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Complexes of rhenium(III) chloride with phosphole derivatives
INORG.
NUCL.
CHEM.
LETTERS
Vol. 9, pp. 1265-1267, 1973. Pergamon
P r e s s . Printed in Great Britain
Complexes of rhenium(Ill) chloride with phosphole derivatives
D.G. Holah, A.N. Hughes and K. Wright Department of Chemistry, Lakehead University Thunder Bay, Ontario, Canada (Receiued 7 August 197~
Since single crystal structural determinations showed that rhenium(III) halides consist of Re3X9 (X = CI, Br) units, there has been considerable interest in the bonding and reactions of these cluster compounds(1).
I t is well known, for example, that
each rhenium in the Re3 cluster is capable of coordinating with one additional ligand forming complexes of the type Re3X9L3, the ligands including oxygen, nitrogen, phosphorus, arsenic and sulfur bases(1).
We therefore briefly report, as part of our con-
tinuing studies(2) on the coordinating properties of some phosphole derivatives, that rhenium(III) chloride reacts, in dry dichloromethane under reflux with the ligands 1,2,5-triphenylphosphole (TPP), its oxide (TPPO) and its selenide (TPPSe), and 5-phenyl-SHPh~Ph
/
dibenzophosphole (DBP), to give complexes formulated as Re3CI9L2.CH2CI2.
Ph (TPP)
A similar reaction of the phosphole
C Zp. 2
sulfide produced an uncharacterized
/
brown solid which decomposed even
Ph
when stored under dry nitrogen.
1265
(DBP)
1266
RHEN1UM(IID CHLORIDE
Analysisb H Cl
Vol. 9, No. 12
Complex (S=CH2CI2)
Colour m.p. a
C
Spectra c , (cmpl 6-I. Visible Re-Cl P=Se
Re3CI9.(TPP)2.S
Brown 249-251 °
34.6 2.3 18.6 34.1 2.3 20.I
8000 12100 18500
338sh 360 s
Re3CIg.(TPPO)2.S
Orangebrown 296-298°
33.0 2.2 20.7 33.4 2.2 1 9 . 7
8000 13300 19600
330 sh ll51 s 359 s (ll81 s) 554 w?
Re3CI9.(TPPSe)2.S
d a r k brown 248-249°
2 9 . 8 2.1 18.3 31.0 2.1 18.3
Re3CI9.(DBP)2.S
Purple 210-212°
29.8 2.0 30.0 1.9
d 7700 12600 18900
362 s 561 m (564 m) 335 sh 257 s
a uncorrected values, all adducts melt with decomposition b lower figures are calculated c
figures in parentheses refer to P=O and P=Se frequencies in free ligand
d
insufficient complex prepared for reflectance measurements Analytical data are shown in the table.
The presence of solvent in the adducts was confirmed by mass spectrometry and the solvent remained even after the complexes had been pumped under high vacuum (lO -6 Torr) at 50°C for several hours. Other solvent molecules could be incorporated into such complexes by carrying out reactions in different solvents, e.g. Re3CI9.(TPPO)2. 0.5(CH3)2C0 has been observed. Reflectanc~ spectra of the complexes (Table) are very similar and show three bands in the near infrared and visible regions, the relative intensities increasing as wavelength decreases. These spectra are consistent with retention of the Re3 cluster (1). The weakness of the Re-P bond in the TRP complex is demon-
Vol. 9, No. 12
RHENIUM(III) CHLORIDE
strated by the immediate displacement of ligand by coordinating solvents such as acetone or ethanol (c.f. TaCIsTPP(3)). Also, i f the Re3CI9-TPP reaction is carried out at room temperature instead of under reflux, complexes such as Re3CI9.TPP.(CH2CI2)n (n = 1-2) are formed. The weakness of the Re-O and Re-Se bonds is also reflected in the shifts of the P=O and P=Se stretching frequencies (Table) which are smaller than the corresponding shifts reported (3) for coordination to other metal systems. This is undoubtedly due to the known poor donor properties of these ligands, but could also be related to steric factors.
The latter, coupled with the already
crowded nature of the Re3 cluster probably determines that only two ligands and a solvent molecule are associated with each cluster. Various steric considerations connected with Re3 clusters have been discussed previously(1).
The results support our previous obser-
vations regarding the general non-availability of the P lone pair of electrons in TPP. We thank the National Research Council of Canada for generous financial support of this work.
REFERENCES I.
For example, see R.A. Walton, Prog. Inorg. Chem. 16, 1 (1972) and references therein.
2.
D.G. Holah, A.N. Hughes and B.C. Hui, Can. J. Chem. 5__00,3714 (1972).
3.
D. Budd, R. Churchman, D.G. Holah, A.N. Hughes and B.C. Hui, ibid. 5(], 1008 (1972).
1267
NUCL.
CHEM.
LETTERS
Vol. 9, pp. 1265-1267, 1973. Pergamon
P r e s s . Printed in Great Britain
Complexes of rhenium(Ill) chloride with phosphole derivatives
D.G. Holah, A.N. Hughes and K. Wright Department of Chemistry, Lakehead University Thunder Bay, Ontario, Canada (Receiued 7 August 197~
Since single crystal structural determinations showed that rhenium(III) halides consist of Re3X9 (X = CI, Br) units, there has been considerable interest in the bonding and reactions of these cluster compounds(1).
I t is well known, for example, that
each rhenium in the Re3 cluster is capable of coordinating with one additional ligand forming complexes of the type Re3X9L3, the ligands including oxygen, nitrogen, phosphorus, arsenic and sulfur bases(1).
We therefore briefly report, as part of our con-
tinuing studies(2) on the coordinating properties of some phosphole derivatives, that rhenium(III) chloride reacts, in dry dichloromethane under reflux with the ligands 1,2,5-triphenylphosphole (TPP), its oxide (TPPO) and its selenide (TPPSe), and 5-phenyl-SHPh~Ph
/
dibenzophosphole (DBP), to give complexes formulated as Re3CI9L2.CH2CI2.
Ph (TPP)
A similar reaction of the phosphole
C Zp. 2
sulfide produced an uncharacterized
/
brown solid which decomposed even
Ph
when stored under dry nitrogen.
1265
(DBP)
1266
RHEN1UM(IID CHLORIDE
Analysisb H Cl
Vol. 9, No. 12
Complex (S=CH2CI2)
Colour m.p. a
C
Spectra c , (cmpl 6-I. Visible Re-Cl P=Se
Re3CI9.(TPP)2.S
Brown 249-251 °
34.6 2.3 18.6 34.1 2.3 20.I
8000 12100 18500
338sh 360 s
Re3CIg.(TPPO)2.S
Orangebrown 296-298°
33.0 2.2 20.7 33.4 2.2 1 9 . 7
8000 13300 19600
330 sh ll51 s 359 s (ll81 s) 554 w?
Re3CI9.(TPPSe)2.S
d a r k brown 248-249°
2 9 . 8 2.1 18.3 31.0 2.1 18.3
Re3CI9.(DBP)2.S
Purple 210-212°
29.8 2.0 30.0 1.9
d 7700 12600 18900
362 s 561 m (564 m) 335 sh 257 s
a uncorrected values, all adducts melt with decomposition b lower figures are calculated c
figures in parentheses refer to P=O and P=Se frequencies in free ligand
d
insufficient complex prepared for reflectance measurements Analytical data are shown in the table.
The presence of solvent in the adducts was confirmed by mass spectrometry and the solvent remained even after the complexes had been pumped under high vacuum (lO -6 Torr) at 50°C for several hours. Other solvent molecules could be incorporated into such complexes by carrying out reactions in different solvents, e.g. Re3CI9.(TPPO)2. 0.5(CH3)2C0 has been observed. Reflectanc~ spectra of the complexes (Table) are very similar and show three bands in the near infrared and visible regions, the relative intensities increasing as wavelength decreases. These spectra are consistent with retention of the Re3 cluster (1). The weakness of the Re-P bond in the TRP complex is demon-
Vol. 9, No. 12
RHENIUM(III) CHLORIDE
strated by the immediate displacement of ligand by coordinating solvents such as acetone or ethanol (c.f. TaCIsTPP(3)). Also, i f the Re3CI9-TPP reaction is carried out at room temperature instead of under reflux, complexes such as Re3CI9.TPP.(CH2CI2)n (n = 1-2) are formed. The weakness of the Re-O and Re-Se bonds is also reflected in the shifts of the P=O and P=Se stretching frequencies (Table) which are smaller than the corresponding shifts reported (3) for coordination to other metal systems. This is undoubtedly due to the known poor donor properties of these ligands, but could also be related to steric factors.
The latter, coupled with the already
crowded nature of the Re3 cluster probably determines that only two ligands and a solvent molecule are associated with each cluster. Various steric considerations connected with Re3 clusters have been discussed previously(1).
The results support our previous obser-
vations regarding the general non-availability of the P lone pair of electrons in TPP. We thank the National Research Council of Canada for generous financial support of this work.
REFERENCES I.
For example, see R.A. Walton, Prog. Inorg. Chem. 16, 1 (1972) and references therein.
2.
D.G. Holah, A.N. Hughes and B.C. Hui, Can. J. Chem. 5__00,3714 (1972).
3.
D. Budd, R. Churchman, D.G. Holah, A.N. Hughes and B.C. Hui, ibid. 5(], 1008 (1972).
1267