C-13 MAGNETIC-RESONANCE SPECTRA OF DIAMAGNETIC CYANO COMPLEXES

Fourier transform 13C NMR spectra are reported for 19 diamagnetic cyano complexes in D2O solution. Data are included for M(CN)6n- complexes of nd6 electron configuration where M=Fe(II), Ru(II), Os(II), Co(III), Rh(III), Ir(III), Pd(IV), or Pt(IV); square-planar M(CN)4n- complexes of nd8 configuration where M=Ni(II), Pd(II), Pt(II), or Au(III); tetrahedral M(CN)4n- complexes of nd10 configuration where M=Cu(I), Zn(II), Cd(II), or Hg(II); and linear M(CN)2n- complexes of nd10 configuration where M=Ag(I), Au(I), or Hg(II). Except for Fe(CN)64-, the 13C resonance in all the cyano complexes is found at higher field than uncomplexed CN, and the range of chemical shifts spans 92.5 ppm. Chemical-shift differences are discussed in terms of changes in σ and π bonding of CN to the metal ion. Metal-13C spin coupling was observed for [FORMULA OMMITED] Relaxation times T1 and T2 are reported for enriched (45% 13C) samples of [FORMULA OMMITED] In addition T1 values for these complexes were measured at 10°C temperature intervals between 30 and 70°C. The mechanism of relaxation of the 13C nucleus in the cyano complexes is discussed with the data in most cases consistent with scalar coupling to 14N. © 1979, American Chemical Society. All rights reserved.