- Email: [email protected]
Complex halides of transition metals—IV The far-infrared spectra (500-200cm−1) of some hexahalo salts
2222
Research
notes
SpectrochimicaActa, 1067, Vol. 238, pp. 2222 to 2223. Pergamon Press Ltd. Printed in Northern Ireland
Complex halides of transition metals-IV* The far-infrared spectra (500-200cm-1) of some hexahalo salts (Received
2 December 1966)
Abstract-The far-infrared spectra of several salts of the complex anions MX,“-, where M = Ti, V, Zr, MO or W and X = Cl or Br, have been measured in the 500-200 cm-1 region. RESTJI,TS AND
DISCUSSION
THE far-infrared spectra of complex halides containing the regular octahedral ions MX,+ (where X = halogen) have attracted considerable interest [l-3]. During our work on the preparation and characterisation of complex ions of the titanium, vanadium and chromium sub-groups [4-61 we isolated several new MX, + ions, and in the present Note report their far-infrared spectra (500-200 cm-l). The absorption bands are listed in Table 1. Table
1. Infrared
Complex [Et,NH,],TiCl, [Et,NH&TiBr, Cs,VCl, [Et,NH],VCI,
325vs, br 238vs, br 238x7s 335x76, br 355vs 305VS
spectra
(500-200
cm-r)
of some MX,+
ions *
Catioll absorptiolln
C’oII+X
42311-n, 406m-w 416m-w, 40311-w 310m-s -
/iSt,NH,],ZrC1, [Et,NH&rBr,
2957-9,br -2OOvs, brt
[Et,NH,],MoCl, [Et,N]MoCl, [Et,N]WBr,
-3OOvs, br$ 33Ovs,br < 2oovst
1’3
Cati
absorptions
42om-IV, 406m-w 417xX-w, 402m-w 296m-s 424m-w, 406m-w -
* Recorded as Nujol mulls 011n Grubb-ParsoIls OnI4 spectrophotometcr. t liand maxima just outside the range of OUPmeasurements. # This band shows oonsiderable structure.
For aregular MX, species the only infrared active modes (ti, symmetry) are us (M-X stretch) and Y,, (bending). The bending mode was not observed above 200 cm-l in any of the complexes investigated in the present work. This is in keeping with the results of others [l-3]. With the exception of ZrBrs2- and WBre-, all other ions listed in the Table have a very intense broad absorption band (sometimes a doublet) between 350 and 230 cm-l. This is assigned to rs, and in the case of TiCI, 2- its position is close to that reported for other salts of these anions [ 11. For the analogous chloride and bromide of a particular metal ion it is found that -0.7, so that us for WBrs- (us for [Et,N]WCl, 305 cm-l) [7] occurs outside the range VM-Br I %-Cl of our measurements. The very broad nature of us probably arises from the site symmetry of the MX, species being this results in the removal of the degeneracy of this mode. For example, a lower than 0,; distinct splitting of us of the VCI, s- ion occurs on changing the counterion from Cs+ to Et,NH,+ (see Fig. 1). This may arise from the packing characteristics of the Et,NH,+ ion and/or its ability to hydrogen-bond. * Part
III.
B. J. BRISDON,
T. E. LESTER and R. A. WALTON,
Spectrochim.
Acta
23,
(1967).
[l] [2] [3] [4] [5] [6] [7]
D. D. D. G. B. B. K.
M. ADAMS and H. A. GEBBIE, SpectrocJLirn. Acta 19, 925 (1963). M. ADAMS, J. CHATT, J. M. DAVIDSON and J. GERRATT, J. Chem. Sot. 2189 (1963). M. ADAMS, H. A. GEBBIE and R. D. PEACOCK, Nature 199, 278 (1963). W. A. FOWLES and R. A. WALTON, J. Inorg. Nucl. Chewa. 27, 735 (1965). J. BRISDON and R. A. WALTON, J. Ghem. Sot. 2274 (1965). J. BRISDON and R. A. WALTON, J. Inorg. Nucl. Chem. 27, 1101 (1965). W. BAGNALL, D. BROWN and J. G. H. Du PREEZ, J. Chem. Sot. 2603 (1964).
1969
Research notes
I
I
400
300
2223
I )O
cm-’
Fig. 1. Infrared spectra of VC1s2- salts: (a) Cs+; (b) Et,NIQ+. A furtherinteresting point is that vsfor [EtsNH,],MoCl, is ~30 cm-l lower than the analogous alkali metal salts of this anion [2]. Although vs was previously shown to decrease as the size of the cation increases(K+ > Rb+ 2 Cs+), it is unlikely that the position of vs for [EtsNH,]sMoCl, is solely a consequenceof the size of the cation. Hydrogen bonding between the cationic protons and the anionic halogen atoms may result in a relative weakening of the Mo-Cl bond and a consequent decrease in vs. Department of Chembtry University of Reading Reading Berkshire
R. A. WALTON
Eng.?und Department of Chemistry Bath U&versity of Technology Bristol 7, England
B. J. BRISDON
Research
notes
SpectrochimicaActa, 1067, Vol. 238, pp. 2222 to 2223. Pergamon Press Ltd. Printed in Northern Ireland
Complex halides of transition metals-IV* The far-infrared spectra (500-200cm-1) of some hexahalo salts (Received
2 December 1966)
Abstract-The far-infrared spectra of several salts of the complex anions MX,“-, where M = Ti, V, Zr, MO or W and X = Cl or Br, have been measured in the 500-200 cm-1 region. RESTJI,TS AND
DISCUSSION
THE far-infrared spectra of complex halides containing the regular octahedral ions MX,+ (where X = halogen) have attracted considerable interest [l-3]. During our work on the preparation and characterisation of complex ions of the titanium, vanadium and chromium sub-groups [4-61 we isolated several new MX, + ions, and in the present Note report their far-infrared spectra (500-200 cm-l). The absorption bands are listed in Table 1. Table
1. Infrared
Complex [Et,NH,],TiCl, [Et,NH&TiBr, Cs,VCl, [Et,NH],VCI,
325vs, br 238vs, br 238x7s 335x76, br 355vs 305VS
spectra
(500-200
cm-r)
of some MX,+
ions *
Catioll absorptiolln
C’oII+X
42311-n, 406m-w 416m-w, 40311-w 310m-s -
/iSt,NH,],ZrC1, [Et,NH&rBr,
2957-9,br -2OOvs, brt
[Et,NH,],MoCl, [Et,N]MoCl, [Et,N]WBr,
-3OOvs, br$ 33Ovs,br < 2oovst
1’3
Cati
absorptions
42om-IV, 406m-w 417xX-w, 402m-w 296m-s 424m-w, 406m-w -
* Recorded as Nujol mulls 011n Grubb-ParsoIls OnI4 spectrophotometcr. t liand maxima just outside the range of OUPmeasurements. # This band shows oonsiderable structure.
For aregular MX, species the only infrared active modes (ti, symmetry) are us (M-X stretch) and Y,, (bending). The bending mode was not observed above 200 cm-l in any of the complexes investigated in the present work. This is in keeping with the results of others [l-3]. With the exception of ZrBrs2- and WBre-, all other ions listed in the Table have a very intense broad absorption band (sometimes a doublet) between 350 and 230 cm-l. This is assigned to rs, and in the case of TiCI, 2- its position is close to that reported for other salts of these anions [ 11. For the analogous chloride and bromide of a particular metal ion it is found that -0.7, so that us for WBrs- (us for [Et,N]WCl, 305 cm-l) [7] occurs outside the range VM-Br I %-Cl of our measurements. The very broad nature of us probably arises from the site symmetry of the MX, species being this results in the removal of the degeneracy of this mode. For example, a lower than 0,; distinct splitting of us of the VCI, s- ion occurs on changing the counterion from Cs+ to Et,NH,+ (see Fig. 1). This may arise from the packing characteristics of the Et,NH,+ ion and/or its ability to hydrogen-bond. * Part
III.
B. J. BRISDON,
T. E. LESTER and R. A. WALTON,
Spectrochim.
Acta
23,
(1967).
[l] [2] [3] [4] [5] [6] [7]
D. D. D. G. B. B. K.
M. ADAMS and H. A. GEBBIE, SpectrocJLirn. Acta 19, 925 (1963). M. ADAMS, J. CHATT, J. M. DAVIDSON and J. GERRATT, J. Chem. Sot. 2189 (1963). M. ADAMS, H. A. GEBBIE and R. D. PEACOCK, Nature 199, 278 (1963). W. A. FOWLES and R. A. WALTON, J. Inorg. Nucl. Chewa. 27, 735 (1965). J. BRISDON and R. A. WALTON, J. Ghem. Sot. 2274 (1965). J. BRISDON and R. A. WALTON, J. Inorg. Nucl. Chem. 27, 1101 (1965). W. BAGNALL, D. BROWN and J. G. H. Du PREEZ, J. Chem. Sot. 2603 (1964).
1969
Research notes
I
I
400
300
2223
I )O
cm-’
Fig. 1. Infrared spectra of VC1s2- salts: (a) Cs+; (b) Et,NIQ+. A furtherinteresting point is that vsfor [EtsNH,],MoCl, is ~30 cm-l lower than the analogous alkali metal salts of this anion [2]. Although vs was previously shown to decrease as the size of the cation increases(K+ > Rb+ 2 Cs+), it is unlikely that the position of vs for [EtsNH,]sMoCl, is solely a consequenceof the size of the cation. Hydrogen bonding between the cationic protons and the anionic halogen atoms may result in a relative weakening of the Mo-Cl bond and a consequent decrease in vs. Department of Chembtry University of Reading Reading Berkshire
R. A. WALTON
Eng.?und Department of Chemistry Bath U&versity of Technology Bristol 7, England
B. J. BRISDON