摘要:
1976 201On the Feasibility of forming Organic Intercalates from the Layered Solid(MoO3'OH2)92By John M. Adams and John R. Fowler, Edward Davies Chemical Laboratories, University College of Wales,Attempts to intercalate some small polar molecules between the (MoO,*OH,), layers of partially dehydratedMoO3*20H, are described, as are characteristic data for two new complexes of MOO, with methanol and formamide.Aberystwyth SY23 1 NEIKTEREST in the preparation and properties of newintercalates is, at present, considerable; and apart fromthe exploration of novel features of the chemistry of suchcomplexes derived from widely known layered hostsolids such as gra~hite,l-~ sheet silicates,4-6 and transi-tion-metal chalcogenides,' there is merit in utilizinghitherto unexamined types of layered hosts with a viewto uncovering new classes of extended (sandwiched)donor-acceptor complexes.One possible potentiallyinteresting host is the monohydrate of MOO,, formed, asdescribed below, by the partial dehydration of MOO,.20H,.The crystal structure of yellow iLIoO,-ZOH, has beenshown by Krebs8 to consist of infinite (MoO,*OH,),layers which are stacked normal to the crystallographic baxis. Five oxygens and one co-ordinated water moleculeform a strongly distorted octahedron around everymolybdenum. An interesting feature of this hydrate isthe occurrence of a second type of water molecule, not(a) (b)Comparison of the schematic structures involved in the topo-tactic dehydration of Mo0,.20Hz : filled circles, co-ordinatedH,O; empty circles, interlayer H,O.(a) (101) projection ofMo0,*20H2, the octahedra being [MoO,(OH,)] ; (b) (001)projection of MOO,-OH, (proposed), the octahedra being[hloO,(OH,)] (after Gunter 9,directly bonded to molybdenum: it occupies the inter-layer region and forms hydrogen bonds linking the twoneighbouring layers (see Figure). The dihydrate may bereadily converted into the monohydrate on moderateN. Ichikawa, T. Kondo, K. Kawase, M. Sudo, T. Onishi,A. Marchand in ' Chemistry and Physics of Carbon,'J. M. Thomas, Phil. Trans. Roy. SOC., 1974, A227, 251.A. Weiss in ' Organic Geochemistry,' eds. G. Eglington andD. T. B. Tennakoon, J. &I. Thomas, M. J. Tricker, and (inand K. Jamaxu, J.C.S. Chem. Comm., 1972, 176.ed.P. L. Walker, jun., Arnold, London, 1971, vol. 7.11. J. T. Murphy, Springer-Verlag, New York, 1969.part) J. 0. Williams, J.C.S. Dalton, 1974, 2207.heating and, as the loosely held water is lost, the layersare stabilized by the movement of every second layer bya/4 + c/4.*99 This partial dehydration is topotacti~.~The possibility therefore exists of forming stable inter-calates when suitable guest species are introduced to themonohydrate host, consisting of layers of (MoO,*OH,),.The polar species chosen for this brief exploratory studywere those known to form stable intercalates with thelayered silicates kaolinite and m~ntmorillonite,~~~~ lo therebeing, in each case, a loose kinship between the oxygenand ' hydroxyl ' moieties bonded to the six co-ordinatedmetal atoms (A1 or Mo) situated in the extended sheets ofkaolinite and (MoO,*OH,),.EXPERIMENTALYellow molybdenum oxide dihydrate was prepared by themethod of Carpeni l1 from molybdenum oxide obtained fromGeorge and Becker Ltd., although the crystallization timerequired was much longer than that indicated.The yellowform of molybdenum oxide monohydrate was preparedfrom the dihydrate by heating in air at 80 "C for severalhours. The X-ray diffraction pattern was in excellentagreement with the data of Gunter.9 Intercalation wasattempted using both the monohydrate and dihydrate asstarting materials. The simple procedure consisted ofshaking the hydrate with the compound in question for aperiod of time up to one week a t room temperature.Atthe end of that time the hydrate was filtered off, allowed todry in air, and an X-ray powder photograph was takenusing an SDC-700 Guinier-Hagg camera.RESULTS AND DISCUSSIONIn most cases (with tetrahydrofuran, tetrahydro-pyran, monochloracetic acid, ethanediamine and 1,4-dioxan) no obvious reaction occurred between theorganic compound and the MOO, hydrates. However,in four cases there was immediate and obvious reactionalthough in two of these the products did not give adiffraction pattern, probably because of small particlesize. Hydrazine hydrate gave a brown material whichcould well have contained molybdenum metal in view ofM. J. Tricker, D. T. B. Tennakoon, J. ICI. Thomas, andG. S. Parry, C. B. Scruby, and P.M. Williams, Phil. Mag.B. Krebs, Chem. Comm., 1970, 50.J. R. Gunter, J. Solid State Chem., 1972, 5, 354.S . H. Graham, Nature, 1975, 253, 110.1974, 29, 601.10 X-ray Identification and Crystal Structures of ClayMinerals ', ed. G. Brown, Mineralogical Society, London, 1961.l1 G. Carpeni, Ritll. SOC. chim. France, 1947, 484202 J.C.S. Daltonthe reducing properties of this compound, whereasabsolute ethanol with the dihydrate yielded a dark bluesolution which, on evaporation of excess ethanol, gavea blue-black pseudocrystalline product. Reaction withmethanol and formamide was, however, more fruitfulsince the products could be investigated by X-raydiffraction. Methanol with MoO,*OH, gave a colourchange from yellow to white in part of the hydratesample; the weak diffraction pattern was that ofMoO,*OH,.Methanol with Mo03-20H, gave a whitepowder which turned blue on filtration. Thisproduct possessed a diffraction pattern different fromthat of the dihydrate (Table 1) and analysis figuresof 6.75% C, 1.95% H suggest MoO,*(CH,OH) butit is to be noted that the hydrogen percentage is lowerthan expected by some 15%. Formamide with eitherof the hydrates gave a white powder, the diffractionpattern of which was distinct from both mono- and di-hydrate diffraction patterns (Table 1); it was alsoTABLE 1&Spacings (in A) for methanol and formamide productsMoO,CH,OH MoO3-2HCONH,7.86s 1 3 . 8 9 ~5.54m 1 1 . 0 4 ~5.48m 9 . 6 3 ~4.65m 8.79w4.19m 6.25s3 . 9 0 ~ 5.91s3.54m 3.54s3.44w 3.44s3.06m 3.21s2.901112 . 8 5 ~2 .7 8 ~2.66m2 . 6 2 ~2 . 6 0 ~2.29m2.21w1.98m1 . 7 8 ~1 . 7 5 ~different from the methanol-molybdenum dihydratepattern. Analysis results of 9.5% C, 2.45% H, 11.1% Ncorrespond to MOO,-( 0H2)0.08( HCONH,) Since thediffraction pattern had weak traces of lines due toMo0,-20H2 we may convert the above formula into(MOO,*~~H,)~.~*(M~O,)~.~~(HCONH,),.,,, i.e. we haveprepared a new product of approximate compositionMoo,*( HCONH,) 1.86 which is reasonably close toMoO3*2HCONH,.A compound of formula Mo0,=2CH30H has beenprepared by Krauss and Huber l2 by stirring powderedMoO2-20H, with absolute methanol at 60 "C. Methanolwas lost from this sample under vacuum at 20 "C. Thei.r.spectrum of this compound is compared with that ofMoO,*CH,OH in Table 2. It may be noted that theTABLE 21.r. spectra (in cm-l)Mo0,.2CH,0H6 Methanol MoO,*CH,OH3 239s 3 400s 3 300s2 922m 2 940m 2 960w2 817m 2 820m 2 920w1 449w 1 460m 1 460m1382w 1410m 1 380m1 115w 1090m 1 lOOw1 050m 998m 1030sFormamide Mo03*HCONH,3 320s 3 320s2 970w 2 960w2 880w 2 91ow1690s 1660s1600w 1570w1445w 1445w1385s 1360w1305s 1 325w1 085s 1.095s1 045s 1 040s935s920s875w 875s695w 695w650sabsorptions for methanol and formamide have beenshifted slightly in the compound from their value in theliquid due to the constraints imposed by the formationof the compound. In the case of the fonnamide com-pound new absorptions appear at 920, 935, and 650 nm.Further study is required before the structure of thetwo new compounds can be ascertained. It may beconcluded, however, that simple organic molecules whichare rather tenaciously retained between the sheets ofmontmorillonite do not form intercalates with (MOO,*OH,),.We thank the S.R.C. for the Advanced Course Student-ship (to J. R. F.) during the tenure of which this work wascarried out. The investigation was suggested by ProfessorJ. M. Thomas.[5/1297 Received, 1st JuZy, 19751l2 H. L. Krauss and W. Huber, Chein. B e y . , 1961, 94, 2864
ISSN:1477-9226
DOI:10.1039/DT9760000201
出版商:RSC
年代:1976
数据来源: RSC