1806 Inorganic Chemistry, VoZ. 11,No. 8, 1972
vents such as benzene, chloroform, and CS2; however, in the case of NiS.&H4 it is noteworthy that there were no significant changes in infrared spectra under these conditions.
R. BALLAND M. J. BENNETT Acknowledgment.-This work was supported in part by the Air Force Office of Scientific Research, Air Force Systems Command, C'nited States Air Force, under AFOSR Contract F44620-72-C-0006.
CONTRIBUTION FROM THE DEPARTMENT OF CHEMISTRY, ALBERTA,CANADA UNIVERSITYOF ALBERTA,EDMONTON,
The Crystal and Molecular Structures of the Cis and Trans Isomers of Bis(trichlorogermany1)tetracarbonylru thenium BY R. BALL
AND
M. J. BENNETT*
Received August 16, 1971 T h e crystal and molecular structures of the trans and cis isomers of bis(trichlorogermany1)tetracarbonylruthenium have been dete5mined. ti,uns-R~(C0)4(GeCl.j~ cTystallizes in the monoclinic space group P21jn with unit cell dimensions Q = 9.152 (1) A, b = 10.025 (1)A, c = 8.399 (1)A, P = 94.84 (I)', and two molecules per unit cell (&bad = 2.46 g cm-3, poitlod = 2.47 g cm-3). cjs-Ru(C0)4(GeC1s)2crystallizes in monoclinic space group P21 with unit cell dimensions u = 9.759 ( 5 ) d, b = 12.608 (10)A, c = 12.878 (9)A, p = 91.57 (IO)', and four molecules per unit cell (pobsd = 2.40 (2) g cm-3, po&d = 2.39 g ~ m - ~ ) Data . were collected using counter methods and the structures were refined using least-squares procedures t o give R = 0.019 and 0.041 for trans and cis isomers, respectively. Both structures contain discrete molecular species with octahedral coordination of the ruthenium atoms. The chemically differentoruthenium-carbon distances in the cis isomer are not significantly different from each other-1.98 A (trans to GeClS), 2.00 A (trans to C0)--gr from that observed in the trans isomer, 1.98 A. The ruthenium-germanium distances are the same in both isomers (2.48 A). These bond lengths are consistent with the force constant calculations t h a t had suggested an unusual T-bonding ability for the trichlorogermanyl groups in these compounds.
Introduction Compounds of the type M(C0)4(M1X& (where M = Fe, Ru, Os; M' = Si, Ge, S n ; X = C1, Br, I, alkyl, aryl) have been found to exist as cis and/or trans There are several factors which can affect the relative stability of the cis and trans isomers. A consideration of n-bonding abilities for the ligands CO and M'X3 suggests that any discrepancy (either CO >> M'X3 or M'X3 >> CO) would favor the cis isomers. These relative n-bonding abilities would be expected to vary with M, M', and X. The other major factor influencing the preferred geometry involves intramolecular repulsions. Thus the investigations of Stone, et U Z . , ~ , ~on trialkyl and triaryl, silyl, and stannyl derivatives of Ru(C0)4, where definite equilibria were established, showed increasing preference for the trans structure as the bulkiness of the M'R3 group increased. However, when X = a halogen in the cis compounds, an additional interaction may be possible but attractive in nature rather than repulsive. This is due to the potential to form intramolecular halogen bridges where the main group I V element increases its coordination number to 5 . Thus Graham and Kummerl recognized the possible importance of structures I and I1 for cisM(M'X3)z fragments. While the formation of a weak halogen bridge has been demonstrated in bipy(C0)aC l h i l ~ S n C H ~ Casl ~yet , ~ there is no direct confirmation that cis M'X3 groups do interact in this way. (1) R . Kummer and W. A. G. Graham, Inorg. Chem., 7, 1208 (1968). (2) J. D. Cotton, S. A. R. Knox, a n d F . G. A. Stone, J . Chem. SOL. A , 2758 11968). (3) R. K. Pomeroy, M. Elder, D. Hail and W. A. G. Graham, J . Chem. SOC. D ,381 (1969). (4) M. Pankowski and M. Bigorgne, J . Organometai. Chem., 19, 393 (1969). ( 5 ) S. A. R. Knox and F. G. A. Stone, J . Chem. SOC.A , 2559 (1969). (6) R . K . Pomeroy and W. A. G. Graham, in preparation. (7) M . Elder and D. Hall, J . Chem. SOC.A , 245 (1970).
X
M
\ I x ,/ x
/"'... 'X
X M
X
p,x
/ \ ;,/ M
x
/
\
x
x
/
\
x
I1
I
Of particular interest was the synthesis and isolation of both the cis and trans isomers of bis(trich1oro-
germanyl)tetracarbonylruthenium ( R U ( C O ) ~ ( G ~ C I ~ ) ~ ) ~ where the spectroscopic studiesS suggested that the 7-acceptor properties of GeC13 were comparable with those of carbon monoxide. The physical properties of the cis and trans isomers raised the question that the cis and trans isomers might contain intra- and intermolecular halogen to Ge bridge bonding, respectively.6 The current structural study was undertaken to investigate these features. Experimental Section (a) tuans-Ru(CO)4(GeC18)2.-The white well-formed crystals, as supplied by Dr. W.A . G. Graham and Mr. R . K . Pomeroy, were found to b e suitable for a n X-ray diffraction study. The l k l , 2kZ (Cu K a Weissenberg) preliminary photography-Okl, the crystals to be and h01, hkO (Mo K a precession)-showed 1 monoclinic, and t h e systematic absences-Ok0 for k = 2n and h0Z for h 1 = 2n 1-suggested the nonstandard space group P21/n. The lattice parameters and their estimatgd standard deviatiyns were obtained*at 22" as a = 9.152 (1) A , b = 10.025 (1) -4, c = 8.399 (1) A, and 0 = 94.84 (l)', by a least-squares refinement using 20 values for 12 high-angle reflections that had been accurately centered on a Picker manual four-circle diffractometer (Cu Knl radiation, X 1.54051 A ) . The observed density, measured by flotation as 2.46 (2) g ~ m - is ~ , in good agreement with that calculated, 2.47 for two mole-
+
+
(8) R. Gray and W . A. G . Graham, in preparation.
+
Inorganic Chemistry, Vol. 11, No. 8, 1972 1807
BIS(TRICHLOROGERMANYL)TETRACARBONYLRUTHENIUM cules per unit cell. The molecules are required to sit a t special positions with site symmetry 1 by these conditions. The faces and dimensions of the study crystal were determined by vjsual (170) 0.18 mm (110), inspection to be (110) 0.19 mm (107) 0.12 mm (iOl), and (011) 0.24 mm (Oiii-the distances indicate the perpendicular distances separating each pair of centrosymmetrically related faces. The crystal was mounted with a* coincident with the 6 axis of the manual diffractometer. Intensity data were collected using Mo K a radiation to minimize absorption correctionsMo K a , p = 58.6 cm-'; Cu K a , 1.1 = 223 cm-'. The radiation was monochromated by an oriented graphite crystal (002 reflection) and detected using a scintillation counter with pulse height analyzer tuned to a %'yowindow. Intensities were measured using the coupled a-20 scanning technique with 28 scanned over the range 20 f 1.5" a t a scan speed of 2"/min. Data were measured to a maximum 20 limit of 45". Backgrounds were estimated from a linear interpolation of two 30-sec stationarycrystal, stationary-counter measurements made a t the limits of the scan. Six standard reflections were measured periodically during data collection and showed no evidence of decomposition, the deviations being i l % . T o provide a guide as to the correctness of the absorption correction, three hOO reflections were measured a t 10" intervals of 6 over the range 0-180". The data were corrected for Lorentz polarization effects and absorption (transmission factor range 0.40-0.45) and were reduced to structure amplitudes with standard deviations estimated using the procedure of Doedens and Ibersg with a p factor of 0.03. The +-scan data showed excellent internal consistency (-1% where counting errors were negligible). Of the 806 independent reflections scanned, 667 were estimated to be significantly above background using the criterion I / u ( I ) > 3.0 where u(I) was calculated from pure counting statistics. (b) ci~-Ru(CO)4(GeC13)~.-Thesame procedures as used for the trans isomer yielded the following data for the white crystals: preliminary photography-hOZ, 811, h21 (Cu Ka Weissenberg) and hkO, OkB (Mo K a precession); systematic absences OkO for k = 2n 1, systematic weaknesses hkl for h I = 2n 1; space group P21 or P21/m approximating to B21 or B 2 1 / ~ ; lattice parameters a t 22' a = 9.759 (5) A, b = 12.608 (10) A , c = 12.878 (9) A, and p = 91.57 (1)'; observed density 2.40 (2) g cm-I and calculated density 2.39 g for four molecules in the unit cell; no imposed symmetry; crystal faces and forms identified as { l O l } , ( l o x } , { OOl), ( O l O } ; approximate dimensions 0.12 X 0.09 X 0.12 mm; crystal mounted with b* coincident with the + axis; Mo K a absorption, p = 57.8 an-'; transmission factor range 0.47-0.65; internal consistency &3%; no decomposition; 1752 reflections scanned-1087 selected on the basis I/u(I) 2 2.0 (a lower standard than used for the trans isomer but this was considered necessary to provide a more suitable number of reflections).
(no),
+
+
group and the general positions were derived as x, y, 2;; 11, j, 3; x, '/z - y, '/z 2; '/z - x, ' / z y , '/z --2. The required symmetry of the molecules (1) locates the ruthenium atoms a t one set of special positions; the set 0, 0, 0 and '/z, '/z, '/z was chosen. A solution for the approximate coordinates of the germanium atom was obtained from a threedimensional Patterson map. The remaining atoms were located from an observed electron density map computed from structure factors phased by the ruthenium and germanium atoms. The least-squares refinement of the structural parameters minimized the function Zw(lF,I - / F c 1 ) 2 ,where w = l/u2(IFo/). Structure factors were calculated using the atomic scattering factors of Cromer and Waberlo with anomalous scattering'' of Ru, Ge, and C1 included in the calculated structure factors.l2 = 0.067, Three models were tested: (1) all atoms isotropic-& RZ = 0.086 (RI defined as 211F.1 - lFc11/21F01;RZdefined as Zw(IF,l - ~Fc~)z/2wFoz)1/2); (2) Ru, Ge, and C1 anisotropic, C and 0 isotropic-R1 = 0.035; RZ = 0.045; (3) all atoms anisotropic-Rl = 0.028, RZ = 0.038. The introduction of anisotropic thermal parameters was justified by electron den-
+
+
+
+
TABLE I1 Atomic Parameters for trans-Ru(C0)4(GeC13)~
+
(9) R. J. Doedens and J. A. Ibers, I n o v g . Chem., 6, 204 (1967). (10) D . T. Cromer and J. A. Waber, Acta Crystallogv., 18, 104 (1965). (11) D. T. Cromer, ibid., 18, 17 (1965). (12) J. A. Ibers and W. C. Hamilton, ibid., 17, 781 (1964).
z 0.0 0.21377 (6) 0.14589 (19) 0,40742 (18) 0,33553 (19) -0.0066 (6) -0.1679 (7) -0.0119 (5) -0,2630 (5)
Y
X
0 0 -0 00568 ( 5 ) n 0 01991 (19) 0 16309 (16) -0 20348 (17) -0 2155 (7) -0 0264 (5) -0 3370 (5) -0 0426 (5)
+
Structure Solution and Refinement trans-R~(CO)~(GeCl~)~.-P2i/n is a nonstandard space (a) '/z
sity difference maps and by the Hamilton statistical test.13 The poor agreement of several strong reflections (lFol < lFcl) suggested that the crystals suffered from extinction and that a correction was desirable. The least-squares program allows extinction corrections to be applied to F, using the F,' = F,/[l p(28)CI], where C formula of Z a c h a r i a ~ e n , ' ~ is a variable parameter. For this study the maximum value of p ( 2 0 ) C I appeared to be 0.2, as judged by the worst discrepancies between Fo and F,. Consideration of crystal size, 28 range, and total extinction correction suggested that the approximate formula for the extinction correction (1 C I ) was acceptable. The structure was refined to convergence (maximum shift onefifth of a n estimated standard deviation) to give RI = 0.019 and The main effect of inRZ = 0.024 with C = 1.06 X cluding the extinction correction was to increase the thermal parameters. Smaller effects were observed for the fractional coordinates of the carbon and oxygen atoms where the average shift was approximately one standard deviation. N o comparable coordinate shifts were observed for the germanium and chlorine atoms. The final value for the standard deviation of an observation of unit weight was 0.91 suggesting that the p factor used in the u ( F ) calculation was slightly too high. However an analysis of local averages of w(lF,,l - / F ~ ~for ) z ranges of F, and (sin 8)/X suggested that the weighting scheme was acceptable on a relative scale.16 Structure factor calculations for the rejected data showed no lFo'sl in excess of 1.31Fm,nl. Final observed and calculated structure amplitudes are listed in Table Ile and the atomic parameters are collected in Table 11.
0.0 0.16971 (5) 0,37406 (15) 0.14574 (16) 0.16794 (16) -0.0174 (5) 0.1386 (5) -0.0277 (4) 0.2161 (4)
Anisotropic Thermal Parametersb ( X lo4) for trans-Ru(CO)4(GeC13)~ Atom Ru Ge Cl(1) Cl(2) Cl(3) C(1) C(2) O(1) O(2)
bii
822
62 9 (9)a 88 1 (9) 237 (3) 137 (2) 123 (2) 103 (10) 69 (7)
54 8 (7) 62 0 (7) 66 0 (2) 145 (2) 135 (2) 61 (6) 84 (7) 156 (6) 106 (5)
66 (6) 162 (7)
Ria
812
833
79 89 157 133 179 112 108 224 137
7 (11) 7 (11) (3) (3) (3) (10) (10) (9)
(7)
2 8 (6) 0 9 (6) -24 (2) 13 (2) 2 (2) -3 (6) 6 (6) -92 ( 5 ) 1 (5)
8 1 (7) 8 1 (6) 0 (2) 42 (2) 61 (2) 10 (7) 20 (7)
8 (6) 6 (6)
Pz3
-1 9 (6) -8 8 (6) 5 (2) -9 (2) -32 (2)
5 -25 24 43
(6) (7) (6) (6)
Numbers in parentheses for the listed parameters are standard deviations and refer t o the last digit listed. *Temperature factor expressed in the form exp[-(h2& k2& Z2P83 2hkP12 2h&3 2kJPz3)I.
+
+
+
+
+
(b) cis-Ru(CO)4(GeC13)z.-A statistical analysis" of the data suggested that the structure was noncentrosymmetric. The space group P21 was assumed for the initial solution and this was subsequently confirmed by refinement. The asymmetric unit then contained two independent molecules. The Patterson showed a very large vector a t ' / z ,0, '/z which suggested that the two independent molecules were related by a pseudo B-face centering as previously expected on the basis of systematic weaknesses in the data (hkl for h I = 2% 1). The approxi-
+
+
(13) W. C. Hamilton, ibid., 18, 502 (1965). (14) W. H . Zachariasen, ibid., 16, 1139 (1963). (15) D. W. J. Cruickshank in "Computing Methods in Crystallography." J. S. Pollet, Ed., Pergamon Press, London, 1965, p 114. (16) Structure amplitude listings, Tables I and 111, will appear following these pages in the microfilm edition of this volume of the journal. Single copies may be obtained from the Business Operations Office, Books and Journals Division, American Chemical Society, 1155 Sixteenth St., N.W., Washington, D . C. 20036, by referring t o code number INORG-72-1806. Remit check or money order for $3.00 for photocopy or $2.00 for microfiche. (17) I. L. Karle, K . S. Dragonette, and S. A. Brenner, Acta Cvystallogv., 19, 713 (1966).
R. BALLAND M. J. BENNETT
1808 Inorgcinic Chemistry, Vol. 11, No. 8, 1972
TABLE V INTRAMOLECULAR GEOMETRY FOR trans-Ru(CO)a(GeC13)z
TABLE IV Atomic Parameters for cis-Ru(C0)4(GeCL)z Atom Ilu(1) Ru(2) Ge(1) Ge(2) Ge(3) Ce(4)
Cl(1) Cl(2) Cl(3) CI(4) Cl(5) Cl(6) Cl(7) Cl(8) Cl(9) Cl(10) Cl(11) Cl(12) C(1) C(2) C(3) C(4) C(5) C(6) C(7) C(8) O(1) 0(2) O(3) O(4) O(5) O(6) O(7) O(8)
Y
2
0.0 -0,01134 (31) -0.02650 (41) 0.1O38i (39) 0.17871 (33) 0.01805 (38) 0.0342 (9) 0 . 0 4 6 0 (IO) -0.1869 (IO) 0.2726 (9) 0.2498 (IO) 0.2863 (9) 0.2321 (8) 0,2295 (8) 0,2930 ( 8 ) 0.0831 (9) -0.1213 (9) 0.1263 (9) -0.0193 (34) 0.0310 (26) -0.1534 (33) 0.0254 ( 2 7 ) -0,0319 (29) 0.0204 (32) - 0 , 0 2 6 0 (25) -0.1594 (36) -0,0251 (25) 0.0451 (18) -0.2406 (29) 0,0376 (19) -0 0373 (20) 0.0450 (18) -0.0384 (19) -0.2468 (23)
0.16628 (18) -0,31807 (19) 0.38814 (25) 0,18929 (30) -0.38153 (25) -0,12909 (26) 0 . 4 2 2 8 (6) 0 . 4 4 7 3 (8) 0.4036 (8) 0,3290 (7) 0.1883 (11) 0.0795 (8) -0.3664 (8) -0,4967 (7) -0,2443 (7) -0.0441 (7) -0.04150 (8) -0,0896 ( 7 ) 0.1854 (27) 0.1639 (20) 0.1628 (29) 0.0166 (23) -0,3233 (25) -0.3002 (25) -0.4678 (22) -0,2874 (31) 0.2025 (21) 0.1632 (15) 0.1370 (24) -0.0733 (17) -0,3220 (16) -0.2903 (16) -0.553 (17) -0.2724 (19)
Y
0 . 4 8 2 8 2 (24)" -0,03844 (23) 0.43687 ( 3 3 ) 0.48238 (36) -0,00246 (32) -0.00281 (32) 0.2848 (8) 0.5976 (9) 0.4473 (10) 0.4308 (IO) 0.6820 (10) 0.35670 (12) 0 , 2 0 5 7 (9) -0,0983 (IO) -0,0858 (9) - 0 . 1693 (9) 0.0481 (11)
0.1586 0.6543 0.2498 0.4235 0,4699 0.1571 -0.2293 -0,0642 -0.0626 0.7646
0.1416 0.4155 0.4799 0.2760 -0.3427 -0,0759 -0,0772
(10) (36)
(28) (37) (26)
(32) (32) (24) (39) (25) (22) (25) (19) (21)
(21) (20) (24)
B,
fiz
b b b b b b b b b b b b b b b b b b
PI1
022
51 ( 3 ) 38 (3) 102 (4) 68 (4) 47 (3) 66 (4) 173 (12) 1 7 9 (15) 133 (12) 112 (11) 124 (13) 79 (IO) 91 (IO) 78 (9) 61 (8) 135 (IO) 98 (IO) 143 (10)
P93
46 47 47 69 56 48 49 96 117 94
(2)
(2) (3) (3) (3) (3) (6) (9) (IO) (9) 301 (19) 101 (IO) 135 (IO) 69 ( 7 ) 77 (7) 65 (8) 77 (9) 81 (9)
013
PI2
-3 2 4 -30 1 14 27 2 5 38 -79 -20 10 -22 29 29 78 25
7 (2) 8 (2) 6 (3) 18 (3) 5 (3) 7 (3) 16 (7) -75 (IO) -18 (10) (12) - 7 (IO) (12) 116 (14) (12) -24 (11) (IO) 26 ( 8 ) (IO) -26 (8) (IO) 17 ( 8 ) (11) 2 2 (8) (13) 11 (IO) (12) 41 ( 1 0 ) (3) (3) (4) (4) (3) (14) (IO) (12) (11)
Dist
Cor distQ
A
Atoms
Dist
Ru-Ge 2.477 (1)b 2.481 (1) Ge-Cl(2) Ru-C(l) 1.976 (6) 1.980 (6) Ge-Cl(3) Ru-C(2) 1.980 (6) 1.981 (6) C(1)-0(1) Ge-Cl(1) 2.145 (2) 2 , 1 6 6 (2) C(2)-0(2)
Cor dista
2.160 (2) 2 , 1 7 9 (2) 2.153 (2) 2,171 (2) 1.114 (6) 1 . 1 5 4 (7) 1 , 1 1 5 (6) 1.151 ( 7 )
Bond Angles, Deg Atoms
Angle
Ge-Ru-C( 1) Ge-Ru-C(2) C(l)-Ru-C(2) Ru-Ge-Cl(1) Ru-Ge-Cl(2) Ru-Ge-Cl(3)
90.0 (1) 8 9 . 8 (1) 8 8 . 9 (2) 117.00 (5) 114.33 (5) 114.11 (5)
Atoms
.4ngle
Ru-C(l)-O[l) Ru-C(2)-0(2) Cl(l)-Ge-C1(2) Cl(l)-Ge-C1(3) C1(2)-Ge-C1(3)
179.3 (5) 179.3 (5) 102.7 (1) 104.4 (1) 102.6 (1)
Selected Intramolecular Contacts,
6 . 7 (9) 3.7 (7) 6 . 0 (9) 3.9 (7) 5 . 2 (8) 6 . 1 (9) 3 . 0 (6) 7 . 0 (10) 8.7 (7) 5 . 3 (5) 1 0 . 0 (9) 5 . 4 (5) 6 . 2 (6) 5 , 3 (5) 5.3 (5) 6 . 6 (7)
Anisotropic Temperature Factors ( X 104) for cis-Ru(CO)d(GeCla)z 90 (3)' 90 (3) 110 (4) 138 (5) 105 (4) 118 (4) 156 (12) 176 (15) 184 (16) 232 (17) 179 (17) 330 (21) 131 (12) 231 (15) 194 (14) 188 (15) 320 (21) 167 (21)
Bond Distances, Atoms
823 0 (2) 2 (2) 13 (3) - 2 1 (3) 2 (3) 6 (3) 1 (1) - 1 6 (IO) 52 (10) 35 (9) -84 (13) 24 ( 8 ) 11 (8) 32 (7) -15 (7)
-8 ( 7 ) 33 (8) 0 (8)
Kumbers in parentheses for the parameters are estimated standard deviations and refer to the last digit listed. * Anisotropic thermal parameters used. Q
mation of the structure to the space group B21 leads to an ambiguity in the solution for the coordinates of the ruthenium and germanium atoms. This ambiguity is simply related t o the correct identification of the true and pseudo 2' axes. A careful investigation of the Patterson map showed a preference for one solution, hut the alternative was also tested in the early stages of refinement. To improve the phasing the calculated positions of the CO groups were introduced into both models. The preferred model refined to RI = 0.28, and an electron density difference map indicated possible positions for the C1 atoms. The alternate solution proved to be a false minimum that failed to reduce R1 below 0.35. Even for the correct solution the identi. fication of the chlorine atoms was not quite routine. Semispecial coordinate relationships within each molecule as well as the pseudosymmetry caused several chlorine atoms to refine to false positions. Several difference maps were required before a sensible geometry was achieved and the structure was refined with isotropic temperature factors to R1 = 0.071, RZ = 0.07'7. The electron density difference maps computed a t this stage suggested the use of anisotropic temperature factors, but considering the shortage of data, anistropic refinement was limited
Atoms
Cl(1). . . Cl(2) Cl(1). . .C1(3) C1(2), . . Cl(3) Cl(1 )-C(2) Correction assuming deviations are given in quoted.
Dist
Atoms
Dist
3.36 C1(2)-C (1)' 3.67 3.40 Cl(Z)-C(2)' 3.67 3,37 C1(3)-C(1) 3.42 3.54 second atom rides on first.lB b Standard parentheses and refer to the final digit
TABLE VI IXTERMOLECULAR NONBOSDED CONTACTS (
