Sergey A. Ibragimov

Non-trivial behavior of palladium(II) acetate

Reaction of activated palladium metal with a HNO3/acetic acid mixture produces both orange Pd3(OAc)6, 1, and purple Pd3(OAc)5(NO2), 2. Compound has a trinuclear structure derived from that of the well-known triangular complex 1 in which one acetate group has been replaced by a nitrite group which is bonded to one palladium atom by the nitrogen atom and to another Pd atom using one of the oxygen atoms. Highly pure 1 can be made by continuous removal of the nitric oxides from the reaction mixture using a flow of N2. 1H NMR spectra of solutions of 1 in CDCl3 and C6D6 show several signals of various intensities when a small amount of water is present in the deuterated solvents but only one signal when the solvents are thoroughly dried. These results are consistent with the occurrence of one or more hydrolysis processes when the solvents contain water and suggest that hypotheses about various [Pd(OAc)2]n aggregates that have previously been brought forward in the literature to explain the complexity of the spectrum of 1 are unnecessary, especially for nonpolar solvents. Compound 2 does not hydrolyze, and in wet or dried solvents shows a 1H NMR spectrum that consists of five equal-intensity signals due to the five nonequivalent acetate groups.

A molecular loop with interstitial channels in a chiral environment: exploration of the chemistry of Mo24+ species with chiral and non-chiral dicarboxylate anions

An enantiomericaly pure chiral loop containing two cis-Mo2(DAniF)22+ (DAniF = di-p-anisylformamidinate) units was obtained by reaction of cis-[Mo2(DAniF)2(NCMe)4](BF4)2 with a chiral dicarboxylate which is easily prepared from hydroquinone and ethyl (S)-lactate. The compound crystallizes in the non-centrosymmetric I222 space group with molecules stacking so as to form channels capable of hosting guest molecules such as CH2Cl2. These properties of the compound, which has been synthesized in high yield, makes it promising for applications in stereoselective catalysis. Similar reactions with isomeric dicarboxylate linkers, as well as with some non-chiral ligands, were studied. The nature of the products depends on the bite angle of the ligand.