Issue 9, 1984

Chemistry of metallacyclobutanones. Part I . Synthesis and ring inversion of some highly puckered metallacyclobutan-3-one (slipped oxodimethylenemethane) complexes of platinum ; crystal structure of 2,4-bis(methoxycarbony1)-1,1-bis(triphenylphosphine)platinacyclobutan-3-one monohydrate

Abstract

The reactions of the carbonato-complexes [ Pt (CO2) L2] with esters of 3-oxopentanedioic acid, RCH2COCH2R, in warm ethanol afford, in high yield, the formally platinacyclobutan-3-one compounds [Pt(CHRCOCHR)L,] (R = C02Me, L = PPh,, AsPh,, PMePh, or PMe2Ph; 2L = Ph2PCH2CH2PPh2; - R = C02Et, L = PPh,, or AsPh,; R = C02Prn, L = PPh,, or AsPh,). The compounds [Pk(CHRCOCHR)- L2] (R = C02Me, L = PPh,, AsPh,, PMePh,, or PMe2Ph; R = C02Et, L = PPh, or AsPh,) are also formed upon treatment of benzene solutions of [PtL,] with RCH2COCH2R in the presence of air. Using the latter method, the triphenylphosphine derivative [ Pi{CH ( C02Me)COCH ( C02Me) I( PPh3)2] is often contaminated with the peroxo-ring compound [P~{OOC(CH2C02Me)20)( PPh,),] which is the major product if the reaction is carried out in diethyl ether. The reaction of [Pt(02)(PPh3)2] with Me02CCH2COCH2C02Me in diethyl ether also gives the peroxo-ring compound. Treatment of Me02CCH2COCH2C02Me with either [Pt(trans-PhCHZCHPh) ( PPh3)2] in benzene in the presence of air, [PtOOC(O)O(PPh,),] in ethanol, ~is-[Pt(OC0Ph)~(PPh,)~l in ethanol, or cis-[PtC12( PPh3)2] and - silver oxide in dichloromethane also affords [Pt{CH(C02Me)COCH(C02Me)}(PPh,),l. A single-crystal X-ray diffraction study has been carried out on [Pt(CH(CO,Me)COkH(CO,Me))( PPh3)2]*H20 (3a). The crystals are triclinic, space group P I , Z = 2, in a unit cell with a = 17.59(1), b = 12.736(6), c = 10.27(1) A, ac = 118.2(1), p = 94.7(1), and y = 74.0(1)". The structure has been refined to R 0.035 (R' 0.036) for 7 263 reflections with / 2 30(/). It can be considered to be based either upon a highly puckered platina- cyclobutan-3-one ring [fold angle = 50.4(4)"] with a weak transannular Pt-C bond of 2.416(5) A, or as a slipped q3-oxodimethylenemethane compound. N.m.r. data ( H, I3C-{ H}, and 31 P-(H}) are reported and variable-temperature H n.m.r. data for the compounds [Pi( CH RCOCH R) L2] (R = C02Me, L = PPh, or AsPh,) are interpreted in terms of inversion of the platinacyclobutan-3-one ring through a planar transition state. The magnitude of the platinum-I95 coupling to the axial and equatorial ring hydrogens of the platinacyclobutan-3-one ring is dependent upon the orientation of of the CH bonds with respect to the square planar platinum function and the magnitudes of 3J(cis- PPtCH) are controlled by the dihedral angle.

Article information

Article type
Paper

J. Chem. Soc., Dalton Trans., 1984, 1993-2002

Chemistry of metallacyclobutanones. Part I . Synthesis and ring inversion of some highly puckered metallacyclobutan-3-one (slipped oxodimethylenemethane) complexes of platinum ; crystal structure of 2,4-bis(methoxycarbony1)-1,1-bis(triphenylphosphine)platinacyclobutan-3-one monohydrate

D. A. Clarke, R. D. W. Kemmitt, M. A. Mazid, P. McKenna, D. R. Russell, M. D. Schilling and L. J. S. Sherry, J. Chem. Soc., Dalton Trans., 1984, 1993 DOI: 10.1039/DT9840001993

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