The complex [(eta-5-C5H5)Ru(DMPP)2(CH3CN)]PF6 (1; DMPP = 1-phenyl-3,4-dimethylphosphole) reacts with the dieneophiles Ph2PCH=CH2 (DPVP), PhP(CH=CH2)2 (DVPP), PhP(CH2CH=CH2)2 (DAPP), PhS(O)CH=CH2, PhSCH=CH2, and 2-vinylpyridine to produce one (10, 12), two (4, 11), or three (5, 9) diastereomers of (eta-5-cyclopentadienyl)(1-phenyl-3,4-dimethylphosphole)[syn-exo-2-(diphenyl-phosphino)-5, 6-dimethyl-7-phenyl-7-phosphabicyclo[2.2.1]hept-5-ene]ruthenium(II) hexafluorophosphate (4a,b), (eta-5-cyclopentadienyl)(1-phenyl-3,4-dimethylphosphole)[syn-exo-2-(phenylvinylphosphino)-5,6-dimethyl-7-phenyl-7-phosphabicyclo [2.2.1]hept-5-ene]ruthenium(II) hexafluorophosphate (5a,b), (eta-5-cyclopentadienyl) {syn-exo-meso-phenylbis[5,6-dimethyl-7-phenyl-7-phosphabicyclo[2.2.l]hept-5-en-2-yl] phosphine}ruthenium(II) hexafluorophosphate (5c), (eta-5-cyclopentadienyl)(1-phenyl-3,4-dimethyl-phosphole) [syn-exo-2-((allylphenylphosphino)methyl)-5,6-dimethyl-7-phenyl-7-phosphabicyclo[2.2.1]-hept-5-ene] ruthenium(II) hexafluorophosphate (9a,b), (eta-5-cyclopentadienyl){syn-exo-dl-phenylbis[(5,6-dimethyl-7-phenyl-7-phosphabicyclo [2.2.1]hept-5-ene-2-yl]phosphine}ruthenium(II) hexafluorophosphate (9c), (eta-5-cyclopentadienyl)(1-phenyl-3,4-dimethylphosphole)[syn-exo-2-(phenylsulfinyl)-5,6-dimethyl-7-phenyl-7-phosphabicyclo [2.2.1]hept-5-ene]ruthenium(II) hexafluorophosphate (10), (eta-5-cyclo-pentadienyl) (1-phenyl-3,4-dimethylphosphole)[syn-exo-2-(phenylthio)-5,6-dimethyl-7-phenyl-7-phospha-bicyclo [2.2.1]hept-5-ene]ruthenium(II) hexafluorophosphate (11), (eta-5-cyclopentadienyl)[syn-exo-2-(2-pyridyl)5, 6-dimethyl-7-phenyl-7-phosphabicyclo[2.2.1]hept-5-ene]ruthenium(II) hexafluorophosphate (12), respectively, by intramolecular [4 + 2] Diels-Alder cycloadditions in high yields. Similar Diels-Alder cycloadditions occur with [(eta-5-C5H5)Ru(DPVP)2(CH3CN)]PF6 (2) and [(eta-5-C5H5)Ru(DVPP)2(CH3CN)]PF6 (3) and DMPP to form 6a,b and 7a,b, respectively. Reactions of 1 with the potential dienophilic ligands L = Me2NC(O)CH=CH2, PhS(O)2CH=CH2, P(OCH2CH=CH2)3, P(C=CPh)3, H2NCH2CH=CH2, N=C-CH=CH2, N(CH2C(CH3)=CH2)3, and C2H5OCH=CH2 produced the [(eta-5-C5H5)Ru(DMPP)2L)]PF6 complexes 14-21, which could not be induced to undergo subsequent [4 + 2] Diels-Alder cycloadditions. New complexes were characterized by elemental analyses, physical properties, cyclic voltammetry, infrared spectroscopy, and H-1, C-13{H-1}, P-31{H-1}, and in some cases by H-1{p-31} nuclear magnetic resonance spectroscopy. Complex 11 is stereochemically nonrigid with sulfur inversion occurring rapidly at room temperature; DELTA-G double dagger = 59.8 kJ mol-1. The structures of 4b, 5c, and 11 were confirmed by X-ray crystallography. They crystallize in the P2(1)/c, P2(1)/m, and C2/c space groups, respectively, in unit cells of the following dimensions: 4b, a = 20.965 (9) angstrom, b = 11.125 (4) angstrom, c = 21.678 (9) angstrom, beta = 118.26 (2)-degrees, rho(calcd) = 1.438 g cm-3, Z = 4; 5c, a = 11.137 (3) angstrom, b = 19.124 (5) angstrom, c = 8.686 (3) angstrom, beta = 102.93 (2)-degrees, rho(calcd) = 1.564 g cm-3, Z = 2; 11, a = 11.392 (2) angstrom, b = 19.018 (5) angstrom, c = 35.610 (8) angstrom, beta = 96.40 (2)-degrees, rho(calcd) = 1.429 g cm-3, Z = 8. Refinements converged to R(F) = 0.051, 0.042, and 0.048 for 4842, 1975, and 3178 independent observed (I greater-than-or-equal-to 3-sigma(I)) reflections, respectively.
