5506
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COMMUNICATIONS TO
than the 365 mp (singlet singlet) absorption band for the compound. The maxima correspond quite well with the previously observed vibrational structure of the singlet -+ triplet transition of phenazine in methyl iodide a t 655, 625, 588, 545, and 510 mp.8 For polystyrene film a magnetic rotation maximum was observed a t 335 mp, quite close to the triplet-state absorption region for toluene a t 347 mp. With polymethylmethacrylate, a normal Faraday effect was obtained; however, no magnetic rotation peaks were observed a t wave lengths longer than 360 m p . The above results demonstrate that magnetic rotatory dispersion measurements are useful for detecting the triplet states of certain molecules. A literature search showed that the use of magnetic rotations to detect triplet states is inherent in the theory of the Faraday effectlo for diatomic molecules. Some experimental evidence for this has been obtained for such molecules as Iz,llIC1 and IBr.I2 This communication illustrates that the method is also applicable t o certain organic compounds and polymers. We are now engaged in examining the scope and utility of magneto-optical rotation spectroscopy. l 3
THE
EDITOR
XlH3.2NMe3
Vol. 82
+ MezNCH2CH2XMe2 -+2NMe3 + AlH3.Me2NCHXH2NMe2
carried out in a tensimeter, 0.473 mmole of AlHr 2NMe3 was found to absorb 0.467 mmole of the diamine and, simultaneously, to release 0.949 mmole of trimethylamine. The adduct prepared in the above manner was a white solid whose vapor pressures a t 99.3' and 119.2' were 1.5 mm. and 10.6 mm., respectively. When a sample prepared using 0.20 "ole of AlH3.2NMe3as a starting material was completely vaporized a t 125', 0.101 mmole of vapor was found to be present. This indicates that the diamine adduct in question is a dimer. We feel that dimerization occurs through hydrogen bridging, rather than through the difunctional amine, and propose the structure
Me2
Me?
Each of the aluminum atoms is 6-coordinate, probably with an octahedral configuration. Infrared spectra of A1H3.2Nhle3and of (A1Hg)z. (8) R. W. Harrell, Ph.D. Thesis, Florida State University, Talla(MezNCH2CH2NMe2)zboth show identical A1-H hassee, Florida, January, 1959. stretch absorptions a t 5 . 9 0 ~from ~ which one is (9) D. S hlcClure, J. Chem. Phys., 17, 905 (1949). tempted to infer that the two substances have (10) R. Serber, P h y s . Rev., 41, 489 (1932). (11) T. Carroll, ibtd., 52, 822 (1937). closely related structures, and, particularly, that (12) W. H . Eberhardt, Wu-chieh Chung and H. Renner, J . Mol. A1H3.2NMe3is dimeric in the vapor phase. (DeSpertuoscopy, 3, 664 (1959). termining the molecular size of A1H3.2NICle3 (13) T h e author wishes t o thank Drs. H. Kobsa and R. W. Harrell directly by tensimetry is not convenient, owing to of the Du Pont Company for helpful discussions. the pronounced tendency for this substance to ENGINEERING RESEARCH LABORATORY ENGINEERING DEPARTMENT VICTORE. SHASHOUA dissociate.) Our proposed structure for this subE. I. DU PONTDE NEMOURS & Co. stance makes it unnecessary to invoke a pentaWILYISGTON, DELAWARE covalency for the aluminum atom. RECEIVED AUGUST9, 1960 Unlike other AlH3 adducts, (A1H3)2.(Me2NCH~CH2Nhfez)z showed no tendency to decompose At the end of this A NEW TYPE OF ALUMINUM HYDRIDE ADDUCT over a 24-hour period a t 133'. time the ratio of aluminum to hydrogen liberated Sir: The Lewis adduct between K,N,N',N'-tetra- on hydrolysis was 1.00 to 3.01. The authors are grateful to the Office of Naval methylethylenediamine and aluminum hydride, which we have recently prepared, probably con- Research for financial assistance in this program. OF CHEMISTRY J. M. DAVIGSON stitutes the first example of chelation in compounds DEPARTMENT PENSSYLVANIA STATE UNIVERSITY of this type. This substance, in addition to being THE ~VARTIK THOMAS ~JSIVERSITY PARK,PENSSYLVASIA thermally more stable than any previously preRECEIVED AUGUST 18, 1960 pared adduct of aluminum hydride, yields information which may have important consequences affecting the structures of all di-adducts of alumi- MAGNETIC OBSERVATIONS OF SOME SUBSTITUTED NICKEL(I1) SALICYLALDIMINE COMPLEXES num hydride. The new compound has been prepared by two Sir: procedures, the first of which involved the action Recently Sacconi, et a.1.,1,2 have reported magof the diamine dihydrochloride on lithium alumi- netic moments (0.5-1.6 B.M.) of N-alkylsalicylnum hydride in an excess of the diamine as a sol- aldimine Ni(I1) complexes over a temperature range vent.' However, a more convenient route in- in the fused state and in dibutyl phthalate soluMe2NCH2CH2SMe2 tion. They interpret their results in terms of a 2LiA41Hc+ Me2NCH2CHzNMe2.2HCl -edistribution of individual planar molecules over 2H2 + 2LiCl + 2H3.41.MenNCH?CH?SMe~ low-lying singlet and triplet states,3 . 4 thus accounting for the partial paramagnetism. This anomavolved treatment of bis- (trimethylamine)-alumi- lous magnetic behavior whereby certain apparently num hydride with an excess of the tertiary diamine f l ) L. Sacconi, R. Cini, 41. Ciampolini and F. hfaggio, T H I S J W R a t room temperature. In one such preparation, I _ _ _ _ -
82, 3487 (1960). (2) L. Sacconi, K . Cini and F. Llaggio, ibid..79, 3933 ( l 9 5 i ) . (3) C. J. Ballhausen and A. D. Liehr, ibid., 81. 538 (1959). (4) G . X a k i , 5 . Chznz. Phys., 29, 1129 (1958).
XAL,
(1) This is a modification of the general method developed b y Ruff and Hawthorne (THIS JOURNAL, 83, 2141 (1960))for the preparation
of amine adducta of aluminum hydride.
