NOTES/norgci&c Chemistry pound, the analyses were performed on samples prepared at different times.
DiscussionThe evidence suggests that the compounds containing tris(acety1acetonato) complexes are similar to the halomethane solvates of these complexes reported by Steinbach and co-workers.10 The most obvious feature of the infrared spectra of the solids is in the 3-fi region, in which N-H vibrations appear. The compounds containing thiourea show three characteristic peaks, with positions and intensities like those of thiourea itself. l1 Urea itself has two characteristic strong peaksl1,l2 a t about 3330 and 3440 cm-l. In the M(acac)3. 3urea compounds an additional strong band appears a t about 3170 cm-'. The dificulties of assigning bands in this region have been discussed by Badger and UTaldron,l2 but the presence of the additional band is strongly-indicative of hydrogen bonding to the acetylacetonato complex. Thus hydrogen bonding appears to be important in the urea compounds, but not in the thiourea compounds.The formulas and properties of the compounds containing cobalt(I1) suggest that these have a structure like that of bis(acetylacetonato)cobalt(II) dihydrate.13 (10) J. F. Steinbach and J. H. Burns, J . A m .Spin delocalization in pyridine complexed with nickel(I1) and cobalt(I1) acetylacetonates, TL(AA)2, has been reported by Happe and Ward.' Using proton magnetic resonance these rorkers concluded that the frequency changes observed for the pyridine protons in the presence of the nickel complex could be interpreted as contact shifts, v,, due principally to spin delocalization in a u orbital of the pyridine ring. The shifts observed in the presence of CO(AA)~ were interpreted as being due to contact shifts and dipolar (pseudo-contact) shifts, v+) operating in opposite directions. The present work involving nickel(I1) and cobalt(I1) benzoylacetonates, M [-OC(CsHj) CHC- . H a l~p e and K . I,. Ward, .7. Ciimz. Phys., 39, 1 2 1 1 (1963).(CH3)O-I2, X ( B L~)~> provides an additional and more extensive test of this interpretation. Experimental Section 2 : 1 Complexes of Pyridine and M(BA~~.--Xnhydrous iU(B=1)2 (M = Ni, Co) m-as prepared b y a previously described method.2 T o solutions of tlie anhydrous chelate in toluene was added an excess of pyridine. Heptane was added, and the crystallized 2: 1 complex was isolated b y filtration and dried in vucuo for 8 hr.The green nickel complex melted a t 163-165" with previous softe r~i n g .~ The orange cobalt complex melted a t 147-148' witli preliminary softening. The visible-near-infrared spectrum of the cobalt complex in chloroform 2.0 AI in pyridine showed a peak at 9850 cm-I and a shoulder a t 18,300 cm-'.In pure pyridine the low-frequency cobalt d-d transition shifted slightly to 9760 cm-I. X-Ray powder diffraction patterns of the cobalt arid nickel complexes were identical. Anal. Calcd for C30H28N2-04Co: C, 66.79; H, 5.23. Found: C, 67.00; H,5.32.Nuclear Magnetic Resonance Spectra.-These were obtained using a modified \*arian A-60A spectrometer capable of scan...