An Unconventional Intermolecular Three-Center NЦH Е H2Re Hydrogen Bond in Crystalline [ReH5(PPh3)3]╖indole╖C6H6.код для вставкиСкачать
COMMUNICATIONS An Unconventional Intermolecular Three-Center H,Re Hydrogen Bond in Crystalline N-H [ReH,( PPh,),] indole * c6H6 -- - Jeremy Wessel. Jesse C. Lee, Jr., E d u a r d o Peris, Glenn P. A . Yap, Jeffrey B. Fortin. John S. Ricci, Gjergji Sini. A l b e r t o Albinati,* T h o m a s F. Koetzle,* Odile Eisenstein,* Arnold L. Rheingold,* and Robert H . Crabtree* In the hope of' introducing ideas from molecular recognition into transition metal complexation and catalysis, we have been studying hydrogen bonding"] i n metal complexes. H-bonding is common between a weak acid A-H and one or two weak bases B, to give a 2-center ( I ) or three-center H-bond (2). In a number of recent caseb.[" for example 3.LZa1intramolecular H-bonds of would be adopted in the absence of geometrical constraints such as those present in the chelate system 3. We chose indole because it is a good H-bond proton donor but does not self-associate significantly because it has no good H-bond proton acceptor site. We now find that the polyhydride [ReHJPPh,),] cocrystallizes with indole to give jReH,(PPh,),] .C,H,NH.C,H, (4) as large yellow crystals. A n X-ray crystal structure clearly showed that the N-H hydrogen atom of indole is close to two of the rhenium hydrides, forming a three-center H-bond of type 2. A subsequent neutron diffraction study (Fig. 1 ) confirmed this result, and both studies located the hydrogens in positions similar to those found"] for free [ReH,(PMePh,),] by neutron diffraction. C105 C104 an unconventional kind have been discovered in which the weak base component is a metal hydride. Structural and spectroscopic data12' suggest H - . . H distances of about 1.7-1.9A and Hbond strengths of 3-6 kcalmol-I. If the Ir-H bond in 3 is replaced b y l r - X ( X = F,CI, Br,or I),conventionalN-H"-X H-bonds arc formed, but surprisingly, these are weaker for X = CI. Br, and I, and only marginally stronger for X = F.131We wanted to find out if intermolecular H-bonding was possible with a suitable H-bond donor AH, and if so, what geometry ""Y Fig. 1 The ORTEP diagram of the neutron diffraction structure (20 K ) o f 4 with ellipsoids dra6n at 50% probability. The metric parameters of the N-H . . . H , R e unit are given in Figure 2. Selected distances [A] and angles [ 1. Re P1. 2.396(3); Re-P2.2.387(4); Re-P3.7.376(3).Pl-Re-P2. IlO.0(1): P?-Re-P3. 105.6(1): PI-ReP3. 133.9(1): Re H1. 1.683(6); ReeH2. 1.683(5): Re - H i . 1.686(5); Re-H4. 1.683(6): Re-H5. 1.681(6); Hl-Re-H2. 79.33). ~ [*I Prof, Dr. R H . Crahtree, J. Wessel. Dr. J. Lee, Jr.. Dr. E. Peris Y'ile C'henii\tr! Department 211 Prospect Street. New Haven. CT 06511 (USA) Telslax. Inr code + (203)432-6144 c'-niail: cr,ihtrcerir minerca.cis.yale.edu Prof. L)r. A . 1.Rheingold. Dr. G. P . A . yap Uni\crsit\. of Delaware Chemistry Department Newrark. Llb 1Y716 (USA) Tclefiih- 1111 code + (302)-831-6335 e.iii:iil : iirni hcinitr strauss.udel.edu P r d Dr. A Alhinati In\titute ol' Pharmaceutical Chemistry L ' n i c c r ~ i t i . of Milan. 1-20131. Milan (Italy) Dr. T. I- K o e r ~ l e Bi-ookhavcii National Laboratory Upton. hY. 11973 (USA) 1clet"i.x l i l t . code + (516)282-5815 c-moil koctzle;(ichin.chm.bnl.gov Prof. I)r 0 Eiaenstein 1 ~ x h o r ; i t ~ ~de i i eChimie Theorique. (URA 506) B i t 490 Uni\,ersitG de Paris-Sud. 91405 Orsay (France) T e l c h x : l n i . code + (1)60-19-33-0? e-mail odile.cisenatein~~i cth.u-psud.fr 1 H. Fortin. I'rof. Dr. J S. Ricci I3NL. Upton. and liniversity of Southern Maine. Portland. M E (USA) r1r.G Sin itc de Cergj-Pontoise (France) [**I T h i s w o r k wiis supported by the NSF. the CNRS (URA 506) and Fellowships irom the NSF and W, R. Grace & Co. to J. W. The neutron study was carried o u t a t the I-tieh Flux Beam Reactor at Brookhaven National Laboratory under contrlict I)E-.AC02-76CH00016 with the US Department of Energy. Office of B:isic Encrx! Sciencec. Division of Chemical Sciences. A similar compound [ReH,(Cyttp)] (Cyttp = [Cy,P(CH,),],PPh) can be protonated with HSbF;C,H, to give [ReH,(Cyttp)]SbF, .['I In our case, [ReH,(PPh,),] cocrystallizes with a much weaker acid, indole. to give crystals in which the L,H,ReH,. . H-NC,H, interaction is strong enough to hold the two components together in the crystal without complete proton transfer. A molecule of benzene was also found. but apart from the ReH, . . H -N interaction. there are no other close contacts in the structure. The unusually precise neutron diffraction study161shows that the two short H " . H distances in 4 are vety asymmetric ( H l A . . . H I , 2.212(9) A; H l A . . . H 2 , 1.734(8) A ) , the shorter being similar to the distances foundr2](1.7-1.9A) in the intramolecular N - H ' ' . H--M examples. Nonbonding H ' . . H contacts are normally about twice the van der Waals radius"' of H, or 2.4A; all other N H . . . H R e distances found here are greater than 2.6A. The finding that the N H proton lies at a distance of only 0.066(7) A from the plane defined by N1, H I , and H2 fulfills the usual criteria[lc1for three-center H-bonding (2). The N - H bond points towards the closer metal hydride. H2 (N-H-H2 = 163.1(6), N-H-HI =130.9(5).), which implies that the dominant interaction is with Re-H2 (Fig. 2). H2 is unique in that it is the only hydrogen in the structure occupying a B-site COMMUNICATIONS I683(5)A ,, a\.. 1.734(8)A I18.9(4)..\.-__ I63 l(6) I' %SI" ,/' \~ I .683(6)A"\P7.2(3), 1309(5) /' **' *'* 12(9)A 0,Fig. 2 . The detailed structure of the N H . . . H,Re unit from the neutron diffraction results. on a very flat potential surface, of the relative positions of the two molecules gives a structure similar to that of4. In particular, a three-center H-bond is preferred over the two- or four-center types, and the asymmetry of the experimental structure is reproduced ( H . . . H distances: 1.92w (H2) and 2.48 A (Hl)). The interaction energy of 8 kcal mol- ' is in reasonable agreement with experiment (4.3 kcal mol- '). In the theoretical study, the N - H is slightly closer to P1 than is found in 4 ; steric effects may be responsible. As is well known." the lone pair in a d Zdodecahedral complex is perpendicular to both trapezoidal planes. Although in this complex it is not far from H2, it does not point towards the N H bond and so is unlikely to contribute much to the stabilization of the hydrogen bond. This emphasizes the electron donor power of the M H bond, which is also apparent in the ready formation of H, complexes by protonation of metal hydrides (even in competition with protonation at the metal),[*] in the ability of M-H in such complexes as [Cp2Zr(H),(CO)]["1 to engage in back donation, and in the M - H/H, "cis effect".[I3' Our studies show that the presence of indole as crystallizing agent for [ReH,(PPh,),] allows rapid formation of much larger (ca. 5 mm3) crystals than in its absence, but that the structure of the complex is not significantly altered by H-bonding. Indole may be a useful agent whenever a compound that is a potential H-bond acceptor fails to crystallize satisfactorily for crystallographic or other single-crystal studies; it complements the Ph,PO agent suggested by Etter114]for compounds having Hbond donor groups. of a dodecahedron (Fig. 3), and so is sterically the least hindered. In order to eliminate the possibility that nonspecific crystal packing forces are responsible for the structure, we attempted to grow crystals using indene, which is isosteric with indole but lacking the N H bond. If the N - H . . H interaction were not important for holding the supramolecule together, indene ought to cocrystallize just as well as indole. However, only small crystals could be grown under conditions identical to those used for 4 but substituting indene for indole. and these F , ~ 3. . The dodecahedra] coordinaExperimental Procedure tion geometry in the same molecular contain only [ReH,(PPh,),] orientation as Figure 1 showing A and no indene (from N M R and The general synthetic and spectroscopic methods were previously described [2a]. and B sites and the two orthogonal IR evidence). This suggests that Pentahydrido(tristriphenylphosphane)Re".indole: A 0.8 mL aliquot of a filtered BAAB trapezoids (dotted). solution of the complex 1151 [ReH,(PPh,),] (1.1 g, 1.1 mmol) in benzene (10mL) the N - H . . H interaction is inwas added to a test tube containing indole (50 mg. 0.4 nimol). Hexanes were added deed important in holding the to form a supernatant layer. and the sample tube refrigerated at 5 "C. After 1 day, assembly together and that the very short H . . H distance is a large yellow crystals formed (18 mg. 21 "A). result of the H-bonding. Weak aromatic stacking interactions between PPh, and indole may well also contribute to the stabiReceived: January 18, 1995 Revised version: August 1. 1995 [Z76391E] lization of the supramolecular assembly, however. German version: A n g w . Clwn. 1995. 107. 271 1-271 3 The IR spectrum (KBr pellet) shows a shift in the N-H band from 3437 cm-' in free indole to 3242 cm-' in crystals of 4. Keywords: hydrogen bonding . hydrides . indoles . rhenium According to the Iogansen equation,['] which relates the bond compounds strength to the shift in I R frequency, the H-bond strength in this case is 4.3 kcalmol-', close to the values (3-6 kcalmol-') determined for intramolecular M - H . . . H - N interactions.l2I [ l ] a) G. A. Jeffrey, W. Saenger. Hwlrogrn Bonding in B i O / O g f C o / Structure3, Figure 2 shows the structural details of the ReH, . . H N Springer, Berlin, 1991. b) ref.[la], p. 110: c) ref.[la]. p. 22. [2) a) J. C. Lee. E. Peris, A L. Rheingold. R. H. Crabtree. J. A m . Chrm. SOC, interaction. The N-H ' . H angles are comparable to those 1994. 116. 11014. G. P.A. Yap, A. L. Rheingold. P. Das, R. H. Crabtree, seen"] in standard three-center H-bonds, but the Re-H . . . H N Ifiorg. Clwm. 1995,34, 3474: b) S. Park, R. Ramachandran. A. J. Lough, R. H. angles (97.2(3) and 118.9(4)") are strongly bent. A nonlinear Morris, J. Chrm So[. C h m . Conimim. 1994. 2201. c) A much weaker interacM-H . . H N arrangement was already apparent[,"] in 3 tion of the same type is also known: R. C. Stevens. R. Bau. D. Milstein. 0. Blum, T. F. Koetzle, J. Chwn Soc. Dulron Trans. 1990, 1429. (Ir-H . . H = 132") and related species[2b1but could have been a [3) E. Peris, J. C. Lee, J. Rambo, 0. Eisenstein, R. H. Crabtree, J. Am. Clzem. SOC. result of she constraints of chelation. Now we see that in an 1995. 117. 3485. unconstrained system like 4, a strongly nonlinear ReH . . . H N  a) T. J. Emge. T. E Koetzle. J. W. Bruno. K . G . Caulton. fnorg. Chum. 1984. 23, arrangement is still preferred. This may be because an elec4012; b) T. F. Koetzle. K G. Caulton. hid.1984, 23, 4012. [S] Y. Kim. H . Deng. D. W. Meek. A. wojcicki, J. Am. Clirm So<.1990, 112.2798. trophile tends to attack a (T bond in a side-on manner.181In this 16) a) Neutron diffraction structure of 4 ( M , = 1173.3), triclinic, space group Pi; view, 4 can be considered to represent the earliest stages of T = 2 0 K ; a=13.037(3), h=13.410(4), t.=19.221(5)A. a=91.67(2). protonation of the Re-H2 hydride to give an H, complex, /j =107.79(2). j. =119.02(2), V = 2733(1)A3, Z = 2 . Q.~,,,, = 1 . 4 2 5 g ~ m - ~ . which would be bound side-on. This picture suggests other types mm3; 2H,,, 91"; p =1.952cm-'; crystal dimensions 3 . 4 1.9x0.72 ~ in,,,,,,, = 1.0462 A; scan mode w:20, 12394 independent reflections observed, of CT bonds should show H-bonding behavior; indeed, we have all of which were used for refinement: conventional R ( F ) ,[ R >3o(F)] = 0.052. now found similar intramolecular B-H . . . H-N interactions, Measurements carried out at the Brookhaven High Flux Beam Reactor. The with bent B-H . . . H-N angles, in a number of amine- b ~ r a n e s . ' ~ ] crystal was sealed in an Al can under He. mounted in a DISPLEX refrigerator. Theoretical work confirms that the interaction is attractive. and placed on the diffractometer. A hemisphere of reciprocal space was Sampled. to a limit of sin O I L = 0.67 k'. The 4 2 0 step-scan profiles were reduced The model compound [ReH,(PH,),].NH, was studied by ECP to inkgrated intensities. assuming the first and last tenth of each scan to be ab initio calculations with functional density theory."'] Free background. Lorentz factors and absorption corrections (range e-U' = 0.702ReH,L, was first optimized and found to be in close agreement 0365). calculated by means of an analytical procedure [6b], were applied. The with the neutron structure.[41It was then frozen, and NH, was crystal was approximated by seven boundary planes, as follows: (010). (001). ( i l l ) . ( i l i ) , ( l i ? ) , (1iO). Initial coordinates for all atoms were taken from the placed in the vicinity of H I and H2. Geometrical optimization, 2508 'f: VCH W~rlagsgasel/schufirnhH, D-694Sl Wrinheim, 1995 OS70-OX331YSi3422-2SOX $ 10.00+ ,25111 Angew. Clzeni. Int. Ed. Engl. 1995, 34, No. 22 X-ray resiilts. Refinernenis were carried out by a least-squares procedur-e [bc]. miniiiii~ing1 1 1 (F:- L'b-:)2 using all independent data. Weights were assigned ii\ 11 = 0 I. uhere 0' = (OF,+ (0.015)fi:)2). The structure model included ad~u.;tahlepositional kind anisotropic thermal parameters for all 136 iitorns. a \tale l"ictor k . and ii parameter for an isotropic-type I extinction correction u i t h Lorenman mosaic spread [6c]. The maximum extinction correction was lo"<). for I l k (T23) reflection. Neutron scattering lengths were taken irom a recznl coiiipilAion by Sears [6b]' h, = 0.66484. b,, = - 0.3741, h, = 0.936. /I,, = 0.511. hKL= 0.920 (all x l o - " crn). Further details of the crystal strucion are available on request from the Director of the Cambridge Iiic Data Centre. 12 Union Road. GB-Cambridge CB2 IEZ ling the full journal citation. b) J. DeMeulenaei-, H. To ~ ' i ) . s r d / o g r1965. . /Y. 1014: L. K. Templeton, D. H . Templeton. Am. y r . ~ W K I. l ~ y, Storrs. C'T Abstract E10. 1973: c) J . 4 . Lundgren. , y r u p l i i ~( ' o i i i / ) i t i e w Pm,qrfii~i.s in Report UUIC-Bl3-4-05, Institure of Chemistry. Iliiivcrsit). ot'IJppsa1,i. Sweden, 1982. d) P. Becker. P. Coppens. Ae,ru Cr)wdbirr S i w .A 1974. 30. 129. i h i d 1975. 3 I . 417: e) V. F. Sears in Iriteriie~tioniil X r I ) / c , \ / o r ( ' r ~~ / u / / r > g r o p / i Vr ,d . C' (Ed.: A. J. C . Wilson). Kluwer. .4c;ideniic Puhlishei-h. Dordreclit. 1993. S. (i K ; ~ ~ ~ i r i ; iPi i ,A . Hamley. M. Poliakoft J. A i r i . C/wir. SIK 1993. 1 1 5 ~ 4 069 R H . ('rahlree. Aiigcw (1/1wr7. 1993. 105. 828: Aiigeii. Ciwni. / t i / . Ed. Eiijii. 1993. 32. 7 X c l T Richard.;(in. S. deG;ila. P. E M . Siegbahn. R. H. Crabtree. J. A m C/irn? .So, . ~ u h i n i t ~ c d i i ) C~aiissiaii92 DFT. Revision F.4: M. J. Frisch, G. W. Trucks. H. B. Schlegel, P. M. W. G i l l , B G. Johnson. M . W. Wong. J. 8 . Foresman. M . A. Robb. M. Replogle, R Gomperts. J. L Andres. K. Raghovxhari. inzale,. R. L Martin. D. J. Fox. D. J Deft-ees. J. Baker. Poplc. Gaussian Inc.. Pittsburgh. PA, 1992 For further tion see ret'[lOb] b) For Re. a relativistic ECP [IOc] wa. shell of Re includes the 5s. 51, w t h a basis set of triple CP of Stevens and Biisch [IOd] was chosen with 'I doubl riz:ition. Indole was represented by a planar N H ,. The h y r l i ideb iiic ieprescnted by a triple basi, set with poliiriration and the H of PH h! \iiiglc ;basis set. For tlic functional density. we used the hqbrid luiic'tioii\ o l Bccke (B3LYP) [loel. c ) D. Andrae. U. Hausserrnann. M. Dolg. H Sroll. ti l%xiss.?liiwr. C ' h h Acrrr 1990. 77. 123: d) W. J. Stevens. H. Bash. M. Kraus\. ,/ C/wiri. Pii~..\. 1984. I?. 6016. e) A. D. Becks. J. (1Ii~w.P/I).S.1993. YS. i64X: P I Ste\cns. F. .I. Deblin. C. F. Chablowski. M. J. Frish. ;bid 1994, < YH. I I h l i . J. K Hurderl. K . Hollmmn. R. C . Fay. /rrorg CIiiw71 1978. 17. 2553. J M Manriclue/, D. R. McAlistei-. R. D. Sanner. J. E. Bercaw. J A I I I .C ~ P I I I . 1978. 100. 2716: flljd. 1976. 98. 6733. .SIR L S Van Slugs. I . Eckert. 0 . Eisenstein. J. H. HAl. J. C. Huffmiin. S. A. Koctrle. Ci. J Kubas. P. J. Verganini, K. G. Caulton, J A m <'/wnr. Sor 1990. 112. 4831. M . ( l-.ttt.i. . 4 < < .( ' / i < ~ . Rcs. 1990. 33. 120. _I ('h;itl. R 5. ('oft'eg. .I ('II~wI. So<..4 1969, 1963 cici 'r t.'. Jxk\~~ii. chalcogenide chemistry have yielded several new "polymeric" materials: [Mo,Se,Js-. [Mo,Se,,]' -. [Mo, ,Se,,]" -, [MO,S,,]~-, and [ M O , S ~ , , ] ~ - . ~I n~ this - ~ I paper we report the formation of a novel puckered Set, ring. stabilized by [Mo,S,,]' - clusters through interchalcogen interactions. This new form of selenium fits into the Q, sequence [Q = chalcogen) of homoatomic sulfur ring structures, S,, Slo. S,,, . . . Szo.r5] Large ring systems of polyselenides and polytellurides have been examined as parts of metal complexes.[6. For example, it has been known that selenium and tellurium ions can form complex rings since the isolation of an S e i + ring in [Se,][AICI,], .[*I Kanatzidis has found isolated Sef; rings in (Ph,P),[Se, l ] . These rings comprise two Set- ions and one Se2+ ion and link to form a cluster of corner-sharing "cyclohexanelike" rings of selenium.[91Very recently, Sheldrick reported that the structure of Cs,Tez, contains a two-dimensional 4, network of tellurium Tei- ions as well as discrete Te, rings."' The synthesis of the above-mentioned polychalcogenides has been achieved through moderate temperature reactions of the elements with oxidizing agentsc8]-in the case of polyselenide ions with a mild oxidant["I---or through methanothermal reactions with the elements.'"] We have had some success in preparing large polysulfide clusters by hydrothermal reactions.[4. 'I and we used this synthetic route to prepare the title compound 1. ' The hydrothermal reaction of (NH,),MoS, with A$, (A = Na, K: .Y = 2-6) generally resulted in the formation of a new phase of (NH,),[Mo,S Replacing the polysulfide salt with A,Se, (A = Na, K ; s = 2-4) yielded primarily selenium metal, molybdenum metal. and some soluble polychalcogenides. By preparing a new heteropolychalcogenide salt, Na,S,Se, ,[''I whose redox potential lies between the polysulfide and poly~elenide,"~. 14] we were able to tune the chemistry of the redox reaction and isolate compound 1. The solid-state structure of 1 is shown in Figures 1 and -. 7 'I Double layers (AB packing) of trinuclear molybdenum Richard A. Stevens, Casey C. Raymond, and Peter K. Dorhout* Since their discovery!'] the [MO,S,,]~- core clusters have spurred researchers on to further study. Electron-poor, trinuclear molybdeniim chalcogenides. sulfides in particular. have aroused considerable interest because of their hydrodesulfurization activity.I2I New ventures into trinuclear molybdenum poly[*I Prof Dr. 1'. K . L h r h o u t , R . A. Stevens. C. C . Raymond L)ep.irlmeiit 01' ('hemistry. Colorado State University I-ort Collins. c'o 80523 (USA) Telet'ix: Int. cude + (303)401-1801 c-iniiil. PKDro LAMAR. COLOSTATE EDU [**I Fin:inci;il hupport w a s provided by the American Chemical Society. Petroleum Rehcarcli F(itiiidstion. and the Research Corporation, Cottrell Fellowship. Addilional help provided by C. M Zclenski (EDS). S . M. Miller (X-ray diff raction). . and Di-. H. Murray. Exxon Kescarch. for providing some molyhden u n \tarting iiiLitcriiils. ' Fig. 1 Crystal structure of I viewed along the c axis . Only halfthe cell is shown forclarity. 6 : N iitoms. 0: Moatoms. 0 : S a t o m s . 0: Seatom\ These-Sebonds within the Se,, ring are nearly all identical: 2.335(2) and 2.327t2) A. The internal Se-Se-Sc ring angles are consistent with those found for Se, and re8 [?I. alternating between 105.14(4) and 102.94(7)'. Instead of [Mo,S,, .,Se, ,] the simplified structure of [Mo,S,,] is shown.