some of these weak hydrogen bonds are maintained in CD₂Cl₂ solution but not in CD₃CN.