1614
Inorg. Chem. 1992, 31, 1614-1620 Contribution from the School of Chemical Sciences, University of Illinois, 505 South Mathews Avenue, Urbana, Illinois 61801
Synthetic Studies on the CpRu-PPh3-(Se2) System: Redox Interconversions of R U ~ ( SCores ~~)~ Jayantha Amarasekera, Eric J. Houser, Thomas B. Rauchfuss,* and Charlotte L. Stern Received July 24, 1991 The reaction of NaSeH and CpRu(PPh3),C1 gave CpRu(PPh,),SeH, while the synthesis of (MeCp)Ru(PPh,),SeH required the use of NMe4SeH. The corresponding H2Se complexes could not be prepared, as CpRu(PPh,),OTf failed to add H,Se and protonation of (MeCp)Ru(PPh3),SeH gave ( M ~ C ~ ) R U ( P P ~ ' ) ~ HThe , + . reaction of CpRu(PPhJ2OTf with elemental selenium gave [CpRu(PPh,),] (fi-qI,ql-Se,)(OTf), (1). The compound 1.PhMe.CH2C12 crystallized in the monoclinic space group El, with a = 15.965 (3) b = 15.898 (5) A, c = 18.406 (4) A, a = y = 90°, 6 = 111.28 (2)O, V = 4353 (3) A3, and Z = 2. The structure was refined to R = 0.054 (R, = 0.061). The crystallographic studies provide evidence for Ru-Se multiple bonding but show that the Ru2Se2core is not planar, unlike the core of the analogous persulfido complex. Solutions of 1 reacted further with The analogous MeC complex (2) was characterized by X-ray selenium to give primarily [CpR~(PPh,)],{fi:ql,q~-Se~)~(OTf')~. b = 13.530 (5) A, c = 10.064 (4) A, a crystallography. It crystallizes in the triclinic space group PI,with a = 10.909 (5) = 110.13 (3)O, 6 = 112.18 (3)O, y = 79.62 (3)O, V = 1289 (2) A', and Z = 1. The structure was refined to R = 0.050 (R, = 0.058). Compound 2 was reduced by Cp2Co to give the unstable compound [(MeCp)R~(PPh~)],(fi-ql,q~-Se~)~, which could be reoxidized to give 2 and which in turn thermally eliminated SePPh, to give (MeCp),Ru4Se4.
k,
1,
Introduction Polychalcogenide ligands form complexes with all of the metals and metalloids, yet many aspects of their reaction chemistry remain unexplored. * Arguments have been advanced and evidence has been accumulated that polychalcogen ligands are involved in primordial chemistry,, the biosynthesis of metal lop rote in^,^ the conversion of metals to binary chalcogenides: hydrogen-transfer catalysis,' and energy-storage devices6 Persulfido ligands in binuclear complexes exhibit a complicated structural chemistry, as this ligand can bind via a number of bonding modes.' Studies by several laboratories have recently demonstrated the interconversion of various p-S, geometries (Scheme I).8-13 Persulfide is a "facultative" ligand, as its coordination mode changes in response to the electronic demands of its host metal. In this paper, we examine the structural chemistry of perselenides and demonstrate the facultative character of the Se2 ligand. This effort builds on our experience with organoruthenium sulfides?J4 Little previous work has appeared (1) Draganjac, M.; Rauchfuss, T. B. Angew. Chem., Inr. Ed. Engl. 1985, 24, 742. Mliller, A.; Diemann, E. Adv. Inorg. Chem. 1987, 31, 89. Ansari, M.; Ibers, J. A. Coord. Chem. Rev. 1990. 100. 223. Wachter. J. Angew. Chem., Int. Ed. Engl. 1989, 28, 1613. Wachterhiuser. G. Microbiol. Rev. 1988. 52. 452. Coucouvanis, D.; Swenson, D.; Stremple, P.; Baenziger, N. C. J . Am. Chem. SOC.1979, 101, 3392. Rauchfuss, T. B.; Ramli, E. R. J. Am. Chem. SOC.1990, 112, 4043. Rakowski, Dubois, M. Chem. Rev. 1989.89, 1. Jacobson, A. J. Solid State Ionics 1981, 5, 65. Alonso Vante, N.; Tributsch, H. Nature 1986, 323, 431. Mliller, A.; Jaegermann, W.; Enemark, J. H. Coord. Chem. Reo. 1982, 46, 245. Bolinger, M. E.; Rauchfuss, T. B.; Rheingold, A. L. J . Am. Chem. Soc. 1983, IOS, 6321. Ogilvy, A. E.; Rauchfuss, T. B. Organometallics 1988, 7, 1884. Brunner, H.; Janietz, N.; Wachter, J.; Nulser, B.; Ziegler, M. L. J . Organomet. Chem. 1988,.356, 85. Brunner, H.; Meier, W.; Wachter, J.; Guggoltz, E.; Zahn, T.; Ziegler, M. L. Organometallics 1982, 1, 1107. Brunner, H.; Men, A.; Pfauntsch, J.; Serhadli, 0.;Wachter, J.; Ziegler, M. L. Inorg. Chem. 1988, 27, 2055. Ogino, H.; Tobita, H.; Inomata, S.; Shimoi, M. J . Chem. SOC.,Chem. Commun. 1988, 586. Inomata, S.; Tobita, H.; Ogino, H. Inorg. Chem. 1991, 30, 3039. Weberg, R. T.; Haltiwanger, R. C.; Rakowski DuBois, M. New J . Chem. 1988, 12, 361. (a) Rauchfuss, T. B.; Rodgers, D. M. P.; Wilson, S. R. J . Am. Chem. SOC.1986, 108, 31 14. (b) Amarasekera, J.; Rauchfuss, T. B.; Rheingold, A. L. Inorg. Chem. 1987, 26, 2017. (c) Amarasekera, J.; Rauchfuss, T. B.; Wilson, S. R. Inorg. Chem. 1987, 26, 3328. (d) Amarasekera, J.; Rauchfuss, T. B.; Wilson, S. R.J . Chem. Soc., Chem. Commun. 1989, 14. (e) Amarasekera, J. Rauchfuss, T. B. Inorg. Chem. 1989, 28, 3875. (f) Howard, K. E.; Rauchfuss, T. B.; Wilson, S. R. Inorg. Chem. 1988,27, 1710. (g) Lockemeyer, J. R.; Rauchfuss, T. B.; Rheingold, A. L. J. Am. Chem. SOC.1989.11, 5733. (h) Houser, E. J.; Amarasekera, J.; Rauchfuss, T. B.; Wilson, S. R. J . Am. Chem. Soc. 1991, 113, 7440.
0020-1669/92/1331-1614$03.00/0
on ruthenium selenides,15and the only binary ruthenium selenide is RuSe2.I6 As with the better known persulfido group, Se, shows a remarkably wide variety of bonding modes. In mononuclear compounds, q2-Se2 coordination is observed wherein the diselenide ligand is coordinated to the metal atom in a side-on fashion. Examples of this coordination mode include [Ir(Se2)(dppe),]+,I7 O S ( S ~ , ) ( C O ) ~ ( P PCp*Mn(C0)2Se2 ~~)~,~~ (Cp* = C5Me5),19and [CpMo(CO),Se,]- (Cp = cyclopentadienyl).20 The solid-state structure of [(CO)sW(Se2)]22+consists of two 17e [(CO)5W(q2-Se2)]+subunits which are joined through a pair of long Se-Se bonds.21 The p-$,q2-Se2 coordination mode is seen in Cp*2Cr2(CO)5(p-Se2)22 and [(tripho~)Rh]~(p-Se,)~~+.~~ This geometry resembles that for an alkylated M(r12-Se2)moiety, e.g., [Ir(dpy~),Se,Me]~+.~~ The compounds Fe2(CO)6(p-Se2),25 [W2$Ma-Se)(p-Wl 2-?6 Nb4(MeCN)4Br,(p-Br)4(cc2-Se2)(~~~Se), and (Me2S)2C12Nb(p-Se2)2NbC12(SMe2)228 feature pq2,g2-Se2 coordination. This same geometry is proposed for C ~ * , M O , S ~Combinations ~.~~ of these bonding motifs are found in (MeCp)2V2(r-Se)(p-q1,91-Se2)(p-q2,q2-Se,)30 and [V2(p-q2Se2)2(~2-S~)2gl-l11,112-Se,)12-.3' truw-p-q1,q1-Se2 bonding modes (15) Draganjac, M.; Dhingra, S.; Huang, S.-P.; Kanatzidis, M. Inorg. Cham. 1990, 29, 590. (16) Stassen, W. N.; Heyding, R. D. Can. J . Chem. 1968, 46, 2159. (17) Ginsberg, A. P.; Lindsell, W. E.; Sprinkle, C. R.;West, K. W.; Cohen, R. L. Ittorn. Chem. 1982, 21, 3666. (18) Farrar, D.H.; Grundy, K. R.; Payne, N. C.; Roper, W. R.; Walker, A. J . Am. Chem. SOC.1979, YOI, 6577. (19) Herberhold, M.; Reiner, D.; Thewalt, U. Angew. Chem., Int. Ed. Engl. 1983. 22. 1000. (20) Ade1,'J.; Weller, F.; Dehnicke, K. J . Orgonomet. Chem. 1988,347, 343. (21) (a) Belin, C.; Makani, T.; RoziEre, J. J . Chem. Soc., Chem. Commun. 1985, 118. (b) Collins, M. J.; Gillespie, R. J.; Kolis, J. W.; Sawyer, J. F.Inorg. Chem. 1986, 25, 2057. (22) Herrmann, W. A.; Rohrmann, J. Chem. Ber. 1986, 119, 1437. (23) Bianchini, C.; Mealli, C.; Meli, A.; Sabat, M. J . Am. Chem. Soc. 1985, 107, 5317. (24) Hoots, J. E. Rauchfuss, T. B. Inorg. Chem. 1983, 22, 2806. (25) Campana, C. F.; Lo, F. Y.-K.; Dahl, L. F. Inorg. Chem. 1979,18,3060. (26) Drew, M.G. B.; Fowles, G. W. A.; Page, E. M.; Rice, D. A. J . Am. Chem. SOC.1979, 101, 5827. (27) Benton, J.; Drew, M. G. B.; Rice, D. A. J . Chem. Soc., Chem. Commun. 1981, 1241. (28) Drew, M. G. B.; Rice, D. A.; Williams, D. M. J . Chem. Soc., Dalton Trans. 1984, 1087. (29) Brunner, H.; Wachter. J.; Wintergerst, H. J . Organomet. Chem. 1985, 235, 77. (30) Rheingold, A. L.; Bolinger, C. M.; Rauchfuss, T. B. Acta Crystallogr. 1986. C42. 1878. (31) Chau, C.-N.; Wardle, R.W. M.; Ibers, J. A. Inorg. Chem. 1987, 26, 2740.
0 1992 American Chemical Society
Inorganic Chemistry, Vol. 31, No. 9, 1992 1615
Synthetic Studies on the CpRu-PPh3-(Se2) System Scheme I
(ref. 8)
(ref. 9)
(ref. 10)
Table I. Selected Bond Distances
(A) and Angles (deg) in [ C ~ R U ( P P ~ , ) ~ ] ~ S ~ ~ ( O T ~ ) ~ C H ~ C ~ ~ . P ~ M ~ Distances
Ru 1-Sel Rul-PI Ru2-P4
2.341 (2) 2.384 (4) 2.366 (4)
Ru2-Se2 RU1-P2 Rul-Cpl
Sel-Rul-P1 P1-Rul-Cpl Se2-Ru2-P3 P3-Ru2-P4 Ru 1-Sel-Se2
102.33 (10) 118.5 (4) 85.9 (1) 101.9 (1) 112.94 (8)
Sel-Rul-P2 P1-Ru 1-P2 Se2-Ru2-P4 P3-Ru2-Cp2 Ru2-Se2-Sel
2.377 (2) 2.352 (4) 1.89 (1)
Sel-Se2 Ru2-P3 Ru2-Cp2
2.265 (2) 2.344 (4) 1.90 (1)
Andes v
have been suggested for [CpMn(C0)2]2Se22and the electronprecise [CpFe(C0)2]Sez.33
Results (C5H4R)Ru(PPh3)2SeH.The complex CpRu(PPh3),SeH is formed in good yields by slurrying C ~ R U ( P P ~ , and ) ~ Cexcess ~ NaSeH in hot methanol. This neutral yellow-brown air-sensitive material is soluble in polar organic solvents. Its 'H NMR spectrum shows a single Cp resonance and a phenyl multiplet along with the SeH resonance, which appears as a triplet at -5.9 ppm NMR spectrum of upfield of TMS (JPH = 7 Hz). The 31P(1HJ this complex consists of a single line at 44.7 ppm downfield of the 85% H3P04standard. It is interesting that the corresponding reaction of NaSeH and ( M e c p ) R ~ ( P P h , ) ~ is c lvery slow. We have found however that this latter reaction proceeds well using (NMe4)SeH. Unlike the case of the CpRu(PPh,),SH system, we were unable to prepare [ c p R ~ ( P P h , ) ~ ( s e H ~ )either ] + by protonation of CpRu(PPhJ2SeH with trifluoromethanesulfonicacid (HOTf) or by reaction of CpRu(PPh3),0Tp4 with H,Se. In order to probe this reaction more thoroughly, we turned to the analogous MeCp complexes because previous work had shown that the H,S complex was more thermally robust than the Cp analogue. Treatment of a dichloromethanesolution of (MeCp)Ru(PPh3)seH with HOTf
86.19 (10) 97.3 (1) 95.9 (1) 121.9 (4) 109.20 (8)
Sel-Ru l-Cpl P2-Rul-Cpl Se2-Ru2-Cp2 P4-Ru2-Cp2
122.9 (4) 122.7 (4) 126.5 (4) 117.7 ( 5 )
afforded -60% yield of the dihydride [ ( M ~ C ~ ) R U ( P P ~ , ) ~ H ~ ] + , which was identified by 'H and 31P(H)NMR measurement^.,^ This dehydrogenation does not proceed via [ C ~ R U ( P P ~ ~ ) ~ ] ~ S ~ ~ + (discussed below), since the latter does not react with hydrogen. [CpRu(PW,)&Se,Z+. The complex [ C ~ R U ( P P ~ ~ ) ~ I ~ S ~ ( O T ~ ) (1)forms in good yields from the reaction of red selenium with a dichloromethane solution of CpRu(PPh,),OTf. This yellowbrown air stable material is soluble in polar solvents. The positive-ion fast atom bombardment (FAB) spectrum of the compound shows envelopes of peaks corresponding to [CpRu(PPh3)J2Se2+and several of its fragments. Its 'H and 31PNMR spectra are indicative of a diamagnetic and centrosymmetric compound. The optical spectrum of 1 is dominated by a lowenergy absorption at 790 nm (c = 8.18 X lo3 M-' cm-') in methylene chloride solutions. A similar low-energy absorption band at 718 nm (c = 3.2 X lo4 M-' cm-' ) was observed for [ C ~ R U ( P P ~ ~ ) ~and ] ~ Swas ? + assigned to transitions involving the Ru2S2core.'& The cyclic voltammogram of 1 in dichloromethane at a Pt electrode shows a reversible wave at 300 mV and a quasi-reversible wave at -680 mV vs Ag/AgCl. Coulometric measurements at -50 mV indicated the 300-mV wave is associated with a le/2Ru reduction. In the crystal, each ruthenium atom in 1 is coordinated to a Cp ring, two triphenylphosphine groups, and one end of a p#,v1-Se2 unit, giving a pseudooctahedral coordination (Figure 1).
(32) Herberhold, M.; Reiner, D.; Zimmer-Gasser, B.; Schubert, U. 2.Narurjorsch. 1980, 358, 1281.
(33) Herrmann, W.A.; Rohrmann, J.; Herdtweck, E.; Hecht, C.; Ziegler, M. L.; Serhadli, 0.J. Organomet. Chem. 1986, 314, 295. (34) Amarasekera, J.; Rauchfuss, T. B.; Wilson, S.R. J . Am. Chem. SOC. 1988, 110, 2332.
(35) Conroy-Lewis, F. M.; Simpson, S.J. J . Chem. Soc., Chem. Commun. 1987, 1675. We had observed formation of small amounts of metal
hydrides in the reaction of [CpRu(PPh3)+3H2]+and C ~ R U ( P P ~ ~ ) ~ O T ~ ; see ref 14e.
1616 Inorganic Chemistry, Vol. 31, No. 9, I992
Amarasekera et al.
Table 11. Selected Bond Distances (A) and Angles (deg) for the Centrosymmetric Cation in [(MeCp)R~(PPh,)l~(r-Se~)~(0Tf), Distances Ru-Sel Se 1 -Se2
2.473 (1) 2.279 (1)
Sel-Ru-Sel S e 1 -Ru-P Se2-Ru-P Ru-Sel-Ru
76.96 (4) 126.32 (8) 80.71 (8) 103.04 (5)
Ru-Sel Ru-P
2.556 (1) 2.407 (3)
S e 1-Ru-Se2 Ru-Se 1 -Se2 Ru-Se2-Sel
Angles -
v vc7
98.13 (5) 114.15 (5) 64.16 (4)
Ru-Se2
S e 1-Ru-P Sel-Ru-Se2 Ru-Se 1 -Se2
2.518 (1)
84.82 (8) 53.38 (4) 62.46 (4)
’ C 1
t17
p2
c9
\ Ru2
2
v
c3
CI 1
21
C 31
Fgrre 1. ORTEP diagram of the cation in [ C ~ R U ( P P ~ ~ ) ~ ] S with ~~(OT~)~ thermal ellipsoids drawn at the 35% probability level. For the sake of clarity, only the ipso phenyl carbon atoms are shown.
The molecule possesses no crystallographic symmetry. Unlike Figure 2. ORTEP diagram of the cation in [(MeCp)R~(PPh,)l~(se,)~the core of its sulfur analogue, the Ru2Se, core is nonplanar with (OTf), with thermal ellipsoids drawn at the 35% probability level. a Ru-Se-Se-Ru dihedral angle of 159.68 (7)O. Bond distances and angles are listed in Table I. In other p-q1,q1-Se2complexes, selenium atoms, one from each of the two Se2 units, bridge the the M2(Se2)units are cisoid, since the metals are constrained by two ruthenium centers, forming an RuzSe2ring. Similar M2E4 M-M bonds. The Se-Se distance of 2.265 (2) A lies between groups with q1,q2-E2(E = S, Se) ligands are found in [(tria Se-Se double bond (2.19A)36and a Se-Se single bond (Sea, p h ~ s ) R h ] , ( S e ~ ) ~Ti2Se82-,40 ~ + , ~ ~ C ~ * , C O ~ S[Mo,(NO)~~,~~ 2.34 A).37 The S e s e bond distance in the ([(C6H,),PI2CSek: ( S Z ) S S ~ ] ~Cp2Fe2(S2)2(C0),43 -,~~ [MOFe3S6(C0)6]2-,44and cation, which features a trans-ql,q1-Se2group, is 2.492 (2) . [Mo2Fe6Sa(S2)z(SC6H4Br)6]e.4s The S e s e bond distance in The Se-Se bond distance in 1 corresponds to an approximate bond 2 is 2.279 (1) A, only slightly longer than that in 1. Ru-Se bond order of 1.4 according to the bond order/distance correlation distances, 2.473 (1) and 2.556 (1) A, are, however, substantially proposed by Dahl;25however, available reference compounds are longer than those in 1 2.377 (2) and 2.341 (2)A). The Ru-Ru so structurally diverse that correlations are difficult. The Ru-Se distance of 3.937 (1) is nonbonding. bond distances of 2.377 (2) and 2.341 (2)A are short compared ((MeCp)Ru(PPh3)l2Se4.The cyclic voltammogram of an to those in the mineral Ruse, (2.44A).16They are more comacetonitrile solution of 2 at a Pt electrode shows two overlapping arable to the average Ru-Se equatorial distance of 2.322 (6) reversible reduction waves centered at 360 and 195 mV and a observed for the 14e complex R~(SeC~H-2,3,5,6-Me~)~- quasi-reversible wave at -1 100 mV vs Ag/AgCl. The first two (CH3CN).39 waves are associated with sequential le reductions of 2. We found [(RC5H4)Ru(PPh3)l2Se4(0Tf),. The reaction of excess red that 2 is readily reduced in solution by Cp&o to give an air-stable selenium with a dichloromethane solution of (MeCp)Rugreen powder formulated as [(MeCp)Ru(PPh3)12Se4.This com(PPh3),0Tf results in formation of an air-stable, red-brown plex is very poorly soluble in organic solvents but it is slightly (2). Aside compound analyzing as [(MeCp)Ru(PPh3)]#e4(0Tf), soluble in CS,, indicating charge neutrality. The thermal instafrom the phenyl resonances, the ‘H NMR spectrum of 2 consists bility of its solutions interfered with purification efforts, and its of three CH3CJ14 signals in the ratio 2:l:l and one methyl singlet. characterization rests on its spectroscopy, electrochemistry, and This indicates equivalent MeCp groups in a molecule with only chemical reactivity. The ‘H NMR spectrum of [(MeCp)Rurotational symmetry. Its 31P(lH)NMR spectrum consists of one (PPh3)]#e4 shows two peaks for CH3C$Z4,indicating a symmetric signal at 31.28 ppm, Compound 2 was further characterized by molecule (for 2 we observe three CH3C5H4signals in the ratio FABMS. The Cp analogue of 2, [CpRu(PPh3)12Se4(0Tf2,was 1:1:2). Oxidation of this green compound with Ph3CBF4gives observed as only a minor product in the synthesis of 1 from a good yield of [(M~C~)RU(PP~,)]~(S~,),(BF~)~. In refluxing CpRu(PPh,),OTf and red selenium. Indeed, solutions of 1 were benzene suspension, the neutral tetraselenide converts to the cufound to react slowly with red selenium to give the Cp analogue bane cluster (MeCp),Ru4Seo. The electrochemical and spectroof 2. A crystallographicstudy showed that each ruthenium atom in 2 is coordinated to a MeCp ring, a PPh3group, and three selenium Kang, D.; Ibers, J. A. Inorg. Chem. 1988, 27, 549. Brunner, H.; Janietz, N.; Meier, W.; Sergeson, G.; Wachter, J.; Zahn, atoms (Figure 2). The two (MeCp)Ru(PPh3)Se2subunits in the T.; Ziegler, M. L. Angew. Chem., Int. Ed. Engl. 1985,24,1060; Angew. structure are related by a crystallographicinversion center. Two Chem. 198597, 1056. See also: Brunner, H.; Janietz, N.; Meier, W.;
A
x
(36) Wells, A. F. Structural Inorganic Chemistry, 4th 4.; Clarendon: Oxford, England, 1975; p 521; (37) Foss, 0.;Janickis, V. J. Chem. Soc., Chem. Commun. 1977, 834. (38) D. Ansew. Chem., Inr. Ed. . . Schmidbaur. H.: Zybill, C. E.; Neugebauer, Engl. 1983, 22. 1 e/A3 > -1.17
Table IV. Atomic Coordinates for
[C~RU(PP~~)~]S~~(OT~)~.CH~CI~-P~M~ xla vlb zlc Ru 1 Ru2 Se 1 Se2 P1 P2 P3 P4 c1 c2 c3 c4 c5 C6 c7 C8 c9 C4 1 c 51 C6 1 C7 1 C8 1 c 91
0.91982 (7) 1.17434 (7) 0.97254 (8) 1.12327 (8) 0.8866 (2) 0.7799 (2) 1.3196 (3) 1.1500 (3) 1.0092 (9) 0.9235 (10) 0.9100 (9) 0.9879 (9) 1.0490 (9) 1.1362 (9) 1.0638 (9) 1.0952 (9) 1.1898 (9) 0.7924 (6) 0.7059 (5) 0.7055 (5) 1.4122 (6) 1.3359 (6) 1.3581 (6)
0.3733 0.09282 (9) 0.2378 (1) 0.2331 (1) 0.4265 (2) 0.3094 (2) 0.1494 (3) 0.0486 (2) 0.3851 (10) 0.4201 (10) 0.4906 (9) 0.4986 (9) 0.4331 (10) 0.077 (1) 0.0459 (9) -0.0213 (9) -0.0359 (9) 0.2068 (5) 0.3709 (6) 0.2813 (6) 0.0817 (6) 0.2472 (5) 0.1812 (6)
0.81272 (6) 0.86765 (6) 0.80383 (8) 0.83425 (8) 0.6842 (2) 0.7908 (2) 0.9069 (2) 0.7388 (2) 0.9371 (8) 0.9278 (9) 0.8770 (8) 0.8562 (8) 0.8918 (8) 0.9738 (8) 0.9073 (8) 0.8774 (8) 0.9218 (8) 0.8413 (5) 0.8262 (5) 0.6922 (4) 0.9059 (6) 0.8605 (5) 1.0101 (4)
Ru
0.37094 (9) 0.4709 (1) 0.5817 (1) 0.4326 (3) 0.227 (1) 0.184 (1) 0.159 (1) 0.185 (1) 0.224 (1) 0.250 (1) 0.292 (1) 0.504 (1) 0.553 (1)
0.44031 (7) 0.41059 (8) 0.45878 (9) 0.2567 (2) 0.5045 (9) 0.4077 (9) 0.4177 (9) 0.5211 (10) 0.5755 (9) 0.534 (1) 0.1751 (8) 0.2294 (8) 0.1902 (8)
0.0407 (1) -0.1543 (1) 0.2648 (1) 0.0175 (3) 0.171 (1) 0.058 (1) -0.087 (1) -0.065 (1) 0.091 (1) 0.333 (1) -0.089 (1) 0.199 (1) -0.075 (1)
zic
Sel Se2 P c1 c2 c3 c4 c5 C6 c7 C13 C19
problems were encountered during data collection, and there was no change in the appearance of the sample during the experiment. The structure was solved by direct methods (SHELX-86); correct positions for the three independent metal atoms were deduced from an E map. A weighted difference Fourier calculation revealed positions for all non-hydrogen atoms of the cation. Subsequent least-squares difference Fourier calculations revealed three disordered positions for the anion. Hydrogen atoms were included as fixed contributors in idealized positions. In the final cycle of least squares, anisotropic thermal coef-
Inorg. Chem. 1992, 31, 1620-1625
1620
ficientswere refined for non-hydrogen cation atoms, and group isotropic thermal parameters were varied for the anion and hydrogen atoms. The triflate was refined as three rigid groups with the site occupancy of each independently varied.51 Successful convergence was indicated by the maximum shift/error for the last cyc1e' The highest
density located in the final difference Fourier map was in the vicinity of the disordered triflate molecule. A final analysis of variance between observed and calculated structure factors showed no apparent systematic errors. Atomic coordinates are presented in Table V. (51) CSD entry TFMSUL (oxonium trifluoromethanesulfonate): Spencer, J. B.; Lundgren, J. 0. Acta Crystallogr. 1973, 829, 1923.
Acknowledgment. This research was supported by the National Science Foundation. Registry No. 1, 139584-16-0; 1.CH2C12.PhMe, 139584-23-9; 2, 139584-18-2;cpR~(pPh,)~SeH, 139606-50-1;C ~ R U ( P P ~ ~32993)~CI, 05-8; (Me4N)SeH,139584-19-3;(MeCp)Ru(PPh3)2SeH,124858-03-3; (MeCp)Ru(PPh,),CI, 55272-36-1; [CpRu(PPh3)I2Se4(0Tf),,13958421-7; [(MeCp)Ru(PPh3)I2Se4,139584-22-8;(MeCp),Ru4Se4,12485808-8; (C6HJ)3CBF4, 341-02-6. Supplementary Material Available: For 1 and 2, tables of thermal parameters, complete positional parameters, bond angles, and bond distances (18 Pages); tables of Structure factors (47 pages). Ordering information is given on any current masthead page.
Contribution from the Department of Chemistry, Texas A&M University, College Station, Texas 77843-3255
Semilocalized Bonding Schemes in Extended Systems: Orbital Localization in Y2C13and Interstitial Derivatives Kyeong Ae Yee and Timothy Hughbanks* Received September 5, 1991 A semilocalizeddescription of bonding in extended metal-metal-bonded systems is described for the prototype title compounds. Beginning with calculated band orbitals, we explicitly construct localized orbitals (Wannier functions) for the metal-metal-bonding orbitals of a M6X12 cluster and the Y2CI3chain compound. Face-localized three-center bond orbitals for a Zr6Cl18cluster are remarkably similar to the HOMO for a (Zr6CIl2H7)C1~cluster in which hydrogens cap seven of eight Zr6 cluster faces. The (Zr6CIj2H,)C1~cluster was chosen to model (Th6Br112H7)BP-86/2, reported recently by Simon and co-workers. A semilocalized bonding picture for semiconductors with the Gd2C13structure type is constructed, providing clarification of both structure-property relationships and trends in interstitial chemistry of these compounds. For the metal-metal bonding, a scheme with two 4c-2e bonds and one 2c-2e bond per cell is extracted from the band structure. The insertion of hydrogens into the tetrahedral interstices are of these chains (to form structures of the @-Y2CI3N type) is seen to be- plausible and chains formulated as Y4CI6H2*+ electronically viable.
Introduction Local Orbitals for Clusters. There are several reasons for the difficulty with which molecular and solid-state inorganic chemists have difficulty communicating. Among the most important of these is the more practiced eye of the solid-state chemists in recognizing the order within extended solid-state structures. But this advantage is often negated by the lack of even qualitatively correct ways of describing bonding in solids within a localized framework. There are a number of reasons for pursuing useful local bonding representations, among them are (i) to offer experimentalists more guidance than is generally given by computational theory. Explanations for materials' properties that boil down to statements which assure us that "its in the band structure" are at best useful only for particular compounds for which computations have been camed out. Uncovering a localized description in the electronic structure can greatly aid in analyzing structurally similar materials and therefore aid in formulating synthetic goals. (ii) Local descriptions will provide a way for chemists to recognize explicit structure-property relationships that are a crucial prerequisite if we are to develop the ability to control properties. (iii) Understanding of the structural and reaction chemistry of the solids under investigation will inevitably be enhanced. Chemistry deals with inherently local phenomena; bonds are clearly made and broken locally. If appropriate analogies are to be drawn with the chemistry of molecules, then we must be able to compare the local electronic structure of molecules and solids. Cluster compounds can serve to illustrate a way in which localized bonding can be extracted from delocalized representations. It has been known for some time that metal-metal bonding in octahedral clusters such as Nb6ClIz2+and Mo6ClS4+,in which nonmetals respectively cap the octahedron's edges and faces, could be understood using localized orbitals.' In the latter case 12 *To whom correspondence should be addressed.
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metal-based electron pairs may be viewed as localized in 2c-2e bonds along the octahedral edges, and in the former case the cluster's 16 Nb-Nb bonding electrons occupy localized 3c-2e bonds in the eight cluster faces. The power of the localized bonding view is underlined by the recent synthesis of the remarkable compound Th6BrlSH7(1).2*3aThe clusters in this
0 Br
1
compound form a body-centered cubic array as in the Nb6FIS structure type; [(Th6H,)Bril2l3+clusters are linked via linear (1) Kettle, S. F. A. Theor. Chim. Acta 1965, 3, 211. ( 2 ) (a) Simon, A.; Bottcher, F.; Cockcroft, J. K. Angew. Chem., Int. Ed. Engl. 1991, 30, 101. (b) Bbttcher, F.; Simon, A.; Kremer, R.; Buchkremer-Hermanns, H.; Cwkroft, J. Z . Anorg. Allg. Chem. 1991, 5981599,
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(3) (a) Andersen, 0. K. Cited in reference 2a. (b) Andersen, 0. K.; Satpathy, S. Basic Properties of Binary Oxides; University of Seville: Seville, Spain, 1983.
0 1992 American Chemical Society
