Nuclear spin coupling effects in 31P MAS NMR spectra of solid bis(triphenylphosphine)(phenylcyanamido)copper(I) complexes
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Solid-state 31P cross polarization (CP) magic angle spinning (MAS) NMR data have been obtained on three solid bis-(triphenylphosphine)(phenylcyanamido)copper(I) complexes, [(Cu(PPh3),(4-RC6H4NCN)},]( R = H, Me, Cl), at magnetic fields of 2.1 1, 7.05,9 .40, and 11.74 T. The highly structured, complex spectra exhibit both heteronuclear 1J(31P,63Cuan) d1J(31P,65Cuan) d homonuclear 2J(31P,31Pis)o tropic spin-spin coupling, in addition to some residual coupling d(31P,63C~) and d(31P,65Ce~m) emanating from second rank interactions. The spectral analyses and subsequent structural implications are aided by studying the magnetic field variation of both 1D 31P CP-MAS and 2D IIP CP-MAS COSY NMR experiments and by simulation of 1D spectra through diagonalizing the nuclear spin Hamiltonian which includes a quadrupolar perturbation from the copper spin states. The asymmetry induced in the J-split multiplets from quadrupole effects in this P2CuN2 system is much smaller than is usually encountered in P2CuX2 (X = halogen) and PzCu02 systems. This may be attributable to an unusually small electric field gradient at the copper site despite marked deviation of the copper coordination sphere from tetrahedral point symmetry.
The Journal of Physical Chemistry
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