Treatment of bis(phosphine)platinum(II) carbonate complexes (LL)Pt(COs) (e.g., LL = 1,3-bis(diphenylphosphino)propane) with vicinal diols (Le., HOCR1R2CR3R40H) gives equilibrium conversion to the corresponding diolate complexes (LL)Pt(OCR'RZCR3RQ), which are readily isolated in good yield. From competition experiments, relative diol complexation constants were determined as a function of both the diol and the phosphine substituents and found to span a range of over 104. Corresponding triolate and alditolate complexes were similarly prepared, for which very distinct equilibrium isomeric regioselectivities are observed, favoring complexation of y,b-threo diols. An X-ray structure of (dppp)Pt(D-mannitolate) shows that the mannitol is bonded to the platinum as its dianion via the oxygens on C3 and C4 to form a 2,5-dioxaplatinacyclopentane chelate ring and that three different strong intramolecular hydrogen-bonding interactions are present between the hydroxyl hydrogens and the metallacycle oxygens (O*-O (av) = 2.65(2) A), forming five-, six-, and seven-membered rings. Crystal data for P~P z O & H~& H~C~Z : P212121,Z = -4, T = 20 OC, a = 11.225(2) A, b = 15.875(3) A, c =
Ru4H4(CO)i2 and Os3H2(CO)iq are obtained in high yield and purity by reaction of H2 at atmospheric pressure at 120°in hydrocarbon solutions of Ru3(CO)i2 and Os3(CO)u, respectively. Further treatment of Os3Fl2(CO)io with H2 leads to Os4H4(CO)i2. Ru4D4(CO)i2 is obtained from Ru3(CO)i2 and D2 in hydrocarbon solvent; however, extensive hydrogen exchange with solvent is observed in the osmium system. Ru4H2D2(CO)i2 is obtained in the reaction of D2 with Ru4H2(CO)i3 and the new mixed metal complex FeRu3H4(CO)i2 is obtained from FeRu3H2(CO)i3 and H2. Substances are characterized by ir, NMR, Raman, and mass spectrometry.We report here our studies of the treatment of metal carbonyls with H2 (or D2) at atmospheric pressure and elevated temperature giving a convenient synthesis2 of a number of hydrido (or deuterio) carbonyl metal clusters. We were led to this reaction through earlier observations in the chemistry of Re4H4(CO)i2.3 This complex is readily transformed into higher carbonyls in contact with CO at atmospheric pressure as indicated in reaction sequence (1); at Re4H4(CO)P + SCO -Re3H3(CO)12 + ReH(CO)r, |h2 + |Re2(CO)10 slightly elevated temperatures, H2 evolution was observed. This suggested to us that the reverse of this transformation might be possible and indeed when H2 at atmospheric pressure is bubbled through a hydrocarbon solution of Re2(CO)io at 150°, the lower carbonyl cluster compounds are obtained, first Re3H3(CO)i2 subsequently replaced by Re4H4(CO)i2.2 We subjected a number of other carbonyls to this treatment and found several hydrido-metal carbonyl cluster complexes of ruthenium, osmium, and a mixed ironruthenium cluster can be obtained through this route.
RutheniumTreatment of Ru3(CO)j2 with H2 gives Ru4H4(CO)i2 conveniently in high yield and purity. Excellent analytical data were obtained for our product which displays five maxima in the carbonyl stretching region of the ir (see Table I) consistent with that independently obtained by Piacenti and coworkers4 in an autoclave reaction of Ru3(CO)i2 with H2 at 110°and 150 atm, but in contrast to earlier reports5 of two isomers a and ß of the same formulation each with different and more complex carbonyl ir absorptions. Both we and the Italian group have shown that the spectrum reported for the "a isomer" is derived from a mixture of Ru4H4(CO)i2 and Ru3(CO)]2 which can easily be separated by column chromatography. Indeed single crystals suitable for structure determination of Ru3(CO)i26 were obtained from a solution containing "a-Ru4H4(CO)i2". Regarding the "ß isomer", we have not been able to observe any evidence for its existence either in the direct reaction of Ru3(CO),2 with H2 or in attempts to repeat the earlier
We used single fibers from rabbit psoas muscle, chemically skinned with Triton X-100 nonionic detergent, to determine the salts best suited for adjusting ionic strength of bathing solutions for skinned fibers. As criteria we measured maximal calcium-activated force (Fmax), fiber swelling estimated optically, and protein extraction from single fibers determined by polyacrylamide gel electrophoresis with ultrasensitive silver staining. All things considered, the best uniunivalent salt was potassium methanesulfonate, while a number of uni-divalent potassium salts of phosphocreatine, hexamethylenediamine N,N,N',N'-tetraacetic acid, sulfate, and succinate were equally acceptable. Using these salts, we determined that changes in Fma x correlated best with variations of ionic strength (1/2 Z c~ z~, where c~ is the concentration of ion i, and z~ is its valence) rather than ionic equivalents (1/2 ~ c~lz ~ I). Our data indicate that increased ionic strength per se decreases Fma~, probably by destabilizing the cross-bridge structure in addition to increasing electrostatic shielding of actomyosin interactions.
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