New precursors to potentially conductive noninteger oxidationstate (NIOS) compounds based on metal complexes[ML
2]
n- [M = Ni,Pd, Pt; L = 5,6-dihydro-1,4-dithiin-2,3-dithiolato(dddt
2-),5,7-dihydro-1,4,6-trithiin-2,3-dithiolato (dtdt
2-), and2-thioxo-1,3-dithiole-4,5-dithiolato(dmit
2-);
n = 2, 1, 0] havebeen investigated. Complexesof the series (NR
4)[ML
2] (R = Me, Et,Bu; L = dddt
2-,dtdt
2-) have been isolated and characterized,and thecrystal structure of(NBu
4)[Pt(dtdt)
2] (
1)has been determined {
1 =C
24H
44NPtS
10,
a =12.064(2) Å,
b = 17.201(3) Å,
c = 16.878(2) Å,
= 102.22(2)
,
V = 3423(1) Å
3, monoclinic,
P2
1/
n, Z = 4}. Oxidation ofthese complexesaffords the corresponding neutral species[ML
2]
0. Another series of generalformula (cation)
n[M(dmit)
2][cation= PPN
+, BTP
+, and(SMe
yEt
3-y)
+with
y = 0, 1, 2, and 3,
n = 2, 1, M = Ni,Pd] has also been studied. All ofthese (cation)
n[M(dmit)
2]complexes have been isolated and characterized [with the exception of(cation)[Pd(dmit)
2] for cation =(SMe
yEt
3-y)
+].The crystal structures of(PPN)[Ni(dmit)
2]·(CH
3)
2CO(
2) and (SMeEt
2)[Ni(dmit)
2] (
3) have been determined{
2 =C
45H
36NNiS
10P
2O,
a = 12.310(2) Å,
b = 13.328(3) Å,
c = 15.850(3)Å,
= 108.19(3)
,
= 96.64(2)
,
=99.67(2)
,
V = 2373(1) Å
3,triclinic,
P,
Z = 2;
3 =C
11H
13NiS
11,
a=7.171(9) Å,
b = 17.802(3) Å,
c =16.251(3) Å,
= 94.39(4)
,
V =2068(2) Å
3, monoclinic,
P2
1/
n,
Z = 4}NIOSsalts derived from the preceding precursors were obtained byelectrochemical oxidation. Electrochemical studiesof the [M(dddt)
2] complexes show that they may be usedfor the preparation of NIOS radical cation salts and[M(dddt)
2][M'(dmit)
2]
xcompounds, but not for the preparation of(cation)[M(dddt)
2]
z NIOSradical anion salts.The electrochemical oxidation of the[M(dtdt)
2]
- complexes always yields theneutral [M(dtdt)
2]
0 species.Thecrystal structure of[Pt(dddt)
2][Ni(dmit)
2]
2(
4) has been determined and is consistent with the lowcompactionpowder conductivity (5 × 10
-5 Scm
-1 at room temperature) {
4 =C
20H
8Ni
2PtS
28,
a = 20.336(4) Å,
b =7.189(2) Å,
c = 14.181(2) Å,
= 97.16(2)
,
V = 2057(1) Å
3, monoclinic,
C2/
m,
Z = 2}. The crystalstructures ofthe semiconducting NIOS compounds(BTP)[Ni(dmit)
2]
3 (
5)and (SMe
3)[Ni(dmit)
2]
2(
6) have been determined{
5 =C
43H
22PNi
3S
30,
a = 11.927(2) Å,
b = 24.919(2) Å,
c = 11.829(3) Å,
= 93.11(1)
,
=110.22(1)
,
=83.94(1)
,
V = 3284(1) Å
3,triclinic,
P,
Z = 2;
6 =C
15H
9Ni
2S
21,
a = 7.882(1) Å,
b = 11.603(2) Å,
c =17.731(2) Å,
= 77.44(1)
,
= 94.39(1)
,
= 81.27(1)
,
V = 1563(1)Å
3, triclinic,
P,
Z = 2}.The parentcompound(SEt
3)[Ni(dmit)
2]
z(unknown stoichiometry) is also a semiconductor with a single-crystalconductivityat room temperature of 10 S cm
-1. Bycontrast, the single-crystal conductivity at room temperature of(SMeEt
2)[Pd(dmit)
2]
2 (
7) is ratherhigh (100 S cm
-1).
7 behavesas a pseudometal down to 150 K and undergoes anirreversible metal-insulator transition below this temperature.The crystal structure of
7 has been determined{
7= C
17H
13NPd
2S
21,
a = 7.804(4) Å,
b = 36.171(18) Å,
c = 6.284(2) Å,
= 91.68(4)
,
=112.08(4)
,
=88.79(5)
,
V = 1643(1) Å
3,triclinic,
P,
Z = 2}. Theelectronic structure of(SMeEt
2)[Pd(dmit)
2]
2(
7) and thepossible origin of the metal-insulator transition at 150 K arediscussed on the basis of tight-binding band structurecalculations.