Dehydration of multivalent ion-exchanged zeolites produced structural hydroxyl groups of varying thermal stability as evidenced by differences in the retention of their L-r. bands on heating in uacuo. The retention increased with the electron af6nity of the base-exchange cation. Although the i.-r. bands in the 3650 and 3545 cm-l regions appeared to have the same chemical identity as those formed by heating the NHZ-zeolite, these hydroxyl groups were less reactive with pyridine (Py). Temperatures of 85-150" were required to react a substantial fraction of them to PyH+, whereas with the decationated zeolites, both bands were removed by Py interaction at room temperature although the 3545 cm-' band could be restored to its original intensity by evacuation at 150".Py also co-ordinated with the base-exchange cations (became Lewis bonded). The strength of this interaction (retention of PyL at elevated temperatures) increased with the electron affinity of the cation and the frequency of the corresponding i.-r. band increased concomitantly from 1443 cm-' (Na+) to 1455 cm-l (Zn2+). Addition of H20, or H20+C02, effected conversion of PyL to PyH+, and again the extent of these reactions paralleled the electron affinity of the cation.

Three OH stretching bands, with maxima at about 3745,3650 and 3545 cm-1, are present in infrared spectra of decationated X-and Y-type zeolites. Pyridine reacted with the 3650 cm-1 species to form pyridinium ion, This band underwent a hydrogen-bonding shift when ethylene was adsorbed at room temperature, indicating a strong physical adsorption which was quantitatively and rapidly reversible on raising or lowering the pressure. NO exchange occurred between C2H4 and the OD groups of an exhaustively deuterated zeolite. The hydrogen-bonding shift from 3650 to 3300 cm-1 was identical when C2D4 was substituted for CzQ. The 3745 and 3545 cm-1 bands were not noticeably altered by the adsorption, at least in the pressure region where the 3650 cm-1 band was affected. Adsorption isotherms, calculated from the spectra, could be superimposed on those determined by volumetric techniques. Both were close to Langmuir-type but showed evidence of a superimposed non-selective adsorption at higher pressures. Ethylene may also adsorb, via a charge-transfer interaction, on the residual Na+ ions of the zeolite. At about 500 torr, the total adsorption of C2H4 was about 30 % greater than the available zeolite hydroxyl groups. It was inferred that the strongest interaction was with the acidic hydroxyl groups and that, at low pressures, most of the adsorbed C2H4 was hydrogen-bonded to these. In the CH bending and stretching regions, only the Q-branch of the spectra of the gaseous molecules appeared, indicating that molecular rotation was hindered in the adsorbed state. Qualitatively similar results were obtained with C3H6. The hydrogen-bonding shift was greater by about 100 cm-1, however, and the adsorption was not entirely reversible. Moreover, the irreversible portion increased with time, and products stemming from polymerized olefin could be recovered ; also, c3D6 exchanged with the OH groups of the 3650 and 3545 cm-1 bands, but not with those of the 3745cm-1 band. Preliminary results for these substrates adsorbed on dehydroxylated, decationated zeolites are given.

P(OCeH5)3] with iodine in dichloromethane was shown by infrared spectroscopy to afford a third product in addition to x-C5H6Fe(CO)2I and x-C6H6Fe(CO)LI; these three compounds were formed in approximately equal amounts. When this iodination was performed in benzene, however, the unknown product separated out while trace quantities of x-CsH5Fe(CO)2I and x-CóH5Fe(CO)LI remained in the benzene solution. The precipitate was shown to be ionic and characterization of the tetraphenylborate derivative showed it to be [x-C5H6Fe(CO)2L]B(CeH6)4. The neutral compounds x-C5H6Fe(CO)LI were identified by comparing their infrared spectra with the spectra of authentic samples previously synthesized from x-C6H6Fe(CO)2l.2SThe physical and spectroscopic data for the ionic complexes are given in the tables. Conductivity data and spectroscopic evidence show, respectively, these derivatives to be 1:1 electrolytes in acetone and diamagnetic. The infrared spectra of these compounds in solution contain two peaks corresponding to C-0 stretching modes; the frequencies decrease with the increase of the over-all ( -) donor ability of the phos-(28) A. L. du Preez, M.S. Thesis, University of Pretoria.Inorganic Chemistry phorus donor ligand as expected. The single cyclopentadienyl proton resonance in the nmr spectra of these ionic compounds is split into a doublet due to phosphorus-hydrogen coupling. The coupling constant could only be measured for the compounds containing the ligands P(C2H3)3 and P(0-f-CsH7)3.The formation of both ionic and neutral compounds in the iodination of the monosubstituted derivatives demonstrates that this reaction occurs by at least two mechanistic pathways, one involving a symmetric cleavage and the other an asymmetric cleavage of the dinuclear parent. A similar scheme has been proposed for the halogenation of [x-C6HóFe(CO)2]2 on the basis of the isolation of [x-C6H6Fe(CO)3 ]X and x-CsHjFe-(CO)2X (X = halogen) from the reaction mixture.29Acknowledgments.-The authors express their gratitude to Dr. K. G. R. Pachler, National Chemical Research Laboratory, CSIR, Pretoria, South Africa, for the measurement of the nmr spectra. A. L. du P. thanks the South African Council for Scientific and Industrial Research and the University of Pretoria for financial support.

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Novel polynuclear iron carbonyl complexes have been isolated from the reactions between the iron carbonyls and the ligands DC=CD(CF2),CF2 ( D = As(CH3j2, n = 1, ffars; D = (C6HB)LP, n = 2, fefos). The complexes have been found to possess the stoichiometry f f a r~F e s ( C O )~~, ffar~Fe3(CO)~, .4~2(CH3)2CHtFe3(CO)g, and fsfosFel(C0)T and their structures have been investigated using various spectroscopic techniques. Some attempt has been made to assign lines in the complicated MOSSbauer spectra of ffarsFes(C0)Q and A s~( C H~)~C H~F~~( C O )~.

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The synthesis of an "unknown" Fe(II) complex originally reported in 1973 and formulated then as [Fe(DMSO)5Cl][SnCl4] was thoroughly reproduced and the compound reformulated as the novel [Fe(DMSO)6][SnCl6] double complex salt. Current elemental analysis and IR and Mössbauer spectroscopy matched the original 1973 data, and Raman spectroscopy and single crystal X-ray diffraction provided additional confirmation of our reformulation. [Fe(DMSO)6][SnCl6] (1) crystallizes in the trigonal space group R[Formula: see text] with octahedral [Fe(DMSO)6]2+ and [SnCl6]2– complex ions with an Fe—O bond length of 2.121(3) Å. The same synthesis was extended to Co(II) and Ni(II) to generate the novel [Co(DMSO)6][SnCl6] (2), which crystallizes in the triclinic space group P[Formula: see text] with a Co—O bond length of 2.093(4)–2.113(5) Å, and [Ni(DMSO)6][SnCl6] (3), which crystallized in the trigonal R[Formula: see text] space group and has a Ni—O bond length of 2.062(2) Å. The Sn—Cl bond length in all three complexes ranged from 2.421(2) to 2.448(2) Å.Key words: DMSO complexes of Fe(II), Co(II) and Ni(II), SnCl62– salts, IR, Raman and Mössbauer spectroscopy, X-ray crystal structures.