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Preparation, properties, and structures of planar anion complexes
S )NTP.I TtlII ELSEVIER
Synthetic Metals 70 (1995) 1177-1178
Preparation, properties, and structures of planar anion complexes H.Mori, a I.liirabayashi, a S.Tanaka, a T.Mori b , and Y.Maruyama c alnternational Superconductivity Technology Center, Shinonome Tokyo 135, Japan bDepartment of Organic and Polymeric Materials, Tokyo Institute of Technology, O-okayama, Tokyo 152, Japan Clnstitute for Molecular Science, Okazaki 444, Japan Abstract Metal 1,1-, 1,2-dithiolates and 1,2-dioxylates based upon BEDT-T1T are prepared. (BEDT-TI'F)[Ni(mnt)2 ] and (BEDTqTF)2[Pd(i-mnt)2 ] have mixed columns and show semiconducting behaviors, whereas (BEDT-T1T)4[Pd(ox)2 ] with a segregatcd column and (BEDT-T1T)4[Pd(i-mnt)2 ] indicate metallic behaviors down to 160K and 180K, respectively.
1. I n t r o d u c t i o n
2. R e s u l t s
So far fifty kinds of organic superconductors have been discovered. Among them, planar anion salts are only (BEDT-TFF)4Pt(CN)4H20 and (BEDT-TIT)4Pd(CN)4H2 O1) (BEDT-'ITF= bis(ethylenedithio)tetrathiafulvalene). In this study, the planer metal 1,1-, 1,2-dithiolates, and 1,2-dioxylate anions are chosen, the complexes based upon BEDT-T1T and EDT-TI'F are prepared, and their electrical properties and crystal and electronic stuructures are investigated. The selected planar anions, [M(CS3)2] 2", [M(imnt)2] 2(i-mnt=a,l-dicyanoethylene-2,2-dithiolate), [M(cdc)2] 2" (cdc=cyanamide dithiocarbonate), [M(ox)2] 2(ox=oxalate) (Fig. 1)2), are irreversible to oxidation and reduction except for [M(mnt)2] 2" (mnt=l,2-dicyanoethylene1,2-dithiolate) and stable as an anion, If the extended 1,1-, 1,2-dithiolates are synthesized like M(dmit)2 (dmit=4,5dimercapto-l,3-dithia-2-thione) with redox potentials, the varieties of anion radical salts will be expected.
The preparation condition, crystal shape, and electrical resistivity of obtained complexes are shown in Table 1. The metallic behaviors are observed in (BEDTT1T)xNiCly (TMI=50K), (BEDT-TIT)4 [Pd(i-mnt)2] 3) (TMI=180K), and (BEDT-TIT)4[Pd(ox)2 ] (TMI-160K). In (BEDT-'ITF)xNiCly' the existance of Ni and C1 is observed by EDXmeasurement. (BEDT-TIT)4[Pd(i-mnt)2 ] (I'MI-160K) has the different phase, (BEDT-TIT)2[Pd(i-mnt)2], that is a semiconductor (gRT=540~cm, Ea=0.19eV) due to the mixed column structure. Figure 2 shows the crystal structure of (BEDTTFF)2[Pd(i-mnt)2]4). The donor (EY).,donor ..anion ([Pd(imnt)2]) are arranged along the [101] and ['I01] directions. The short S..S contacts (<3.6 ,,~) are observed along the sideby-side direction. The central C=C bond of BEDT-TFF molecule is 1.37(1)/kwhich indicates (BEDT-TIT) +1. The crystal structure of (BEDT-T1T) [Ni(mnt)2] 5) is different from that of the reported (BEDT-TI'F)[Ni(mnt)2]6). The central C=C bond of BEDT-qTF molecule, 1.38(3) ,fi,, is close to 1.38 A of (BEDT-TI'F)+1 of (BEDTT1T)ReO4 07_IF)0.5 7), which indicates (BEDTTIT)+l[Ni(mnt)2] -1. The donors (BEDT-qq'F) and acceptors ([Ni(mnt)2]) stack side-by-side along the [01~] direction, while the mixed stacking is observed along the c-axis. The crystal structure of (BEDT-TFF)4[Pd(C204)2] 8) is that an anion sheet and a donor layer stack along the baxis. The donor arrangement is shown in Fig. 3. The donor has the contacts along the three kinds of directions, clc2(82"), pl-p3(13*), and ql-q3(24*), which is very similar to that of I3-(BEDT-T1T)213 .9) In order to investigate the intermolecular interaction, the overlap integrals of donor HOMO are calculated to be c1=-9.8, c2=-22.1, pl=0.70, p2=5.5, p3=-0.2, q1=12.4, q2=14.2, q3=-22.1x(10"3). The intermolecular interaction along the ql-q3 direction are relatively large. The calculated band structure has small pockets around the F and Z point, which is a semimetallic band structre and is consistent with the metallic behavior of this salt. (Fig. 4)
.o s, :s> o.
S
S
NC
[M(CS3)2]2-
NC
S
S
CN
[M(i_mnt)2]2-
.S ,S
NC--.K~S.,S--..KCN
"4 S :M,S >., CN .o sM, s c, [M(cdc)2 ]2-
ouo o2o
[M(mr, t)2 ]2-
o/-o:4o [M(ox)2]2-
,S....K~S
,S--..K~S
S- sJLs: ,s)E._s :S [M(dmit)2]2Fig. I Molecular structures of planer anions.
0379-6779/95/$09.50 © 1995 Elsevier Science S.A. All rights reserved SSDI 0379-6779(94)02809-D
and D i s c u s s i o n
1178
H. Mori et al. / Synthetic Metals 70 (1995) 1177-1178
Table 1. Preparation condition, crystal shape, electrical resistivity, of planar anion complexes (ET=BEDT-'ITF, 18-c-6=18-crown6 ether, 112-TCE=l,l,2-triehroloethane, and EtOIl=ethanol). Complexes
Preparation condition
Crystal shape
Electrical resistivity
EFxNiCIy ET.Br ET[Ni(mnt)2]6) ET[Ni(mnt)2]5) ET2[Pd(i-mnt)2]4) ET4 [Pd(i-mnt)2]3) ET4[Pd(ox)2] 8) (EDToTIT)4[Pd(ox)2] ETx[Pt(mnt)2 ] E£x[Cu(mnt)2 ] EFx[Au(CN)4]
[ET+KCI+NiC12+IS-c-6 in (112-TCE+10% EtOH)] [ET+KBr+NiBr2+18-c-6 in (112-TCE+10% EtOIt)] [ET+TBA.Ni(mnt)2in 112-TCE] [ET+TBA.Ni(mnt)2in ll2-TCE] [ET+TBA-Pd(i-mnt)2in ll2-TCE] [ET+TBA.Pd(i-mnt)2in ll2-TCE] [ET+TBA-Pd(ox)2in 112-TCE] [EDT-TI'F+TBA'Pd(ox)2in ll2-TCE] [ET+TBA.Pt(mnt)2 in 112-TCE] [ET+TBA.Cu(mnt)2 in ll2-TCE] [ET+KAu(CN)4+18-c-6 in (112-TCE+10% EtOIt)]
black plate black plate black plate 1 black plate 2 black needle black plate black plate black plate black plate black plate black plate
ORT=12Scm"1, TMI=50K ORT=130Qcm, Ea=0.20eV PRT=2.4x 103f2cm, Ea=0.20eV ORT=I.I xl03g2cm PRT=540f2cm, Ea=0.19eV ~JR'i'=4Scm'l, TMI=180K ORT=3Scm"1, TMI-160K ORT=4Scm-1, Ea=0.03eV 9RT=3.7xl03Qcm PRT=3.7x 103ff]cm PRT=3.2xl03f~cm
b
a) f-"-.~
kc
\ F
Z
X
C
Fig. 4. Band structure of (BEDT-TFF)4[Pd(C204)2].
a
0 b)
C
VC
. 2 : : I I"
Fig. 2. a)Crystal structure and b)molecular arrangement of (BEDT-T1T)2 [Pd(i-mnt)2].
Fig. 3. Donor arrangement of (BEDT-TFF)4[Pd(C204)2].
References 1) a)It. Mori ct al., Solid State Commun., 80, 411(1991); b)T. Mori et al., Solid State Commun., 82, 177(1992). 2) J. P. Fackler et al., J. Am,,Chem. See., 88, 3913(1966); F. A. Cotton et al., ]norg. Chem., 6, 229(1967); B. G. Werden et al., Inorg. Chem., 5, 78(1966). 3) Crystal data of (BEDT-TIT)4[Pd(i-mnt)2]; triclinic, space group P], a=11.946(8) b=17.858(8), c=8.346(9),,k, ct= 90.90(6)), ~--104.20(7), y--81.23(5)', V=1705(2)Z 3. 4) Crystal data of (BEDT-TFF)2[Pd(i-mnt)2]; triclinic, space group Pi, a=10.634(6), b=13.472(7), c=7.427(3).A, ~= 91.54(4), 1~=99.59(4), y=104.49(4) °, V=1013.1(9)A 3, Z=I, and R=0.042. 5) Crystal data of (BEDT-TTF)[Ni(mnt)2]; triclinic, space group Pi, a=14.500(7), b=17.332(9), c=8.388(8)],,, a= 98.44(6), [3=102.35(6), y=106.70(4)*, V=1923(2),~3 , Z=3, and R=0.077. 6) W Reith et al., Angew. Chem. Int. Ed. Engl., 5, 27(1988). 7) II. Kobayashi et al., Mol. Cryst. Liq. Cryst., 107, 33(1984). 8) Crystal data of (BEDT-TYF)4[Pd(C204)2]; triclinic, space group Pi, a=11.877(6), b=15.820(7), c=8.704(2)A, ct= 91.10(3), 15=92.49(3), y=105.37(4) °, V=1575(1)]~3, Z=I, and R=0.073. 9) V. F. Kaminskii et al., Pis'ma Eksp. Teor. Fiz. 39, 15(1984).
Synthetic Metals 70 (1995) 1177-1178
Preparation, properties, and structures of planar anion complexes H.Mori, a I.liirabayashi, a S.Tanaka, a T.Mori b , and Y.Maruyama c alnternational Superconductivity Technology Center, Shinonome Tokyo 135, Japan bDepartment of Organic and Polymeric Materials, Tokyo Institute of Technology, O-okayama, Tokyo 152, Japan Clnstitute for Molecular Science, Okazaki 444, Japan Abstract Metal 1,1-, 1,2-dithiolates and 1,2-dioxylates based upon BEDT-T1T are prepared. (BEDT-TI'F)[Ni(mnt)2 ] and (BEDTqTF)2[Pd(i-mnt)2 ] have mixed columns and show semiconducting behaviors, whereas (BEDT-T1T)4[Pd(ox)2 ] with a segregatcd column and (BEDT-T1T)4[Pd(i-mnt)2 ] indicate metallic behaviors down to 160K and 180K, respectively.
1. I n t r o d u c t i o n
2. R e s u l t s
So far fifty kinds of organic superconductors have been discovered. Among them, planar anion salts are only (BEDT-TFF)4Pt(CN)4H20 and (BEDT-TIT)4Pd(CN)4H2 O1) (BEDT-'ITF= bis(ethylenedithio)tetrathiafulvalene). In this study, the planer metal 1,1-, 1,2-dithiolates, and 1,2-dioxylate anions are chosen, the complexes based upon BEDT-T1T and EDT-TI'F are prepared, and their electrical properties and crystal and electronic stuructures are investigated. The selected planar anions, [M(CS3)2] 2", [M(imnt)2] 2(i-mnt=a,l-dicyanoethylene-2,2-dithiolate), [M(cdc)2] 2" (cdc=cyanamide dithiocarbonate), [M(ox)2] 2(ox=oxalate) (Fig. 1)2), are irreversible to oxidation and reduction except for [M(mnt)2] 2" (mnt=l,2-dicyanoethylene1,2-dithiolate) and stable as an anion, If the extended 1,1-, 1,2-dithiolates are synthesized like M(dmit)2 (dmit=4,5dimercapto-l,3-dithia-2-thione) with redox potentials, the varieties of anion radical salts will be expected.
The preparation condition, crystal shape, and electrical resistivity of obtained complexes are shown in Table 1. The metallic behaviors are observed in (BEDTT1T)xNiCly (TMI=50K), (BEDT-TIT)4 [Pd(i-mnt)2] 3) (TMI=180K), and (BEDT-TIT)4[Pd(ox)2 ] (TMI-160K). In (BEDT-'ITF)xNiCly' the existance of Ni and C1 is observed by EDXmeasurement. (BEDT-TIT)4[Pd(i-mnt)2 ] (I'MI-160K) has the different phase, (BEDT-TIT)2[Pd(i-mnt)2], that is a semiconductor (gRT=540~cm, Ea=0.19eV) due to the mixed column structure. Figure 2 shows the crystal structure of (BEDTTFF)2[Pd(i-mnt)2]4). The donor (EY).,donor ..anion ([Pd(imnt)2]) are arranged along the [101] and ['I01] directions. The short S..S contacts (<3.6 ,,~) are observed along the sideby-side direction. The central C=C bond of BEDT-TFF molecule is 1.37(1)/kwhich indicates (BEDT-TIT) +1. The crystal structure of (BEDT-T1T) [Ni(mnt)2] 5) is different from that of the reported (BEDT-TI'F)[Ni(mnt)2]6). The central C=C bond of BEDT-qTF molecule, 1.38(3) ,fi,, is close to 1.38 A of (BEDT-TI'F)+1 of (BEDTT1T)ReO4 07_IF)0.5 7), which indicates (BEDTTIT)+l[Ni(mnt)2] -1. The donors (BEDT-qq'F) and acceptors ([Ni(mnt)2]) stack side-by-side along the [01~] direction, while the mixed stacking is observed along the c-axis. The crystal structure of (BEDT-TFF)4[Pd(C204)2] 8) is that an anion sheet and a donor layer stack along the baxis. The donor arrangement is shown in Fig. 3. The donor has the contacts along the three kinds of directions, clc2(82"), pl-p3(13*), and ql-q3(24*), which is very similar to that of I3-(BEDT-T1T)213 .9) In order to investigate the intermolecular interaction, the overlap integrals of donor HOMO are calculated to be c1=-9.8, c2=-22.1, pl=0.70, p2=5.5, p3=-0.2, q1=12.4, q2=14.2, q3=-22.1x(10"3). The intermolecular interaction along the ql-q3 direction are relatively large. The calculated band structure has small pockets around the F and Z point, which is a semimetallic band structre and is consistent with the metallic behavior of this salt. (Fig. 4)
.o s, :s> o.
S
S
NC
[M(CS3)2]2-
NC
S
S
CN
[M(i_mnt)2]2-
.S ,S
NC--.K~S.,S--..KCN
"4 S :M,S >., CN .o sM, s c, [M(cdc)2 ]2-
ouo o2o
[M(mr, t)2 ]2-
o/-o:4o [M(ox)2]2-
,S....K~S
,S--..K~S
S- sJLs: ,s)E._s :S [M(dmit)2]2Fig. I Molecular structures of planer anions.
0379-6779/95/$09.50 © 1995 Elsevier Science S.A. All rights reserved SSDI 0379-6779(94)02809-D
and D i s c u s s i o n
1178
H. Mori et al. / Synthetic Metals 70 (1995) 1177-1178
Table 1. Preparation condition, crystal shape, electrical resistivity, of planar anion complexes (ET=BEDT-'ITF, 18-c-6=18-crown6 ether, 112-TCE=l,l,2-triehroloethane, and EtOIl=ethanol). Complexes
Preparation condition
Crystal shape
Electrical resistivity
EFxNiCIy ET.Br ET[Ni(mnt)2]6) ET[Ni(mnt)2]5) ET2[Pd(i-mnt)2]4) ET4 [Pd(i-mnt)2]3) ET4[Pd(ox)2] 8) (EDToTIT)4[Pd(ox)2] ETx[Pt(mnt)2 ] E£x[Cu(mnt)2 ] EFx[Au(CN)4]
[ET+KCI+NiC12+IS-c-6 in (112-TCE+10% EtOH)] [ET+KBr+NiBr2+18-c-6 in (112-TCE+10% EtOIt)] [ET+TBA.Ni(mnt)2in 112-TCE] [ET+TBA.Ni(mnt)2in ll2-TCE] [ET+TBA-Pd(i-mnt)2in ll2-TCE] [ET+TBA.Pd(i-mnt)2in ll2-TCE] [ET+TBA-Pd(ox)2in 112-TCE] [EDT-TI'F+TBA'Pd(ox)2in ll2-TCE] [ET+TBA.Pt(mnt)2 in 112-TCE] [ET+TBA.Cu(mnt)2 in ll2-TCE] [ET+KAu(CN)4+18-c-6 in (112-TCE+10% EtOIt)]
black plate black plate black plate 1 black plate 2 black needle black plate black plate black plate black plate black plate black plate
ORT=12Scm"1, TMI=50K ORT=130Qcm, Ea=0.20eV PRT=2.4x 103f2cm, Ea=0.20eV ORT=I.I xl03g2cm PRT=540f2cm, Ea=0.19eV ~JR'i'=4Scm'l, TMI=180K ORT=3Scm"1, TMI-160K ORT=4Scm-1, Ea=0.03eV 9RT=3.7xl03Qcm PRT=3.7x 103ff]cm PRT=3.2xl03f~cm
b
a) f-"-.~
kc
\ F
Z
X
C
Fig. 4. Band structure of (BEDT-TFF)4[Pd(C204)2].
a
0 b)
C
VC
. 2 : : I I"
Fig. 2. a)Crystal structure and b)molecular arrangement of (BEDT-T1T)2 [Pd(i-mnt)2].
Fig. 3. Donor arrangement of (BEDT-TFF)4[Pd(C204)2].
References 1) a)It. Mori ct al., Solid State Commun., 80, 411(1991); b)T. Mori et al., Solid State Commun., 82, 177(1992). 2) J. P. Fackler et al., J. Am,,Chem. See., 88, 3913(1966); F. A. Cotton et al., ]norg. Chem., 6, 229(1967); B. G. Werden et al., Inorg. Chem., 5, 78(1966). 3) Crystal data of (BEDT-TIT)4[Pd(i-mnt)2]; triclinic, space group P], a=11.946(8) b=17.858(8), c=8.346(9),,k, ct= 90.90(6)), ~--104.20(7), y--81.23(5)', V=1705(2)Z 3. 4) Crystal data of (BEDT-TFF)2[Pd(i-mnt)2]; triclinic, space group Pi, a=10.634(6), b=13.472(7), c=7.427(3).A, ~= 91.54(4), 1~=99.59(4), y=104.49(4) °, V=1013.1(9)A 3, Z=I, and R=0.042. 5) Crystal data of (BEDT-TTF)[Ni(mnt)2]; triclinic, space group Pi, a=14.500(7), b=17.332(9), c=8.388(8)],,, a= 98.44(6), [3=102.35(6), y=106.70(4)*, V=1923(2),~3 , Z=3, and R=0.077. 6) W Reith et al., Angew. Chem. Int. Ed. Engl., 5, 27(1988). 7) II. Kobayashi et al., Mol. Cryst. Liq. Cryst., 107, 33(1984). 8) Crystal data of (BEDT-TYF)4[Pd(C204)2]; triclinic, space group Pi, a=11.877(6), b=15.820(7), c=8.704(2)A, ct= 91.10(3), 15=92.49(3), y=105.37(4) °, V=1575(1)]~3, Z=I, and R=0.073. 9) V. F. Kaminskii et al., Pis'ma Eksp. Teor. Fiz. 39, 15(1984).