May, 1949
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1899
Tests for halogen in these washed solutions have been negative. The solutions then have been dried, and the solvent ether removed by evaporation a t low temperatures on a vacuum line. Some volatile manganese generally distills with the ether and may be collected in a trap a t -80'. Less volatile ether-soluble manganese compounds remain in the residue. The compounds also are soluble in n-pentane. Manganese is extracted from a n ether solution of manganese carbonyl by aqueous alkali. Acidification of the resulting solution in a stream of carbon monoxide releases a volatile manganese compound which can be collected in a subsequent trap a t -80'. This may be the Mn(C0)4Ha which has been predicted.2 HARVARD CHEMICAL LABORATORY J. F. AMBROSE 12 OXFORD STREET G. B. KISTIAKOWSKY The addition of mercuric chloride t o an ethereal A. G. KRIDL solution of manganese carbonyl results in a slow CAMBRIDGE 38, MASS. evolution of gas and a precipitate containing manRECEIVED APRIL21, 1949 ganese and mercury. Heating the dried precipitate liberates free mercury, leaving a residue containing manganese. This behavior is consistent MANGANESE CARBONYL for a mercuric salt of manganese carbonyl hydride. Sir : The peaks observed for manganese carbonyl in The synthesis of volatile manganese com- the mass spectrometer are strong, occur a t regupounds, believed to be carbonyls of manganese, lar intervals following a pattern similar t o that of has been accomplished by reducing manganese other metal carbonyls, and do not correspond to iodide with Grignard reagent under pressure of any of the predictable impurities The observacarbon monoxide. The general reaction tech- tion of the fragments ~ ~ I ~ ( C OMnz(C0)6+ )~+, and nique has been that described for the preparation Mn2(CO)1+, formed in the spectrometer by elecof chromium carbonyl by Owen, English, Cassidy tron bombardment, indicates the existence of a and Dundon.' dimeric manganese carbonyl but does not define Identification of the volatile manganese com- the formula since i t is not uncommon for the pounds as carbonyls has been made by the obser- parent peak to be absent in a mass spectrometric vation that they behave chemically as would be analysis. Peaks corresponding to Mn+, MnC+, predicted from a consideration of their relation to MnCO+, MnC(C0) +, Mn(CO)zf, MnC(C0)2+, the carbonyls of iron and cobalt, and by mass Mn(C0)3+, and MnC(CO)$+ also have been obspectrometric analyses which show characteris- served. The appearance of the intermediate tic peaks predicted for manganese carbonyl. fragments containing C atoms is typical of the Qualitative tests for manganese in distillation mass spectra of all metal carbonyls investigated fractions, etc., have been made by decomposing so far and will be reported later. the samples with nitric acid and developing the Transparent crystals (containing manganese) permanganate color with the highly specific per- have been isolated by subliming solvent-free masulfate test. terial in a stream of carbon monoxide. The quanThe ethereal solutions from the synthesis reac- tity of material has been small and no pure comtions have been subjected to repeated washings pounds have been identified as yet. with dilute hydrochloric acid and distilled water GENERAL ELECTRIC DALLAST. HURD to remove manganese halide, and unreacted man- RESEARCH W. SENTELL, JR. LAB. GEORGE ganese iodide, and to destroy any organomanga- SCHESECTADY, h7.Y . FRANCIS J. NORTON nese compounds possibly formed in the reaction. RECEIVED APRIL22, 1949
of this reaction is 11,000cal./mole of active centers of the enzyme and is independent of the PH. This value differs considerably from that estimated by Kistiakowsky and Lumry, and is more accurate because of a more direct method of determination and a greatly improved reproducibility of measurements. The inhibition by sulfite, similarly to the inhibition by phosphate ions described by Niemann and Harmon, has been found to be competitive with urea. We also find that certain organic sulfur compounds, such as sodium benzene sulfinate, inhibit the enzyme in the same manner as sulfite ions, and our experiments in this direction are continuing.
(1)
B. B. Owen, et al., THISJOURNAL, 89, 1723 (1947).
(2) Blanchard, Chem. Rev., l l , 35 (1937).
