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An infrared study of organothallium thiocyanates
27
Jolrrnnl of Organometallrc Chemwtc, @ Elsevler Sequoia S.A , Labsanne -
AN INFRARED
Y BERTAZZI,
Istltuto
81 (1974)
27-32
Prlnted In The Netherlands
STUDY OF ORGANOTHALLICllLI THIOCYANATES
G C STOCCO,
dr Chrmlca Generale,
L PELLERITO
and A SILVESTRI
D’ruL~erslta dl Pdermo.
901’3
Palermo
(l:alla)
(Recewed hhy !?3rd, 1971)
Summary
Some structural
‘aspects of the organothall~um(III)
RITICNS
thlocyanates
(R = Me, Ph). [ Ph,As][Me,Tl(CNS),] and PhTI(CNS)? have been studled by IR spectroscopy. From the frequencies of the NCS group wbratlotx m the sohds, and the Integrated mtenslty of the C-N stretchmg absorption m solution, It was ascerramed
that
the
dlorganothalllum
derlratlves
art = :sothlocyanntes
1%lth a cer-
tam amount of lonlc character in the Tl-NCS bond;, whereas PhTI(CNS)? 1s essentially a TI-SCN bonded compound. Apparently both sohd Me,TICNS and [Ph3As][ILle,Tl(CNS)2] do not she\\ IR actwe r~,(TIC,)bands. The compound hIe,TlCNS dlspiays a double v,,(TIC,) band, from which the presence m the solid of non-equivalent Me,TI”’ moleties could be Inferred. Possible configurations of the dlmethylthalhurn dewatwes are discussed. Whtie organothaUwm( III) thlocyanates have been known for a long time, of their structures have been reported The hterature contams references to the preparation of R?TICNS (R = Me [ 1,2], Et [3], Ph [2]) and PhTl(CNS)2 [ 41. Compounds [ PhqAs][ R2Tl(CNS),] (R = hle, Ph), formulated as salts contamIng R?TI(CNS); anions In acetone solution, have also been reported [ 2] These amoruc species, as well as PhTI( CNS)ien (n = 3, 4) [ 5.61, have been detected also in aqueous soluhon (at suitable thlocyanate-llgand concentration). The monophenylthail~um compleses, In coneast to the related PhTlX,?,-” (12 = 3, no investlgatrons
X = Cl, Br, i, CN; n = 4, X = Cl) [2,4.7], have not been Isolated rn the solid state This paper reports an infrared study on solld Rle,TlCNS, Ph,TICNS, compounds The [ hIe,TJ( CNS)?] and PhTI( CNS),, chosen as representatwe mvestlgatlon has been extended to solution spectra, measunng the apparent integrated absorption mtenslty of the C-N stretchmg frequency, m order better to
[Ph.&]
elucidate
the nature of thallium-thlocyanate
bonds In these compounds
Experimental The organothallwm methods [ 2,4]
thlocyanates
were prepared
according
to published
38 T9BLE
1
RELEVAYT
IR 4BSORPTIONS
hle~TIC%S
Ph?TICNS
2050 2035 950 935 800 750 650 540 110 -165
3050
(sh) vs (br) t& %b \1s(br) s m m ms ins
\ B (br)
(cm-‘)
OF SOLID
THIOCYANATES
[Ph~.~~][hle~Tl(CNS)~1
PhTl(CiuS)z
1-056 s
2130
1-030
800 755
ORGANOTHALLIUhl(lll)
mtbr)
5
4wgnmenls
1 1
m (br)
I (C-S)
5-15 mw i,
455
s
2 X E(NCS) P(CH~)
m
480
u(CEN)
1
355 m 430 1, 435 ms 280 m
I
~~,,(TI-C2
B
6(NCS)
rv(TI-Ph) v(TI-S)
All spectra were taken wrth a Perkm--Elmer Model 457 spectrometer. Solids were erarmned as NUJOImulls, and theu- absorptron bands are Irsted below; u-r Table 1 are summarized the assignments made for mtemal vrbratronal modes of the thlocyanate group, as well as for other frequencres useful to the drscussron. The compound PhTI(CNS)2 showed apprecrable decomposition m the radratron beam and its spectrum was recorded repeatedly renelb m”g the sample during scannmg. Me,TlCNS: 2050 (sh), 2035 vs( br), 1115 w( br), 950 IV, 935 w, SO0 vs( br), 750 s, 615 w(br), 550 m, 510 m, 470 ms, 465 m cm-’ Ph,TICNS: 2030 vs(lx), 1430 m, 1325 w, 1300 w, 106Ow, 1015m, 995 m, 960 w(br), 900 mw(br), 755 m. 730 s, 720 s, 685 s, 665 (sh), 480 IV, 455 s cm-’ [ Ph,As][ Me,Tl( CNS)?]: 2050 s, 2030 s, 1435 m, 1305 w(br), 1185 w, 1165 w, lOS0 s, 1020 w, ‘395 m, 965 w, 920 w, 800 m(br), 740 (sh), 730 s, 685 s, 545 mw, 475 ms, -I70 s, 350 m cm-’ PhTI(CNS)?: 2130 m(br), 1435 m, 1325 w, 1160 VW, 106Ovw, 1010 ms, 990 ms, 910 w, 840 w(br), 735 s, 675 ms, 650 m, 455 m, 435 ms, 120 w, 280 m cm-‘. For the intensity measurements of the v(C-N) band of compounds m acetone solutron (c = 1 to 2 >I lo-‘AI), a CsI cell of 0 03 cm path length (I) was used m order to record solvent and solutron spectra u-rthe regron 2200 to 2000 cm- ‘, employing a IO X abscissa expansron of the rnstrument The apparent mtensrty cf the band (A) was evaluated by dtrect graphrc integration of the espression IS]: A=_
2-3 T0 dv !g T ncl s
where II IS the number of throcyanate groups u-rthe compound, u-rorder to normake results for different stolchiometries. To and T are respectively the transrruttances of solvent and sample solutron All experiments were run in duphcate; for comparison purposes, analogous measurements were performed on KCNS and MeJNCNS solut-rons. The results are reported III Table 2.
31
by Me2TICNS, which would mdlcate the existence UI the solid of non-eqluvalent Me,Tl”’ moieties Whether an IR-active v&TI&) E present or not in both spectra is questlonable, as m the region of Interest. there are absorptlons due to 6 (NCS) and to phenyl groups (for the tetmphenplarsomum salt) Nevertheless, some coslderations seem to lndlcate the IR-mactwlty of this band In fact, pubhshed data[32] show that the difference between u,,(TIC,) and U&TIC!,) frequencies in dlmethylthallium derwatwes 1s of the order of 45-65 cm-‘, and that there eslsts a 1mea.r correlation between the methyl rocking frequency, p (CH,), and v~, uas(TIC2) [33] These critena should locate the value of us(T1C2), for Me,TlCNS and [Ph,As] cm-’ and 500--I80 cm-‘, These frequent> [ hlezT1( CNS)2], In the regona 505-475 ranges In the recorded spectra are actually free from bands, suggesting the POWble lineanty of Me,Ti”’ moletles ln both compounds. A lmear C-Tl-C skeleton has been reported in many solld compounds Me,TlX (X = Cl, Br, I, CIOJ, NOJand others) VIbrational studies on hIe,TlClO, and Me,Tl.N03 [ 1,311 indicate that these are loruc compounds contammg Me?Ti’ cations and the correspondmg free amens. The X-ray structure of dlmethylthaihum halides [ 341 consists of layers in whxh a Me2Tl”’ group 1s surrounded by four halogens and each halogen by four hIe,TI”’ groups: this structure has been often referred to as an lonlc lattic P, but, at least m the case of the chiorlde, it has been also described [ 351 as an extended polymer \vlth brlrlg;lng halogex, where Tl”’ would assume an octahedral stereochemlstry For dlmethylthalhum thlocyanate an lonlc Me2T1’NCSstructure seems unhkely (as there wll be a certam amount of covalency In the Tl-KCS bonds), and an explanation of both lmeanty and non-equwalence of the Me?Tl moieties should perhaps consider the solid formulated as [ Me2TI][ Rle,Tl( NCS): I, contaming (as hmlt case) Me,Tl’catlons and polymeric Rle,Tl(NCS); species In whwh T1 atoms are heuacoordmated. The structure of Me,TlCNS and of[ Ph,As] [ Me,Tl(CNS)2] would then probably be closely related. Further stnlctur‘al InvestIgatlons on these compounds are clearly needed, and ~11 be soon carried out m this laboratory. Acknowledgements The fmancial
support
by C N R. (Roma)
IS gratefully
acknowledged.
References 1
G
2
G.
D Sbter and R S Dmgo. J Or~~nomelal Chem 5 (19fih) 330 Furagha. L Roncucc~ Fmraru. B Lassandro Pepr and R Bsrblcrl.
10 (1967) 363 3 A E GoddYrd, .I C-hem Sot . (1931) 671, J Chem Sot (1934) 405 1 F Ch~llengcr and 0 \’ Rlchvds 5 G Faragln, A CJWOI and R Barblen Proc Journees Hellknee 6 7 8 9
10
Chromalognphle N Berro2z1. 4 G F.u-a&a. L 2 (1966) 277 D A Ramwv J Chart and L PC H hlllchell
J Orgtinometal
dc Stpamt~on
lmmedkle
(III J I S I C ) 4s~ Greek Chem Ed . Athens (1966) 271 Srlteslrl 2nd G Alowo Garz Chum ltal 10-l (1974) 155 Roncuc~! Florar~. B Larwqdro Pepe and R Bsrbierl. Irwrg lvucl .I Amer Chem Sot. 76 (1952) 72 A Duncac~on. Nature (London). 176 (1956) 997 and R J P WdUms J Chem Sot .(1960) 1912
Chem
Chtm
,
~1 ae
Lerr
.
32 11
J Lews.
12
A Tranwr. J. Chem. Phys.. 59 (1963) 232 D Forgerand D hl L Goodgame. inorg Chem 4 SabatIm and I Bertlm. Inorg Chtim -1 (1965)
13 14
R S
Nvbolm
and PI%
Smllh
J Chem
Sot
, (1961)
4 (1965) 959
4590
715
15 R J H ClarF and C S Wdhams Spectrocblm 9cta. 22 (1966) 1081 16 S J Pate]. J lnorg NucL Chem .32 (19iO) 3508 Ii A G Lee. J 0rganomeL;rL Chem .32 (lSi0) 537 18 D H WhIffen. J Chem Sot (1956) 1353 19 D X1 Adams. hfetal-Llgand and related Vlbrarlons Edrrard Arnold London 20 D B Solrerby. J 4mer Chem Sot . 8-t (1962) 1831 “1 S J Pate1.J lnorg Nucl Cbem .33(1971J 17 ‘22 S J Pate1 aod D G Tuck Can J Chem -IT (1969) 229 23 PL Goggm. I J hlccolmand R Shore J Chem Sot A (1966; 131-1 94 S J Pete1 D B Sowerbv and D G Tucl J Chem Sot A (1967) 1187 25 4 H Norbury. J Chem Sot A. (19ilJ 1089 144i 26 S Fronaeus and R Lsrsson. ?cta Chrm Stand . 16 (1962) Zi C Pecll:. lnorg Chcm . 5 (1966) 210 18 R Larson and A hllezls ~cta Chem Scsnd 23 (1969) 3i 29 R A B&c\ T hl hllchelzensnd W U \I& J inorg Yucl Chem 33 (1971) 30 N BcrU:z~. G ~lonzo. 4 Sllvt-str; and G Cons~gl~o. J Organometal Chem 31 G B Deacon. J H S Green and R S Nyholm. J Chem Sot . (1965) 3411
32 33 3-l 35
1967.
p 319
3206 (1972)
. 37
281
See for example H Kurosaua and R Obarrara OrCanometal Chem Rev A. 6 (1970) 65 and references lhereln H Kuros;r\\a and R Oha\barz. Tnns h \ Acad SC! Ser II. 30 (1968) 962 (rroorted m r~f 32. p 89) H hl PoLbeUand D hf Cronfoof. 2 fins1 8i (193-l) 370 I R Bealrle and P 4 Cocblng. J Chem Sot . (1965) 3860
Jolrrnnl of Organometallrc Chemwtc, @ Elsevler Sequoia S.A , Labsanne -
AN INFRARED
Y BERTAZZI,
Istltuto
81 (1974)
27-32
Prlnted In The Netherlands
STUDY OF ORGANOTHALLICllLI THIOCYANATES
G C STOCCO,
dr Chrmlca Generale,
L PELLERITO
and A SILVESTRI
D’ruL~erslta dl Pdermo.
901’3
Palermo
(l:alla)
(Recewed hhy !?3rd, 1971)
Summary
Some structural
‘aspects of the organothall~um(III)
RITICNS
thlocyanates
(R = Me, Ph). [ Ph,As][Me,Tl(CNS),] and PhTI(CNS)? have been studled by IR spectroscopy. From the frequencies of the NCS group wbratlotx m the sohds, and the Integrated mtenslty of the C-N stretchmg absorption m solution, It was ascerramed
that
the
dlorganothalllum
derlratlves
art = :sothlocyanntes
1%lth a cer-
tam amount of lonlc character in the Tl-NCS bond;, whereas PhTI(CNS)? 1s essentially a TI-SCN bonded compound. Apparently both sohd Me,TICNS and [Ph3As][ILle,Tl(CNS)2] do not she\\ IR actwe r~,(TIC,)bands. The compound hIe,TlCNS dlspiays a double v,,(TIC,) band, from which the presence m the solid of non-equivalent Me,TI”’ moleties could be Inferred. Possible configurations of the dlmethylthalhurn dewatwes are discussed. Whtie organothaUwm( III) thlocyanates have been known for a long time, of their structures have been reported The hterature contams references to the preparation of R?TICNS (R = Me [ 1,2], Et [3], Ph [2]) and PhTl(CNS)2 [ 41. Compounds [ PhqAs][ R2Tl(CNS),] (R = hle, Ph), formulated as salts contamIng R?TI(CNS); anions In acetone solution, have also been reported [ 2] These amoruc species, as well as PhTI( CNS)ien (n = 3, 4) [ 5.61, have been detected also in aqueous soluhon (at suitable thlocyanate-llgand concentration). The monophenylthail~um compleses, In coneast to the related PhTlX,?,-” (12 = 3, no investlgatrons
X = Cl, Br, i, CN; n = 4, X = Cl) [2,4.7], have not been Isolated rn the solid state This paper reports an infrared study on solld Rle,TlCNS, Ph,TICNS, compounds The [ hIe,TJ( CNS)?] and PhTI( CNS),, chosen as representatwe mvestlgatlon has been extended to solution spectra, measunng the apparent integrated absorption mtenslty of the C-N stretchmg frequency, m order better to
[Ph.&]
elucidate
the nature of thallium-thlocyanate
bonds In these compounds
Experimental The organothallwm methods [ 2,4]
thlocyanates
were prepared
according
to published
38 T9BLE
1
RELEVAYT
IR 4BSORPTIONS
hle~TIC%S
Ph?TICNS
2050 2035 950 935 800 750 650 540 110 -165
3050
(sh) vs (br) t& %b \1s(br) s m m ms ins
\ B (br)
(cm-‘)
OF SOLID
THIOCYANATES
[Ph~.~~][hle~Tl(CNS)~1
PhTl(CiuS)z
1-056 s
2130
1-030
800 755
ORGANOTHALLIUhl(lll)
mtbr)
5
4wgnmenls
1 1
m (br)
I (C-S)
5-15 mw i,
455
s
2 X E(NCS) P(CH~)
m
480
u(CEN)
1
355 m 430 1, 435 ms 280 m
I
~~,,(TI-C2
B
6(NCS)
rv(TI-Ph) v(TI-S)
All spectra were taken wrth a Perkm--Elmer Model 457 spectrometer. Solids were erarmned as NUJOImulls, and theu- absorptron bands are Irsted below; u-r Table 1 are summarized the assignments made for mtemal vrbratronal modes of the thlocyanate group, as well as for other frequencres useful to the drscussron. The compound PhTI(CNS)2 showed apprecrable decomposition m the radratron beam and its spectrum was recorded repeatedly renelb m”g the sample during scannmg. Me,TlCNS: 2050 (sh), 2035 vs( br), 1115 w( br), 950 IV, 935 w, SO0 vs( br), 750 s, 615 w(br), 550 m, 510 m, 470 ms, 465 m cm-’ Ph,TICNS: 2030 vs(lx), 1430 m, 1325 w, 1300 w, 106Ow, 1015m, 995 m, 960 w(br), 900 mw(br), 755 m. 730 s, 720 s, 685 s, 665 (sh), 480 IV, 455 s cm-’ [ Ph,As][ Me,Tl( CNS)?]: 2050 s, 2030 s, 1435 m, 1305 w(br), 1185 w, 1165 w, lOS0 s, 1020 w, ‘395 m, 965 w, 920 w, 800 m(br), 740 (sh), 730 s, 685 s, 545 mw, 475 ms, -I70 s, 350 m cm-’ PhTI(CNS)?: 2130 m(br), 1435 m, 1325 w, 1160 VW, 106Ovw, 1010 ms, 990 ms, 910 w, 840 w(br), 735 s, 675 ms, 650 m, 455 m, 435 ms, 120 w, 280 m cm-‘. For the intensity measurements of the v(C-N) band of compounds m acetone solutron (c = 1 to 2 >I lo-‘AI), a CsI cell of 0 03 cm path length (I) was used m order to record solvent and solutron spectra u-rthe regron 2200 to 2000 cm- ‘, employing a IO X abscissa expansron of the rnstrument The apparent mtensrty cf the band (A) was evaluated by dtrect graphrc integration of the espression IS]: A=_
2-3 T0 dv !g T ncl s
where II IS the number of throcyanate groups u-rthe compound, u-rorder to normake results for different stolchiometries. To and T are respectively the transrruttances of solvent and sample solutron All experiments were run in duphcate; for comparison purposes, analogous measurements were performed on KCNS and MeJNCNS solut-rons. The results are reported III Table 2.
31
by Me2TICNS, which would mdlcate the existence UI the solid of non-eqluvalent Me,Tl”’ moieties Whether an IR-active v&TI&) E present or not in both spectra is questlonable, as m the region of Interest. there are absorptlons due to 6 (NCS) and to phenyl groups (for the tetmphenplarsomum salt) Nevertheless, some coslderations seem to lndlcate the IR-mactwlty of this band In fact, pubhshed data[32] show that the difference between u,,(TIC,) and U&TIC!,) frequencies in dlmethylthallium derwatwes 1s of the order of 45-65 cm-‘, and that there eslsts a 1mea.r correlation between the methyl rocking frequency, p (CH,), and v~, uas(TIC2) [33] These critena should locate the value of us(T1C2), for Me,TlCNS and [Ph,As] cm-’ and 500--I80 cm-‘, These frequent> [ hlezT1( CNS)2], In the regona 505-475 ranges In the recorded spectra are actually free from bands, suggesting the POWble lineanty of Me,Ti”’ moletles ln both compounds. A lmear C-Tl-C skeleton has been reported in many solld compounds Me,TlX (X = Cl, Br, I, CIOJ, NOJand others) VIbrational studies on hIe,TlClO, and Me,Tl.N03 [ 1,311 indicate that these are loruc compounds contammg Me?Ti’ cations and the correspondmg free amens. The X-ray structure of dlmethylthaihum halides [ 341 consists of layers in whxh a Me2Tl”’ group 1s surrounded by four halogens and each halogen by four hIe,TI”’ groups: this structure has been often referred to as an lonlc lattic P, but, at least m the case of the chiorlde, it has been also described [ 351 as an extended polymer \vlth brlrlg;lng halogex, where Tl”’ would assume an octahedral stereochemlstry For dlmethylthalhum thlocyanate an lonlc Me2T1’NCSstructure seems unhkely (as there wll be a certam amount of covalency In the Tl-KCS bonds), and an explanation of both lmeanty and non-equwalence of the Me?Tl moieties should perhaps consider the solid formulated as [ Me2TI][ Rle,Tl( NCS): I, contaming (as hmlt case) Me,Tl’catlons and polymeric Rle,Tl(NCS); species In whwh T1 atoms are heuacoordmated. The structure of Me,TlCNS and of[ Ph,As] [ Me,Tl(CNS)2] would then probably be closely related. Further stnlctur‘al InvestIgatlons on these compounds are clearly needed, and ~11 be soon carried out m this laboratory. Acknowledgements The fmancial
support
by C N R. (Roma)
IS gratefully
acknowledged.
References 1
G
2
G.
D Sbter and R S Dmgo. J Or~~nomelal Chem 5 (19fih) 330 Furagha. L Roncucc~ Fmraru. B Lassandro Pepr and R Bsrblcrl.
10 (1967) 363 3 A E GoddYrd, .I C-hem Sot . (1931) 671, J Chem Sot (1934) 405 1 F Ch~llengcr and 0 \’ Rlchvds 5 G Faragln, A CJWOI and R Barblen Proc Journees Hellknee 6 7 8 9
10
Chromalognphle N Berro2z1. 4 G F.u-a&a. L 2 (1966) 277 D A Ramwv J Chart and L PC H hlllchell
J Orgtinometal
dc Stpamt~on
lmmedkle
(III J I S I C ) 4s~ Greek Chem Ed . Athens (1966) 271 Srlteslrl 2nd G Alowo Garz Chum ltal 10-l (1974) 155 Roncuc~! Florar~. B Larwqdro Pepe and R Bsrbierl. Irwrg lvucl .I Amer Chem Sot. 76 (1952) 72 A Duncac~on. Nature (London). 176 (1956) 997 and R J P WdUms J Chem Sot .(1960) 1912
Chem
Chtm
,
~1 ae
Lerr
.
32 11
J Lews.
12
A Tranwr. J. Chem. Phys.. 59 (1963) 232 D Forgerand D hl L Goodgame. inorg Chem 4 SabatIm and I Bertlm. Inorg Chtim -1 (1965)
13 14
R S
Nvbolm
and PI%
Smllh
J Chem
Sot
, (1961)
4 (1965) 959
4590
715
15 R J H ClarF and C S Wdhams Spectrocblm 9cta. 22 (1966) 1081 16 S J Pate]. J lnorg NucL Chem .32 (19iO) 3508 Ii A G Lee. J 0rganomeL;rL Chem .32 (lSi0) 537 18 D H WhIffen. J Chem Sot (1956) 1353 19 D X1 Adams. hfetal-Llgand and related Vlbrarlons Edrrard Arnold London 20 D B Solrerby. J 4mer Chem Sot . 8-t (1962) 1831 “1 S J Pate1.J lnorg Nucl Cbem .33(1971J 17 ‘22 S J Pate1 aod D G Tuck Can J Chem -IT (1969) 229 23 PL Goggm. I J hlccolmand R Shore J Chem Sot A (1966; 131-1 94 S J Pete1 D B Sowerbv and D G Tucl J Chem Sot A (1967) 1187 25 4 H Norbury. J Chem Sot A. (19ilJ 1089 144i 26 S Fronaeus and R Lsrsson. ?cta Chrm Stand . 16 (1962) Zi C Pecll:. lnorg Chcm . 5 (1966) 210 18 R Larson and A hllezls ~cta Chem Scsnd 23 (1969) 3i 29 R A B&c\ T hl hllchelzensnd W U \I& J inorg Yucl Chem 33 (1971) 30 N BcrU:z~. G ~lonzo. 4 Sllvt-str; and G Cons~gl~o. J Organometal Chem 31 G B Deacon. J H S Green and R S Nyholm. J Chem Sot . (1965) 3411
32 33 3-l 35
1967.
p 319
3206 (1972)
. 37
281
See for example H Kurosaua and R Obarrara OrCanometal Chem Rev A. 6 (1970) 65 and references lhereln H Kuros;r\\a and R Oha\barz. Tnns h \ Acad SC! Ser II. 30 (1968) 962 (rroorted m r~f 32. p 89) H hl PoLbeUand D hf Cronfoof. 2 fins1 8i (193-l) 370 I R Bealrle and P 4 Cocblng. J Chem Sot . (1965) 3860