532
W. GANTMCPHERSQN AND EDWARD A. MEYERS
The Crystal Structures of Bismuth Halide Complex Salts. 11. Bispiperidinium Pentabromobismuthate(II1) by W. Gant McPherson' and Edward A. Meyers Department o j Chemistry, Tezas A & M University, College Station, Teza8 77849
Bispiperidinium Bi'11Br6 (piperidine
=
(Received June SO, 1967)
CHzNH) is orthorhombic, P212121,
2 = 4. The anion shows a distorted octahedron of Br atoms around Bi, with two Br bridges that link adjacent Bi atoms. The bridge distances and angle are BiBr3 = 3.019 f 0.008 8, = 3.125 0.008 8, and (Br3)(Bi)(Br3') = 91.9 f 0.2". Opposite the bridges are E 2 = 2.694 f 0.009 8 and B m = 2.649 f 0.007 8; perpendicular to = 2.837 0.007 A and B x 4 = 2.877 i the plane of the other Bi-Br bonds are 0.007 8. There is little evidence for the influence of the Bi "lone pair" upon the coordination around Bi, and the total Pauling bond order for the Bi-Br bonds is 2.9. However, since no satisfactory correction was made for the effect of thermal motion on bond distance, these values may be too small and less reliable than indicated. The cations are in the chair conformation, and the N ring atoms have been identified from their close contacts with Br atoms.
m'
*
*
Introduction Because of the relatively small amount of structural data on bismuth compounds and the ready availability to us of a number of group V halogen complex compounds12J we have undertaken a systematic series of X-ray studies of a number of these materials. Our previous work4 has shown that the configuration of the bismuth-halogen groups in the isomorphous crystals of 2-picolinium Bi"'Br4 and Bi1"14 differ considerably from those reported for antimony-halogen groups in Sb"'F4 compounds.6rs I n this study, the structure of the bismuth-halogen unit in a BilIIBrs compound is reported and compared to those found previously for the antimony-halogen groups in Sb'"F6' and Sb111Cls8salts.
Experimental Section A needle-like single crystal of bispiperidinium Bi"'Br6 of cross section 0.1 X 0.2 mm was selected from a sample of the compound prepared and analyzed by Osborn.2 The crystal was sealed within a thin-walled glass capillary and mounted on a Buerger precession camera. Precession data were collected for the (hOZ), (Okl), and (hh2) zones with (Zr filtered) Mo K, radiation (X = 0.7107 8) and a precession angle of 30". The space group is orthorhombic, p24-P2~2~21 with a = 18.53 f 0.03 8, b = 12.65 f 0.03 A, and c = 8.83 f 0.02 A; dobsd (flotation) = 2.52 f 0.02 g/cc, = 4. dcslcd = 2.51 g/CC for The crystal was transferred to the Weissenberg camera, and (hkl) data collected for Z = 0 to 1 = 5. A The Journal of Phusical Chemistry
multiple film pack and (Ni filtered) Cu K, radiation (A = 1.5418 A) were employed. Lorentz, polarization, and absorption corrections were applied to the data. For absorption corrections, the crystal was treated as a cylinder, r = 0.0075 om: With Mo radiation, pctr = 1.69; with Cu radiation p r = 2.69 for the (hkO) zone. The optical densities of 1523 reflections were read with a Welch Densichron, Model I, and these optical densities were converted to intensities via an internal calibration. Bismuth atom coordinates were obtained from the one-dimensional Patterson projections constructed from the axial reflections. The bismuth atom was used to calculate structure factors'o and electron-density funcQ
(1) Submitted to the Graduate College of Texas A & M University in partial fulfillment of the requirements for the degree of Doctor of Philosophy, 1967. (2) J. F. Osborn, Master's Thesis, Texas A & M University, College Station, Texas, 1960. (3) J. C. Scott, Master's Thesis, Texas A & M University, College Station, Texas, 1960. (4) B. K. Robertson, W. G. McPherson, and E. A. Meyers, J . Phgs. Chem., 71,3531 (1967). (5) A. Bystrom, S. Backlund, and K. A. Wilhelmi, Arkiv. Kemi, 4, 175 (1952).
S. Backlund, and K. A. Wilhelmi, ibid., 6, 77 (1953). (7) A. Bystrom and K. A. Wilhelmi, ibid., 3, 461 (1951) (8) M. Edstrand, M. Inge, and N. Ingri, Acta Chem. Scand., 9, 122 (1955). (9) A. J. Serewicz, B. K. Robertson, and E. A. Meyers, J . Phye. Chem., 69, 1915 (1965). (10) Atomic scattering factors for Bi, Br, N, and C were taken from (6) A. Bystrom,
I
"International Tables for X-Ray Crystallography," Vol. 111, Kynoch Press, 1962: Bi, p 212; Br,pp 206, 207; N and C, pp 202, 203.
THECRYSTAL STRUCTURES OF BISMUTH HALIDE COMPLEX SALTS tions” were plotted from (hot) and (Okl) data. From these two projections, the five bromine peaks were easily located and least-squares12 refinement of the heavy atom (Bi and Br) positions was satisfactory for (h01) and (Okl) data. In order to locate the lighter atoms of the two independent piperidinium rings, A and B, least-squares refinement, with isotropic temperature factors, was carried out on the heavy-atom parameters for the Weissenberg data, and a three-dimensional difference electrondensity map was constructed. Two different ring structures, A and B, were visible and these atoms labeled CA and CB, respectively, were included in the least-squares refinement. Neither peak heights nor bond distances served to distinguish C from N, so that all ring atoms were assigned the carbon scattering factor. For 80 of the Weissenberg data which have (FoI > 180 the optical densities were too large to measure accurately even on the lightest film, and these reflections were omitted from the least-squares refinements. Unit weights were assigned to the remaining reflections. The discrepancy indexes
for the least-squares refinement of all parameters including scale factors for the individual zones for Weissenberg and precession data with isotropic temperature factors were R1 = 0.127, R2 = 0.146. The introduction of anisotropic temperature factors for the heavy atoms reduced the value of R1 to 0.087 and Rz to 0.108. The light-atom temperature factors were isotropic in this calculation. The least-squares refinements with isotropic temperature factors for the Weissenberg and precession data separately gave R1 = 0,119, Rz = 0.131, and R1 = 0.106, Rz = 0.128, respectively. There were too few precession data (148) to permit refinement of the light-atom parameters, so they were fixed at the values obtained in the isotropic refinement of all of the data. When the effect of anomalous dispersion1* was included in the calculations with isotropic temperature factors, the Weissenberg and the precession data gave RI = 0.112, RZ = 0.123, and R1 = 0.113, Rz = 0.136, respectively. Our final conclusion was that the anisotropic refinement results were satisfactory and the parameters obtained from these calculations are given in Table I. A table of observed and calculated structure factors ma,y be obtained from the authors upon request. A comparison of the bond distances from the results of several refinements is given in Table 11, and it may be seen that there are no significant differences between corresponding values obtained in the various refinement procedures. However, there were
533
Table Ia : Atomic Coordinates of Bispiperidinium Pentabromobismuthate( III)a 2
Bi Brl Br2 Br3 Br4 Br5 CA1 CA2 CA3 CA4 CA5 CA6 CB1 CB2 CB3 CB4 CB5 CB6
0.1778 (1) 0 0659 (3) 0.1178 (6) 0.2489 (4) 0.3068 (3) 0,1103 (4) 0.5054 (31) 0.5828 (35) 0.5822 (19) 0.5287 (31) 0.4505 (38) 0.4371 (30) 0.1027 (42) 0.1675 (31) 0.2178 (68) 0.2464 (46) 0.1768 (35) 0.1273 (40) I
1(
0.3683 (1) 0.5213 (6) 0.2698 (7) 0.4936 (7) 0.2418 (5) 0,2396 (5) 0.0881 (48) 0.0309 (55) -0.0384 (28) - 0.1127 (47) - 0.0489 (58) 0.0054 (49) 0.8086 (64) 0.7427 (42) 0.7530 (101) 0.8553 (67) 0,9542 (44) 0.9377 (55)
E
0.3008 (2) 0.2956 (9) 0.5404 (9) 0 0508 (8) 0.3071 (9) 0.1110 (8) 0,1510 (64) 0.1717 (83) 0.2828 (56) 0,3087 (80) 0.3244 (94) 0.1750 (79) 0 1998 (100) 0.2066 (77) 0.3030 (137) 0.3213 (95) 0 3224 (81) 0.1773 (92) I
I
I
’ Standard deviation is given in parentheses and applies to the last digit of the number. sufficient differences between the temperature factors, Bt,, for the Bi and Br atoms, that we felt it desirable to obtain some estimate of the magnitude of the reduction in Bi-Br bond lengths caused by thermal vibrsltions.l6-17 We could decide on no satisfactory vibration model for the infinite chains, so we simply calculated the bond distances that would be expected if the Br atoms rode on the Bi atoms.18 The corrections were large, and the corrected bond distances are 1--= 2.858 rt 0.007, BiBr2 = 2.738 rt 0.009, BiBr3 = 3.032 f 0.008, BiBr4 = 2.899 0.007 BiBr5 = 2.670 i0.007, and BiBr3’ = 3.138 0.008, The average correction is +0.022 and the maximum correction is for BiBr2, of +0.044 A. Since these corrections are uncertain, the discussion is based upon uncorrected values.
* *
Discussion The bond distances found for bispiperidinium Bi”’Br6 are given in Table 11, column 2 and the bond (11) W. G . Sly, D. P. Shoemaker, and J. H. Van den Hende, “Two and Three-Dimensional Crystallographic Fourier Summation Program for the IBM 709 Computer,” CBRL-22M-62, Massachusetts Institute of Technology-Esso Research and Engineering Co., 1962. (12) W. R. Busing. K. D. Martin, and H. A. Levy, “ORFLS, A FORTRAN Crystallographic Least-squares Program,” ORNL-TM-306, Oak Ridge National Laboratory, Oak Ridge, Tenn., 1962. (13) “International Tables for X-Ray Crystallography,” Vol. 111, Kynoch Press, 1962, pp 214-216. (14) W. R. Busing, K. D. Martin, and H. A. Levy, ”ORFFE, A FORTRAN Crystallographic Function and Error Program,” ORNLTM-306, Oak Ridge Laboratory, Oak Ridge, Tenn., 1964. (16) D. W. J. Cruickshank, Acta Cryst., 9 , 747 (1966). (16) D. W. J. Cruickshank, ibid., 9, 764 (1966). (17) D. W . J. Cruickshank, ibid., 9, 767 (1966). (18) W. R. Busing and H. A. Levy, ibid., 17, 142 (1964). Volume 74, Number 2
February 1908
534
W. GANTMCPHERSON AND EDWARD A. MEYERS
Table Ib: Anisotropic Temperature Factors (Aa)
Bi Brl Br2 Br3 Br4 Br5 CA1 CA2 Ch3 CA4 CA5 CA6 CB 1 CB2 CB3 CB4 CB5 CB6
Bu
Biz
Baa
Biz
Bis
Bta
5 . 1 (1) 4 . 9 (2) 15.7 (7) 6 . 2 (3) 6 . 3 (3) 8.7(4) 6 . 6 (28) 7 . 8 (33) 2 . 8 (13) 7 . 1 (27) 8 . 8 (39) 6 . 6 (27) 10.0 (44) 6 . 3 (25) 17.1 (82) 10.4 (43) 6 . 8 (27) 8 . 5 (37)
4.9 (1) 8 . 7 (4) 9 . 4 (5) 7 . 9 (3) 6 . 8 (3) 6 . 6 (3)
2.6 (1) 8 . 5 (5) 6 . 7 (5) 5.1(4) 9 . 5 (5) 5 . 7 (4)
-0.8 (1) 1.1 (3) - 5 . 3 (5) -1.3(3) 0.7 (3) -1.7(3)
0 . 1 (1) -0.0 (4) 2 . 1 (5) 0 . 9 (2) - 0 . 3 (4) -2.4 (3)
0 . 1 (1) -0.7 (5) 2 . 6 (4) 1.7(2) 0 . 7 (4) - 1. 5 (3)
Standard deviation is given in parenthesis and applies to the last digit of a number.
Table 11: Comparison of the Bond Distances from Various Types of Refinement of the X-Ray Data from Bispiperidinium Pentabromobismuthate(III)a b
c
d
e
f
ff
BiBr1 BiBr2 __ BiBr3 BiBr4 BiBr5 BiBr3' -CAlCA2 CA2CA3 CA3CA4 CA4CA5 CAlCA6 CABCA6 CBlCB2 CB2CB3
2.838 (10) 2.724 (13) 3.013 (11) 2.864 (10) 2.643 (10) 3.129(11) 1 . 6 3 (10) 1.23 (10) 1.44 (9) 1.54(10) 1.96 (9) 1.28 (12) 1.58 (13) 1.07 (12)
2.837 (7) 2.694 (9) 3.019 (8) 2.877 (7) 2.649 (7) 3.125 (8) 1.62 (8) 1.32 (8) 1.38 (7) 1.66 (9) 1.66 (8) 1.51 (10) 1.46 (9) 1.27 (12)
2.843 (8) 2.714 (13) 3.009 (11) 2.876 (9) 2.645 (9) 3.133 (11) 1.74 (13) 0.94 (14) 1.42 (13) 1.45 (12) 1.68 (12) 1.38 (14) 1.52 (12) 1.24 (13)
2.82 (4) 2.72 (4) 3.03 (3) 2.84 (4) 2.64 (4) 3.11 (3)
2.81 (4) 2.73 (4) 3.04 (4) 2.84 (4) 2.63 (4) 3.10 (4)
CB3CB4 CB4CB5 CBlCB6 CB5CB6
1.27(13) 1.85 (13) 1.87 (12) 1.46 (11) 0.127 0.146
1.41 (14) 1.so (10) 1 . 7 1 (10) 1.59 (9) 0.087 0.108
1.50 (13) 1.65 (13) 1 . 5 8 (13) 1.59 (13) 0.119 0.131
2.837 (8) 2.724 (12) 3.000 (10) 2.874 (8) 2.642 (9) 3.142 (10) 1.56 (9) 1 . 0 3 (9) 1.50 (8) 1.51 (10) 1.69 (9) 1.44 (11) 1.57 (9) l.lS(9) 1.25 (15) 1.84 (16) 1.63 (11) 1.54 (11) 0.112 0.123
__ ~
R1 Rz
0.106 0.128
0.113 0.136
'
Results calculated from Weissenberg and a Standard deviation is given in parenthesis and applies to the last digit of a number. As b, but with anisotropic temperaprecession data with isotropic temperature factors, but no corrections for anomalous dispersion. As b, but with Weissenberg data only. ' As 6, but with precession data only. Light atom coture factors for the heavy atoms. Results calculated from Weissenberg data with isotropic temperature factors and with anomordinates fixed a t values obt.ained in b. As 6 , but with precession data. Light atom coordinates fixed a t values obtained in b. alous dispersion included.
'
angles are given in Table 111. Each Bi atom is surrounded by a distorted octahedron of Br atoms. The octahedra are linked by bromine bridges, BiBr3 = The Journal of Physical Chemistry
3.019 f 0.008 A, BiBr3' = 3.125 f 0.008 A, and (Br3)(Bi) (Br3') = 91.9 f 0.2", as depicted in Figure 1. The shortest Bi-Br bonds in the structure, BiBr2 = 2.694 f
THECRYSTAL STRUCTURES OF BISMUTH HALIDECOMPLEX SALTS
Figure 1.
0.009 8 and = 2.649 r+ 0.007 8, are directly opposite the bridging bonds, while BiBrl = 2.837 0.007 and B T i = 2.877 i 0.007 are perpendicular to the plane of the other Bi-Br bonds. Within the octahedron, the bond angles between adjacent Br atoms with Bi at the apex vary from (Br2) (Bi) (Br3') = 83.3 0.3" to (Br2)(Bi)(Br4) = 94.0 0.3". The chain structure found here is similar to that observed
*
*
*
Table 111: Bond Angles of Bispiperidinium Pentabromobismuthate(II1) Obtained in Anisotropic Refinement" (Brl )(Bi)(Br2) (Brl ) (Bi)(Br3) (Brl)(Bi)(BrS) (Br2)(Bi)(Br4) (Br2)(Bi)(Br5) (BrS)(Bi)(Br4) (Br3)(Bi)(Br5) (Brp)(Bi)(BrB) (Brl)(Bi)(Br3') (Br2)(Bi)(Br3') (Br3)(Bi)(Br3') (Br4)(Bi)(Br3'1
91.5(3) 8 7 . 1 (2) 93.7 (3) 94.0 (3) 91.0 (3) 86.7 (2) 93.8 (3) 93.6 (3) 87.0 (2) 83.3 (3) 91.9 (2) 86.3 (2)
(CAl)(CA2)(CA3) (CA2)(CA3)(CA4) (CA3)(CA4)(CA5) (CA4)(CA5)(CA6) (CA5)(CA6)(CA1) (CA6)(CA1)(CA2) (CBl)(CBP)(CB3) (CB2)(CB3)(CB4) (CB3)(CB4)(CB5) (CB4)(CB5)(CB6) (CB5)(CB6)(CB1) (CBG)(CBl)(CBP)
112 ( 5 ) 126 ( 5 ) 108 ( 5 ) 107 (6) 106 (5) 112 ( 5 ) 125 (8) 117 (11) 112 (8) 109 ( 5 ) 101 (6) 109 (6)
Standard deviation is given in parenthesis and applies to the last digit of the number.
in NaSbF4,e and quite different from the discrete units present in Sb1''F6' and Sb"'C1~ salts. In the complicated structure of BiI2Cll4,l9 discrete Bi"'C16 groups have also been found. The major obvious difference in the dructure described here and those reported earlier is that there appears to be little indication here of the effect of the lone pair of Bi electrons
535
upon the coordination around Bi. A similar result was obtained for Bi"IBr4 and Bi"'I4 salts.4 The effect is apparently not restricted to Bi among the group V elements, since one of us (EAM) has carried out the analysis of precession data for bispiperidinium Sb11'Br6, and found the crystals to be isomorphous with those of bispiperidinium BiI'IBre. Hence the lack of lone-pair effects upon coordination around Bi or Sb seems to be associated in our present studies with the presence of higher halogens (Br or I) or of large organic cations in the structures. The total bond order for the Bi-Br bonds can be calculated from Pauling's equation20 d, = dl
- 0.6 log n
where d, is the length of a bond, dl is the single bond length (taken to be 2.63 8 for21Bi-Br), and n is the bond order. The total bond order is 2.9 in this structure, compared to 2.9 and 3.1 in the Bi111Br4 and Bi11114 respectively. The ring atoms refined satisfactorily, but with large standard errors in the coordinates. Despite the difficulty in distinguishing C from N by means of electron density peak heights or ring bond distances, calculations showed that only one atom of the A ring, CA3 and only one atom of the B ring, CB2, have close contacts with Br atoms, 3.47 f 0.05 A from a Br3 atom and 3.45 i 0.07 from a Brl atom, respectively. The next closest contact is from CA3 to a Br4 atom, 3.56 f 0.05 A, and other ring atom contact distances are greater than 3.7 8. It may be reasonably concluded from these results that CA3 and CB2 are nitrogen atoms. A referee has pointed out that (CA2)(CA3)(CA4) = 126 i 8" and (CBl)(CBS)(CB3) = 125 f 8" are the largest angles found in the rings. Both rings are in the chair conformation.
Acknowledgments. The financial support of The Robert A. Welch Foundation is gratefully acknowledged. The facilities of the Data Processing Center of The Texas A & M University System have been used extensively in this research. Dr. Roger D. Whealy has kindly supplied us with a sample of the compound studied. (19)A. Hershaft and J. D. Corbett, Inorg. Chem., 2, 979 (1963). (20) L Pauling, J. Am. Chem. Soc., 69, 542 (1947). (21) H.A. Skinner and L. E. Sutton, Trans. Faraday Soc., 36, 681 (1941).
Volume 78, Number 2 February 1068
