Crystals of compound (I) and (II) are black in reflected light and brown-black in transmitted light. The 'H-nmr of the cations of (I), recorded in D6-DMSO, show peaks, relative to the 'H of D6-DMSO, at + 0.46 ppm(re1. int. = 3); +0.85 ppm(re1. int. = 1.2); + 1.80 ppm (rel. int. = 3); and -4.18 ppm(re1. int.=l). The magnetic susceptibility of (I) is C', (293.18 K ) = 588.45 x c.g.s. units, which corresponds to a &*=0.295 B.M. per Co ion; however, the small shifts and sharp 'H-nmr lines in the DMSO spectrum preclude the presence of paramagnetic clusters. Cyclic voltametry of the cation present in (I) shows highly distorted, irreversible, oxidation and reduction waves which indicate the lack of stability of any oxidized or reduced form -a fact which accords with the sharp lines of the N M R spectra; e.g., no stable paramagnetic species are present in (I). Compound ( l ) , M.W.=941.24, crystallizes in P21/n (No. 14), with cell constants a= 11.789(2), 6 = 13.855(2), c = 21.534(3) A, p = 91.94(1)"; V = 3515.44 A3, d (meas; z= 4) = 1.778gm-~m-~. A total of 4705 data were collected in the range 4" 5 2 8 5 50". They were corrected for absorption (p = 19.562cm-'; rel. trans. coeK range=0.8642 to 0.9997); of these, 2623 were unique and had I > 340. The structure was solved by direct methods, none of the hydrogens of the amine ligands were found experimentally at sensible positions; thus, they were left out. Refinement of the heavy atoms (anisotropic) ied to final residuals of R(F)=O.O637 and 0.0771. Compound (10, M.W.=950.20, crystallizes in space group P1 (bar; No. 2), with cell constants a= 12.858(3 , b = 12.475(2), c = 12.1 14(2)A, a=96.63(1), p=91.94(1) and y = in the range 4" 5 2 8 5 50". They were corrected for absorption (p=21.301cn-'; rel. trans. coeff. range = 0.7372 to 0.9998); of these, 4456 were unique and had I 2 340. The structure was 61.71(2)"; V = 1615.68 A ' , d(meas; z=2)= 1.953 g m -~m -~. A total of 5657 data were collected *In Memoriam Alfred Werner: On the 109th Anniversary of the Presentation of his $Participant in the Undergraduate Special Studies Program. Habilitationschnft, October, 1891. 185 Downloaded by [The University of Manchester Library] at 08:05 14 October 2014 186 I. BERNAL et al. solved by direct methods, the majority of the hydrogens of the amine ligands were found experimentally at sensible positions, the rest were calculated at idealized positions (N-H = 0.95A). The hydrogens of the OH ligands were located experimentally in a final difference Fourier map. Refinement of the heavy atoms (anisotropic) with fixed hydrogens (B= 5.00 8') led to final residuals of R(F) = 0.0348 and 0.0440. Precisely as visualized by Werner, the hexol cations consist of a central Co(II1) cation surrounded by three [Co(NH&(OH),] ' + ligands. In (I), the 0-Col -0 angles are acute (av. value = 82.97"), as expected from the electrostatic repulsion of the Co(II1) central cation and the monopositive ligands surrounding it. Consequently, the Co. . . .Co distances are long (2.896, 2.888 and 2.889 A; on average, 2.891 ...
