SYNTHESIS AND REACTIVITY OF (ETA(6)-ARENE)(PHOSPHINO ENOLATO)RUTHENIUM(II) COMPLEXES, THEIR COUPLING REACTION WITH PHENYLACETYLENE, AND THERMAL REARRANGEMENT TO A PHOSPHAMETALLACYCLOPROPANE - X-RAY CRYSTAL-STRUCTURES OF (RU[ETA(3)-CH=C(PH)CH(PPH2)C(BUT)=O](P-CYMENE))(PF6), OF (RU[ETA(3)-CH=C(PH)C(ME)(PPH2)C(ET)=O](MESITYLENE))(BF4), AND OF (RU[ETA(3)-CH(PPH2)CPH=C(H)C(BUT)=O](MESITYLENE))(BF4)

The reaction of lithium enolates with chlorodiphenylphosphine provides a convenient large scale synthesis of beta-keto phosphines. The coordination of beta-keto phosphines 1 at an (eta6-arene)Cl2Ru fragment affords neutral complexes (eta6-arene)Cl2Ru[eta1-P-Ph2PCHR2C(=O)R1], 2, cationic complexes {(eta6-arene)ClRu[eta2-P,O-Ph2PCR3R2C(R1)=O]}+, 3, and neutral enolato derivatives (eta6-arene)ClRu[eta2-P,O-OC(R1)=C(R2)PPh2],4. Compounds 4 react under mild conditions with ligands L (L = Me2S or RC=N) to give cationic derivatives {(eta6-arene)(L)ClRu[OC(R1)=C(R2)PPh2]}+, 5. When L is PhC=CH, carbon-carbon bond formation leads via regioselective coupling of the C=C bond to both ruthenium and =C(PPh2) carbon to complexes {(eta6-arene)Ru[eta3-CH=C(Ph)C(R2)(PPh2)C(R2)=O]}+, 6. The crystal structures of the compounds 6a (arene = p-cymene, R2 = H, R1 = Bu(t)), monoclinic, space group P2(1)/n (No. 14) with Z = 4, a = 14.870(4) angstrom, b = 20.087(6) angstrom, c = 12.454(5) angstrom, alpha = 90.0-degrees, beta = 92.67(3)degrees, gamma = 90.0-degrees, d(calcd) = 1.37 g/cm3, and 6c (arene = mesitylene, R2 = Me, R1 = Et), triclinic, space group P1BAR (No. 2) with Z = 2, a = 10.962(1) angstrom, b = 15.473(2) angstrom, c = 10.910(1) angstrom, alpha = 100.10(1)degrees, beta = 113.64(1)degrees, gamma = 102.41(1)degrees, d(calcd) = 1.55 g/cm3, have been determined. 6b (arene = mesitylene, R2 = H, R1 = Bu(t)) is cleanly thermally converted to the metallaphosphacyclopropane derivative {Ru[eta3-CH(PPh2)CPh=C(H)C(But)=O] (mesitylene)}+, 7, as shown by the X-ray structure determination: triclinic, space group P1BAR (No. 2) with Z = 2, a = 14.034(2) angstrom, b = 11.944(1) angstrom, c = 10.957(1) angstrom, alpha = 106.56-degrees, beta = 98.34(1)degrees, gamma = 109.24(1)degrees, d(calcd) = 1.44 g/cm3.