Photo-heterolysis and -homolysis of substituted diphenylmethyl halides, acetates, and phenyl ethers in acetonitrile: characterization of diphenylmethyl cations and radicals generated by 248-nm laser flash photolysis

Abstract

Tetrahydridocarbonyltris(dimethylpbenylphospbine)rhenium( V) Tetrafluoroborate (2a) and LMhydrido(dihydrwen~cnrbonvltris(dimethvIke-HB).31P['H) NMR (298 K): d -20.2.jiP{'H) NMR (193 K): d K): 6 203.2 (q, 2Jpc = 9.2 Hz, CO), 142.8 (d, 'Jpc = 38.8Hz, C, of Ph), = 7.4 Hz, C3 of Ph), 25.6 (d, 'Jpc = 31.5Hz, Me).13CI'H) NMR (193 K): 6 202.6 (dt, ?Jpc = 51.8,10.1 Hz, CO), 141.7 (t, 'Jpc = 42.5 Hz, C , of P B M ~~P ~) , 140.3 (d, lJpc = 35.1 Hz, C , of PAMe2Ph), 130.1 (d, 2Jpc = 9.0 Hz.C2 of PAMe2Ph), 129.3 (t, zJpc = 11.0Hz, Cz of PAMe2Ph), 25.7 (t, 'Jpc = 37.0 Hz, PBMezPh), 24.3 (t, lJpc = 33.3Hz, P&' 2Ph), 21.4 (d, ' J , = 25.9Hz, PAMe2Ph).ReD3(CO)(PMe2Ph)3 was prepared similarly by treatment of ReCI,(CO)(PMe2Ph)z with LiAID4 followed by hydrolysis with D,O.The isotopomeric mixture of ReH,-,D,(CO)(PMe2Ph)3 ( x = 0-3) was prepared by treatment of ReCl3(CO)(PMe2Ph), with LiAlD4 and hydrolysis with H 2 0 / D z 0 (1:I molar ratio).-15.4 (d, 29 Hz, 2 P, PB), -30.4 (t, 29 Hz, I P, PA)."CI'H) NMR (298 130.5 (d.'Jpc = 1 1 . 1 Hz, C2 of Ph), 128.8 (s, C4 of Ph), 128.0 (d, 'Jpc PBMezfh), 128.1 (S, C4 Of PBMelPh), 127.9 (S, C4 Of PAMe2Ph), 127.4 (t, 'Jpc 8.4 Hz, C3 of PBMezPh), 127.1 (d, 'Jpc = 7.4 Hz, C, of phenylphosphine)rhenium(IIIj Tetrafluoroborate (2b): ReH,(CO)-(PMe,Ph), (1; 25 Mg) was dissolved in CD2CI2 (0.4 mL) in a 5-mm NMR tube.The sample was cooled to -80 "C (dry ice/acetone).HBF,.OEt, (6 pL) was added via a microsyringe.The sample was shaken and then quickly introduced into an NMR probe.precooled to -80 OC. 'H NMR (193 K): d 6.8-7.7 (c, Ph), 2.17 (d, 'JpH = 9 Hz, Me, 2b), 1.92 (d, 2JpH = 5 Hz, Me, Za), 1.90 (d, 2JpH = 5 Hz, Me, 2a), 1.72 (d, 'JpH = 7 Hz, Me, 2b), 1.55 (d, 2JpH = 7 Hz, Me, 2b), 1.19 (d, 2JpH = 7 Hz, Me, Za), -3.91 (q, 2JpH = 17.9 Hz, Re-H, Za), -4.90 (pseudo t, 'JPH = 55 Hz, Re-H, 2b), -5.40 (br, q2-H2, 2b)."P{lH) NMR (193 K): 6 -26.6 (t, 'Jpp = 15 Hz, PA, 2a), -27.9 (d, 'Jpp = 15 Hz, PB, 2a), -27.6 (t, *Jpp = 1 1 Hz, PA, 2b), -27.7 (d, 2Jpp = I 1 Hz, PB.Zb).After the NMR experiments, excess NEt3 was added and NMR spectra were taken again to show that 1 was regenerated quantitatively.