Tin(IV) alkoxides react with pentane-2,4-dione (acetylacetone) and other β-diketones to yield Sn(OR)3(chel) or Sn(OR)2(chel)2 derivatives. Sn(Opri)3(acac) has been shown to be dimeric in the solid state by a single-crystal X-ray diffraction study, the tin atoms being linked by two alkoxide bridges. In solution l19sn n.m.r. spectral data show that this single complex rapidly converts into a mixture of tin-containing species followed by slow disproportionation to the bis derivative Sn(OPri)2(acac)2 and Sn(Opri)4. The bis complexes Sn(OR)2(acac)2 appear to exist predominantly in solution with cis arrangements of alkoxide groups even when OBut or 2,2,6,6-tetramethylheptane-3,5-dione (dipivaloylmethane) are present.

The constitutions of the cyclopolyarsines (AsR)n (R = methyl, ethyl, n-propyl, and phenyl) have been investigated by nuclear magnetic resonance and mass spectrometric techniques. A systematic study of their fragmentation under electron impact at different ionization potentials has confirmed the presence of pentameric alkyl and hexameric phenyl cyclic arsines. Variable temperature N.M.R. spectra obtained for pentamethylcyclopentaarsine have been interpreted in terms of a rapid pseudorotation process. Some mixed methylphenyl cyclic arsines have been identified.

Size and Hydration of Inorganic Ions 1567 to resist removal as carbonyl by a carbon monoxide stream at 80°, while the rest of the nickel is easily so removed.10 It also has been shown that it is the larger particles of nickel which may be selectively removed in this way.11 It appears, then, that the larger over-all nickel concentrations give, on the whole, larger particles, and that these particles more readily form partial or true solid solutions with copper. The nickel in those samples with low over-all nickel concentrations is, on the other hand, less likely to form solid solutions with copper because of the diminished accessibility to copper in the preparative stage.These conclusions are supported by the results on samples (4) and ( 5). The preparation method for these samples would suggest that mechanical mixtures would be the only result. This is obviously the case. It may, in fact, be stated that no appreciable amount of the nickel is diluted with copper in these two samples.Sample (6) was studied for the express purpose of determining whether the procedure used by Best (10) G.

The constitution of a number of 2-(iminomethyl)benzenethiols and 2- (iminomethyl)-4-nitrobenzene-thiols has been studied by 1H N.M.R. spectroscopy. A zwitterionic imminium structure is suggested for all the compounds studied except for the 4'-methoxyphenylimine derivative which exists in the thiol form.

New salicylaldimine chelates of divalent and trivalent ruthenium have been synthesized from RuCl2(PPh3)3. The RuII complex trans- Ru(salen)(PPh3)2 is stable in the solid but very unstable to oxidation in solution. The RuIII derivative, Ru(salen)Cl(PPh3), displays magnetic and e.s.r. properties consistent with a low-spin d5 system under a ligand-field of rhombic symmetry.