Synthesis of Tungsten Carbonyl and Nitrosyl Complexes of Monodentate and Chelating Aryl-N-sulfonylphosphoramides, the First Members of a New Class of Electron-Withdrawing Phosphine Ligands. Comparative IR and 13C and 31P NMR Study of Related Phosphorus Complexes

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Abstract
Reaction of N,N‘-bis(tolylsulfonyl)-1,2-diaminoethane with PhPCl2 gives in 62% yield the phosphonous diamide 2-phenyl-1,3-bis(p-tolylsulfonyl)-1,3,2-diazaphospholidine (4, “TosL”) and with Ph2PCl in 43% yield the diphosphinous amide N,N‘-bis(diphenylphosphino)-N,N‘-bis(p-tolylsulfonyl)-1,2-ethanediamine (5, “diTosL”). Reaction of 4 with (THF)W(CO)5 gives (TosL)W(CO)5 (6) in 77% yield, and reaction of 5 with trans-BrW(CO)4NO gives cis, cis, trans-(diTosL)W(CO)2(NO)Br (8) in 86% yield. The IR, 13C NMR, and 31P NMR spectra of 4, 5, 6, and 8 are compared to those of a variety of compounds including LW(CO)5 (L = PMe3, PPh3, PPh(NEt2)2, P(OMe)3, P(CF3)3), L2W(CO)2(NO)Br (L2 = Ar2PCH2CH2PAr2 (Ar = Ph (diphos), C6F5 (diphos-F20)), (CH3CN)2), and the free ligands as appropriate. The IR data are interpreted to suggest a relative ordering of ligand acceptor ability of P(CF3)3 > 4 ≈ P(OMe)3 > PPh3 ≈ PPh(NEt2)2 and a relative ordering of ligand donor ability of PPh(NEt2)2 ≥ P(OMe)3 > PPh3 > 4 > P(CF3)3. The chelating ligand diTosL is about as electron-withdrawing as diphos-F20, on the basis of the IR data. The 31P NMR data qualitatively support the conclusion that TosL and diTosL are highly electron-withdrawing ligands, on the basis of 1JPW. The 13C data do not permit any such generalizations, although the spectra of the diphosphine ligands and adducts are of interest due to the observation of “virtual coupling” that surprisingly can be simulated only as ABX rather than AA‘X spin-systems.

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