330
F.A.
C O T T O N AND
c. B.HARRIS
Inorganic Chemistry
or only slowly, to [Re2X8]2-. It is also puzzling that no other reducing agents have been found which lead to any isolable quantity of [RezX8]*-salts, although NaBHl and hydrazine have been tried under a variety of conditions. The mechanism by which the binuclear ions are formed from the mononuclear starting material is a t present entirely obscure. Characteristic Properties of the [Re2X8Iz-Ions.-The magnetic susceptibility of [ ( E - C ~ H ~ [Re?Cls] ) ~ N ] ~ was found to be -530 X 10F6 c.g.s. unit a t 25". From Pascal's constantsz1 for the cations and the chlorine atoms, and taking -440 X 1 V 6for a rhenium atom, we estimate the diamagnetic susceptibility to be about -600 X 10F6. Thus, while there may be a small, probably temperature-independent paramagnetism, the [Re2Cl8I2-ion is essentially diamagnetic. It has no unpaired electrons and thus consists entirely of closed shells of electrons. ,4 treatment of its electronic structure must account for this fact. Other properties of the [Re2XsIz-compounds have been mentioned and discussed above. It remains only to report their electronic spectra. Electronic Absorption Spectra.-The electronic absorption spectra in the visible and near-ultraviolet regions for the [Re2C1B]z-and [Re2Br8I2-ions have been measured by reflectance on all the compounds prepared and are essentially constant and characteristic. Figure 1 shows the complete spectrum of the [Re2C18]zion from 200 to 800 mp and Table IV gives numerical data for this spectrum recorded in acidified methanol as well as for spectra recorded in other solvents. (21) See, for example, P. W. Selwood, "Magnetochemistry," Interscience Publishers, S e w York, S. Y . 1956, , p. 93.
2nd Ed.,
TABLE IV SPECTRAL DATAFOR [( ~ - C I H ~ ) ~ K ] Z [ R ~ P C I ~ ] Solvent
---Maxima---mir
Molar extinction cm. -1
coeff,
Oscillator strengthn
Methanolh
690 14,500 1530 0.023 305 32,800 5650 0.31 255 39,200 8840 0.65 Acetonitrile 680 14,700 2340 0.035 307 32,600 8670 0.48 2 50 40,000 9970 0.73 Acetone 680 14,700 2480 0.030 a Calculated from the formula f = 4.6 X 10-Qe,,,A~, where eInar is the decadic molar extinction coefficient and AV is the frequency difference, in cm.-', between the points where e is -0. For the higher energy peaks, AV is estimated by resolution of the observed envelope into Gaussian peaks. Containing 1 ml. of concentrated aqueous HC1 per 100 mi.
It may first be noted that this spectrum is quite different from that of the [Re3CIlzl3- ion, or those of any compounds containing the Re,&& gr0up,~-6 and is sufficient evidence, in itself, that we are dealing here with a different type of compound. The spectrum consists of three bands, one a t -14,500 cm.-' which, from its oscillator strength of -0.03, is a forbidden band and two others a t -33,000 and -40,000 cm.-l which are presumably electric-dipoleallowed transitions since their oscillator strengths are -0.4 and -0.7, respectively. Discussion of the assignments of these bands will be given in a later article. The spectrum of the [RezBr812-ion is similar to that of the [Re~C18]~ion in the red, but absorption rises sharply around 450 mp. More extensive experimental studies of the spectra are being conducted.
CONTRIBUTION FROM THE DEPARTMENT O F CHEMISTRY, TECHSOLOGY, CAXBRIDGE, MASSACHUSETTS
L~ASS~~CHUSET INSTITUTE TS OF
The Crystal and Molecular Structure of Dipotassium Qctachlorodirhenate(II1) Dihydrate, K2[Re2Cls]2H2Q1 e
BY F. A. COTTON
ASD
c. B. HARRIS
Received Se9tembev 22, 1964 A three-dimensional, single crystal X-ray diffraction study of the structure of K2[Re2C18]2Hz0 is reported. The crystals are triclinic with a = 6.75, b = 7.86, and c = 7.61 A. and oi = 102.0" , p = log", and y = 105'. There is one formula unit in ion therefore has a center of symmetry; its idealized point symmetry is the cell, and the space group is Pi. The [Re2C18124"," (D4,,), The mean Re-C1 distance is 2.29 A,, the mean Re-Re-CI angle is 104", the mean C1-Re-CI angle is 87", and the Re-Re distance is 2.24 if. The water molecules are coordinated to K+ions.
Introduction The preparation and characterization of compounds containing the octachlorodirhenate(II1) and octabromodirhenate(II1) ions, [Re2ClgIz- and [RezBrsIz-, has been reported.z The full characterization of these species requires both chemical and X-ray evidence. The preceding paper2 describes the chemistry and certain physical properties of various compounds ; this paper reports an X-ray diffraction study of the (1) Suppot-ted by the U. S . Atomic Energy Commis4ion.
crystal and molecular structure of one such compound, namely, Kz [Re2CIg]* 2H20, of sufficient accuracy to show unambiguously the structure of the [RezCl8l2ion. Experimental The crystals of K2[Re~C18] . 2 H ~ 0were obtained from a sample of the compound prepared in a manner described elsewhere.2 (2) F.A. Cotton, N. F. Curtis, B. F. G. Johnson, and W. R. Robinson, Inoug. Chem., 4 , 326 (1965).
Vol. 4 , No. 3, March 1965
DIPOTASSIUM OCTACHLORODIRHENATE (111) DIHYDRATE331
The crystal class and unit cell dimensions were established from zero layer Weissenberg photographs. The crystals are tricliFic with the dimensions: a = 6.752 A.; b = 7.855 c = 7.610 A.; CY = 102.0'; p = 108.9'; y = 104.8'. The calculated density assuming one formula weight per unit cell is 3.66 g. cm.-3; the approximate density, estimated by flotation in CH&, is 3.5 g. cm.-3, thus establishing t h a t Z = 1. Intensity data were collected by the equi-inclination Weissenberg method with Cu KCY radiation using a crystal with approximate dimensions 0.02 X 0.02 X 0.05 mm. The levels Okl-4kl were recorded; 579 reflections within half a sphere ( h 3 0) with 45" were recorded. sin e/A Intensities were estimated visually using an intensity wedge prepared by timed exposures of one reflection from the same crystal. On upper layers the elongated spots read were corrected for elongation. Lorentz and polarization corrections were made, but in view of the small size of the crystal, absorption corrections were omitted ( p = 480 cm.-'; pima, = 2.5).
w.;
Determination of Structure Using the corrected intensities, a three-dimensional Patterson synthesis was computed. The Re-Re vector was immediately obvious. Placing one Re atom a t the origin, coordinates for the other were derived. A Fourier synthesis was then computed3 using phases determined by Re atoms alone and assuming the acentric space group P1. The eight chlorine atoms and two potassium atoms were found in this Fourier map. The positional parameters for these atoms as well as five scale factors (one for each level) were subjected to one cycle of full-matrix least-squares refinements4 The atomic scattering factors used here and subsequently were taken from the International Tables.5 Those of Table 3.3.1A were used for K f , C1-, and Oo, while those for Reo were taken from Table 3.3.1B. No corrections were made for anomalous dispersion. The set of calculated structure factors now a t hand was used to compute a three-dimensional difference Fourier function from which all Re, K, and C1 atoms were removed. Only two significant peaks appeared ; these were assigned to the oxygen atoms. The positional parameters of all 14 atoms as well as a scale factor for each level were now subjected to two cycles of full-matrix least-squares refinement. I n these cycles, temperature parameters of 1.0 for Re, 2.0 for K and C1, and 4.0 for 0 were assigned and kept fixed. The calculated structure factors obtained from the second of these cycles were used to compute a threedimensional Fourier map, which showed no significant unexplained peaks and which also showed an essentially centric distribution of atoms about the midpoint of the Re-Re line. It was therefore concluded that the correct space group is pi. Using P i and assigning the above-mentioned initial temperature factors and using the average values of the pairs of atomic coordinates for the 21 coordinates now required, eight cycles of full-matrix least-squares refinement were now executed. The scale factors were (3) Using ERFR-2, a two- and three-dimensional Fourier program for the IBM 709/7090, 1962, by W. G. Sly, D. P. Shoemaker, and J. H. Van den Hende. (4) Using a full-matrix least-squares refinement program for the IBM 709/7090, 1962, by C. T Prewitt. ( 5 ) International Tables for X-Ray Crystallography, Vol 111, Kynoch Press, Birmingham, England, 19fi2.
not varied. Following this, one cycle was run in which the 21 positional parameters and the five scale factors were varied, but not the temperature factors. Finally, one cycle was run varying positional parameters and temperature parameters, but not the scale factors, The residual6 was now 0.168 and the changes in positional parameters were less than the estimated standard deviations. As a final check on the correctness of the structure a three-dimensional difference Fourier map was computed. It showed no peaks of significant magnitude. The relatively high value of the final residual is probably due to inaccurate reading of spots from the very small crystal and to the lack of absorption corrections. The final set of calculated structure factors (F,) together with the observed absolute values of the structure factors are listed in Table I. The atom coordinates and isotropic temperature factors are listed in Table 11. The standard deviations, u, were obtained from the least-squares formula uz((j) = aP1(Z2eA2)/(m - n)
where ajj is a diagonal element in the matrix inverse to the normal equation matrix. Discussion The [Re2Clsl2-Ion.-The two ReC14 halves of the ion are related by a crystallographic center of symmetry. This fact requires that the rotomeric configuration of the ion be the eclipsed one. The principal dimensions of the ion are listed in Table 111. From these, it can be seen that the symmetry of the ion is D4h (4/mmm) within the significance of the individual dimensions. Thus all Re-C1 bonds have lengths in the range 2.29 =t 0.03 fi., all C1-Re-C1 angles are in the range 87 f 2", and all Re-Re-C1 angles are in the range 103.7 2.1'. Figure 1 is a sketch of the A
I
'P.7t 2.1
W
Figure 1.-A sketch of the [Re&l8l2- ion in Kz[Re&l8] .2Hz0. The numbering of atoms with single subscripts corresponds with that in Tables I1 and 111. An atom with a double subscript is related t o the atom with the corresponding single subscript by the center of inversion. The distances and angles are the averages of those in Table 111, with the intervals representing mean deviations of the individual dimensions from these averages. ; the refinement program, how.
Inorganic Chemistry TABLE I H
K
9
0 -! i n 2
0
0
1
0 0 0
c r
0
0 0
0
n
0
L F09
! -2 2 3 -3
91 99 113 122 116 19 19 5 17 47
4
4
0 - 5 0 5
~
3
0 -6 0 6 0 -7 c 7
0
0 n 1
06
69 65 37
0 -5
1 1 1
0
8
-1
C c
-9 81 83 133 13" :33 123 12' 59 63 116 25 65 32
1 1 -1
9
.J
-;
4
i
I -2 -1 2 : ? 1 3 1 -1 1 7
0 7
1
1
-i
7 1 4 I -1 /I 3 -1 5 > ! 5 i 1 -= 2 1 -6 0 1 6
I -7 I 7 n -2 " 2
c
1 -2
1 2 1 o 2 -2 0 -2 2 n 2 2 2 -3 7 -2 3 2 3 'j
'
7
0
n -7 2 2 -2
0
-
1
2
~
n - 2 n > 'I 2 "
?
-'
'
4
5 5 -5 6 - 5 '.
li "
-1 1
0
-2
c
3
r
3 -3
0
3
r -3
,'
3
4
0 -4
3
.
1 1 2 2 3
1
6
31
05
-,4
42
-13
99 ?I 92 96 129 27 37 16 116 1'6
-76 -75 121 121
76
5?
3
'
-19 1 -k8 115
45
-6 -7 -2 1 -9 2 0
n
C
r
r
1
" C
62 57 39 '1
11
7,
. . -, 1 1
I
: 1
1 1 1 1
._I
-'
:9; $2 14:
69 59 65 77 59
6 2 2 -7 3 7 1 : - 1 -1 1 ! -1
I ,
-3
91
53
8s 36
IC? :L7 52 i
79 25
-59 -13
' "
2 -2
8
1C2 62
83 33
-7
-
4L
7
51
:
29 47
-1 1
IO 54 69 117
2 -2 - 2 -; 9 3 3c 7 i -2 -3 1:4 119 2 -5 2 -7 7 -7 2 -2 ~~
3
77 54
1
-' -' '
6
1
-'-1
27,
-2 -4 2 4 2 -4 -3 4 3 -84
175 -62 86
3
-4
4 - 4 -4 * 4 -6
-4
-,
-5
-4
5
i -6
5 6
-6
7
i
?
! 1
-7
'li
6
RC
91 -32
:?I 91 -88 -4'
l ? i
55 71
58 -73
51 53 36 31 56
-I44
41
e7
i
2 -5 -2 5 2 5 2 -6 -2 -6 -2 6 6 2 2 -7 2 7 ~
C
-,
i -1 -3 1 3 1 1 - 3 2 1 - 2 -2 1 ? 2
22
58 39 -39 -7;
31
3"
?? 19 58 39 53 16 78
-75 -52 57 -53 -59 12 69
21 61 15
52
6
128 91
!a
-a
3 135 -98
1
: 1 1
I
1 1
, 7
-7 -7
-e
c
:
2
:
3 L 5
7
0
:
c
1
2
7
-2 3 -3 0 3 0 -4
2 7 2
7 3
7
2 2
; : ' 2
c
-5 5
-e
°
C
2 -1 2 ! : 2 -:
:
7
:
1
2 -1
: i
? l i 2 -1 - 2
*i
67
54 22 96 11
23
'
-7q
76 -48 -47 -59 23 21 03 1:7 38
33 L
7
_.
1
~
2 -1 - 1 2 2
-'
87
92 88 93 d9
?
7
-7
?
3
2
-3
2
?
7 -2
3 ' 1
2 -3
xla
Re
0 8193(8)
C11 C1,
0.754(5)
Y/b
0.9854(5) 0 046(3) 0.279(4) 0.909(3)
B/C
i
-5 5 2 3 5 ? -3 6
51 -22 -I& 10' -92
-96
6C 97 59
35
1:
-4
0
'
3:
-98 -d6 71 6'
-83
3 3 3
3 1 2
3 ; 3 3
3 3
1
*3 7:
57 96 91
-5;
>5 -Ye
65 -55 .58 - 1 1 5 7; -53 77 -,b 5 -9
85 73
53 $7 66 51 55 1 3
5s
88
3 4
3
c
0 -1 c I
c
2
1 c1 :
1
1 -I
:
3 - 1 3 1 3 1 3 - 1 3 1 -1 1 -1
5: -84 -65 51 -59 -76 8: -13; -31 -79 -55 -63 -ib8 6 -58 -65
3 -4
4 -4
4
5 -5
-5 -6 -6
! -7
-1
I
3
1 ?
3
2 -4 4 - 2 5 -2 - 5 2 -5 2 -6 -2 -6 2 - 7 -3 1 3 0
- 3 -1 -3 1 I 1 1
-1.
-3 2 3 - 3 -2 3 3 2 ? -3 3 ? -3 - 3 1 3 3 3 3 4 3 -3 -e 1
-52 -59 '3 -51
-81 33
-86 -59
-,3 19 12
1
-3
;
-2
i
- 7
&
1 1
-4
-65 -7c -43 -19 -5s -1:3 -1i9 -9c -95 -63
-*
0 91(7) 1 3(4) 0.826(6) 2 l(5) Cla 0.709(5) 1 5(5) C14 0.639(5) 0.675(4) 0.892(3) 1 7(5) K 0.878(5) 0.659(4) 0.326(3) 2 7(5) 0 0.78(2) 0.46(1) 0.56(1) 3 (2) " Xumbers in parentheses are standard deviations occurring in the last significant figure for each parameter.
[RezClsI2- ion showing the numbering system for the atoms and giving the mean values for each type of principal dimension together with the mean deviation of the individual dimensions of each type from their mean value. The eight chlorine atoms lie approximately a t the corners of a cube with edges ca. 3.2 A. in length.
U
1
-4
-4 -4
i,
5
-5
5
c c
-5 1 - 5 -1 5 1 5 7 -5 i
81 09
-9: -85
a -2 (i -7
-32
.Y
I4
-5 5 ? I
~
-6 -6
-6
2
-6 -6 -6
i
-7
3
5:
--.'
6 19 5 !9
8: 53 9: 11 28 :5 66
-?
-93
*
1 2 -7
-19 4: -4; -c7
-6 -22 -9? -5: -96 -5: -25 5 -57
li
-6
-45 -92
3
95 2s 21
3
-7
2
3
-7
1
-7
3 4 0
0
4
c
6
1
4
i ? C -2 2 -3
&
c
3 0
-1
65
4 0 -5
Cu
5e
-ai
6i 48
-71 -6b -4'
52 6
3'
52 8r
-0
1"-
0
-7
e4
4 4
-I 1
:
4
'
-!
I
i
l
' -1
ii - 1
' 4 ii 4 4 4 4 4
1
7
35
-i
4 I 4 I -4 : -5 5 4 -1 '4 -1 - 5 i 1 -6 4 -! -6 ii - 2 0 4
i i
4
2 U 2 -1
4 4 2 1 4 -2 -1
4 -2 1 -2 2 2 2 -2 - 2 4 2 -2 3 4 -2 4 2 3 4 - 2 -3 4 -2 4 I 4 -2 - 2 - 45
B 4
8 35
75
-61 -dr
' 8
36 - 1 1, i; - 2 2 7*
I -2
-
?t 5 25
-1 l 2
- 1 -2 -1 3 1 3 -1 -5 -1 -4
-54
56 -92 115 - 1 1 2 39 *B IC6 -?!
0
1 -1
-22
ii 47
ii 4
C
-31 -26 -52 -67
:a
1
3 -'
-90
-P(
I ? " -1r89
'i
48
7R
4 - 3 -! 4 j -2 Y 1 1
-2:
q2
-7
li li
29 13 45 -101 b -9 6 9 ?5 17 35 -32 6 21 23 :5 5 6 09 -1c9 87 - 8 1 122 -57 -90 97 7 6 -6: 67 -76 1 1 8 -126 56 -51 -12 2: 95 -85 95 -69 22 -1: 6 8 22 - 2 1 6 -15 26 Ilr 1: -28 -Rg
-11
17
-2 2
3
'
7
R2
-67
24
Li
-1
4 5 3 -1 I
1 -7
-63 95 - 1 c 7 68 -7 8 7 -1:7 -56 97 96 -94 li -18 -72 55 126 -82 27 37 3: -27
!*a
61
0
-11 -?$
'
-3 2
*
'
-7
/i
-1
'
- 2
' -i ti
1
Li L,
-3
-3 -3
ii 6 LI
-1
4
-8,
Y
-i
-?
2 -? 3 ? 4 -4
s 27 25 L3 5: 97 6 11: 2c 49 47
1" 27
-'
-9-
?'.
'F 55
82
-76
5
55
-i
'j
79 -62 5
6 ' -a
.
0
-1
:
5 5 1:7
2)
-12 -91 12 21
1 ii ir 2 -ii 2 6 -i- 2 -L 3 Ii - 4 -3
24 :3 P5 19 e4
-20
c
Zh
-?I
4
ii 4
i
71 56
4
:e
-t5 -56
-5 -6 2 -7 4 -? (I
138 - 1 2 2 i35 -98
Li
-5'
4
' '
4 -5 i - 5 -5
' ' -5 ' -5 &
-6
-5 Y -5 ir - 5 (i -6 4 -6 4
A (i
L -6 -6 -6
' -7
41 -h4
it -7-
6 e P
103
1 -7' -Pi
;
j'
2
22
>,
e' 29 33 82
-7"
-3
'
:4
2i.
75 46 -9' -1,
91 90
-8 6 dL
7
79
-23
?
6
5 C
i
- 6 --: -5 2
&
*
1 -1 -2
L5
'
-1
0
,R '7
-55
26
4
-7
1
?,'
-?$
il
-7
7
22
-22
-i1
5 - 3 ?II d
42
70 -129 7 -76 '7 43
L6 41 5 2 -5: 144 -111 5c 52 51) 58 97 -33 1:4 -E4 4* 5L -'2 e7
52
-i9
PL
-70
13 36 17 29 61 :7 26
'
35
0
27
3 27 -76
-11 25 3d
5 " -1:2 36 -4i 56 54
4b
3c
97
-9
29
33 - 7611
- d7 5
TABLE 111 CRYSTALLOGR4PHICALLY INDEPENDEST'
B
0.9504(5) 0.226(3) 0.957(3) 0.615(3)
1
-3
:7
-125
4
-2
?
-'
2
'7
-2 - 4
2
-78
ir
LA
2
=
-2 -6 2 4 2
25
:20
2
-53
1
-*
4L
5
-?
-46 36 -79 -61 60
12'3
1
4
1 8c 39 - 1 73 3 63 -88 5 5 -91 53 -63 63 -7: 87 - 1 1 2 1 4 3 -111 31 1i 89 - 6 s 6 -13 115 -51 6 6 6' -52 6 -12 5 i 23 b 6 -7 17 3 22 12
c
2 1 2 -1 2 -2 -2 2 2 2 - 2 -2 - 2 -3
-1b
l? 96
7
-7
-66 -2 71 -89 -70 58 -9: -76 69 -74
63 4i 93 59
-2 -2
-83
44
-1
-4
'
3 -1
-Ph -73
7i
-*
-'7 39 -46 -41 -6;
55 0 -? ill -:32 0 -3 29 -21 0 3 -96 3 -i :35 : :9 -15 6 5 i 5 15 -9 C -5 C -6 6 -11 -1 0 54 -66
21
3
26
? .
14
48 36 33 45 6? 21 I9 64
: 1 -1 3 1 2 1 -1 2 7 -: - 2 1 - 1 -3 > -: 3 3 : -3
-81 66 69
7'
3c 79 73 71 2 1 3 1 41 ? -4 ! 5 2 -4 -1 57 2 4 -: 73 2 4 : 2 -4 : 97 72 2 4 2 5 2 - 4 -2 77 2 -il -3 89 2 -4 ? 72 2 4 3 7 --i -(I 6) 7 -4 91 2 " 77 73 2 -6 -5 57 2 -4 5 77 2 -4 6 i6 2 -5 0 56 2 5 0 69 7 - 5 -1 58 2 5 1 63 2 -5 i 48 2 -5 -? 45 2 -5 2 65 2 5 2 19 2 - 5 -3 08 2 5 3 73 ? -5 3 *I 2 - 5 -6 .i 78 , L 4 i 2 -5 5 61 2 -5 6 72 ? -6 0 ?? ? -5 -1 7
TABLE I1 FINALPOSITIONAL ASD ISOTROPIC TEMPERATURE PARA METERS^ Atom
-4 1
? -3 ? -%
'
;;
-2 2
-2
7 -3 7 -3
33 -,3 4, -55 26 ,3 117 - 1 5 6 53 - 5 ~ 122 -116 26 36 16 e9 -91 57 39 69 -73 191 78 83 -9? 117 1 0 5 25 -33 1 0 2 -:29 hl -5' ;47 -151 52 -6: 114 - 1 1 5 69 -71 8 -G
2 - 1 -: ? 1 -3 2 : 3 2 -1 3 2 -1 2 : -4 2 -1 4
c
? -6 -7 -5 -2 5
7 2 -7 7 3 3 2 -3 i 3 -1 7 -1 ' 2 3 1
-14
-42
d7 5d
2 -2
-36 -54 -62 67 51 57 21 1c2 -8k 39 -:o
i
1
-2 2
-5 2 -6 5 2 -1 c 2 -7 -1 2 -7 1 2 -7 2 2 -7 3 2 -7 4 2 -1 5
9;
-
,
-**
1,
2 -6 2 -6 2 -6 2 -6
36 5b -63 -63
2 - 2 -! 79 75 2 -2 > 56 -61 2 2 : 96 -93 2 2 -: 7 3 - 5 6 7 2 7 111 - 1 8 2 2 - 2 -2 i 6 37 43 -ui i -? 2 i -2 19 -115 -7 - 7 '7 23 7 2 1 55 -53 2 - ? -4 62 51 2 2 -4 6, 39 8 d -8: 2 -2 4 6 5 7 2 2 2 L 7 2 -5 45 31 53 18 2 -2 - 5 27 -33 7 2 5
-2
37 64
-53
5e 52 58 57 73 53 57
:5 2 1 5 5 i -1 6 7 1 -7 li5 .~ 2 -2 " 126 2 2 : 9:
1 ,
31 44
-'
,'
7 ~~
102 -55 29 -25 l i l -:Cb 54 53 1 5 -rr, ?6 A2 77 -65 64 -54 57 -63 62 -73 38 3' 59 46 65 72 i6 -14 63 91 5: 72 53 -52 1" 13
.
59
' 3 -66 -53
1
-66 -59 62 9a -55
-e
1
:
21 13 1l4 115 15 43 91 57
I
-1 -5 2 i -5 7 1 5 7 -1 5 7 -: - 0 2
2: 2:
9'
-7'
i
.
2
b I61 -84 74
- 5 -3 5 3 -5 L _i 6 -> ? -5 d
-6 -1 -6 2 -6 -2 e ? -6 1 -6 4 -6 5 -6 t -7 ; - 7 -1 -7 . -7 2
lL(i
-2 - 5
3 -1
5
71 '7
6
2 -1 1 -2
2
91 7'
!
-4
-9
-2
151 123 52
7
5
01
64
5' a0 47 51
5 6
- 5 -1 -5 1 5 1 - 5 -2 .. : 2 5 2
1 1 1 -1
61 73 54 52 118 51 bt
3 -5
29
177
5 5
= -3 -3
57
3
-5
-3 a
28
9"
U
3 -5
28 ::2
62 S? 19 5 41 41 3
.,
1
-73
S,
'
PIS
-1
'
- 2 %
67
*
1 -3 I -3
!2
:4 9 i
46
155
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Distances,
Re:-Rell Rel-CI1 Rel-C12 Rel-C13 Re,-C14 C12-Cl44 c13-clll
A.
DISTAXCES AND ANGLES
[RenCls12Bngles, deg.
2.241 (7) 2.26(2) 2.29(3) 2.31 ( 2 ) 2.31 (3) 3.31 (5) 3 . 3 3 (4)
CIl-Rel-C12 85.4(8) C12-Re,-CIa 88(1) Cls-Re,-Clr 86.0(9) C14-Rel-C1, 8 7 . 9 (8) Re,,-Rei-C1, 1 0 5 . 8( 6 ) Rell-Rel-C1:! 103.4 (7) Rell-Rel-Cls 101.7(6) Reil-Rel-Cld 103.6(6) a The numbers in parentheses are standard deviations occurring in the last significant figure of each dimension. They were calculated from the standard deviations in Table I1 by the method of D. W. J. Cruickshank and A. P. Robertson, Acta Cryst., 6, 698 (19491, using a molecular geometry program for the IBM 709/ 7090/7094 computer written by Dr. J. S. Wood.
The dimensions of the [RezClsI2- ion may be compared with those of the Re+& group which has been
Vol. 4 , No. 3, March 1965
DIPOTASSIUM OCTACHLORODIRHENATE(III) DIHYDRATE333
found in Re(II1) compounds derived directly from rhenium(II1) chloride7-’” and in rhenium(II1) chloride itself.ll The average Re-Re distance in the triangular Re3 cluster which occurs in these compounds is 2.48 8. Since the order of the Re-Re bond is found to be 2.0 by a molecular orbital treatment,l2~l3 it is evident that the Re-Re bond order in must be quite high indeed, since the bond is some 0.24 8. shorter. It will be shown subsequently13 that it is, in fact, a quadruple bond. The Re-C1 distance in [RezClsI2-, 2.29 f 0.02 8.,is approximately the same as those for R e to nonbridging C1 atoms in the Re3C19 derivatives. Thus, for [Re3CllZI3-we have’ 2.36 =!= 0.03 A., and for Re3C19[(C2H5)2CBH5P]3 the crystallographically independent distanceslO of this kind are 2.32 f 0.02 and 2.31 i. 0.02 A. Crystal Packing.-The crystal of KZ[RezCls].2Hz0 is an array of K+ and [RezCls]2- ions and H20 molecules. The arrangement of nearest neighbors around the potassium ions (both of which are crystallographically equivalent) is quite irregular. The K+ ion lies approximately above the center of the square set of four C1 atoms, Cll, Ch, C ~ Z C133, Z , of one [RezClsI2-ion. These four chlorine atoms lie a t distances of 3.52, 3.21, 3.41, and 3.63 8., respectively, from K+, each distance having a standard deviation of 0.03-0.04 8. I n other directions about the K + ion there are C1 atoms of other [Re&bI2- ions a t distances of 3.31, 3.38, 3.40, 3.50, 4.52, and 4.98 A. ; a t least the first four of these are t o be considered coordinated. Finally, the oxygen atom is 2.66 i 0.08 8. from K+. The 0 atom has six C1 atoms a t distances of 3.3-3.7 8. from it, in directions such that 0-H. . .C1 bonds might exist; how(7) J. A. Bertrand, F. A. Cotton, and W. A. Dollase, J . A m . Chem. Soc., 86, 1349 (1963); Inorg. Chem., 2, 1166 (1963). ( 8 ) W. T. Robinson, J. E. Fergusson, and B. R. Penfold, Pvoc. Chem. Soc., 116 (1963). (9) J. E. Fergusson, B. R . Penfold, and W. T. Robinson, Nature, 201, 181 (1964). (10) F. A. Cotton and J. T. Mague,Inoug. Chem., 3, 1094 (1964). (11) F. A. Cotton and J. T. Mague, ibid., 3, 1402 (1864). (12) F. A Cotton and T. E. Haas, ibid., 3, 10 (1964). (13) F. A. Cotton, ibid., 4, 334 (1965).
ever, these distances are all somewhat greater than those considered typical of HOH . C1- b0nds.1~ The eight K+-C1 distances in the range 3.21-3.63 A. and the K+-0 distance of 2.66 8. are all reasonable. The closest intermolecular Re. * -C1 contacts are 3.58, 4.66, and 4.84 A., all with standard deviations of 0.03 8. None of these C1 atoms lies a t all close to the extended Re-Re line. Thus, each Re atom can be considered to be coordinated by only the four C1 atoms to which i t is bound in its own [RezCls]2-ion. Comparison With Previous Work-As shown in the preceding paper,2 KZ[RezCls]* 2H20 is the correct formula for a compound previously reported15 as KH[ReC14].Hz0,that is, as a compound of Re(I1). An X-ray study has recently been carried out on the corresponding pyridinium compound, written by the Russian workers15 as (C5HeN)H [ReCL], by Kuznetsov and Koz’min.16 They found it to contain a dimeric group, but the formula they assigned to it was [RezC&l4-. Some of the dimensions they report disagree rather markedly with those we have found in Kz[Re2C18].2Hz0; thus they give the Re-Re distance as 2.22 f 0.02 8. and the Re-C1 distance as 2.43 f 0.03 8. Their method of refinement was described simply as “trial and error,” however, and on subjecting their intensity data t o full-matrix least-squares refinement, well have effected marked changes in atom coordinates such as to bring the dimensions of the [RezClsI2ion in their compound in good agreement with those of Figure 1. Our reinvestigation of the structure of (C6H6N)z[RezCle] as well as an in~estigation’~ of the corresponding collidinium compound, (CsHl2N) [RezCIS],which has the advantage over the pyridinium salt that i t does not form twinned crystals, will be reported in detail later. (14) See, for example, d a t a summarized by G. C. Pimentel and A. L. McClellan, “The Hydrogen Bond,” Freeman, San Francisco, Calif., 1960, Table 9-XXV, p. 290. (15) A. S. Kotel’nikov and V. G. Tronev, Z h . Neovgan. Khim., 3, 1008 (1958). (16) B. G. Knznetsov and P. A. Koz’min, Zh. Stvukt. Khim., 4, 55 (1963). (17) F. A. Cotton and W. R. Robinson, t o be published.
