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Some chromium(II) complexes of triphenylarsine oxide
J. inorg, nu¢l. Chem., 1967, Vol. 29, pp. 2101 to 2102. Pergamon Press Ltd. Printed in Northern Ireland
NOTES Some ehromium(II) complexes of triphenylarsine oxide (Received 7 January 1967) AI.rrIouGn many complexes of triphenylarsine oxide with a variety of acceptor elements have been studied t" no complexes of chromium(II) have been reported, presumably because of their extreme air-sensitivity. Some properties of the chromium(II) complexes which we have prepared are given in Table 1. TABLE 1
/~eft* (B.M.)
0 (°K)
~ (cm-O
Reflectance spectrat *5~a~m-X)
9.24 9-36
4.6
0
850, 879
18,000 s, b; 15,500m, b; 13,000 sh
10-64 10.75
4.89
0
860
21,000 w,:~ b; 17,700 w,b; 15,700 sh
---
4.89
0
865
20,000 sh;:~ 16,400 m, v.b
~C
%H
~Hal
CrC12(Ph3AsO)2 violet-pink
Calc. 56.35 Obs. 56-10
3-94 4'02
CrBr2(Ph3AsO)4 pink
Calc. 57-61 4.00 Obs. 57.35 4.22
Cr(CIO4)~(Ph3AsO)4 pale blue
Calc. 56.15 Obs. 56.06
3.93 3.95
* At 299°K. J" In the range 25,0(0)-10,000 cm -~. s = strong, m = medium, w = weak, sh = shoulder, b = broad, v = very. :~ Possibly due to a trace of an oxidation product, as commonly found c~m in chromium(II) systems. The compounds were prepared in absolute ethanol under nitrogen. Magnetic measurements down to liquid nitrogen temperatures show that the compounds obey the Curie law and contain high-spin chromium(II). ~3~ High-spin, six-co-ordinate chromium(II) complexes, even of identical ligands, have tetragonally distorted structures, ~-4~ and although in a regular octahedral environment high-spin (t~aae~1) chromium(II) complexes are expected to show only one spin-allowed transition (sEg --* 5T2~), the distortion reduces the degeneracies of the E~ and T2o states, and leads to the appearance of one very broad band, or, more commonly, two or more bands, in their visible and near i.r. spectra. Thus, the diffuse reflectance spectra show that these arsine oxide complexes have considerably distorted octahedral structures. Infrared measurements indicate that in the perchlorate complex the anion interacts only weakly, if at all, with the metal, and that the structures of the bromide and perchlorate are similar. The chlorocomplex is considered to have a chlorine-bridged, tetragonal structure. Formulation as [Cr(PhvA.sO)d[CrCld is ruled out by the differences between its i.r. and reflectance spectra and those of CrBr2(Ph3AsO)4 and Cr(C104)2(Ph3AsO)~. Amongst other things, the As-O stretching bands of the chloro-complex are quite different. The presence of three bands in the reflectance spectrum of this complex suggests that it has the least symmetrical structure, and is compatible with the chlorine-bridged formulation. m G. A. RODLEY,D. M. L. GOODGAMEand F. A. COTTON,3". chem. Soc. 1499 (1965); and references therein. n~ A. EARNSHAW,L. F. LARKWOP,Trrr and K. S. PAT~L,J. chem. Soc. 3267 (1965). ~8~j. p. FACKLERand D. G. HOLAH, lnorff. Chem. 4, 954 (1965). 14~A. EARNSHAW,L. F. LARKWORTaYand K. S. PATEL,3". chem. Soc. 363 (1966). 2101
2102
Notes
We have partially characterized a 4:1 arsine oxide chloro-complex and an iodo-complex and are also investigating related amine and phosphine oxide systems.
Acknowledgement--We thank Mr. K. C. PATEL for carrying out the magnetic measurements. Chemistry Department University of Surrey Battersea Park Road London S. W.I 1
L . F . LARKWORTHY D . J . PHILLIPS
J. inorg, nucl. Chem., 1967, Vol. 29, pp. 2102 to 2106. Pergamon Press Ltd. Printed In Northern Ireland
Le comportement des atomes de recul dans le chromate de potassium dop6 au barium
(Received 10 February 1967) UNE NOUVELLEm6thode d'investigation de l'influence des d6fauts sur la r6activit6 des atomes de recul a 6t6 propos6e par At,IDFgSONet al. a~ qui ont montr6 que la sensibilit6 all recuit thermique pour le chromate de potassium dop6 au calcium est plus grande clue celle du cristal pur. Le ph6nom~ne a 6t6 expliqu6 par la contribution des lacunes introduites par les ions bivalents de calcium. La recherche ult6rieure de l'influence des concentrations variables d'ions (TI +, Ca n+, La 8+) a mis en 6vidence la diff6rence de comportement des atomes de recul. ¢~ L'interpr6tation de ces effets par l'intervention exclusive des lacunes n'6tant pas satisfaisante, il est en plus n6cessaire d'envisager l'influence des tensions locales produites dans le r6seau ainsi que le caract~re chimique de l'616ment dopant, l.#.s derni~res recherches ont d6montr6 une non-reproductibilit6 des r6sultats qui est apparemment fonetion de conditions d'irradiation diff6rentes (cas du calcium) et en m~me temps de comportements diff6rents en pr6sence d'ions bivalents similaires (Ca n+, Sr ~+, Ba2+). ~8~ Nos r6sultats sur le chromate de potassium dop6 au barium conduisent A des conclusions qui permettraient rinterpr6tation de la non-reproductibilit6 des donn6es obtenues dans diff6rentes conditions d'irradiation, et celle de la sensibilit6 au recuit thermique en tenant compte de l'6nergie d'activation et des facteurs qui peuvent rinfluencer. Les 6chantillons de chromate de potassium dop6 au barium ont 6t6 pr6par6s, darts les proportions molaires de 10-4, 10-8, 10-2, par la fusion des chromates respectifs; ils ont &6 irradi6s dans des capsules d'aluminium, en pr6sence d'air, dans la zone active (A) et darts la colorme thermique (B) du r6acteur IFA. Les 6chantillons C ont &6 aussi irradi6s dans la colonne thermique mais darts une tube de plomb (6paisseur de parois: 6 mm). Les conditions d'irradiation Sont donn6es dans le Tableau 1. La s6paration du Cr ~+ et du Cr e+ a 6t6 r6alis6e par le passage de la solution ac6tique de l'6chantillon irradi6 sur une colonne d'6changeurs d'ions. Les r6sultats ont 6t6 identiques/t ceux obtenus par la pr6cipitation du chromate de plomb. L'activit6 a 6t6 mesur6e avec un compteur/t scintillation muni d'un cristal de NaI(T1). Le traitement isothermique a 6t6 effectu6/t 170°C, 200°C et 221°C (C) ou 225°C (B). TABLEAU1.--LES Sth (cm -2 sec -2)
coNDrnoNs
Sr (cm -2 see -x)
D'IRRADIATION
d~, (tad hr -x)
Temp (°C)
Time (hr)
A
5,0" 10TM
1,0" 10 TM
,~I0 s
130-170
1
B
1,2 • 1011
6,3 • 109
4,2.10 e
,~40
88
C
~ 1 , 2 " 1011
~ 6 , 3 • 109
<4,2" 106
,-~40
2
u~ T. ANDERSONet A. G. MADDOCK, Nature, Lond. 194, 371 (1962). ¢m T. ANDERSONet A. G. MADDOCK, Trans. Faraday Soc. 59, 2362 (1963). ~8~T. ANDERSENet K. OLESSN, Trans. Faraday Soc. 61, 781 (1965).
NOTES Some ehromium(II) complexes of triphenylarsine oxide (Received 7 January 1967) AI.rrIouGn many complexes of triphenylarsine oxide with a variety of acceptor elements have been studied t" no complexes of chromium(II) have been reported, presumably because of their extreme air-sensitivity. Some properties of the chromium(II) complexes which we have prepared are given in Table 1. TABLE 1
/~eft* (B.M.)
0 (°K)
~ (cm-O
Reflectance spectrat *5~a~m-X)
9.24 9-36
4.6
0
850, 879
18,000 s, b; 15,500m, b; 13,000 sh
10-64 10.75
4.89
0
860
21,000 w,:~ b; 17,700 w,b; 15,700 sh
---
4.89
0
865
20,000 sh;:~ 16,400 m, v.b
~C
%H
~Hal
CrC12(Ph3AsO)2 violet-pink
Calc. 56.35 Obs. 56-10
3-94 4'02
CrBr2(Ph3AsO)4 pink
Calc. 57-61 4.00 Obs. 57.35 4.22
Cr(CIO4)~(Ph3AsO)4 pale blue
Calc. 56.15 Obs. 56.06
3.93 3.95
* At 299°K. J" In the range 25,0(0)-10,000 cm -~. s = strong, m = medium, w = weak, sh = shoulder, b = broad, v = very. :~ Possibly due to a trace of an oxidation product, as commonly found c~m in chromium(II) systems. The compounds were prepared in absolute ethanol under nitrogen. Magnetic measurements down to liquid nitrogen temperatures show that the compounds obey the Curie law and contain high-spin chromium(II). ~3~ High-spin, six-co-ordinate chromium(II) complexes, even of identical ligands, have tetragonally distorted structures, ~-4~ and although in a regular octahedral environment high-spin (t~aae~1) chromium(II) complexes are expected to show only one spin-allowed transition (sEg --* 5T2~), the distortion reduces the degeneracies of the E~ and T2o states, and leads to the appearance of one very broad band, or, more commonly, two or more bands, in their visible and near i.r. spectra. Thus, the diffuse reflectance spectra show that these arsine oxide complexes have considerably distorted octahedral structures. Infrared measurements indicate that in the perchlorate complex the anion interacts only weakly, if at all, with the metal, and that the structures of the bromide and perchlorate are similar. The chlorocomplex is considered to have a chlorine-bridged, tetragonal structure. Formulation as [Cr(PhvA.sO)d[CrCld is ruled out by the differences between its i.r. and reflectance spectra and those of CrBr2(Ph3AsO)4 and Cr(C104)2(Ph3AsO)~. Amongst other things, the As-O stretching bands of the chloro-complex are quite different. The presence of three bands in the reflectance spectrum of this complex suggests that it has the least symmetrical structure, and is compatible with the chlorine-bridged formulation. m G. A. RODLEY,D. M. L. GOODGAMEand F. A. COTTON,3". chem. Soc. 1499 (1965); and references therein. n~ A. EARNSHAW,L. F. LARKWOP,Trrr and K. S. PAT~L,J. chem. Soc. 3267 (1965). ~8~j. p. FACKLERand D. G. HOLAH, lnorff. Chem. 4, 954 (1965). 14~A. EARNSHAW,L. F. LARKWORTaYand K. S. PATEL,3". chem. Soc. 363 (1966). 2101
2102
Notes
We have partially characterized a 4:1 arsine oxide chloro-complex and an iodo-complex and are also investigating related amine and phosphine oxide systems.
Acknowledgement--We thank Mr. K. C. PATEL for carrying out the magnetic measurements. Chemistry Department University of Surrey Battersea Park Road London S. W.I 1
L . F . LARKWORTHY D . J . PHILLIPS
J. inorg, nucl. Chem., 1967, Vol. 29, pp. 2102 to 2106. Pergamon Press Ltd. Printed In Northern Ireland
Le comportement des atomes de recul dans le chromate de potassium dop6 au barium
(Received 10 February 1967) UNE NOUVELLEm6thode d'investigation de l'influence des d6fauts sur la r6activit6 des atomes de recul a 6t6 propos6e par At,IDFgSONet al. a~ qui ont montr6 que la sensibilit6 all recuit thermique pour le chromate de potassium dop6 au calcium est plus grande clue celle du cristal pur. Le ph6nom~ne a 6t6 expliqu6 par la contribution des lacunes introduites par les ions bivalents de calcium. La recherche ult6rieure de l'influence des concentrations variables d'ions (TI +, Ca n+, La 8+) a mis en 6vidence la diff6rence de comportement des atomes de recul. ¢~ L'interpr6tation de ces effets par l'intervention exclusive des lacunes n'6tant pas satisfaisante, il est en plus n6cessaire d'envisager l'influence des tensions locales produites dans le r6seau ainsi que le caract~re chimique de l'616ment dopant, l.#.s derni~res recherches ont d6montr6 une non-reproductibilit6 des r6sultats qui est apparemment fonetion de conditions d'irradiation diff6rentes (cas du calcium) et en m~me temps de comportements diff6rents en pr6sence d'ions bivalents similaires (Ca n+, Sr ~+, Ba2+). ~8~ Nos r6sultats sur le chromate de potassium dop6 au barium conduisent A des conclusions qui permettraient rinterpr6tation de la non-reproductibilit6 des donn6es obtenues dans diff6rentes conditions d'irradiation, et celle de la sensibilit6 au recuit thermique en tenant compte de l'6nergie d'activation et des facteurs qui peuvent rinfluencer. Les 6chantillons de chromate de potassium dop6 au barium ont 6t6 pr6par6s, darts les proportions molaires de 10-4, 10-8, 10-2, par la fusion des chromates respectifs; ils ont &6 irradi6s dans des capsules d'aluminium, en pr6sence d'air, dans la zone active (A) et darts la colorme thermique (B) du r6acteur IFA. Les 6chantillons C ont &6 aussi irradi6s dans la colonne thermique mais darts une tube de plomb (6paisseur de parois: 6 mm). Les conditions d'irradiation Sont donn6es dans le Tableau 1. La s6paration du Cr ~+ et du Cr e+ a 6t6 r6alis6e par le passage de la solution ac6tique de l'6chantillon irradi6 sur une colonne d'6changeurs d'ions. Les r6sultats ont 6t6 identiques/t ceux obtenus par la pr6cipitation du chromate de plomb. L'activit6 a 6t6 mesur6e avec un compteur/t scintillation muni d'un cristal de NaI(T1). Le traitement isothermique a 6t6 effectu6/t 170°C, 200°C et 221°C (C) ou 225°C (B). TABLEAU1.--LES Sth (cm -2 sec -2)
coNDrnoNs
Sr (cm -2 see -x)
D'IRRADIATION
d~, (tad hr -x)
Temp (°C)
Time (hr)
A
5,0" 10TM
1,0" 10 TM
,~I0 s
130-170
1
B
1,2 • 1011
6,3 • 109
4,2.10 e
,~40
88
C
~ 1 , 2 " 1011
~ 6 , 3 • 109
<4,2" 106
,-~40
2
u~ T. ANDERSONet A. G. MADDOCK, Nature, Lond. 194, 371 (1962). ¢m T. ANDERSONet A. G. MADDOCK, Trans. Faraday Soc. 59, 2362 (1963). ~8~T. ANDERSENet K. OLESSN, Trans. Faraday Soc. 61, 781 (1965).