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EDITOR
abundant evidence t h a t the heats of donor acceptor type interactions are generally small in value and do not vary widely with changes in component structure. Further work on the heats of formation of these complexes is under way. The authors are indebted to the National Science Foundation for a grant in support of this research.
were the nitrito form. The molecular extinction coefficients (extrapolated) of compounds I and I1 are exactly the same as for the known inactive compounds and quite different from the dinitro compounds. The compounds d-cis-[Co(en)z(NOz)(ONO)]d-BCS2, d-cis- [Co(en)z(X02)(OXO) ]C104? and dl-cis- [Co(en)z(NOz)(ONO) ]C104* had values Of t 4 mp ~ = 82, €434 = 106, €439 = 113,€481 = 130 + 2 while the extinction coefficients for d cis-[Co(en\,zDEPARTMENT OF CHEMISTRY and dlC. E. CASTRO (N02)2]d-BCS3,d-cis-[C~(en)~(NO~)~]ClO~ USIVERSITYOF CALIFORNIA L. J, ASDREWS cis-[C~(en)~(T\jOz)~]ClO~~ DAVIS,CALIFORNIA were C4C8 = 120, ~ 4 3= ~ RECEIVED AUGUST29, 1965 180,€439 = 181, €461 = 129 f 2 . Either I or TI mutarotates rapidly a t room temperature reaching a constant value after several RESOLUTION AND MUTAROTATION O F cis-NITRITOhours owing to the formation of the optically stable NITRO-BIS-'ETHYLENEDIAMINE '-COBALT I11j d-cis-[C0(en)~(N20)~] + ion. On warming this with Sir: dilute sodium hydroxide solution overnight, only It previously has heen demonstrated' that the the activity of the resolving agent remains. Table nitrite ion can attach itself to the inner codrdina- I compares the observed changes in rotation with tion sphere of a cobalt ion in two ways: through those calculated. Preliminary kinetic studies india x oxygen (Sitrito or through the nitrogen TABLE I Sitro . The conversion of the nitrito form to the MOLECULAR ROTATIOXS nitro takes place rapidly and completely i n soluCompound I Compound 11 tion or in the solid state with little or no ris--fmns Obs. Calcd. Obs. Calcd. interconversion. The mechanism of this reaction Initial2 +469 $470 +228 +230 is of especial interest since it may provide valuable After 24 hours 4-394 +384 f116 4-144 information on the mode of substitution in coAfter heating in dilute ordination compounds. SaOH +240 $241 0 0 In connection with a study oi the mechanism of thc formation oi nitrito compounds and of the cate that the rate of mutarotation and the rate of nitrito-nitro conversion, we have reccntlj- suc- conversion to the nitro form are equal, and have a ceeded iii resolving cis- [Co/cn' ? ( S O 2 ' ( 0 S O1- half-time of about TO minutes (19'). Thus the by the use of aminoniuiii tl-a-bromocamphor-r- reaction sulion:ite, :(!-TH:RCS , and a partial resolution d-cis-[Co(en)~(XO~)(ONO)]--+-d-ciS-[Co(en)Z(~02)21 has been achieved with actii-e pon.derec1 quartz. proceeds with no appreciable racemization and This is believed to bc the first reported isolation of 3 of the starting material and the since the d-form nitrito complex in optically active form. The resolution was achieved by the addition of a product is the least soluble diastereomer with dslight excess of solid d-NH4RCS to a saturated BCS-, the generic configuration is probably rea t~ 0". t a i r ~ e d . ~Tracer experiments now in progress solution of ris-[Co/en 2 / S O ?: O S O I ] C ~ O Reddish-yellow needles were deposited, which were indicate that this reaction proceeds completely dissolved in water a t 0" and rccrystallizcd by the by a n intramolecular process. In the near future a more detailed account of this addition oi solid d-SH:RCS. The crystals were washed with ice-cold acetone and dried under work as well as new results on the kinetics of these vacuum: i I tl-cis- [Co'en .:'SOr 1 O S O ' Id-BCS, reactions will be communicated. (3) Prepared b y allowing d-cis-[Co(en)n(iYO?)(0x0)Id-BCS to [.]"D --';lC.? The resolving agent was remo\-ed in water overnight. by triturating thc diastercoincr with a saturated stand (4) A. Werner, Be?., 44, 2452 (1911). solution of sodium perchlorate :it 0" and washing ( 5 ) A. Werner, Buil. SOC. chim., [4]11, xix (1912); J. P. Mathiew. the precipitated powdcr with ict-cold ethanol. Comfit. rend., 199,278 (1934); 201, 1183 (1935). Recrystallization was accomplishecl b?, solution DEPARTMENT O F CHEMISTRY R. KEST MURMAXV in cold water and addition (-if solid sodiunn per- UXIVERSITY O F COSiYECTICUT chlorate. The orange crystals were ireetl of STORRS,CONXECTICUT RECEIVED AUGUST22, 1955 sodiuni perchlorate by n.:ishiii~: with ice-cold tthanol and dried under vzicuuin: 1.11 tf-ris-[Colen',JTO?itOSO ]C104, [ a l : j ~ A @ . 3 3 2 . Am!. REQUIREMENT OF TRIPHOSPHOPYRIDINE Calculatetl inr CoC4HlsSc0,C1; Co, 15.92; C, THE NUCLEOTIDE I N FATTY ACID SYNTHESIS' 1;3,02; H, 4,,3:3; S . 22 7 6 . Found: '211, 13.61; C , 13.13: 13, 4.42; S ,22,>
