Synthesis and crystal structure of (PCl4)[Re2Cl9]

Article abstract of DOI:10.1002/(sici)1521-3749(199908)625:8<1240::aid-zaac1240>3.0.co;2-4

The reaction between PCl₃ and ReCl₅ yielded at 200 °C the ionic tetrachlorophosphonium dirhenium nonachloride, (PCl₄)[Re₂Cl₉]. Single crystal X-ray diffraction analysis revealed a monoclinic unit cell: a = 8.616(3) A?, b = 10.449(4) A?, c = 9.397(3) A?, β= 99.72(3)°, V = 833.9(5) A?³, Z = 2, sp. gr. P2₁/m, wR₂ = 0.1083 and R₁ = 0.0527. The ionic compound is built from tetrahedra PCl₄⁺ and face-sharing bioctahedra Re₂Cl₉^-. The Re-Re distance, 2.724 A?, indicates the presence of direct Re-Re interaction.

Full text of DOI:10.1002/(sici)1521-3749(199908)625:8<1240::aid-zaac1240>3.0.co;2-4

Synthesis and Crystal Structure of (PCl4)[Re2Cl9]
A. I. Baranov, G. V. Khvorykh, and S. I. Troyanov*
Moscow/Russia, Moscow State University, Department of Chemistry
Received April 8th, 1999.
+
Abstract. The reaction between PCl3 and ReCl5 yielded at
200 °C the ionic tetrachlorophosphonium dirhenium nona-
chloride, (PCl4)[Re2Cl9]. Single crystal X-ray diffraction
compound is built from tetrahedra PCl4 and face-sharing
±
Ê
bioctahedra Re2Cl9 . The Re±Re distance, 2.724 A, indicates
the presence of direct Re-Re interaction.
Ê
analysis revealed a monoclinic unit cell: a = 8.616(3) A, b =
3
Ê
Ê
Ê
10.449(4) A, c = 9.397(3) A, b = 99.72(3)°, V = 833.9(5) A ,
Z = 2, sp. gr. P21/m, wR2 = 0.1083 and R1 = 0.0527. The ionic
Keywords: Rhenium phosphorus halide; Crystal structure
The compounds in ternary systems of transition metal, phos-
phorus and chlorine are known to be built from tetrahedral
cations PCl4 and metal-chloride anions. Some examples
X-ray powder diffraction of the brown sublimate showed
the presence of ReCl5 and a few lines of new phase. Unfor-
tunately, the quantities of differently colored solids were too
small to perform the X-ray phase analysis. We supposed
these solids to be the mixture of Re3Cl9, ReCl5, and PCl5.
The brown powder was further sublimed in quartz ampoule
at 230 °C/90 °C that resulted in brown plate-like crystals. The
total yield of sublimed crystals, which were later identified
as (PCl4)[Re2Cl9], was about some percents relative to
ReCl5.
+
are (PCl4)[Ti2Cl9], (PCl4)2[Ti2Cl10] [1], (PCl4)[VCl5] [2],
(PCl4)[MCl6] (M = Nb, Ta) [3], and (PCl4)[FeCl4] [4]. All
these substances contain metal atoms in high oxidation state.
Recently we reported about the synthesis and crystal struc-
ture of MoIV compound, (PCl4)2[Mo2Cl10] [5]. For rhenium,
the compound with the formula of RePCl8, found by ele-
mental analysis, was described in [6]. From the magnetic
measurements data, this substance was suggested to be an
adduct ReCl5 ´ PCl3; however, no structure characterization
was given. In this paper, we present the synthesis and single
crystal X-ray structure of (PCl4)[Re2Cl9], the first ternary
compound of rhenium with phosphorus and chlorine, charac-
We have also tried to perform the interaction between Re
and PCl5 analogous to that of carried out for Mo in [5] and
Re in [6]. Heating of 0.001 mol of Re and 0.0024 mol of PCl5
during 48 h at 600 °C in sealed quartz ampoule resulted in a
dark crystalline solid and a few drops of transparent hygro-
scopic liquid. The ampoule was opened and the liquid was
removed in vacuo. X-ray powder diffraction of the dark sol-
id residue showed it to be the rhenium trichloride, Re3Cl9.
X-ray crystallography. The single crystal with the dimen-
sions of 0.3 ´ 0.2 ´ 0.1 mm was placed into a thin-walled glass
capillary and sealed off. The diffraction data were collected
at 160 K on an IPDS diffractometer (STOE) using MoKa
±
terized structurally. The cluster anion Re2Cl9 , containing
metal±metal bond, is discussed in comparison with that of
reported earlier.
Experimental Part
Ê
radiation (k = 0.71073 A, graphite monochromator). The
Synthesis. The compound was synthesized by the reaction of
ReCl5 with PCl3 in quartz tube. Firstly, the red-brown crys-
talline solid of ReCl5 was obtained by chlorinating rhenium
(0.01 mol) powder with dry Cl2 at 550±600 °C. Then, the re-
action media was cooled down to 100 °C in N2 atmosphere
and PCl3 vapor (total 0.4 mol) was allowed to interact with
solid ReCl5 under slight heating (100±200 °C) in N2 stream.
During this process the melting and evaporating of ReCl5
occurred that can be assigned to the heat of interaction be-
tween PCl3 and ReCl5. Simultaneously, a light-brown smoke
was observed, which condensed in the cold part of the tube
to form a brown powder. In addition, the minor quantities of
red, green, and yellow solids were observed in the cold reac-
tor zones. Since the rhenium and phosphorus chlorides are
hygroscopic, all operations on handling reaction products
were performed in a glove box under air dried with P2O5.
monoclinic unit cell parameters were determined and then
Ê
refined with 2305 reflections to a = 8.616(3) A, b =
3
Ê
Ê
Ê
10.449(4) A, c = 9.397(3) A, b = 99.72(3)°, V = 833.9(5) A ,
Z = 2, q(calc) = 3.442 g/cm3, sp. gr. P21/m. The intensities of
6520 reflections were measured, from which 1666 reflections
were unique and 1244 reflections were used for the structure
Table 1 Atomic coordinates and equivalent isotropic dis-
2
Ê
placement parameters (A ) for (PCl4)[Re2Cl9]
Atom
x
y
z
U(eq)
Re(1)
Re(2)
Cl(1)
Cl(2)
Cl(3)
Cl(4)
Cl(5)
Cl(6)
Cl(7)
Cl(8)
Cl(9)
P
0.3228(1)
0.1689(1)
0.4549(8)
0.1459(6)
0.1966(9)
0.4890(6)
±0.1016(9)
0.1905(6)
0.8165(8)
0.5171(12)
0.8119(10)
0.7414(9)
0.2500
0.2500
0.2500
0.0831(4)
0.2500
0.0918(4)
0.2500
0.0936(5)
0.2500
0.2500
0.1006(6)
0.2500
0.8646(1)
0.0952(1)
0.1125(6)
0.9159(4)
0.6255(6)
0.8169(5)
0.0723(7)
0.2707(5)
0.7125(6)
0.4755(9)
0.4169(6)
0.5066(7)
0.0138(4)
0.0128(4)
0.021(2)
0.018(1)
0.026(2)
0.023(1)
0.022(2)
0.024(1)
0.022(2)
0.093(5)
0.057(2)
0.019(2)
* Dr. S. I. Troyanov,
Moscow State University,
Department of Chemistry,
Vorob'evy Gory,
119899 Moscow/Russia
E-mail: troyanov@thermo.chem.msu.su
1240 Ó WILEY-VCH Verlag GmbH, D-69451 Weinheim, 1999 0044±2313/99/6251240±1242 $ 17.50+.50/0 Z. Anorg. Allg. Chem. 1999, 625, 1240±1242

Synthesis and Crystal Structure of (PCl4)[Re2Cl9]
(nBu4N)[Re2Cl9], disregarding the small geometry differ-
ences between the anions in question.
Ê
Table 2 Bond lengths (A) and angles (°) for (PCl4)[Re2Cl9]
Re(1)±Cl(1)
Re(1)±Cl(2)
Re(1)±Cl(3)
Re(1)±Cl(4)
Re(1)±Re(2)
P±Cl(7)
2.414(6)
2.418(5)
2.325(6)
2.280(5)
2.724(2)
1.934(8)
Re(2)±Cl(1)
Re(2)±Cl(2)
Re(2)±Cl(5)
Re(2)±Cl(6)
P±Cl(8)
2.442(7)
2.409(4)
2.304(8)
2.307(4)
1.905(12)
1.921(8)
The analogous anion with Ti is known in (PCl4)[Ti2Cl9]
[1], which structure is not isotypical to (PCl4)[Re2Cl9].
The mutual arrangement of cations and anions resembles
CsCl structure type: every anion is surrounded by eight cat-
ions and vice versa. Two of nearby cations are situated on
P±Cl(9)
Cl(1)±Re(1)±Cl(2)
Cl(1)±Re(1)±Cl(3)
Cl(1)±Re(1)±Cl(4)
Cl(2)±Re(1)±Cl(2 a)
Cl(2)±Re(1)±Cl(3)
Cl(2)±Re(1)±Cl(4)
Cl(2)±Re(1)±Cl(4 a)
Cl(3)±Re(1)±Cl(4)
Cl(4)±Re(1)±Cl(4 a)
Re(1)±Cl(1)±Re(2)
Cl(8)±P±Cl(9)
91.0(2)
179.8(3)
88.9(2)
92.3(2)
89.1(2)
87.4(2)
179.7(2)
91.0(2)
92.9(3)
68.2(2)
108.7(4)
108.7(6)
Cl(1)±Re(2)±Cl(2)
Cl(1)±Re(2)±Cl(5)
Cl(1)±Re(2)±Cl(6)
Cl(2)±Re(2)±Cl(2 a)
Cl(2)±Re(2)±Cl(5)
Cl(2)±Re(2)±Cl(6)
Cl(2)±Re(2)±Cl(6 a)
Cl(5)±Re(2)±Cl(6)
Cl(6)±Re(2)±Cl(6 a)
Re(2)±Cl(2)±Re(1)
Cl(9)±P±Cl(7)
90.6(2)
178.5(2)
89.6(2)
92.7(2)
88.4(2)
88.5(2)
178.7(2)
91.4(2)
90.2(2)
68.72(12)
111.2(3)
108.2(5)
±
an elongation axis of Re2Cl9 anion coinciding the Re±Re
bond direction. The rest of neighbor cations are outlying
from anion, so that the chains of alternatively-charged ions
directed along [±101] can be viewed. On Fig. 2 one chain
fragment is marked by dotted line on the top picture and
chain packing as view along [±101] can be seen neatly on the
bottom picture. We have also noted the presence of well-de-
fined layers parallel to (110) of bioctahedral anion, which al-
ternate along c axis with cation layers (Fig. 2 top).
Cl(9)±P±Cl(9 a)
Cl(8)±P±Cl(7)
solution (SHELXS-86 [7]) and refinement (SHELXL-93
[8]). All atoms were refined anisotropically with 86 para-
meters to wR2 = 0.1083 and R1 = 0.0527 for 919 reflections
with I > 2r(I).
The atomic coordinates and equivalent isotropic displace-
ment parameters are listed in Table 1. The bond distances
and angles are given in Table 2.
Results and Discussion
Fig. 1 The structure of anion in (PCl4)[Re2Cl9].
In the earlier work [6], the product of reaction of rhenium
metal with PCl5 was supposed to be a new compound
RePCl8. Its X-ray powder pattern was rationalized by author
Ê
of [6] in terms of a tetragonal unit cell with a = 13.42 A,
Ê
c = 11.34 A. In our experiments, we proved the product of
this reaction to be rhenium trichloride, Re3Cl9. We suggest
that the paramagnetism and phosphorus content in the sam-
ple investigated in [6] could be assigned to the presence of
ReCl5 and PCl3 or PCl5 as impurities. Preparation of pure
Re3Cl9 sample is not a very easy task; for example, the ear-
lier work [9] also reported Re3Cl9 to be a paramagnetic.
The formation of (PCl4)[Re2Cl9] can be presented as:
2 ReCl5 + PCl3 ® (PCl4)[Re2Cl9]
Presence of Re3Cl9 and PCl5 as the reaction products could
be explained by deeper reduction of ReCl5 by PCl3:
3 ReCl5 + 3 PCl3 ® Re3Cl9 + 3 PCl5.
X-ray structural analysis showed that the structure of
+
(PCl4)[Re2Cl9] is built from tetrachlorophosphonium PCl4
±
cations and cluster Re2Cl9 anions. The cation has the form
of nearly regularly tetrahedron, while the anion represents a
face-sharing bioctahedron. A mirror plane passes through
the both ions: one P and two Cl atoms lie in the mirror
+
plane of PCl4 cation; two Re atoms, one bridging Clb, and
±
two terminal Clt lie in the same plane in Re2Cl9 anion
(Fig. 1). The former ion is present in a variety of crystal
structures, while the latter has been previously found only in
two compounds, (NSCl2)[Re2Cl9] [10] and (nBu4N)[Re2Cl9]
Ê
[11]. The length of Re±Re bond, 2.724 A, and the value of
Re±Clb±Re angle, 68.2° (Table 2), show the direct metal±me-
tal interaction. We suppose that Re±Re bond in our com-
Fig. 2 Ion packing in the crystal structure of
(PCl4)[Re2Cl9].
±
pound is single as was reported in [11] for Re2Cl9 anion in
Z. Anorg. Allg. Chem. 1999, 625, 1240±1242
1241

A. I. Baranov, G. V. Khvorykh, S. I. Troyanov
nBu4N+ in (nBu4N)[Re2Cl9] might be much weaker due to
the effective screening of charge by nBu groups.
Ê
Table 3 Average interatomic distances (A) and angles (°)
±
in M2Cl9 ions
±
±
±
Distance/
Angle
Ti2Cl9 [1]
Re2Cl9
Re2Cl9± [10]
Re2Cl9 [11]
(this work)
M±M
3.466
2.204
2.512
98.27
77.78
87.21
2.724
2.304
2.420
91.37
91.66
68.49
2.700
2.297
2.414
91.51
91.75
68.02
2.704
2.283
2.407
91.4
91.5
68.4
M±ClÃt
[1] T. J. Kistenmacher, G. D. Stucky, Inorg. Chem. 1971, 10,
122.
[2] M. L. Ziegler, B. Huber, K. Weidenhammer, G. Koch,
Z. Naturforsch. 1976, 32 b, 18.
M±ClÃb
Clt±M±Clt
Clb±M±Clb
M±Clb±M
[3] H. Preiss, Z. Anorg. Allg. Chem. 1971, 380, 56.
[4] T. J. Kistenmacher, G. D. Stucky, Inorg. Chem. 1968, 7,
2150.
* Clt ± terminal chlorine atom; Clb ± bridge chlorine atom lying on
shared face.
[5] G. V. Khvorykh, S. I. Troyanov, A. I. Baranov, A. A. Se-
rov, Z. Anorg. Allg. Chem. 1998, 624, 1026.
[6] P. Machmer, Inorg. Nucl. Chem. Lett. 1968, 4, 91.
[7] G. M. Sheldrick, SHELXS-86, Program for Solution of
Crystal Structures form Diffraction Data, UniversitaÈt
GoÈttingen, 1986.
Actually, the Re±Re distance in (PCl4)[Re2Cl9] is about
Ê
0.02 A longer than that of found in (NSCl2)[Re2Cl9] and
(nBu4N)[Re2Cl9] (Table 3). We suggest that the elongation
can be accounted for the packing effect in (PCl4)[Re2Cl9]
±
crystal structure. The Re2Cl9 anion due to its special orien-
tation is slightly stretched along Re±Re bond by electro-
static forces from opposite-charged cations in chains men-
tioned above. Probably, the stretching results also in slight
elongating of Re±Cl bonds as compared with those in the
structures of (NSCl2)[Re2Cl9] and (nBu4N)[Re2Cl9]. These
structures do not contain well-defined layers or chains of
ions (Table 3). Moreover, the electrostatic influence of
[8] G. M. Sheldrick, SHELXL-93, Program for Crystal
Structure Refinement, UniversitaÈt GoÈttingen, 1993.
[9] W. SchuÈth, W. Klemm, Z. Anorg. Ch. 1934, 220, 195.
[10] H. G. Hauck, P. KlingelhoÈfer, U. MuÈller, K. Dehnicke,
Z. Anorg. Allg. Chem. 1984, 510, 180.
[11] G. A. Heath, J. E. McGrady, R. G. Raptis, A. C. Willis,
Inorg. Chem. 1996, 35, 6838.
1242
Z. Anorg. Allg. Chem. 1999, 625, 1240±1242