Hexacyanodiazahexadiene (Hcdah) Dianion as a Component of Conducting Complexes
- PDF / 404,704 Bytes
- 6 Pages / 414.72 x 648 pts Page_size
- 4 Downloads / 170 Views
new complexes. As a subsequent study to our previous investigation on small sized anions of CF-, PCA,
HCT
2- 7,
here we
on the 2 complexes of HCDAH
N
CN
CN CN
for which a NC
NC NC
planar geometry having
a big size is expected.
I
I
report our recent results
CF
,
e
CN
CN PCA"
NC
N
NC
CN NC
CN NC HCTMM 2-
CN
H\NNC N CN
NC HCDAH
2
-
EXPERIMENTAL
Electrooxidation experiments in CH3 CN, C12CH-CHCI 2+MeOH, THF, Ph-CN of tetrathiafulvalene (TTF) derivatives were carried out in constant current conditions (0.1 - 2.0 giA) in the presence of bistetrabutylammonium salt of HCDAH ((Bu 4N) 2(HCDAH)) which was prepared according to the synthetic procedure for the bistetraethylammonium salt 8. The results were summarized in Table 1 along with the first redox potentials of the donor molecules used. Metathesis of (TTF)3 (BF4)2 and (Bu 4N) 2(HCDAH) was carried out in an acetonitrile solution to give black needles and black block-shaped crystals as major and minor product, respectively. Among these two modifications, only the latter one gave crystals which were suitable for the crystal structure analysis though the dimension and total amount obtained were too small to measure the resistivity and carry out the elemental analysis. The reflection data for X-ray single crystal structure analyses were collected on a fourcircle diffractometer irradiating monochromated MoKcX radiation at room temperature. RESULTS and DISCUSSION Formation of Solid Charge Transfer Complexes The electrocrystallization of TTF derivatives in the presence of (Bu 4N)2(HCDAH) afforded no solid CT complexes with weak donor molecules so far. Including the results of metathesis reaction with (TTF) 3(BF4) 2, it seems that the lower first oxidation potential (E112) of the donor molecule than approximately that of HCDAH 2 is needed to give solid CT complexes of HCDAH. The exception is the case of (EDO)2DBTTF which is known to have a strong tendency to give solid CT complexes regardless the properties and structures of counter component molecules. 9 Among the obtained CT complexes, the composition of the black block-shaped TTF complex and BEDO-TTF complex were determined as (TTF) 2(HCDAH)(CH 3 CN) and (BEDOTTF)6(HCDAH) by the single crystal X-ray structure analysis and the elemental analysis (C, H, N, 0, S), respectively. Block-shaped TTF complex [(TTF)?(HCDAH)(CH3CN] Figure 1 shows the b-axis projection of the crystal structure in which the layers consist of (TTF) 2(CH 3CN) and of HCDAH pile up alternately along the c-axis. Crystallographically one and half molecule of TTF and HCDAH are unique, respectively. The bond lengths in the donor molecule indicate that the charge on TTF is unity or at least very close to +L. As a result, HCDAH anion is in the dianion state in this complex. In the (Tff)2 (CH3CN) layer, face-to-face
642
Table 1. Summary of the electrocrystallization*1 of TTF derivatives in the presence of (Bu4N) 2(HCDAH). Donor*2
El/ 2*3
R, R
Result
TMTTF
CH 3, CH 3
0.29
Powder
OMTTF
-(CH2 ) 4 -
0.29
Few amount of powder
Data Loading...
