Organometallics 1996,14, 238-244
238
[C ~ S , C ~ tr~n~-RuCl2( S, C0)2{ Ph2P(CH2CH20),CH2CH2PPh2-PP'} 1, (n = 4, 5; m = 1, 2, ...)Metallacrown Ethers. X-ray
Crystal Structures of cis,cis,tr~n~-R~C12( C0)2{ P ~ ~ P ( C H ~ C H ~ O ) ~ C H Z C '}H ~ P P ~ ~ a Complex Which Exhibits Rotational Isomers in the Solid State, and [cis,cis,truns-RuCl~(CO)~= {pPh2P(CH2CH20)4CH2CH2PPh2=P,P'}12, an Unusual Dimetallacrown Ether Gary M. Gray,* Ashima Varshney, and Christina H. Duffey Department of Chemistry, The University of Alabama at Birmingham, 242-OB15 UAB Station, Birmingham, Alabama 35294, and Department of Chemistry, Samford University, Birmingham, Alabama 35229 Received August 16, 1994@
The reactions of Ph2P(CH2CH20),CH2CH2PPh2 ( n = 4,5 ) ligands with RuC12(C0)3(THF) give a variety of complexes of the type [c~s,c~s,~~u~s-RuC~~(CO)~{P~~P(CH~CH~~),C PPhz-PQ '}Im. Multinuclear NMR and IR spectroscopic studies indicate that the major product in each reaction is the mononuclear (m = 1)complex in which the P ~ ~ P ( C H ~ C H Z O ) , CH2CH2PPh2 ligand spans two trans positions. The minor products are polynuclear ( m = 2, 3, ...I complexes in which each P ~ ~ P ( C H ~ C H Z O ) , C H ~ Cligand H ~ P Pbridges ~~ two rutheniums. X-ray crystal structures of cis,cis,truns-RuC12(C0)2{Ph2P(CH2CH20)4CH2CH2PPhz-PQ '}, 4a, (monoclinic space group P2l/n, a = 10.194(1),b = 22.907(3), c = 15.259(2) p = 92.46(1)";V = 3560.0(8)A3;2 = 4) and [cis,cis,trans-RuCl2(CO)2{~-Ph2P(CH2CH20)4CH2CH2PPh2-PQ '}12*(CH&CO, 4b.(CH&CO, (monoclinic space group P21/a, a = 18.976(3), b = 22.076(5), c = 10.426(8) /3 = 111.64(1)"; V = 4060(1) A3; 2 = 4) confirm these conclusions. The monomeric 4 a is a rare example of an octahedral complex with a transspanning bis(phosphine) ligand. Two different rotamers of 4a are observed in the solid state. In the major rotamer the trans-spanning ligand passes between one chloride and one carbonyl while in the minor rotamer the trans-spanning ligand passes between the two chlorides. The dimeric 4 b is the first example of a dimetallacrown ether. The trans phosphines in 4 b cause the formation of two, distinct metallacrown ether sites separated by a chloride and a carbonyl ligand on each ruthenium.
A;
A;
Introduction One of the most interesting classes of metallomacrocycles1are the metallacrown ethers, formed by chelation of R2PX(CH2CH20),CH2CH=R2 (R = Ph, 0-alkyl; X = -, 0;n 1 3) ligands to transition These metallacrown ethers readily coordinate hard metal
* To whom correspondence should be addressed at The University of Alabama at Birmingham. Abstract published in Advance ACS Abstracts, November 1,1994. (1)This class of complexes has recently been reviewed van Veggel, F. C. J. M.; Werbloom, W.; Reinhoudt, D. N. Chem. Reviews 1994,94, 279. (2)(a) Powell, J.; Kuksis, A,; May, C. J.; Nyberg, S. C.; Smith, S. J. J . Am. Chem. SOC.1981,103,5941. (b) Powell, J.; Nyberg, S. C.; Smith, S. J. Inorg. Chim. Acta 1983,76,L75.( c ) Powell, J.; Ng, K. S.; Ng, W. W.; Nyberg, S. C. J . Organomet. Chem. 1983,243,C1.(d) Powell, J.; Gregg, M.; Kuskis, A.; Meindl, P. J . Am. Chem. SOC.1983,105,1064. (e) Powell, J.; Gregg, M. R.; Kuksis, A.; May, C. J.; Smith, S. J. Organometallics 1989,8,2918. (0 Powell, J.; Kuskis, A.; May, C. J.; Meindl, P. E.; Smith, S. J. Organometallics 1989,8,2933.(g) Powell, J.; Gregg, M. R.; Meindl, P. E. Organometallics 1989,8, 2942. (h) Powell, J.;Lough, A.; Wang, F. Organometallics 1992,11, 2289. (3) (a) Alcock, N. W.; Brown, J . M.; Jeffery, J. C. J . Chem. SOC., Chem. Commun. 1974,829.(b) Alcock, N.W.; Brown, J . M.; Jeffery, J . C. J . Chem. Soc., Dalton Trans. 1976,583.( c ) Thewissen, D. H. W.; Timmer, K.; Noltes, J. G.;Marsman, J. W.; Laine, R. M. Inorg. Chim. Acta 1986,97,143.(d) Timmer, K.; Thewissen, D. H. W. Inorg. Chim. Acta 1986,100, 235.(e) Timmer, K., Thewissen, H. M. D.; Marsman, J. W. Recl. Trav. Chim. Pays-Bas 1988,107,248. @
0276-733319512314-O238$O9.OOIO
cations, and the stabilities of the alkali metal cation complexes depend upon the relative sizes of the cation and the metallacrown ether ~ a v i t y . ~Cations , ~ , ~ bound to the metallacrown ethers can interact with the oxygen lone pairs of the carbonyl ligands in cis-Mo(CO)4{RzPX(CH~CH~~),CHZCH~XPR~-PQ '} metallacrown ethers. Coordination of Li+ activates the carbonyl ligands of cisMO(C~)~{RZPO(CHZCH~O)~CH~CH~OPR~-PQ '] metallacrown ethers toward nucleophilic attack by alkyland aryllithium reagents.2 Coordination of Hg2+catalyzes the cis to trans isomerization of the cis-Mo(CO)r{ Ph2P(CH2CH20)4CH&H2PPh2-P,P'} metallacrown ether.6 These results suggest that hard metal ion complexes of metallacrown ethers could be used to activate a variety of bifunctional ligands, such as carbonyls, that can coordinate to both metal centers. This property could be quite useful in the design of catalysts for reactions involving such ligands. The phosphorus-donor groups are cis coordinated iq all reported metallacrown ethers except trans-Mo(CO)4{Ph2P(CH2CH20)4CH2CH2PPh2-PQ'}, l.5 The chelate (4)(a) Varshney, A,; Gray, G. M. Inorg. Chem. 1991,30, 1748.(b) Varshney, A.; Webster, M. L.; Gray, G. M. Inorg. Chem. 1992,31,2580. ( 5 ) Gray, G, M.; Duffey, C. H. Organometallics 1994,13,1542. (6) Gray, G, M.; Duffey, C.H. Organometallics, in press.
0 1995 American Chemical Society
Organometallics, Vol. 14, No. 1, 1995 239
Ruthenium Metallacrown Ethers
Table 1. 31Pand Phenyl 13C NMR Data" P no. lb
2e
3'
4a 4b 4d
Sa
ortho
ipso
6 ( W (ppm) 32.57 s -21.68 s -21.69 s 9.74 s 13.43 s 14.77 s 11.16 s
W3C) (ppm) 139.48 aq 138.17 d 138.29 d 132.74 aq 131.02 aq
lJ(PC)I (Hz) 34d 12e 12' 47d 45d
i 131.85 aq
46d
613C (ppm) 131.70 aq 132.68 d 132.71 d 132.55 aq 132.85 aq 132.93 bs 132.63 aq
meta
IJ(PC)I (Hz) 1lf 188 178 8f
sf 1N
W3C) (ppm) 128.28 bs 128.56 d 128.58 d 128.74 aq 128.52 bs 128.43 bs 128.71 bs
Ob = broad, s = singlet, d = doublet, aq = apparent quintet. *Data from ref 5 . Data from ref 3a. IIJ(PC) g 12J(PC)I. 13J(PC)I. 13J(PC) 5J(OC)I.j Not observed.
+
para W3C) (ppm)
IJ(PC)I (Hz)
129.16 s 128.41 s 128.41 s 130.79 s 130.71 s 130.70 s 130.81 s
12h loh 8'
+ 3J(PC)I.
e
IIJ(PC)/.f I2J(PC)
+ 4J(PC)l.
Table 2. AliDhatic and Carbonyl 13C NMR Data"
lb
2' 3c
4a 4b 4d
Sa r?
34.38 aq 28.73 d 28.73 d 27.05 aq 24.54 aq 24.13 aq 25.47 aq
22d 12e 13' 2gd 27d 27d 2gd
66.96 aq 68.53 d 68.49 d 65.18 s 66.01 s 66.05 s 65.54 s
12 268 258
C3, C4, C5, C6 W3C) (ppm) 71.07 s, 71.03 s, 70.24 s 70.58 s, 70.53 s, 70.10 s 70.55 s, 70.51 s, 70.51 s, 70.07 s 70.46 s, 69.98 s, 69.07 s 70.61 s, 70.44 s, 69.95 s 70.43 s, 70.36 s, 69.86 s 70.97 s, 70.69 s, 69.89 s, 69.69 s
210.59 t
8
191.67 t 192.23 t 192.25 t 191.94 t
11 11 11 11
+ 3J(PC)I.
b = broad, s = singlet, d = doublet, t = triplet, aq = apparent quintet. Data from ref 5. Data from ref 3a. I*J(PC) IZJ(PC)I.
+ 4J(PC)I.
ring in 1 has very different solution and solid state conformations from those of the chelate rings in the metallacrown ethers with cis phosphorus-donor groups. In addition, the Mo(C0)4group in 1 freely rotates within the chelate ring making this complex a 'molecular gyroscope'. Both these properties suggest that metallacrown ethers with trans-coordinated phosphorusdonor groups (trans-metallacrown ethers) could exhibit properties that are quite different from those with ciscoordinated phosphorus-donor groups (cis-metallacrown ethers). In this paper, we report the results of our studies of the reactions of RuC12(CO)&THF') with Ph2P(CH2CH20),CH2CH2PPh2 (n = 4 (2),5(3)). These reactions yield a variety of trans-metallacrown ethers, and these have been characterized by multinuclear NMR and IR spectroscopy. The insights that these spectroscopic studies provide into the solution structures of these metallacrown ethers are discussed. X-ray structures of the major product and one of the minor products from the reaction of RuC12(CO)3(THF)with Ph2P(CH2CH20)4CH2CH2PPh2 have also been determined and are presented.
Experimental Section The 31P{lH} and 13C{'H} NMR spectra were recorded on a GE NT-300, multinuclear NMR spectrometer. The 31PNMR spectra were referenced to external 85% H3P04, and the 13C NMR spectra were referenced to internal SiMe4. The 31Pand 13C NMR data for the complexes are given in Tables 1 and 2 with positive chemical shifts downfield from those of the references. Infrared spectra of KBr disks of the complexes were run on a Nicolet IR44 spectrometer. Elemental analyses were carried out by Atlantic Microlab, Inc., Norcross, GA. All free ligands, tetrahydrofuran (THF) and diethyl ether were handled under high purity nitrogen, and all reactions and recrystallizations were carried out under high purity nitrogen. The solid products were air stable. All solvents were of reagent grade and were used as received except for diethyl ether and THF which were distilled from sodium-benzophenone. All starting materials were reagent grade and were used as received. The deuterated solvents were opened and handled under a nitrogen atmosphere at all times. The PhzP(CH2-
e
IIJ(PC)I.f I2J(PC)
CH20),CH2CHzPPh2 (n = 4 (2), 5 (3))ligands4*and RuClz(C0)3(THF)' were prepared using literature procedures. [ ~ i s p i s a m - R ~ ( C O ) & lPhap(CHzCH20)4CHzCHapph2 2{ P Q '}Im (4). Solutions of 1.00 g (3.05 mmol) of RuC12(CO)3(THF) in 500 mL of dichloromethane and 1.85 g (3.23 mmol) of 2 in 500 mL of dichloromethane were added dropwise and simultaneously to 1000 mL of dichloromethane over a period of 5 h. The reaction mixture was then stirred for an additional 18 h after which it was evaporated t o dryness to yield 2.56 g (100%) of crude 4 as a white foam. The 31PNMR (chloroformd l ) of the material contained four singlets at 9.71 (4a,major), 13.42 (4b,minor), 14.35 (4c,very minor) and 14.77 (4d,minor) ppm. A portion of the material (0.80 g) was chromatographed on silica gel. Elution with a 3:l mixture of ethyl acetatehexanes yielded 4a (0.46 g, 58%). Next, elution with a 4:l mixture of ethyl acetate-hexanes initially yielded 4b (0.13 g, 16%) and then a mixture of 4b,4c and 4d. Finally, elution with a 1 O : l mixture of ethyl acetate-methanol yielded pure 4d (0.07 g, 9%). Each fraction that contained a single component was triturated with hexanes to give the compounds as analytically pure white powders (mp 203-205 "C for 4a, 192-195 "C for 4b, 90-95 "C for 4d). Anal. Calcd for C ~ ~ H ~ ~ C ~ Z C, O 53.86; ~P~R H,U4.99%. : Found for 4a: C, 53.65; H, 5.09%. Found for 4b: C, 53.56; H, 5.06%. Found for 4d: C, 53.62: H, 5.13%. IR (KBr): v(C0) 2058, 1995 cm-l, 4a; 2058, 1995 cm-l, 4b;2058, 1995 cm-l, 4d. [C~&S&YJIW-RU(CO)~C~Z{ PhaP(CHzCH2O)&HzCI&PPhr P Q '}I,,, (5). Using the procedure for the preparation of crude 4, 0.10 g (0.32 mmol) of 3 and 0.10 g (0.30 mmol) of RuC12(C0)3(THF)were reacted t o yield a white waxy residue. A 31P NMR spectrum of the material in chloroform-dl had singlets at 11.17 (Sa,major), 13.99 (Sb,minor) and 14.75 (Sc,minor). The residue was chromatographed on silica gel. Elution with a 2:l mixture of ethyl acetate-hexanes yielded 0.20 g (74%) of analytically pure Sa (mp 280 "C). Anal. Calcd for C38H44C1207P2R~: C, 53.91; H, 5.24%. Found: C, 54.49; H, 5.32%. IR (KBr): v(C0) 2058, 1997 cm-l. (7) We originally reported that this complex was [Ru(C0)&121. 0.75THF based upon analytical results. (Reddy, V. V. S.; Whitten, J. E.; Redmill, K. A.; Varshney, A.; Gray, G. M. J. Organomet. Chem. 1989,372, 207). We have now obtained a crystal structure of this complex (Duffey, C. H.; Gray, G. M. Unpublished results) which indicates that the correct formula is as shown in the text. The difference in formulas most likely is due to loss of THF during drying of the analytical sample.
Gray et al.
240 Organometallics, Vol. 14,No.1, 1995 X-ray Structure Determination of 4a and 4b(C&)&O. A colorless, needlelike crystal of 4a was grown by slowly diffusing hexanes into a dichloromethane/methanol solution of the complex. A colorless, blocky crystal of 4b.(CH&CO was grown by slowly diffusing acetone into a dichloromethane solution of 4b. The crystals were mounted on glass fibers with epoxy cement, and the cell constants were obtained from leastsquares refinement of 25 reflections with 25 5 8 5 35" for 4a and 12 5 8 5 16" for 4b.(CH&CO. All measurements were carried out on an Enraf-Nonius CAD4 diffractometer at 23 "C using graphite-monochromated Cu Ka radiation (A = 1.5418 A) for 4a and at 22 "C usin graphite-monochromated Mo Ka radiation (A = 0.710 73 ) for 4b.(CH&CO. Data were collected by 0-20 scans for both crystals. No decay correction was applied to the data for 4a, but an empirical absorption correction was applied. Both linear decay and empirical absorption corrections were applied to the data for 4b.(CH&
1
co.
Both structures were solved by heavy-atom methods and refined by a full-matrix least squares procedure that minimized w(lFol - lFc1)2where w = l/u2(Fo)using the Crystals programs in the MolEN package of programs from EnrafNonius. The structure of 4a was disordered due to rotational isomerism that exchanged one carbonyl and one chloride ligand. The sum of the occupancies of the chloride and carbonyls in the two sites were set equal to one, the occupancy of the chloride in one site was linked to that of the carbonyl in the other site and the occupancies were refined. The polyether chains in 4b.(CH&CO were quite mobile and gave poor bond lengths when freely refined. In order to obtain a reasonable structure, the C-C bond lengths were restrained to 1.54 A and the C - 0 bond lengths were restrained to 1.43 A during the refinement. This did not materially affect the R factors and did result in reasonable bond angles. All hydrogen atoms in both structures were placed in calculated positions (C-H = 0.96 A, UISO(H)= 1.3U1so(C))and were ridden on the heavy atoms to which they were attached. Both data sets were weighed using a non-Poisson scheme. A secondary extinction correction was applied t o each set of data: and the extinction coefficients were refined. In the last stage of the refinement for each structure, no parameter varied by more than 0.01 of its standard deviation, and the final difference Fourier map had no interpretable peaks. Heavy atom scattering factors were taken from the compilations of Cromer and Weber,gand those for hydrogen were taken from the International Tables for X-Ray Crystallography, Vol.W.loCorrections for anomalous dispersion were taken from the compilations of Cromer and Liebermanl' and applied to chlorine, phosphorus and ruthenium. Data for the X-ray structure analyses are given in Table 3. Positional parameters for 4a are given in Table 4, and those for 4b.(CH&CO are given in Table 5. Values of selected bond lengths for 4a are given in Table 6, and those for 4b.(CH&CO are given in Table 7. Values of selected bond angles for 4a are given in Table 8, and those for 4b.(CH&CO are given in Table 9. Values of selected torsion angles for both structures and for 1 are given in Table 10. Tables of hydrogen atomic positional parameters, thermal parameters, torsion angles and least squares planes for 4a and 4b are available as supplementary material. ORTEP12drawings of the major and minor rotamers of 4a are given in Figures 1 and 2, and that for 4b.(CH&CO is given in Figure 3.
Table 3. Data Collection and Structure Solution and Refinement Parameters for 4a and 4b 4a
P21/n 10.194( 1) 22.907(3) 15.259(2) 92.46(1) 3560.0(8) 4 1.497 0.11 x 0.10 x 0.21 12, 0 28,O 19, -19 Cu Ka (1.541 84) 23 62.890 0.1-74 none
P21/a 18.976(3) 22.076(5) 10.426(8) 11 1.64(1) 4060.(1) Z 4 1.408 dCdc(g/cm3) cryst dimens, mm 0.37 x 0.34 x 0.50 24, -24 h m a , hmin 0, -28 kmax, kmin 13,O &I" radiation (A (A)) Mo Ka (0.710 73) 22 temp ("C) 6.324 abs coeff (cm-I) 0.1-27.5 8 (limits (deg) decay corr linear 6.9 decay (%) abs corr empirical empirical 99.9,94.6 99.6, 84.8 Tma. Tmm (%) refl measd 10 073 8036 scan width (deg) 1.35 1.34 refl with I ? nu(l) 4310 ( n = 3) 4305 (n = 2) 46 1 no. of variables 423 function minimized W(lF0I - IFcl)2 W(lF0l - IFCIY weighing scheme non-Poisson non-Poisson (w = l/u2(Fo)) (w = l/u2(Fo)) instrumental uncertainty factor 0.03 0.02 secondary extinction corr type Zachariesen Zachariesen minimized extinction coeff 7.608 x lo-* 2.867 x lo-* R, %" 7.13 5.58 8.68 6.04 Rw GOFC 1.324 1.972 1.057, -0.287 0.721, -0.140 max, min resid electron density (e/A3) max shifuerror 0.01 0.01
GOF R = E(IF0I - lFcl)/zlFol). R, = Ew(lF0l - lFcl)2/XIFo12)o~5. = [Zw(llFoi - IFcl)2/n- mlO.5.
plexes. I n contrast to t h e reactions of t h e PhzP(CH2CH20),CHzCH2PPhz ( n = 4 (2), 5 (3)) ligands with Mo(C0)4(norbornadiene) a n d PtC1~(1,5-cyclooctadiene) in 1:lratios, which yield single product^,^ the reactions of these ligands with RuClz(C0)3(THF) in 1:l ratios under similar conditions yield a variety of products (eq 1). Elemental analyses of t h e crude reaction mixtures
+
RuCl,(CO),(THF) Ph2P(CHzCHzO),CH2CHzPPh2 2 (n = 4),3 (n = 5 )
-
RuC1,(C0),{Ph2P(CH2CH,0),CH,CH,PPh,1
(1)
4 (n = 4),5 (n = 5 )
indicate that all of these products have empirical formulas of t h e type RuCl2(CO)z{PhzP(CHzCHzO),CH2CHzPPhz} ( n = 4 (41, 5 (5)). The various products do not interconvert as indicated by t h e fact that t h e 31P NMR spectra of t h e mixture did not vary with either Results and Discussion temperature or concentration a n d by t h e fact that t h e Syntheses and Solution Conformations of the major components a n d some of t h e minor components R U C ~ ~ ( C ~ ) ~ { P ~ ~ P ( C H ~ C H ~ OCom) ~ C H ~could C H ~beP separated P ~ ~ } by column chromatography on silica gel. (8) Zachariasen, W. H. Acta Crystallogr. 1963,16, 1139. Each of t h e RuCl~(CO)~{Ph2P(CH2CH~O)~CH~CH2( 9 )Cromer, D. T.;Waber, D. T. Acta Crystallogr. 1966,18, 104. PPhz} complexes have identical ruthenium coordination (10)International Tables for Crystallography; Hahn, T.,Ed.; The Kynoch Press: Birmingham, U.K., 1974; Vol. IV,p 72. geometries with cis carbonyls, cis chlorides a n d trans (11)Cromer, D . T.; Lieberman, D. J. J. Chem. Phys. 1970,53,1891. phosphines as shown by their IR a n d 31Pand I3C NMR (12)Johnson, C. K. ORTEPII. Report ORNL-5138. Oak Ridge National Laboratory: Oak Ridge, TN, 1976. spectra (Tables 1 a n d 21. The IR spectrum of each
Organometallics, Vol.14,No.1, 1995 241
Ruthenium Metallacrown Ethers Table 4. Positional Parameters and Isotropic Thermal Factors (Az)for 4a'
Table 5. Positional Parameters and Isotropic Thermal Factors (Az)for 4b.(CH3)zCO"
atom
X
Y
Z
B"
atom
X
Y
Z
BO
Ru c11 c12 C12' P1 P2 01 02 03 04 05 06 06' c1 c2 c3 c4 c5 C6 c7 C8 c9 c10 c11 c12 C13 C14 C15 C16 C17 C18 C19 c20 c 21 c22 C23 C24 C25 C26 C27 C28 C29 C30 C3 1 C32 c33 c34 c35 C36 C36'
0.58941(6) 0.7932(2) 0.6528(4) 0.4986(7) 0.4982(2) 0.6808(2) 0.5492(7) 0.772 l(8) 0.835(1) 0.8076(7) 0.3393(7) 0.503( 1) 0.695(3) 0.4672(9) 0.5882(9) 0.637( 1) 0.768( 1) 0.767( 1) 0.798( 1) 0.851(1) 0.9025(9) 0.800(1) 0.6977(9) 0.3376(8) 0.3280(9) 0.207( 1) 0.093( 1) 0.1011(9) 0.2208(9) 0.5887(8) 0.5282(9) 0.599( 1) 0.725( 1) 0.783( 1) 0.719( 1) 0.841 l(9) 0.888(1) 1.008(1) 1.084(1) 1.040(1) 0.9 192(9) 0.5757(8) 0.507( 1) 0.426( 1) 0.412(1) 0.479( 1) 0.559( 1) 0.432( 1) 0.533( 1) 0.659(3)
0.52967(3) 0.5718(1) 0.5260(2) 0.5273(3) 0.62620(9) 0.43447(9) 0.7107(3) 0.6840(3) 0.5342(4) 0.4133(3) 0.474%3) 0.5382(5) 0.532( 1) 0.6670(4) 0.6885(4) 0.7495(5) 0.7264(5) 0.6275(5) 0.5854(5) 0.4837(5) 0.4356(5) 0.4443(4) 0.4128(4) 0.6239(4) 0.6023(5) 0.5942(5) 0.6087(5) 0.6290(5) 0.6361(5) 0.6788(4) 0.7317(4) 0.7727(4) 0.7600(4) 0.7084(5) 0.6681(4) 0.4 176(3) 0.3593(4) 0.3460(5) 0.3873(5) 0.4440(5) 0.4591(4) 0.3766(4) 0.3375(5) 0.2960(5) 0.2919(5) 0.3314(5) 0.3734(5) 0.4957(4) 0.5351(6) 0.531(1)
0.75769(4) 0.7086(2) 0.9125(3) 0.6141(5) 0.7759( 1) 0.7334(2) 0.5487(5) 0.4291(5) 0.4268(5) 0.4880(4) 0.8153(5) 0.5705(8) 0.955(2) 0.674 l(5) 0.6309(6) 0.5 130(9) 0.497 l(9) 0.4554(8) 0.3850(8) 0.3722(7) 0.4306(6) 0.5680(6) 0.6195(6) 0.8238(6) 0.9091(6) 0.9443(6) 0.8975(8) 0.8131(8) 0.7773(7) 0.8449(6) 0.8658(6) 0.9174(6) 0.9479(7) 0.9287(8) 0.8747(7) 0.7868(6) 0.7814(7) 0.8231(9) 0.8635(8) 0.8690(8) 0.8299(7) 0.7739(6) 0.7 192(7) 0.7570(9) 0.8437(8) 0.8982(7) 0.8629(6) 0.7932(6) 0.6307(9) 0.884(2)
2.15(1) 3.34(4) 4.29(7)* 3.2(1)* 2.16(4) 2.49(4) 4.5(2) 5.1(2) 6.1(2) 3.7(1) 4.3(2) 5.1(3)* 5.1(6)* 2.7(2) 3.4(2) 5.5(3) 533) 6.0(3) 5.3(3) 4.1(2) 3.4(2) 3.5(2) 3.0(2) 2.5(2) 3.6(2) 3.6(2) 4.3(2) 4.6(3) 3.5(2) 2.6(2) 3.1(2) 3.2(2) 3.6(2) 4.2(2) 3.8(2) 2.7(2) 3.9(2) 5.1(3) 4.8(3) 4.5(2) 3.5(2) 2.5(2) 5.0(3) 6.8(3) 5.3(3) 4.6(2) 3.9(2) 3.2(2) 3.3(2)* 3.0(5)*
Ru c11 c12 P1 P2 01 02 03 04 05 06 c1 c2 c3 c4 c5 C6 c7 C8 c9 c10 c11 c12 C13 C14 C15 C16 C17 C18 C19 c20 c 21 c22 C23 C24 C25 C26 C27 C28 C29 C30 C3 1 C32 c33 c34 c35 C36 07 c37 C38 c39
0.22681(3) 0.2518(1) 0.1715(1) 0.10206(9) -0.3453( 1) -0.0708(3) -0.1664(4) -0.2993(3) -0.4267(3) 0.2964(3) 0.1903(3) 0.0565(4)
0.07645(3) 0.00032(9) 0.0017(1) 0.08849(9) -O.O498( 1) 0.0502(3) 0.1474(3) 0.1729(3) 0.1013(3) 0.1737(3) 0.1646(3) 0.0154(3) 0.0077(4) 0.045 l(4) 0.0881(4) 0.1877(5) 0.2158(5) 0.1968(4) 0.1548(4) 0.0516(4) 0.0314(4) 0.1378(3) 0.1161(4) 0.1561(5) 0.2183(4) 0.2394(5) 0.1994(4) 0.1209(3) 0.1498(3) 0.1705(3) 0.1643(4) 0.1352(3) 0.1 140(3) 0.0736(3) 0.0699(4) 0.0809(4) 0.0972(4) 0.1010(4) 0.0898(4) 0.0792(4) O.O415(4) 0.0679(5) 0.1279(5) 0.1642(5) 0.1388(4) 0.1372(3) 0.1305(4) 0.2328(4) 0.1752(6) 0.1977(5) 0.18 12(7)
0.00749(6) -0.1402(2) 0.1115(2) -0.1677(2) -0.1860(2) -0.3333(8) -0.4275(7) -0.3448(7) -0.3953(6) -0.1051(6) 0.1933(6) -0.2078(8) -0.337( 1) -0.453( 1) -0.426( 1) -0.327( 1) -0.384( 1) -0.374( 1) -0.3 14(1) -0.3 140(8) -0.2071(8) -0.105 l(7) -0.0375(8) 0.0227(8) 0.0178(9) -0.0490(8) -0.1090(9) -0.333 l(6) -0.4163(7) -0.5449(7) -0.5911(7) -0.5108(7) -0.3809(6) 0.1624(7) 0.0314(7) 0.0113(9) 0.1 193(9) 0.2509(9) 0.2712(8) 0.3558(6) 0.4531(7) 0.5785(8) 0.6040(8) 0.5064(8) 0.3835(8) -0.0630(7) 0.1217(8) 0.1868(8) 0.022( 1) 0.151(1) 0.253( 1)
4.08(1) 5.46(5) 7.86(6) 3.96(4) 4.48(5) 8.9(2) 11.5(3) 8.3(2) 8.5(2) 6.9(2) 8.9(2) 5.7(2) 9.4(3) 9.4(4) 12.5(4) 12.8(5) 10.9(4) 10.3(4) 9.4(3) 6.8(2) 5.8(2) 4.3(2) 6.5(2) 9.2(3) 8.9(3) 8.2(3) 6.2(2) 3.7(2) 4.6(2) 5.4(2) 6.0(2) 5.0(2) 4.1(2) 4.5(2) 5.5(2) 7.3(2) 733) 7.2(3) 5.8(2) 4.8(2) 6.8(2) 7.8(3) 8.4(3) 7.6(3) 6.2(2) 4.3(2) 6.2(2) 12.1(3) 17.9(6) 9.6(3) 25.9(7)
a Starred B values are for atoms that were refined isotropically. Anisotropically refined atoms are given in the form of the isotropic equivalent displacement parameter defined as (4/3)[a2B(l,l) b(2,2) c2B(3,3) &cos y)B(1,2) ac(cos Pp(1.3) bc(cos a)B(2,3)].
+
+
+
+
+
complex has two equally intense bands at approximately 1995 and 2058 cm-' indicating that the carbonyls in each of the complexes are cis-coordinated.13 The 13C NMR spectrum of each complex has a single 1:2:1 triplet for the two carbonyls at approximately 192 ppm with a relatively small 12J(PC)Iof approximately 11Hz. This demonstrates that the carbonyls are chemically equivalent and are cis to both phosphines.13 Each complex also has a single 31P NMR resonance indicating that the phosphines are chemically equivalent. The above data suggests that the reactions shown in (13)(a) Lindner, E.; Schober, U.; Fawzi, R.; Hiller, W.; Englert, U.; Wegner, P. Chem. Ber. 1987,120,1621. (b) Reddy, V. V. S. R.; Whitten, J. E.; Redmill, K. A,; Varshney, A.; Gray, G. M. J. Organomet. Chem. 1989,372, 207.(c) Lindner, E.; Karle, B. Chem. Ber. 1990,123,1469. (d) Lindner, E.; Mockel, A.; Mayer, H. A.; Fawzi, R. Chem. Ber. 1992, 125,1363. (e) Lindner, E.; Mockel, A.; Mayer, H. A.; Kuhlbauch, H.; Fawzi, R.; Steimann, M. h o g . Chem. 1993,32,1266.
-0.0155(5)
-0.1389(5) -0.1960(5) -0.1748(6) -0.2544(5) -0.3734(5) -0.4182(4) -0.4344(4) -0.3576(4) 0.0454(3) 0.0006(4) -0.0346(4) -0.0247(5) 0.0195(5) 0.0544(4) 0.0936(3) 0.0288(4) 0.0215(4) 0.0798(4) 0.145 l(4) 0.1530(4) 0.4309(3) 0.4339(4) 0.5009(4) 0.5653(4) 0.5638(4) 0.4972(4) 0.3541(3) 0.3423(4) 0.3452(4) 0.3615(4) 0.3719(4) 0.3680(4) 0.2694(4) 0.2042(4) 0.8469(4) 0.7521(7) 0.7936(5) 0.7673(8)
Anisotropically refined atoms are given in the form of the isotropic equivalent displacement parameter defined as (4/3)[a2B(l,l) b2B(2,2) c2B(3,3) ab(cos y)B(1,2) ac(cos P)B(1,3) bc(cos a)B(2,3)].
+
+
+
+
+
Table 6. Selected Bond Lengths (A) for 4a Ru-Cl1 Ru-C12 Ru-C12' Ru-P1 Ru-P2 Ru-C35 Ru-C36 Ru-C36' P1-c1 P1-c11 P1-C17 P2-c10 P2-C23 F'2-C29 01-c2
2.438(2) 2.424(4) 2.343(7) 2.420(2) 2.406(2) 1.88(1) 2.00(1) 2.02(3) 1.829(9) 1.822(8) 1.824(9) 1.82(1) 1.836(9) 1.828(9) 1.39(1)
01-C3 02-C4 02-C5 03-C6 03-C7 04-C8 04-C9 05-C35 06-C36 06'-C36' Cl-C2 c3-c4 C5-C6 C7-C8 C9-C10
1.39(1) 1.42(2) 1.36(1) 1.38(1) 1.44(1) 1.43(1) 1.42(1) 1.13(1) 0.96(2) 1.14(4) 1.51(1) 1.47(2) 1.49(2) 1.50(1) 1.51(1)
eq 1 yield mixtures of monomers and oligomers. The minor products of each reaction appear to be oligomers as demonstrated by the fact that their 31P NMR
242 Organometallics, Vol. 14,No. 1, 1995
Gray et al.
Table 7. Selected Bond Lengths (A, for 4bKHdCO Ru-Cl1 Ru-C12 Ru-P1 Ru-PI Ru-C35 Ru-C36 P1-c1 P1-c11 P1-C17 P2-c10 P2-C23 P2-C29 01-c2 01-C3
2.440(2) 2.417(3) 2.413(2) 2.404(3) 1.853(8) 1.843(9) 1.807(7) 1.811(8) 1.819(7) 1.81l(8) 1.809(8) 1.834(7) 1.42(1)n 1.431(9)”
02-C4 02-C5 03-C6 03-C7 04-C8 04-C9 05-C35 06-C36 Cl-C2 c3-c4 C5-C6 C7-CS C9-C10
a C-0 distances were constrained to 1.43 constrained to 1.54 A.
A.
1.43(1)n 1.43(1)” 1.43(1)” 1.43(1)” 1.43(1)“ 1.43(1)” 1.13(1) 1.16(1) 1.53(l)b 1.54(l)b 1.54(l)b 1.54(l)b 1.538(9)b C-C distances were
Table 8. Selected Bond Angles (deg) for 4a Cll-Ru-Cl2 C11 -Ru-C12’ C11-Ru-P1 Cll-Ru-P2 Cll-Ru-C35 Cll-Ru-C36 Cll-Ru-C36’ C12-Ru-Pl C12-Ru-P2 C12-Ru-C35 C12-Ru-C36 C12’-Ru-P1 C12’-Ru-P2 C12’-Ru-C35 C12’-R~-C36’ P 1-Ru -P2 Pl-Ru-C35 Pl-Ru-C36 Pl-Ru-C36’ P2-Ru-C35 P2-Ru-C36 P2-Ru-C36’
96.8(1) 91.7(2) 90.58(8) 88.34(8) 178.5(3) 83.7(4) 91.1(9) 90.4(1) 91.7(1) 84.3(3) 178.0(4) 89.4(2) 88.6(2) 87.3(3) 177.2(9) 177.70(8) 90.5(3) 87.6(4) 90.2(9) 90.6(3) 90.2(4) 91.9(9)
C35-Ru-C36 C35-Ru-C36’ Ru-P1-C1 Ru-P1-C11 Ru-Pl-Cl7 Ru-P2-C 10 Ru-P2-C23 Ru-P2-C29 C2-01-C3 C4-02-C5 C6-03-C7 C8-04-C9 P1 -Cl-C2 01-c2-c1 01-C3-C4 02-C4-C3 02-C5 -C6 03-C6-C5 03-C7-C8 04-C8-C7 04-C9-C 10 P2-ClO-C9
95.3(5) 90.0(9) 115.0(3) 112.1(3) 118.8(3) 116.6(3) 117.8(3) 111.6(3) 115.0(8) 115.6(9) 116.9(9) 114.3(7) 115.1(6) 107.8(7) 116(1) 115(1) 113(1) 106(1) 107.0(8) 113.6(8) 105.8(8) 117.4(6)
Table 10. Selected Torsion Angles (deg) for 4a, 4b*(CH&CO,and 1 C11-Ru-P1-C1 C11-Ru-P2-C10 Ru-Pl-Cl -C2 Ru-P2-ClO-C9 C3-01-C2-C1 C2-01-C3-C4 C5-02-C4-C3 C4-02-C5-C6 C7-03-C6-C5 C6-03-C7-C8 C9-04-C8-C7 C8-04-C9-C10 Pl-Cl-C2-01 01-C3-C4-02 02-C5-C6-03 03-C7-C8-04 04-C9-ClO-P2
4a
4b(CH3)zCO
1‘
67.3(3) -7 1.1(3) -71.7(7) 69.4(7) 158.8(8) 61U) -95(1) -169(1) 171(1) 175(1) -86(1) -178.3(7) 171.2(6) 6W) 159(1) 71(1) 170.8(6)
5333) -46.1(3) -166.5(6) 176.6(5) 179.6(7) 173.5(7) - 141.2(9) -83(1) 172.2(8) -172.1(8) 153.5(7) -78.8(8) -55.3(9) 67(1) 8W) -66.7(9) -139.4(6)
65.5(4) -65.3(4) -166.4(5) -61.5(8) 157.9(7) -177.8(6) 168.9(6) 173.9(5) 82.8(5) 178.4(4) -173.4(3) -50.5(9) 142.4(6) -79.6(5) -173.5(3)
a Data from ref 5 . Numbering is identical except Ru should be replaced with Mo.
c3
01
04
cloL 7
C26
Table 9. Selected Bond Angles (deg) for 4b.(CH&CO Cll-Ru-C12 C11-Ru-P1 Cll-Ru-P2 Cll-Ru-C35 Cll-Ru-C36 C12 -RU-P 1 C12-Ru-P2 C12-Ru-C35 C12-Ru-C36 P1 -Ru-P2 Pl-Ru-C35 Pl-Ru-C36 P2-Ru-C35 P2-Ru-C36 C35-Ru-C36 Ru-P1-C1 Ru-P1-C11 Ru-PI-Cl7
91.74(8) 87.88(7) 88.62(7) 91.9(2) 176.5(3) 87.01(7) 85.52(7) 176.3(2) 84.8(3) 171.65(8) 94.0(2) 91.2(2) 93.7(2) 91.8(2) 91.6(4) 109.2(2) 109.9(2) 118.7(2)
Ru-P2-C10 Ru-P2-C23 Ru-P2-C29 C2-01-C3 C4-02-C5 C6-03-C7 C8-04-C9 Pl-Cl-C2 01-c2-c1 01-C3-C4 02-C4-C3 02-C5-C6 03-C6-C5 03-C7-C8 04-C8-C7 04-C9-C10 P2-ClO-C9
112.2(2) 117.0(2) 112.8(2) 111.4(7) 114.4(9) 109.8(7) 107.3(7) 119.8(6) 109.4(8) 105.4(8) 104.9(8) 109.3(8) 103.2(8) 109.8(7) 102.4(8) 112.1(6) 114.9(5)
coordination chemical shifts (d31P complex - d31P ligand) (4b,35.11 ppm; 4c, 36.03 ppm; 4d, 36.45 ppm; 5b, 35.68 ppm; 5c, 36.44 ppm) are similar to those of cis,cis,trans-Ru(CO)~C12{Ph2P(CH2CH~O)~CH3-P}2 (6, 36.00 ~ p m 1 . lThis ~ ~ similarity is due to the fact that bridging bis(phosphine1ligands in oligomeric complexes can adopt conformations similar to those of monodentate phosphine ligands.14 The major products for each reaction appear to be monomers with trans-spanning P ~ Z . P ( C H ~ C H ~ O ) , C H ~ Cligands H ~ P Pas ~ ~demonstrated by the fact that their 31PNMR coordination chemical (14)Hill, W. E.; Minahan, D. M. A.; Taylor, J. G.; McAuliffe, C. A. J.Am. Chem. SOC.1982,104, 6001.
C15
14
Figure 1. ORTEP12drawing of the molecular structure of the major rotamer of 4a.Thermal ellipsoids are drawn at the 50% probability level, and hydrogen atoms are omitted for clarity.
shifts (4a,31.42 ppm; 5a,32.85 ppm), are smaller than that of 6. This difference is due to the fact that transspanning bis(phosphine) ligands cannot adopt conformations similar to those of monodentate phosphine ligands.14 These conclusions are supported by the X-ray crystal structures of 4a and 4b discussed below, and by the fact that the longer ligand, 3, gives a higher yield of the monomeric product, 5a. The variations in chemical shifts of the ipso, ortho, meta, and pura phenyl and the C1 and C2 methylene 13C NMR resonances are also consistent with the assignment of the solution structures of the RuC12(CO)~{P~~P(CHBCH~O),CH~CH~PP~~} complexes made in the previous paragraph. The chemical shifts of these resonances are similar for 4b and 4d, in which the Ph2P(CH2CH20)&H2CH2PPh2ligands are bridging, but are significantly different from those for 4a, in which the same ligand is trans-spanning. The chemical shifts of these resonances for Sa,in which the longer Ph2P(CH2CH20)&H2CH2PPh2 ligand is trans-spanning, are in-
Ruthenium Metallacrown Ethers
Organometallics, Vol. 14,No. 1, 1995 243
c3
0 4 h c 9 f o
I
gb
cll
l
I c19
W
Figure 2. ORTEPI2 drawing of the molecular structure of the minor rotamer of 4a.Thermal ellipsoids are drawn at the 50% probability level, and hydrogen atoms are omitted for clarity.
Figure 3. 0RTEPl2 drawing of the molecular structure of 4b.Thermal ellipsoids are drawn at the 50%probability level, and hydrogen atoms are omitted for clarity. termediate between those for 4a, on the one hand, and those for 4b and 4d, on the other. Although the complexes in this study are the first octahedral complexes observed to form both monomers with trans-spanning bis(phosphine) ligands and oligomers with bridging bis(phosphine) ligands, it is well established that such mixtures are formed when bis(phosphine) ligands react with square-planar platinumgroup metal (Rh(I), Ir(I), Pd(II), and Pt(I1)) precurs o r ~ . ~ ~ , ~ ~ the behavior of the 31P NMR However, (15)(a) March, F. C.; Mason, R.; Thomas, K. M.; Shaw, B. L. J. Chem. SOC.,Chem. Commun. 1976, 584. (b) Pryde, A.: Shaw, B. L.; Weeks, B. J. Chem. SOC.,Dalton Trans. 1976,322.(c) Appleton, T. G.: Bennett, M. A.; Tompkins, B. I. J . Chem. Soc., Dalton Trans. 1976, 439. (d) Sanger, A. R. J . Chem. Soc., Dalton Trans. 1977, 120. (e) Alcock, N.W., Brown, J. M.; Jeffery, J. C. J . Chem. Soc., Dalton Trans. 1977,888.(0 Sanger, A. R. J. Chem. SOC.,Dalton Trans. 1977,1971. (g) Al-Salem, N.A.; Empsall, H. D.; Markham, R.; Shaw, B. L.; Weeks, B. J. Chem. SOC.,Dalton Trans. 1979,1972.(h)Hill, W. E.; McAuliffe, (i) C. A.; Niven, I. E.; Parrish, R. V. Inorg. Chim. Acta 1980,38,273. Crocker, C.; Errington, J.; Markham, R.; Moulton, C. J.; Odell, K. J.; Shaw, B. L. J. Am. Chem.SOC.1980,102,4373.(i) Hill, W.E.; Minahan, D. M. A.; McAuliffe, C. A. Inorg. Chem. 1983,22,3382. (16)Gray, G. M.; Redmill, K. A. Inorg. Chem. 1985,24,1279.
coordination chemical shifts is quite different for the two types of complexes. In the square planar complexes, the coordination chemical shifts from trans-coordination of bidentate ligands increase as the length of the ligand decreases,14but the opposite trend is observed for 4a and Sa. This suggests that the additional cis ligands in octahedral complexes cause the conformations of trans-spanning ligands in these complexes to be different from those of trans-spanning ligands in square planar complexes. A final point of interest is that a single NMR resonance is observed for the carbonyl ligands in both 4a and 5a. This suggests that the RuC12(CO)2 group moves freely within the chelate ring to average the environments of the two carbonyl ligands because the chemical shifts of carbonyl resonances in transition metal complexes are quite sensitive to asymmetry in the phosphine ligands.15 The rotation of the RuC12(C0)2 around the P-Ru-P axis is strongly supported by the fact that two rotamers of 4a are observed in the solid state, as discussed below. The carbonyl 13C NMR resonance of 4a does not broaden as much as does that '1, of ~~~~~-Mo(CO)~{P~~P(CH~CH~O).&H~CH~P :1 as the temperature is lowered from 21 "C t o -80 "C. This suggests that the barrier to rotation about the P-M-P axis is somewhat lower in 4a than in 1. The lower rotation barrier in 4a could be due to the fact that the carbonyl ligands in 4a can be averaged by rotating the RuC12(CO)2group so that the trans-spanning ligand moves over the smaller chlorides but not over the larger carbonyl ligands. This is not possible in 1. X-ray Crystal Structure of cis,cis,truns-RuCl~(CO>~{P~&'(CH&HZO>&HZCHZ~P~~-P~ '1,4a. The X-ray crystal structure of 4a has been determined. The ruthenium has an octahedral coordination geometry with a trans-spanning Ph2P(CH2CH20)4CH2CH2PPhz ligand, cis carbonyl ligands and cis chloride ligands consistent with the NMR data. Two rotamers of the RuCl2(C0)2 group relative to the trans-spanning ligand are observed, and ORTEP drawings of the major and minor rotamers Of 4a are shown in Figures 1and 2. In the major rotamer (-70%), the trans-spanning ligand passes between one carbonyl and one chloride while in the minor rotamer (-30%), the trans-spanning ligand passes between the two chlorides. There is no evidence of the third rotamer in which the trans-spanning ligand would pass between the two carbonyls. The relative abundances of the two rotamers are consistent with a statistical occupancy of the sites. The presence of rotamers in the crystal structure of 4a may be due to the fact that rotation about the P-Ru-P bond to generate the two different rotamers does not affect the orientation of the phenyls and the trans-spanning polyether chain. Because these are the outermost portions of the molecule, the rotamers would have the same shapes and could cocrystallize. However, if this is the case, it is somewhat surprising that the third rotamer, in which the trans-spanning ligand passes between the two carbonyls, is not observed. It is possible that this rotamer is not observed because, when the trans-spanning ligand is between two larger carbonyl ligands, it adopts a different and less stable conformation that prevents cocrystallization with the other two rotamers. This hypothesis is supported by the fact that conformation of the trans-spanning ligand
244
Gray et al.
Organometallics, Vol. 14,No. 1, 1995
in 4a is quite different from that of the identical ligand in 1 as indicated by torsion angles (Table 10)that differ by as much as 60". X-ray Crystal Structure of [cis,cis,truns-RuCl2(CO)2(C1-Ph2P(CH2CH20)4CH2CH2PPh2PQ '}, 4b.The X-ray crystal structure of 4b has been determined and shown to be a cyclic dimer. A n ORTEP drawing of the structure is shown in Figure 3. Consistent with the NMR data, each Ru has an octahedral coordination geometry with trans, bridging Ph2P(CH&H20)4CH2CH2PPh2 ligands, cis carbonyl ligands and cis chloride ligands. The bond lengths and angles about the Ru are similar to those observed in 4a with the largest difference in the P-Ru-P angles (4b: 171.65(8)";4a: 177.70(8)"). This is consistent with the fact that the 31PNMR coordination chemical shift of 4b was larger than that of 4a which suggested that the phosphorus environments were different in the two complexes. The most interesting feature of this structure is that the trans coordination of the bridging bidphosphine) ligands results in two, separate metallacrown ether sites. Because each ruthenium is octahedral and the molecule crystallizes around an inversion center, both a chloride and a carbonyl ligand stick into the cavity and separate these two sites. This results in a Ru-Ru distance of 9.1961(9) A indicating that there is no interaction between the two ruthenium centers. These
cavities are enclosed by the phenyl groups on P1 and P2 that are located above and below the cavities. This conformation suggests that it may be possible to coordinate a hard metal cation to each of these sites to form tetrametallic complexes. It may also be possible to bridge a bidentate ligand between the two rutheniums to generate a more rigid dimetallacrown ether. Such complexes could exhibit unusual catalytic activities and selectivities.
Acknowledgment. The authors thank the donors of the Petroleum Research Fund, administered by the American Chemical Society, for partial support of this research, Johnson Mathey for a generous loan of RuCl3-nH20, and Dale C. Smith, Jr., for helpful discussions. A.V. thanks the Graduate School of the University of Alabama a t Birmingham for a Graduate Fellowship. Supplementary Material Available: Tables of X-ray crystallographic data for 4a and 4b including hydrogen coordinates and B values, anisotropic thermal parameters, complete bond lengths and angles, torsion angles, and least squares planes (16 pages). Ordering information is given on any current masthead page.
0M940650+
