123642-47-7Relevant academic research and scientific papers
Synthesis of unsymmetrical bidentate and tridentate phosphines by [4 + 2] diels-alder cycloadditions and Michael additions of (phosphole)- and (vinylphosphine)molybdenum carbonyl complexes
Affandi, Salina,Nelson, John H.,Fischer, Jean
, p. 4536 - 4544 (2008/10/08)
The reaction of divinylphenylphosphine with (1-phenyl-3,4-dimethylphosphole)pentacarbonylmolybdenum(0) (1) yields two diastereomers of syn-exo-[2-(phenylvinylphosphino)-5,6-dimethyl-7-phenyl-7-phosphabicyclo[2.2.1] hept-5-ene]tetracarbonylmolybdenum(0) (2a,b) by an intramolecular [4 + 2] Diels-Alder cycloaddition. These two diastereomers were separated by a combination of column chromatography on silica gel and fractional crystallization. The major diastereomer (2a) undergoes Michael additions with Ph2PH and Ph2AsH to produce Mo(CO)4 complexes of the new unsymmetrical asymmetric ligands 2-((2-(diphenylphosphino)ethyl)phenylphosphino)-5,6-dimethyl-7-phenyl-7- phosphabicyclo[2.2.1]hept-5-ene (3) and 2-((2-(diphenylarsino)ethyl)phenylphosphino)-5,6-dimethyl-7-phenyl-7- phosphabicyclo[2.2.1]hept-5-ene (4), respectively. In 3 and 4 the ligands are bidentate with dangling phosphino and arsino donor arms. Heating 3 and 4 liberates CO and converts them into their fac-LMo(CO)3 counterparts (5 and 6). Similar Diels-Alder cycloadditions occur with 1 and vinyldiphenylphosphine and vinyldiethylphosphine and with the (vinylphosphine)molybdenum pentacarbonyl complexes and 1-phenyl-3,4-dimethylphosphole. New complexes have been characterized by elemental analyses, physical properties, 1H, 1H{31P}, 13C{1H}, 31P{1H}, 1H/13C HETCOR, COSY, and 2-DJ nuclear magnetic resonance spectroscopy and infrared spectroscopy. Compounds 2b and 5 have been characterized by X-ray crystallography. Crystal data for 2b: monoclinic, C2/c, a = 18.277 (5) ?, b = 10.006 (3) ?, c = 27.650 (8) ?, β = 91.99 (2)°, V = 5053.6 ?3, Z = 8, R = 0.033 for 2596 independent observed (I > 3σ(I)) reflections. The donor abilities of the two phosphorus donors are quite different; Mo-P = 2.449 (1) and 2.513 (2) ?, and the C-P-C angle for the bridging phosphorus is small (80.1 (2)°). The chelate ring is rigid, and the molecule contains five asymmetric centers. Crystal data for 5: monoclinic, P21/c, a = 18.286 (5) ?, b = 11.379 (3) ?, c = 16.109 (4) ?, β = 91.99 (2)°, V = 3329.1 ?3, Z = 4, R = 0.030 for 3061 independent observed (I > 3σ(I)) reflections. The donor abilities of the three phosphorus donors are slightly different; Mo-P = 2.486 (1), 2.470 (1), and 2.481 (1) ?, and the C-P-C angle for the bridging phosphorus is small (79.7 (2)°). The molecule contains two fused five-membered chelate rings and five asymmetric centers.
