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Synthesis, physical properties and X-ray crystal structure of [(DMNP)2(MNP)2SiMo12O40·2DMF] a charge-transfer salt between organic donor and polyoxometalate acceptor
Polyhedron Vol. 16, No. 1, pp. 95 102, 1997
~
Pergamon S0277-5387 (96) 00236-7
Copyright © 1996 Elsevier Science Ltd Printed in Great Britain. All rights reserved 0277- 5387/97 $15.00+0.00
Synthesis, physical properties and X-ray crystal structure of [(DMNP)2(MNP)2SiMo12040" 2DMF] a charge-transfer salt between organic donor and polyoxometalate acceptor Xiao-Min Zhang, Bao-Zhen Shan and Xiao-Zeng You* Coordination Chemistry Institute, State Key Laboratory of Coordination Chemistry, Nanjing University, Centre for Advanced Studies and Technology of Microstructures, Nanjing 210093, P.R. China
and Hoong-KunFun X-ray Crystallography Unit, School of Physics, Universiti Sains Malaysia, 11800, USM, Penang, Malaysia (Received 6 February 1996; accepted 7 May 1996)
Abstract--The title complex [(DMNP)2(MNP)2SiMo~2040" 2DMF] (where DMNP is MeNCsH4NMe2, MNP is MeNCsH4NHMe and DMF is N,N-dimethyl formamide) has been synthesized and characterized by elemental analysis, XPS, ESR and IR spectra studies. The X-ray crystal structure revealed that the title complex possesses a noncentrosymmetrical arrangement in the unit cell. Keywords: crystal structure; charge-transfer; donor; acceptor; polyoxometalate; Keggin structure.
In the last few years there has been a rapidly growing number of reports in the literature addressing the use of polyoxometalates (POM) in many fields of research such as catalysis, biology, medicine and materials scienceJ 3Numerous heteropoly anions can be reversibly reduced to mixed-valence species (heteropoly "blues" and "browns") by addition of various specific numbers of electrons, which are delocalized over a significantly large number of atoms of the heteropoly framework, retaining the gross structure of the oxidized anions. 4 The above property of polyoxoanions makes them attractive precursors for the preparation of charge-transfer hybrid salts made up of organic donors and inorganic acceptors derived from the polyoxometalates? By use of the special properties of the polyoxoanion such as Keggin structures M120,]o
(M = Mo, W; n = 3-4), our aim is to design and synthesize molecular materials with the applications in non-linear optics, photorefractive effect and magnetism. Here, we report the preparation of a charge-transfer salt by use of the organic donor DMNP and inorganic acceptors (TBA)4SiMo~2040 (TBA = tetrabutylamino). The compound was characterized by IR, UV-Vis spectra, ESR measurements. The X-ray structure determination reveals that the title complex has non-centrosymmetric character, and probably possesses non-linear optical properties. The lost methyl of the N atom may be catalyzed by the polyoxometalate. Further related work is being done.
EXPERIMENTAL All chemicals were reagent grade and used without further purification. The polyoxometalate (TBA)4
* Author to whom correspondence should be addressed 95
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Xiao-Min Zhang et al.
S i M O l 2 0 4 o w a s synthesized according to the procedure described earlier. 6 The D M N P was obtained by the literature method. 7
Preparation of (DMNP)~(MNP)2SiMo~2040" 2 D M F To a solution of (TBA)4SiMoj2040 (0.3 retool, 0.69 g) in 50 cm 3 acetonitrile, the D M N P - i o d i d e (1.2 mmol, 0.422 g) was added. The mixture was refluxed for 2 h. After cooling to r o o m temperature, the green precipitate was filtered by suction and washed three times with acetonitrile. Yield : 0.63 g, 90%. The green crystals of the title complex were obtained from D M F solution by diffusion of ether. F o u n d : C, 17.8; H, 2.9; N, 6.0. Calc. for C36H62MoI2Nj0042Si: C, 17.6; H, 2.8 ; N, 5.7%.
Table 1. Crystallography data for [CsH,3N2]2[C7Ht,N:]z[C,H7NO]2[Mo,204oSi] Molecular formula Formula weight Colour Crystal size (mm) Crystal system Space group Unit cell a (/~) b (A) c (A) fl (°) V (A 3) Z # (mm-~) F (000) Dx (Mg/m 3)
C36H62Mo12NI0042Si
2486.33 green 0.30 x 0.32 x 0.60 monoclinic P2~ 14.294(4) 14.245(1) 16.709(1) 94.26(1) 3392.9(10) 2 2.259 2404 2.434
Rint
0.021
Collection range
h : - 1 to 18, k : - 1 to 18, l; -21 to 21
Reflections collected Independent reflections Reflections on refinement with I > 2.0a(I)
9171 8695 8692
20max = 55 °
Physical measurements Elemental analysis was performed on a PerkinElmer 240C analytical instrument. The I R spectrum was recorded on a Nicolet F T - I R 170SX spectrophotometer with KBr pellet in the range of 4000400 c m - L The solid state reflectance spectrum was recorded on a Shimadzu UV-240 spectrophotometer. Electronic spectra was obtained on a Shimadzu U V 3100 spectrometer in solution. The powder E S R spectrum was carried out using a Bruker 2000-SRC spectrometer at 110K. XPS was performed on a V G E S C A L A B MK-II.
F~o f
1.048
R Residual extrema in final difference map
0.0517 + 1.303 to - 1.385 e A 3
of data collection and refinement are listed in Table 1. The final atomic coordinates, the thermal parameters, together with observed and calculated structure factors, have been deposited as supplementary material with the Editor, from w h o m copies are available on request.
X-ray structure determination of the complex A green prism crystal of size 0.30 x 0.32 x 0.60 m m was used for data collection. The data were collected using a Siemens P4 four-circle diffractometer with graphite m o n o c h r o m a t e d Mo-K~ radiation (2 = 0.71073 A) using 0/20 scan mode. Intensities were measured for 9717 reflections of which 8695 independent reflections, and the 8692 observed reflections (I > 2.0a(I)) were used for further computation. The data were corrected for Lorentz and polarization effects during data reduction using X S C A N S . 8
Structure solution and refinement The structure was solved by direct methods using SHELXL869 and refined on F 2 by Full-matrix leastsquares methods using SHELXL93.~° All non-hydrogen atoms were refined anisotropically, but the hydrogen atoms were refined isotropically. The final reliability factor was R = 0.0517. All computations were performed on an IBM compatible 486/DX2 personal computer. The crystal data and the parameters
RESULTS AND DISCUSSION
IR spectrum Comparing the I R spectra of the title c o m p o u n d with the I R spectra of (TBA)4SiMoI2040, the vibrational band of Mo~---Od band of the title compound has a red shift from 954(s) cm -1 to 946(s) cm -~. The bands of MO-Ob-MO and M o - O c - M o both have red shifts from 890(w) cm -~, 797(vs) cm -~ to 880(w) cm I and 787(vs) cm -~, respectively, ~ due to the presence of partial charge transfer between the organic donor and polyoxometalate acceptor. This has been verified by the later E S R spectra and the central SiO4 tetrahedron has been little influenced by the electron transfer, so the vibrational frequency of the Si-O bond remains unchanged at 900(vs) cm -1. The band at 1655(vs) cm ~ is due to the C = O vibration from D M F molecule of the compound. The v ( N - H ) vibration appears at 3046 cm -~, which provides evidence of the loss of a methyl group from D M N P to give M N P .
Charge-transfer salt between organic donor and polyoxometalate acceptor
97
0.5
g = 1.936 e~
<
200
I
I
400
600
I 800
;~ (nm)
Fig, 1.
1150
Electronic speetra
Figure 1 shows the reflectance electronic spectra of the title compound. The bands are 282 nm and 418 nm belong to O ~ M o and d - d transition of MoO6 octahedra, respectively. .2 The band at 740 nm is assigned to intervalence charge transfer ( M o S + o M o 6+) IVCT band of [SiMol204o] 5 , which indicates that electron transfer occurs between the organic substrate and polyoxoanion, converting [SiMo1:O40] 4 to the heteropoly blue [SiMol2040] 5 . Figure 2 compares the U V spectra of the title compound with the (TBA)4SiMo1204o dissolved in D M F . The title c o m p o u n d has a broad band at 790 nm similar to that of the solid, which is assigned to an M o 5 ~ ---*Mo 6+ 1VCT band. The solution of (TBA)4 SiMoL2040 has very weak absorption that can be omitted in the wavelength range. The above results indicate that the charge-transfer of the polyoxometalate anion is obviously influenced by the presence of D M N P .
E S R spectra
The ESR spectrum of the title complex at 110K is shown in Fig. 3. The spectrum reveals the presence of a single isotropic signal g = 1.936, which is ascribed
0.300
.........
0.200
, .........
,
....
. . . .
//2~
0.300
Fig. 3.
to the M o 5+, which is close to those observed in similar polyoxoanions containing M o 5+ (S = 5/2) species. 6'~ N o hyperfine splitting of the ESR signal of M o 5+ of the complex has been observed due to the rapid intraionic hopping of the unpaired electron being comparable with the E S R time-scale. 4
X P S study
X-ray photoelectron spectroscopy provides useful information on the oxidation state of the metal ion in the polyoxometalates, and can assess the stoichiometric ratio of the elements present in the compounds. The binding energies of Mo3ds.2 in the title compound and tetraalkylammonium polyoxomolybdenum(VI) are 232.4ev and 232.3ev respectively. The binding energy o f O L,.in the title c o m p o u n d is 530.5ev, which is also close to that of (TBA)4 SiMol2040 (530.2ev). The above effects are due to the fact that the molybdenum atoms are all equivalent and the value of the binding energy is quite close to the value found for the completely oxidised anion. The existence of reduced molybdenum in the polyoxoanion cannot be ruled out as this is of class IIIA of the Robin and Day scheme? 4 In this case, the shift in energy would be very small as the extra electron is delocalized over all the molybdenum atoms.
0.200
< v
X-ray crystal structure
0.100
0.00[3 . . . . . . . . . 400
~......... 600 (nm) Fig. 2.
I ......... 800
1000
0.000
The bond distances and angles of the title complex are listed in Tables 2 and 3, respectively. The crystal structure of the polyoxoanion and a stereoview of the molecular packing are shown in Figs 4 and 5, respectively. The analysis of the crystal structure reveals that the compound possesses the P2t space group, which is non-centrosymmetric. There exists the
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Xiao-Min Zhang et al.
Table 2. Selected bond lengths (A.) Mo(1)--0(26) Mo(l)--O(13) Mo(l)--O(14) Mo(1)--0(23) Mo(1)--0(33) Mo(1)--O(lO) Mo(2)--0(32) Mo(2)--0(38) Mo(2)--0(9) Mo(2)--0(25) Mo(2)--0(34) Mo(2)--0(3) Mo(3)--0(31) Mo(3)--0(16) Mo(3)--0(18) Mo(3)--O(1) Mo(3)--0(14) Mo(3)--O(lO) Mo(4)--0(8) Mo(4)--0(28) Mo(4)--0(24) Mo(4)--0(20) Mo(4)--0(9) Mo(4)--0(3) Mo(5)--O(1 l) Mo(5)--0(27) Mo(5)--O(l 5) Mo(5)--0(38) Mo(5)--0(2) Mo(5)--O(35) Mo(6)--O(6) Mo(6)--O(22) Mo(6)--O(21) Mo(6)--O(13) Mo(6)--O(5) Mo(6)--O(40) Mo(7)--O(7) Mo(7)--O(12)
1.683(9) 1.823(9) 1.828(11) 1.942(10) 1.988(13) 2.377(8) 1.652(10) 1.885(14) 1.924(11) 1.941(12) 1.952(11) 2.336(7) 1.642(13) 1.831(9) 1.877(14) 1.951(9) 2.016(10) 2.414(9) 1.670(11) 1.821(12) 1.872(10) 1.99(2) 2.06200 ) 2.349(9) 1.673(11) 1.805(13) 1.902(9) 1.905(13) 2.081 ( 1 0 ) 2.319(8) 1.654(9) 1.842(11) 1.912(13) 1.937(9) 1.970(13) 2.395(9) 1.676(10) 1.825(12)
Mo(7)--0(33) Mo(7)--0(18) Mo(7)--0(28) Mo(7)--O(lO) Mo(8)--0(4) Mo(8)--0(25) Mo(8)--0(37) Mo(8)--0(21) Mo(8)~(27) Mo(8)--0(40) Mo(9)--0(39) Mo(9)--0(17) Mo(9)--0(16) Mo(9)--0(34) Mo(9)--0(24) Mo(9)--0(3) Mo(10)--O(29) Mo(10)--O(l) Mo(10)--O(5) Mo(10)--O(17) Mo(10)--O(37) Mo(10)--O (40) Mo(11)--0(30) Mo(11)---O(20) Mo(11)--O(2) Mo(l 1)--0(12) Mo( 11)--0(19) Mo(11)~0(35) Mo(12)--0(36) Mo(12)--0(23) Mo(12)--0(19) Mo(12)--0(22) Mo(12)--O(15) Mo(12)--0(35) Si--O(40) Si--O(lO) Si--O(3) Si--0(35)
1.871(11) 1.951(13) 1.961(11) 2.360(8) 1.675(12) 1.828(11) 1.838(12) 1.987(11) 2.025(13) 2.335(9) 1.677(12) 1.798(10) 1.947(9) 1.962(11) 2.051(11) 2.400(8) 1.636(13) 1.800(9) 1.844(12) 1.984(10) 2.038(13) 2.428(10) 1.666(13) 1.79(2) 1.926(10) 1.959(12) 2.034(10) 2.347(8) 1.649(11) 1.825(9) 1.894(10) 1.938(11) 2.016(9) 2.364(9) 1.580(9) 1.591(9) 1.638(9) 1.683(10)
Charge-transfer salt between organic donor and polyoxometalate acceptor
Table 3. Selected bond angles (~) 0(26)--Mo(1)--0(13) 0(26)--Mo(1)--0(14) 0(13)--Mo(1)--0(14) 0(26)--Mo(1)--0(23) 0(13)--M o(1)--0(23) 0(14)--Mo(1)--0(23) 0(26)--M o( 1)--0(33) 0(13)--Mo(1)--0(33) 0(14)--Mo(1)--0(33) 0(23)--Mo(1)--0(33) 0(26)--Mo(1)--0(10) O( 13)--Mo(l)--O(l O) O(14)--Mo(1)--O(lO) 0(23)--Mo(1)--0(1 O) 0(33)--Mo(1)--0(10) 0(32)--Mo(2)--0(38) 0(32)--Mo(2)--0(9) 0(38)--Mo(2)--0(9) 0(32)--Mo(2)--0(25) 0(38)--Mo(2)--0(25) 0(9)--Mo(2)--0(25) 0(32)--Mo(2)--0(34) 0(38)--Mo(2)--0(34) 0(9)--Mo(2)--0(34) 0(25)--Mo(2)--0(34) 0(32)--Mo(2)--0(3) 0(38)--Mo(2)--0(3) 0(9)--Mo(2)--0(3) 0(25)--Mo(2)--0(3) 0(34)--Mo(2)--0(3) 0(31 )--Mo(3)--0(16) 0(31)--Mo(3)--0(18) 0(I 6)--Mo(3)--0(18) 0(31)--Mo(3)--O(1) 0(I 6)--Mo(3)--0(1) O(18)--Mo(3)--0(1) 0(31 )--Mo(3)--0(14) O( 16)--Mo(3)--0(14) 0(18)--Mo(3)--0(14) O( 1)--Mo(3)--O(14)
0(31)--Mo(3)--0(10) O( 16)--Mo(3)--0( 1O) 0(18)--Mo(3)--0(10) O( 1)--Mo(3)--O(1 O)
106.1(5) 100.1(7) 93.2(5) 103.5(7) 87.6(4) 155.1(4) 97.1 (5) 156.0(5) 88.8(5) 80.8(5) 164.5(5) 88.4(4) 72.8(4) 82.4(4) 69.4(4) 103.4(7) 96.4(5) 93.3(6) 100.5(6) 85.8(6) 162.8(5) 94.4(6) 161.9(5) 87.9(5) 87.8(5) 165.3(6) 88.4(5) 73.9(4) 88.9(5) 74.5(4) 109.3(6) 101.8(7) 91.2(5) 104.1(6) 87.1(4) 153,1(5) 97.1 (6) 153.1(4) 88,2(5) 81,5(5) 163,6(5) 85.4(4) 69.9(5) 83.2(4)
O( 14)--Mo(3 )--0( 1O)
69.1 (4)
0(8)--Mo(4)--0(28) 0(8)--Mo(4)--0(24) 0(28)--Mo(4)--0(24) 0(8)--Mo(4)--0(20) 0(28)--Mo(4)--0(20) 0(24)--Mo(4)--0(20) 0(8)--Mo(4)--0(9) 0(28)--Mo(4)--0(9) 0(24)--Mo(4)--0(9) 0(20)--Mo(4)--0(9)
104.1(6) 97.3(7) 98.4(5) 100.8(7) 84.1(6) 160.5(7) 94.5(5) 159.7(5) 87.2(5) 84.4(6)
0(8)--Mo(4)--0(3) 0(28)--Mo(4)--0(3) 0(24)--Mo(4)--0(3) 0(20)--Mo(4)--0(3) 0(9)--Mo(4)--0(3) 0(11)--Mo(5)--0(27) 0(1 I)--Mo(5)--0(15) 0(27)--Mo(5)--0(15) 0(11)--Mo(5)--0(38) 0(27)--Mo(5)--0(38) 0(15)--Mo(5)--0(38) 0(11)--Mo(5)--0(2} 0(27)--Mo(5)--0(2) 0(15)--Mo(5)--0(2)
0(38)--Mo(5)--0(2) 0(11)--Mo(5)--0(35) 0(27)--Mo(5)--0(35) O(15)--Mo(5)--M(35) 0(38)--Mo(5)--0(351 0(2)--Mo(5)--0(35) 0(6)--Mo(6)--0(22) 0(6)--Mo(6)--0(21) 0(22)--Mo(6)--0(21) 0(6)--Mo(6)--0(13) 0(22)--Mo(6)--0(13) 0(21)--Mo(6)--0(13) 0(6)--Mo(6)--0(5) 0(22)--Mo(6)--0(5) 0(21 )--Mo(6)--0(5) 0(13)--Mo(6)--0(5) 0(6)--Mo(6)--0(40) 0(22)--Mo (6)--0(40) 0(21)--Mo(6)--0(40) O(13)--Mo(6)--0(40) 0(5)--Mo(6)--0(40) 0(7)--Mo(7)--o(12) 0(7)--Mo(7)--0(33) O( 12)--Mo(7)--0( 33) 0(7)--Mo(7)--0(18) 0(12)--Mo(7)--0(18) 0(33)--Mo(7)--0(18) 0(7)--Mo(7)--0(28) O(12)--Mo(7)--0(28) 0(33)--Mo(7)--0(28) O(18)--Mo(7)--0(28) 0(7)--Mo(7)--0(I0) O( 12)--Mo(7)--0( 1O) 0(33)--Mo(7)--0(10) O( 18)--Mo(7)--0( 1O) 0(28)--Mo(7)--0(10) 0(4)--Mo(8)--0(25) 0(4)--Mo(8)--0(37) 0(25)--Mo(8)--0(37) 0(4)--Mo(8)--0(21 ) 0(25)---Mo(8)--0(21)
163.9(5) 91.1 (5) 74.9(4) 85.7(6) 71.3(4) 102.7(6) 96.3(6) 96,6(5) 101.8(6) 89.9(6) 158.9(5) 91.8(5) 165.3(5) 84.4(4) 84.4(5) 161.8(5) 94.0(5) 74.3(4) 85,315) 72.1(3) 108.6(7) 98.6(5) 92.7(5) 103.9(5) 87.6(4) 156.2(5) 96.5(8) 154.1(6) 89.6(6) 80.2(6) 163.0(6) 86.1 (4) 71.6(4) 84.7(4) 70.2(4) 102.7(7) I 01.5(6) 94.2( 5) 99.5(7 ) 156.4(6) 89.3(5) 100.4(6) 85.8(5) 157.5(6t 82.2( 51 167.1(6) 88.9(5) 7l .5(5) 70. I(5) 86.0(5) 101.4(6) 99.8(7) 95.7(5) 97.0(6) 159.0(6) continued ot>er
99
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Xiao-Min Zhang
et al.
Table 3.--Continued.
0(37)--Mo(8)--0(21) 0(4)--Mo(8)--0(27) 0(25)--Mo(8)--0(27) 0(37)--Mo(8)--0(27) 0(21)--Mo(8)--0(27) 0(4)--Mo(8)--0(40) 0(25)--Mo(8)--0(40) 0(37)--Mo(8)--0(40) 0(21)--Mo(8)--0(40) 0(27)--Mo(8)--0(40) 0(39)--Mo(9)--0(17) 0(39)--Mo(9)--0(16) 0(17)--Mo(9)--0(16) 0(39)--Mo(9)--0(34) 0(17)--Mo(9)--0(34) 0(16)--Mo(9)--0(34) 0(39)--Mo(9)--0(24) 0(17)--Mo(9)~(24) 0(16)--Mo(9)--0(24) 0(34)--Mo(9)--0(24) 0(39)--Mo(9)--0(3) 0(17)--Mo(9)--0(3) 0(16)--Mo(9)--0(3) 0(34)--Mo(9)--0(3) 0(24)--Mo(9)--0(3) 0(29)--Mo(10)--0(1) 0(29)--Mo(10)--0(5) O(l)--Mo(lO)--O(5) 0(29)--Mo(10)--0(17) O(1)--Mo(lO)--O(17) 0(5)--Mo(10)--0(17) 0(29)--Mo(10)--0(37) O(1)--Mo(lO)--O(37) O(5)--Mo(10)--0(37) 0(17)--Mo(10)--0(37) 0(29)--Mo(10)--0(40) O(1)--Mo(lO)--O(40) 0(5)--Mo(10)--0(40) O(17)--Mo(10)--0(40) 0(37)--Mo(10)--0(40) O(30)--Mo(11)--0(20) O(30)--Mo(11)--0(2) 0(20)--Mo(11)--0(2) O(30)--Mo(l 1)--0(12) O(20)--Mo(11)--0(12) 0(2)--Mo(11)--0(12) O(30)--Mo(l 1)--0(19) O(20)--Mo(11)--0(19) O(2)--Mo(11)--0(19) O(12)--Mo(11)--0(19) O(30)--Mo(11)--0(35) O(20)--Mo(11)--0(35) O(2)--Mo(l 1)--0(35) O(12)--Mo(l 1)--0(35) 0(19)--Mo(11)--0(35) 0(36)--Mo(12)--0(23) 0(36)--Mo(12)--0(19) 0(23)--Mo(12)--0(19) 0(36)--Mo(12)--0(22) 0(23)--Mo(12)--0(22) 0(19)--Mo(12)--0(22) 0(36)--Mo(12)--0(15)
91.0(5) 98.9(6) 85.8(5) 160.5(6) 81.5(5) 167.0(5) 90.8(5) 74.4(5) 71.8(5) 86.2(5) 108.0(7) 104.9(5) 88.7(4) 97.9(5) 94.7(4) 154.7(4) 94.5(6) 157.3(5) 82.6(4) 84.8(4) 163.0(6) 87.3(4) 82.3(3) 72.8(4) 70.8(4) 108.9(7) 99.9(7) 92.4(6) 106.4(6) 87.5(4) 152.2(5) 96.0(7) 154.2(5) 90.2(6) 78.5(5) 162.1(7) 87.5(4) 71.3(5) 81.0(4) 69.1(4) 103.7(7) 95.8(5) 100.7(6) 101.3(6) 84.2(6) 160.5(5) 94.1(6) 160.4(5) 85.3(4) 84.4(4) 163.1 (6)
91.6(6) 74.1(4) 87.0(5) 71.9(4) 106.8(5) 97.6(5) 94.4(4) 102.9(5) 86.8(4) 157.9(4)
94.2(5)
0(23)--Mo(12)--0(15) 0(19)--Mo(12)--0(15) 0(22)--Mo(12)--0(15) 0(36)--Mo(12)--0(35) 0(23)--Mo(12)--0(35) 0(19)--Mo(12)--0(35) 0(22)--Mo(12)--0(35) 0(15)--Mo(12)--0(35) O(40)--Si--O(lO) 0(40)--Si--0(3) O(lO)--Si--O(3) 0(40)--Si--0(35) 0(10)--Si--0(35) 0(3)--Si--0(35) Mo(lO)--O(1)--Mo(3) Mo(11)--0(2)--Mo(5) Si--O(3)--Mo(2) Si--O(3)--Mo(4) Mo(2)--O(3)--Mo(4) Si--O(3)--Mo(9) Mo(2)--O(3)--Mo(9) Mo(4)--O(3)--Mo(9) Mo(lO)--O(5)--Mo(6) Mo(2)--O(9)--Mo(4) Si--O(lO)--Mo(7) Si--O(lO)--Mo(l) Mo(7)--O(lO)--Mo(l) Si--O(lO)--Mo(3) Mo(7)--O(lO)--Mo(3) Mo(1)--O(lO)--Mo(3) Mo(7)--O(12)--Mo(11) Mo(l)--O(13)--Mo(6) Mo(1)--O(14)--Mo(3) Mo(5)--0(15)--Mo(12) Mo(3)--O(16)--Mo(9) Mo(9)--O(17)--Mo(lO) Mo(3)--O(18)--Mo(7) Mo(12)--O(19)--Mo(11) Mo(11)--0(20)--Mo(4) Mo(6)--O(21)--Mo(8) Mo(6)--O(22)--Mo(12) Mo(12)--O(23)--Mo(l) Mo(4)--O(24)--Mo(9) Mo(8)--O(25)--Mo(2) Mo(5)--O(27)--Mo(8) Mo(4)--O(28)--Mo(7) Mo(7)--O(33)--Mo(1) Mo(2)--O(34)--Mo(9) Si--0(35)--Mo(5) Si--O(35)--Mo(11) Mo(5)--O(35)--Mo(11) Si--0(35)--Mo(12) Mo(5)--O(35)--Mo(12) Mo(11)--0(35)--Mo(12) Mo(8)--O(37)--Mo(lO) Mo(2)--O(38)--Mo(5) Si--O(40)--Mo(8) Si--O(40)--Mo(6) Mo(8)--O(40)--Mo(6) Si--O(40)--Mo(1 O) Mo(8)--O(40)--Mo(lO) Mo(6)--O(40)--Mo(lO)
158.3(5) 87.3(4) 83.3(4) 163.2(4) 88.5(4) 73.8(4) 84.2(4) 71.3(3) 114.2(5) 110.4(5) 110.4(5) 107.8(5) 108.5(5) 105.2(5) 151.8(6) 118.5(5) 124.2(5) 124.9(5) 94,8(3) 119,9(5) 91,8(3) 92,4(3) 127,9(7) 119.8(5) 126.3(5) 123.3(5) 93.1(3) 121.2(5) 92.1(3) 91.5(3) 148.6(7) 149.3(6) 126.5(5) 120.9(5) 150.4(5) 149.4(5) 127.8(8) 121.1(5) 149.2(8) 123.4(7) 149.9(6) 150.4(6) 121.7(5) 148.1(8) 142.9(8) 148.1(8) 125.9(7) 120.7(5) 123.4(5) 123.1(5) 95.2(3) 120.8(4) 93.4(3) 93.1(3) 124.3(7) 146.7(7) 127.5(5) 123.1(5) 93.0(3) 120.9(5) 92.0(3) 90.5(3)
101
Charge-transfer salt between organic donor and polyoxometalate acceptor 0(31)
0(39) 0(29)
Mo(3)
o(18)
0(16)
i o(17)
o(i
Mo(lO)
)(37)
0(7) Mo(7) o(10) Mo(I)
0(21) 0(23)
4o(5)
0(30) O(19) 0(15)
0(1 l)
0(36) Fig. 4.
Fig, 5. Crystal packing of the title compound viewed down the Y axis,
0(4)
102
Xiao-Min Zhang et al.
Keggin structure of the [SiMoj2040]4 anion built up of four MO3013 groups which result from the association of three edge-sharing MoO6 octahedra. The four Mo3013 groups tetrahedrally surround the central Si heteroatom in such a way that the full unit has Td symmetry.4 This situation is rare in salts containing XMI2040 which form easily a disordered pseudo-Keggin polyoxoanion. 15The polyanion has four kinds of oxygen atoms. Oa (the oxygen atoms in SiO4 tetrahedra), Ob (the bridging oxygen atoms within one triplet group of M o O 6 octahedra), Oc (the bridging oxygen atoms between two triplet groups of MoO 6 octahedra) and Oo (the terminal oxygen atoms). The sets of M o O bond lengths corresponding to the four types of oxygen atoms, central tetrahedron Mo-Oa 2.319(8)-2.428(10) A, bridging Mo-Ob.c 1.800(9)-2.081(10) A, and terminal M o - Q 1.636(13)-1.683(9) ,~ are in the expected range. TM The Si-Oa distances are in the range of 1.580(9)-1.683(10) A. The organic cations of the title complex can be divided into two types DMNP and MNP. From the least-squares planes in the compound, the two types organic cation are planar. The counterpart dihedral angle between the two planes of DMNP and MNP is in the range of 17.37(0.59)-19.81 ° (0.54) in the unit cell. The shortest distances between polyoxoanion and organic donor is 3.00 A[N(4B)...O(21)], and 3.08 A,[C(14A)-..O(34)], which is shorter than the Van der Waals distance (3.20 A). This may explain why charge transfer occurs between the polyanion and organic cation. The relevant bond distances and angles of the organic cations are in the range of related compounds, TM and are not discussed further here. Acknowledgements--The authors would like to thank the
State Science Technology Commission and the National Nature Science Foundation of China for a major key research project and the Malaysia Government and Univ-
ersiti Sains Malaysia for research grant RD No. 123~43172201. REFERENCES
1. M. T. Pope and A. Muller, Agnew. Chem. Int. Ed. Engl. 1991, 30, 34 and refs therein. 2. M. T. Pope and A. Muller, Polyoxometalates :from platonic solids to Antiretroviral Activity. Kluwer Acad. Pub., Dordrecht, The Netherlands. (1994). 3. E. Coronado and C. J. Gomez-Garcia, Comments Inorg. Chem. 1995, 17, 255 and refs therein. 4. M. T. Pope, Heteropoly and lsopoly Oxometalates. Springer-Verlag ; Berlin, (1983). 5. L. Ouahab, M. Bencharif, A. Mhanni, D. Pelloquin, J. F. Halet, O. Pena, J. Padion and D. Grandjean, Chem. Mater. 1992, 4, 666. 6. C. Sanchez, J. Livage, J. P. Launay, M. Fournier and Y. Jeannin, J. Am. Chem. Soe. 1982, 104, 3194. 7. A. P. Phillips, J. Org. Chem. 1948, 13, 302 and refs therein. 8. Siemens, X S C A N S (Version 2.1) User Manual. Siemens Analytical X-ray Instruments Inc., Madison, USA (1994). 9. G. M. Sheldrick, Acta Cryst. 1990, A46, 467. 10. G. M. Sheldrick, SHELXL93. Program for Crystal Structure Refinement. Universityof Gottingen, Germany (1993). 11. C. Rocchiccioli-Deltcheff,M. Fournier, R. Franck and R. Thouvenot, Inorg. Chem 1983, 22, 207. 12. B. Z. Wan, J. H. Lunsford, Inorg. Chim. Acta 1982, 65, L29. 13. L. Ouahab, M. Bencharif, A. Mhanni, D. Pelloquin, J.F. Halet, O. Pena, J. Padion and D. Grandjean, Chem. Mater. 1992, 4, 666. 14. M. B. Robin and P. Day, Adv. Inorg. Chem. and Radiochem. 1967, 10, 247. 15. H. T. Jr. Evans and M. T. Pope, lnorg. Chem. 1984, 23, 501. 16. L. Yu, J. Wang and H. Chen, J. SolidState Chem. 1992, 97, 239. 17. X. Xue-Xiang, Y. Xiao-Zeng and H. Xiao-Ying, Polyhedron 1995, 14, 1815. 18. F. Hoong-Kun, S. Kandasamy, Y. Boon-Chuan, T. YuPeng, D. Chun-Ying, L. Zhong-Lin and Y. Xiao-Zeng, Aeta Cryst. 1995, C51, 2080.
~
Pergamon S0277-5387 (96) 00236-7
Copyright © 1996 Elsevier Science Ltd Printed in Great Britain. All rights reserved 0277- 5387/97 $15.00+0.00
Synthesis, physical properties and X-ray crystal structure of [(DMNP)2(MNP)2SiMo12040" 2DMF] a charge-transfer salt between organic donor and polyoxometalate acceptor Xiao-Min Zhang, Bao-Zhen Shan and Xiao-Zeng You* Coordination Chemistry Institute, State Key Laboratory of Coordination Chemistry, Nanjing University, Centre for Advanced Studies and Technology of Microstructures, Nanjing 210093, P.R. China
and Hoong-KunFun X-ray Crystallography Unit, School of Physics, Universiti Sains Malaysia, 11800, USM, Penang, Malaysia (Received 6 February 1996; accepted 7 May 1996)
Abstract--The title complex [(DMNP)2(MNP)2SiMo~2040" 2DMF] (where DMNP is MeNCsH4NMe2, MNP is MeNCsH4NHMe and DMF is N,N-dimethyl formamide) has been synthesized and characterized by elemental analysis, XPS, ESR and IR spectra studies. The X-ray crystal structure revealed that the title complex possesses a noncentrosymmetrical arrangement in the unit cell. Keywords: crystal structure; charge-transfer; donor; acceptor; polyoxometalate; Keggin structure.
In the last few years there has been a rapidly growing number of reports in the literature addressing the use of polyoxometalates (POM) in many fields of research such as catalysis, biology, medicine and materials scienceJ 3Numerous heteropoly anions can be reversibly reduced to mixed-valence species (heteropoly "blues" and "browns") by addition of various specific numbers of electrons, which are delocalized over a significantly large number of atoms of the heteropoly framework, retaining the gross structure of the oxidized anions. 4 The above property of polyoxoanions makes them attractive precursors for the preparation of charge-transfer hybrid salts made up of organic donors and inorganic acceptors derived from the polyoxometalates? By use of the special properties of the polyoxoanion such as Keggin structures M120,]o
(M = Mo, W; n = 3-4), our aim is to design and synthesize molecular materials with the applications in non-linear optics, photorefractive effect and magnetism. Here, we report the preparation of a charge-transfer salt by use of the organic donor DMNP and inorganic acceptors (TBA)4SiMo~2040 (TBA = tetrabutylamino). The compound was characterized by IR, UV-Vis spectra, ESR measurements. The X-ray structure determination reveals that the title complex has non-centrosymmetric character, and probably possesses non-linear optical properties. The lost methyl of the N atom may be catalyzed by the polyoxometalate. Further related work is being done.
EXPERIMENTAL All chemicals were reagent grade and used without further purification. The polyoxometalate (TBA)4
* Author to whom correspondence should be addressed 95
96
Xiao-Min Zhang et al.
S i M O l 2 0 4 o w a s synthesized according to the procedure described earlier. 6 The D M N P was obtained by the literature method. 7
Preparation of (DMNP)~(MNP)2SiMo~2040" 2 D M F To a solution of (TBA)4SiMoj2040 (0.3 retool, 0.69 g) in 50 cm 3 acetonitrile, the D M N P - i o d i d e (1.2 mmol, 0.422 g) was added. The mixture was refluxed for 2 h. After cooling to r o o m temperature, the green precipitate was filtered by suction and washed three times with acetonitrile. Yield : 0.63 g, 90%. The green crystals of the title complex were obtained from D M F solution by diffusion of ether. F o u n d : C, 17.8; H, 2.9; N, 6.0. Calc. for C36H62MoI2Nj0042Si: C, 17.6; H, 2.8 ; N, 5.7%.
Table 1. Crystallography data for [CsH,3N2]2[C7Ht,N:]z[C,H7NO]2[Mo,204oSi] Molecular formula Formula weight Colour Crystal size (mm) Crystal system Space group Unit cell a (/~) b (A) c (A) fl (°) V (A 3) Z # (mm-~) F (000) Dx (Mg/m 3)
C36H62Mo12NI0042Si
2486.33 green 0.30 x 0.32 x 0.60 monoclinic P2~ 14.294(4) 14.245(1) 16.709(1) 94.26(1) 3392.9(10) 2 2.259 2404 2.434
Rint
0.021
Collection range
h : - 1 to 18, k : - 1 to 18, l; -21 to 21
Reflections collected Independent reflections Reflections on refinement with I > 2.0a(I)
9171 8695 8692
20max = 55 °
Physical measurements Elemental analysis was performed on a PerkinElmer 240C analytical instrument. The I R spectrum was recorded on a Nicolet F T - I R 170SX spectrophotometer with KBr pellet in the range of 4000400 c m - L The solid state reflectance spectrum was recorded on a Shimadzu UV-240 spectrophotometer. Electronic spectra was obtained on a Shimadzu U V 3100 spectrometer in solution. The powder E S R spectrum was carried out using a Bruker 2000-SRC spectrometer at 110K. XPS was performed on a V G E S C A L A B MK-II.
F~o f
1.048
R Residual extrema in final difference map
0.0517 + 1.303 to - 1.385 e A 3
of data collection and refinement are listed in Table 1. The final atomic coordinates, the thermal parameters, together with observed and calculated structure factors, have been deposited as supplementary material with the Editor, from w h o m copies are available on request.
X-ray structure determination of the complex A green prism crystal of size 0.30 x 0.32 x 0.60 m m was used for data collection. The data were collected using a Siemens P4 four-circle diffractometer with graphite m o n o c h r o m a t e d Mo-K~ radiation (2 = 0.71073 A) using 0/20 scan mode. Intensities were measured for 9717 reflections of which 8695 independent reflections, and the 8692 observed reflections (I > 2.0a(I)) were used for further computation. The data were corrected for Lorentz and polarization effects during data reduction using X S C A N S . 8
Structure solution and refinement The structure was solved by direct methods using SHELXL869 and refined on F 2 by Full-matrix leastsquares methods using SHELXL93.~° All non-hydrogen atoms were refined anisotropically, but the hydrogen atoms were refined isotropically. The final reliability factor was R = 0.0517. All computations were performed on an IBM compatible 486/DX2 personal computer. The crystal data and the parameters
RESULTS AND DISCUSSION
IR spectrum Comparing the I R spectra of the title c o m p o u n d with the I R spectra of (TBA)4SiMoI2040, the vibrational band of Mo~---Od band of the title compound has a red shift from 954(s) cm -1 to 946(s) cm -~. The bands of MO-Ob-MO and M o - O c - M o both have red shifts from 890(w) cm -~, 797(vs) cm -~ to 880(w) cm I and 787(vs) cm -~, respectively, ~ due to the presence of partial charge transfer between the organic donor and polyoxometalate acceptor. This has been verified by the later E S R spectra and the central SiO4 tetrahedron has been little influenced by the electron transfer, so the vibrational frequency of the Si-O bond remains unchanged at 900(vs) cm -1. The band at 1655(vs) cm ~ is due to the C = O vibration from D M F molecule of the compound. The v ( N - H ) vibration appears at 3046 cm -~, which provides evidence of the loss of a methyl group from D M N P to give M N P .
Charge-transfer salt between organic donor and polyoxometalate acceptor
97
0.5
g = 1.936 e~
<
200
I
I
400
600
I 800
;~ (nm)
Fig, 1.
1150
Electronic speetra
Figure 1 shows the reflectance electronic spectra of the title compound. The bands are 282 nm and 418 nm belong to O ~ M o and d - d transition of MoO6 octahedra, respectively. .2 The band at 740 nm is assigned to intervalence charge transfer ( M o S + o M o 6+) IVCT band of [SiMol204o] 5 , which indicates that electron transfer occurs between the organic substrate and polyoxoanion, converting [SiMo1:O40] 4 to the heteropoly blue [SiMol2040] 5 . Figure 2 compares the U V spectra of the title compound with the (TBA)4SiMo1204o dissolved in D M F . The title c o m p o u n d has a broad band at 790 nm similar to that of the solid, which is assigned to an M o 5 ~ ---*Mo 6+ 1VCT band. The solution of (TBA)4 SiMoL2040 has very weak absorption that can be omitted in the wavelength range. The above results indicate that the charge-transfer of the polyoxometalate anion is obviously influenced by the presence of D M N P .
E S R spectra
The ESR spectrum of the title complex at 110K is shown in Fig. 3. The spectrum reveals the presence of a single isotropic signal g = 1.936, which is ascribed
0.300
.........
0.200
, .........
,
....
. . . .
//2~
0.300
Fig. 3.
to the M o 5+, which is close to those observed in similar polyoxoanions containing M o 5+ (S = 5/2) species. 6'~ N o hyperfine splitting of the ESR signal of M o 5+ of the complex has been observed due to the rapid intraionic hopping of the unpaired electron being comparable with the E S R time-scale. 4
X P S study
X-ray photoelectron spectroscopy provides useful information on the oxidation state of the metal ion in the polyoxometalates, and can assess the stoichiometric ratio of the elements present in the compounds. The binding energies of Mo3ds.2 in the title compound and tetraalkylammonium polyoxomolybdenum(VI) are 232.4ev and 232.3ev respectively. The binding energy o f O L,.in the title c o m p o u n d is 530.5ev, which is also close to that of (TBA)4 SiMol2040 (530.2ev). The above effects are due to the fact that the molybdenum atoms are all equivalent and the value of the binding energy is quite close to the value found for the completely oxidised anion. The existence of reduced molybdenum in the polyoxoanion cannot be ruled out as this is of class IIIA of the Robin and Day scheme? 4 In this case, the shift in energy would be very small as the extra electron is delocalized over all the molybdenum atoms.
0.200
< v
X-ray crystal structure
0.100
0.00[3 . . . . . . . . . 400
~......... 600 (nm) Fig. 2.
I ......... 800
1000
0.000
The bond distances and angles of the title complex are listed in Tables 2 and 3, respectively. The crystal structure of the polyoxoanion and a stereoview of the molecular packing are shown in Figs 4 and 5, respectively. The analysis of the crystal structure reveals that the compound possesses the P2t space group, which is non-centrosymmetric. There exists the
98
Xiao-Min Zhang et al.
Table 2. Selected bond lengths (A.) Mo(1)--0(26) Mo(l)--O(13) Mo(l)--O(14) Mo(1)--0(23) Mo(1)--0(33) Mo(1)--O(lO) Mo(2)--0(32) Mo(2)--0(38) Mo(2)--0(9) Mo(2)--0(25) Mo(2)--0(34) Mo(2)--0(3) Mo(3)--0(31) Mo(3)--0(16) Mo(3)--0(18) Mo(3)--O(1) Mo(3)--0(14) Mo(3)--O(lO) Mo(4)--0(8) Mo(4)--0(28) Mo(4)--0(24) Mo(4)--0(20) Mo(4)--0(9) Mo(4)--0(3) Mo(5)--O(1 l) Mo(5)--0(27) Mo(5)--O(l 5) Mo(5)--0(38) Mo(5)--0(2) Mo(5)--O(35) Mo(6)--O(6) Mo(6)--O(22) Mo(6)--O(21) Mo(6)--O(13) Mo(6)--O(5) Mo(6)--O(40) Mo(7)--O(7) Mo(7)--O(12)
1.683(9) 1.823(9) 1.828(11) 1.942(10) 1.988(13) 2.377(8) 1.652(10) 1.885(14) 1.924(11) 1.941(12) 1.952(11) 2.336(7) 1.642(13) 1.831(9) 1.877(14) 1.951(9) 2.016(10) 2.414(9) 1.670(11) 1.821(12) 1.872(10) 1.99(2) 2.06200 ) 2.349(9) 1.673(11) 1.805(13) 1.902(9) 1.905(13) 2.081 ( 1 0 ) 2.319(8) 1.654(9) 1.842(11) 1.912(13) 1.937(9) 1.970(13) 2.395(9) 1.676(10) 1.825(12)
Mo(7)--0(33) Mo(7)--0(18) Mo(7)--0(28) Mo(7)--O(lO) Mo(8)--0(4) Mo(8)--0(25) Mo(8)--0(37) Mo(8)--0(21) Mo(8)~(27) Mo(8)--0(40) Mo(9)--0(39) Mo(9)--0(17) Mo(9)--0(16) Mo(9)--0(34) Mo(9)--0(24) Mo(9)--0(3) Mo(10)--O(29) Mo(10)--O(l) Mo(10)--O(5) Mo(10)--O(17) Mo(10)--O(37) Mo(10)--O (40) Mo(11)--0(30) Mo(11)---O(20) Mo(11)--O(2) Mo(l 1)--0(12) Mo( 11)--0(19) Mo(11)~0(35) Mo(12)--0(36) Mo(12)--0(23) Mo(12)--0(19) Mo(12)--0(22) Mo(12)--O(15) Mo(12)--0(35) Si--O(40) Si--O(lO) Si--O(3) Si--0(35)
1.871(11) 1.951(13) 1.961(11) 2.360(8) 1.675(12) 1.828(11) 1.838(12) 1.987(11) 2.025(13) 2.335(9) 1.677(12) 1.798(10) 1.947(9) 1.962(11) 2.051(11) 2.400(8) 1.636(13) 1.800(9) 1.844(12) 1.984(10) 2.038(13) 2.428(10) 1.666(13) 1.79(2) 1.926(10) 1.959(12) 2.034(10) 2.347(8) 1.649(11) 1.825(9) 1.894(10) 1.938(11) 2.016(9) 2.364(9) 1.580(9) 1.591(9) 1.638(9) 1.683(10)
Charge-transfer salt between organic donor and polyoxometalate acceptor
Table 3. Selected bond angles (~) 0(26)--Mo(1)--0(13) 0(26)--Mo(1)--0(14) 0(13)--Mo(1)--0(14) 0(26)--Mo(1)--0(23) 0(13)--M o(1)--0(23) 0(14)--Mo(1)--0(23) 0(26)--M o( 1)--0(33) 0(13)--Mo(1)--0(33) 0(14)--Mo(1)--0(33) 0(23)--Mo(1)--0(33) 0(26)--Mo(1)--0(10) O( 13)--Mo(l)--O(l O) O(14)--Mo(1)--O(lO) 0(23)--Mo(1)--0(1 O) 0(33)--Mo(1)--0(10) 0(32)--Mo(2)--0(38) 0(32)--Mo(2)--0(9) 0(38)--Mo(2)--0(9) 0(32)--Mo(2)--0(25) 0(38)--Mo(2)--0(25) 0(9)--Mo(2)--0(25) 0(32)--Mo(2)--0(34) 0(38)--Mo(2)--0(34) 0(9)--Mo(2)--0(34) 0(25)--Mo(2)--0(34) 0(32)--Mo(2)--0(3) 0(38)--Mo(2)--0(3) 0(9)--Mo(2)--0(3) 0(25)--Mo(2)--0(3) 0(34)--Mo(2)--0(3) 0(31 )--Mo(3)--0(16) 0(31)--Mo(3)--0(18) 0(I 6)--Mo(3)--0(18) 0(31)--Mo(3)--O(1) 0(I 6)--Mo(3)--0(1) O(18)--Mo(3)--0(1) 0(31 )--Mo(3)--0(14) O( 16)--Mo(3)--0(14) 0(18)--Mo(3)--0(14) O( 1)--Mo(3)--O(14)
0(31)--Mo(3)--0(10) O( 16)--Mo(3)--0( 1O) 0(18)--Mo(3)--0(10) O( 1)--Mo(3)--O(1 O)
106.1(5) 100.1(7) 93.2(5) 103.5(7) 87.6(4) 155.1(4) 97.1 (5) 156.0(5) 88.8(5) 80.8(5) 164.5(5) 88.4(4) 72.8(4) 82.4(4) 69.4(4) 103.4(7) 96.4(5) 93.3(6) 100.5(6) 85.8(6) 162.8(5) 94.4(6) 161.9(5) 87.9(5) 87.8(5) 165.3(6) 88.4(5) 73.9(4) 88.9(5) 74.5(4) 109.3(6) 101.8(7) 91.2(5) 104.1(6) 87.1(4) 153,1(5) 97.1 (6) 153.1(4) 88,2(5) 81,5(5) 163,6(5) 85.4(4) 69.9(5) 83.2(4)
O( 14)--Mo(3 )--0( 1O)
69.1 (4)
0(8)--Mo(4)--0(28) 0(8)--Mo(4)--0(24) 0(28)--Mo(4)--0(24) 0(8)--Mo(4)--0(20) 0(28)--Mo(4)--0(20) 0(24)--Mo(4)--0(20) 0(8)--Mo(4)--0(9) 0(28)--Mo(4)--0(9) 0(24)--Mo(4)--0(9) 0(20)--Mo(4)--0(9)
104.1(6) 97.3(7) 98.4(5) 100.8(7) 84.1(6) 160.5(7) 94.5(5) 159.7(5) 87.2(5) 84.4(6)
0(8)--Mo(4)--0(3) 0(28)--Mo(4)--0(3) 0(24)--Mo(4)--0(3) 0(20)--Mo(4)--0(3) 0(9)--Mo(4)--0(3) 0(11)--Mo(5)--0(27) 0(1 I)--Mo(5)--0(15) 0(27)--Mo(5)--0(15) 0(11)--Mo(5)--0(38) 0(27)--Mo(5)--0(38) 0(15)--Mo(5)--0(38) 0(11)--Mo(5)--0(2} 0(27)--Mo(5)--0(2) 0(15)--Mo(5)--0(2)
0(38)--Mo(5)--0(2) 0(11)--Mo(5)--0(35) 0(27)--Mo(5)--0(35) O(15)--Mo(5)--M(35) 0(38)--Mo(5)--0(351 0(2)--Mo(5)--0(35) 0(6)--Mo(6)--0(22) 0(6)--Mo(6)--0(21) 0(22)--Mo(6)--0(21) 0(6)--Mo(6)--0(13) 0(22)--Mo(6)--0(13) 0(21)--Mo(6)--0(13) 0(6)--Mo(6)--0(5) 0(22)--Mo(6)--0(5) 0(21 )--Mo(6)--0(5) 0(13)--Mo(6)--0(5) 0(6)--Mo(6)--0(40) 0(22)--Mo (6)--0(40) 0(21)--Mo(6)--0(40) O(13)--Mo(6)--0(40) 0(5)--Mo(6)--0(40) 0(7)--Mo(7)--o(12) 0(7)--Mo(7)--0(33) O( 12)--Mo(7)--0( 33) 0(7)--Mo(7)--0(18) 0(12)--Mo(7)--0(18) 0(33)--Mo(7)--0(18) 0(7)--Mo(7)--0(28) O(12)--Mo(7)--0(28) 0(33)--Mo(7)--0(28) O(18)--Mo(7)--0(28) 0(7)--Mo(7)--0(I0) O( 12)--Mo(7)--0( 1O) 0(33)--Mo(7)--0(10) O( 18)--Mo(7)--0( 1O) 0(28)--Mo(7)--0(10) 0(4)--Mo(8)--0(25) 0(4)--Mo(8)--0(37) 0(25)--Mo(8)--0(37) 0(4)--Mo(8)--0(21 ) 0(25)---Mo(8)--0(21)
163.9(5) 91.1 (5) 74.9(4) 85.7(6) 71.3(4) 102.7(6) 96.3(6) 96,6(5) 101.8(6) 89.9(6) 158.9(5) 91.8(5) 165.3(5) 84.4(4) 84.4(5) 161.8(5) 94.0(5) 74.3(4) 85,315) 72.1(3) 108.6(7) 98.6(5) 92.7(5) 103.9(5) 87.6(4) 156.2(5) 96.5(8) 154.1(6) 89.6(6) 80.2(6) 163.0(6) 86.1 (4) 71.6(4) 84.7(4) 70.2(4) 102.7(7) I 01.5(6) 94.2( 5) 99.5(7 ) 156.4(6) 89.3(5) 100.4(6) 85.8(5) 157.5(6t 82.2( 51 167.1(6) 88.9(5) 7l .5(5) 70. I(5) 86.0(5) 101.4(6) 99.8(7) 95.7(5) 97.0(6) 159.0(6) continued ot>er
99
I00
Xiao-Min Zhang
et al.
Table 3.--Continued.
0(37)--Mo(8)--0(21) 0(4)--Mo(8)--0(27) 0(25)--Mo(8)--0(27) 0(37)--Mo(8)--0(27) 0(21)--Mo(8)--0(27) 0(4)--Mo(8)--0(40) 0(25)--Mo(8)--0(40) 0(37)--Mo(8)--0(40) 0(21)--Mo(8)--0(40) 0(27)--Mo(8)--0(40) 0(39)--Mo(9)--0(17) 0(39)--Mo(9)--0(16) 0(17)--Mo(9)--0(16) 0(39)--Mo(9)--0(34) 0(17)--Mo(9)--0(34) 0(16)--Mo(9)--0(34) 0(39)--Mo(9)--0(24) 0(17)--Mo(9)~(24) 0(16)--Mo(9)--0(24) 0(34)--Mo(9)--0(24) 0(39)--Mo(9)--0(3) 0(17)--Mo(9)--0(3) 0(16)--Mo(9)--0(3) 0(34)--Mo(9)--0(3) 0(24)--Mo(9)--0(3) 0(29)--Mo(10)--0(1) 0(29)--Mo(10)--0(5) O(l)--Mo(lO)--O(5) 0(29)--Mo(10)--0(17) O(1)--Mo(lO)--O(17) 0(5)--Mo(10)--0(17) 0(29)--Mo(10)--0(37) O(1)--Mo(lO)--O(37) O(5)--Mo(10)--0(37) 0(17)--Mo(10)--0(37) 0(29)--Mo(10)--0(40) O(1)--Mo(lO)--O(40) 0(5)--Mo(10)--0(40) O(17)--Mo(10)--0(40) 0(37)--Mo(10)--0(40) O(30)--Mo(11)--0(20) O(30)--Mo(11)--0(2) 0(20)--Mo(11)--0(2) O(30)--Mo(l 1)--0(12) O(20)--Mo(11)--0(12) 0(2)--Mo(11)--0(12) O(30)--Mo(l 1)--0(19) O(20)--Mo(11)--0(19) O(2)--Mo(11)--0(19) O(12)--Mo(11)--0(19) O(30)--Mo(11)--0(35) O(20)--Mo(11)--0(35) O(2)--Mo(l 1)--0(35) O(12)--Mo(l 1)--0(35) 0(19)--Mo(11)--0(35) 0(36)--Mo(12)--0(23) 0(36)--Mo(12)--0(19) 0(23)--Mo(12)--0(19) 0(36)--Mo(12)--0(22) 0(23)--Mo(12)--0(22) 0(19)--Mo(12)--0(22) 0(36)--Mo(12)--0(15)
91.0(5) 98.9(6) 85.8(5) 160.5(6) 81.5(5) 167.0(5) 90.8(5) 74.4(5) 71.8(5) 86.2(5) 108.0(7) 104.9(5) 88.7(4) 97.9(5) 94.7(4) 154.7(4) 94.5(6) 157.3(5) 82.6(4) 84.8(4) 163.0(6) 87.3(4) 82.3(3) 72.8(4) 70.8(4) 108.9(7) 99.9(7) 92.4(6) 106.4(6) 87.5(4) 152.2(5) 96.0(7) 154.2(5) 90.2(6) 78.5(5) 162.1(7) 87.5(4) 71.3(5) 81.0(4) 69.1(4) 103.7(7) 95.8(5) 100.7(6) 101.3(6) 84.2(6) 160.5(5) 94.1(6) 160.4(5) 85.3(4) 84.4(4) 163.1 (6)
91.6(6) 74.1(4) 87.0(5) 71.9(4) 106.8(5) 97.6(5) 94.4(4) 102.9(5) 86.8(4) 157.9(4)
94.2(5)
0(23)--Mo(12)--0(15) 0(19)--Mo(12)--0(15) 0(22)--Mo(12)--0(15) 0(36)--Mo(12)--0(35) 0(23)--Mo(12)--0(35) 0(19)--Mo(12)--0(35) 0(22)--Mo(12)--0(35) 0(15)--Mo(12)--0(35) O(40)--Si--O(lO) 0(40)--Si--0(3) O(lO)--Si--O(3) 0(40)--Si--0(35) 0(10)--Si--0(35) 0(3)--Si--0(35) Mo(lO)--O(1)--Mo(3) Mo(11)--0(2)--Mo(5) Si--O(3)--Mo(2) Si--O(3)--Mo(4) Mo(2)--O(3)--Mo(4) Si--O(3)--Mo(9) Mo(2)--O(3)--Mo(9) Mo(4)--O(3)--Mo(9) Mo(lO)--O(5)--Mo(6) Mo(2)--O(9)--Mo(4) Si--O(lO)--Mo(7) Si--O(lO)--Mo(l) Mo(7)--O(lO)--Mo(l) Si--O(lO)--Mo(3) Mo(7)--O(lO)--Mo(3) Mo(1)--O(lO)--Mo(3) Mo(7)--O(12)--Mo(11) Mo(l)--O(13)--Mo(6) Mo(1)--O(14)--Mo(3) Mo(5)--0(15)--Mo(12) Mo(3)--O(16)--Mo(9) Mo(9)--O(17)--Mo(lO) Mo(3)--O(18)--Mo(7) Mo(12)--O(19)--Mo(11) Mo(11)--0(20)--Mo(4) Mo(6)--O(21)--Mo(8) Mo(6)--O(22)--Mo(12) Mo(12)--O(23)--Mo(l) Mo(4)--O(24)--Mo(9) Mo(8)--O(25)--Mo(2) Mo(5)--O(27)--Mo(8) Mo(4)--O(28)--Mo(7) Mo(7)--O(33)--Mo(1) Mo(2)--O(34)--Mo(9) Si--0(35)--Mo(5) Si--O(35)--Mo(11) Mo(5)--O(35)--Mo(11) Si--0(35)--Mo(12) Mo(5)--O(35)--Mo(12) Mo(11)--0(35)--Mo(12) Mo(8)--O(37)--Mo(lO) Mo(2)--O(38)--Mo(5) Si--O(40)--Mo(8) Si--O(40)--Mo(6) Mo(8)--O(40)--Mo(6) Si--O(40)--Mo(1 O) Mo(8)--O(40)--Mo(lO) Mo(6)--O(40)--Mo(lO)
158.3(5) 87.3(4) 83.3(4) 163.2(4) 88.5(4) 73.8(4) 84.2(4) 71.3(3) 114.2(5) 110.4(5) 110.4(5) 107.8(5) 108.5(5) 105.2(5) 151.8(6) 118.5(5) 124.2(5) 124.9(5) 94,8(3) 119,9(5) 91,8(3) 92,4(3) 127,9(7) 119.8(5) 126.3(5) 123.3(5) 93.1(3) 121.2(5) 92.1(3) 91.5(3) 148.6(7) 149.3(6) 126.5(5) 120.9(5) 150.4(5) 149.4(5) 127.8(8) 121.1(5) 149.2(8) 123.4(7) 149.9(6) 150.4(6) 121.7(5) 148.1(8) 142.9(8) 148.1(8) 125.9(7) 120.7(5) 123.4(5) 123.1(5) 95.2(3) 120.8(4) 93.4(3) 93.1(3) 124.3(7) 146.7(7) 127.5(5) 123.1(5) 93.0(3) 120.9(5) 92.0(3) 90.5(3)
101
Charge-transfer salt between organic donor and polyoxometalate acceptor 0(31)
0(39) 0(29)
Mo(3)
o(18)
0(16)
i o(17)
o(i
Mo(lO)
)(37)
0(7) Mo(7) o(10) Mo(I)
0(21) 0(23)
4o(5)
0(30) O(19) 0(15)
0(1 l)
0(36) Fig. 4.
Fig, 5. Crystal packing of the title compound viewed down the Y axis,
0(4)
102
Xiao-Min Zhang et al.
Keggin structure of the [SiMoj2040]4 anion built up of four MO3013 groups which result from the association of three edge-sharing MoO6 octahedra. The four Mo3013 groups tetrahedrally surround the central Si heteroatom in such a way that the full unit has Td symmetry.4 This situation is rare in salts containing XMI2040 which form easily a disordered pseudo-Keggin polyoxoanion. 15The polyanion has four kinds of oxygen atoms. Oa (the oxygen atoms in SiO4 tetrahedra), Ob (the bridging oxygen atoms within one triplet group of M o O 6 octahedra), Oc (the bridging oxygen atoms between two triplet groups of MoO 6 octahedra) and Oo (the terminal oxygen atoms). The sets of M o O bond lengths corresponding to the four types of oxygen atoms, central tetrahedron Mo-Oa 2.319(8)-2.428(10) A, bridging Mo-Ob.c 1.800(9)-2.081(10) A, and terminal M o - Q 1.636(13)-1.683(9) ,~ are in the expected range. TM The Si-Oa distances are in the range of 1.580(9)-1.683(10) A. The organic cations of the title complex can be divided into two types DMNP and MNP. From the least-squares planes in the compound, the two types organic cation are planar. The counterpart dihedral angle between the two planes of DMNP and MNP is in the range of 17.37(0.59)-19.81 ° (0.54) in the unit cell. The shortest distances between polyoxoanion and organic donor is 3.00 A[N(4B)...O(21)], and 3.08 A,[C(14A)-..O(34)], which is shorter than the Van der Waals distance (3.20 A). This may explain why charge transfer occurs between the polyanion and organic cation. The relevant bond distances and angles of the organic cations are in the range of related compounds, TM and are not discussed further here. Acknowledgements--The authors would like to thank the
State Science Technology Commission and the National Nature Science Foundation of China for a major key research project and the Malaysia Government and Univ-
ersiti Sains Malaysia for research grant RD No. 123~43172201. REFERENCES
1. M. T. Pope and A. Muller, Agnew. Chem. Int. Ed. Engl. 1991, 30, 34 and refs therein. 2. M. T. Pope and A. Muller, Polyoxometalates :from platonic solids to Antiretroviral Activity. Kluwer Acad. Pub., Dordrecht, The Netherlands. (1994). 3. E. Coronado and C. J. Gomez-Garcia, Comments Inorg. Chem. 1995, 17, 255 and refs therein. 4. M. T. Pope, Heteropoly and lsopoly Oxometalates. Springer-Verlag ; Berlin, (1983). 5. L. Ouahab, M. Bencharif, A. Mhanni, D. Pelloquin, J. F. Halet, O. Pena, J. Padion and D. Grandjean, Chem. Mater. 1992, 4, 666. 6. C. Sanchez, J. Livage, J. P. Launay, M. Fournier and Y. Jeannin, J. Am. Chem. Soe. 1982, 104, 3194. 7. A. P. Phillips, J. Org. Chem. 1948, 13, 302 and refs therein. 8. Siemens, X S C A N S (Version 2.1) User Manual. Siemens Analytical X-ray Instruments Inc., Madison, USA (1994). 9. G. M. Sheldrick, Acta Cryst. 1990, A46, 467. 10. G. M. Sheldrick, SHELXL93. Program for Crystal Structure Refinement. Universityof Gottingen, Germany (1993). 11. C. Rocchiccioli-Deltcheff,M. Fournier, R. Franck and R. Thouvenot, Inorg. Chem 1983, 22, 207. 12. B. Z. Wan, J. H. Lunsford, Inorg. Chim. Acta 1982, 65, L29. 13. L. Ouahab, M. Bencharif, A. Mhanni, D. Pelloquin, J.F. Halet, O. Pena, J. Padion and D. Grandjean, Chem. Mater. 1992, 4, 666. 14. M. B. Robin and P. Day, Adv. Inorg. Chem. and Radiochem. 1967, 10, 247. 15. H. T. Jr. Evans and M. T. Pope, lnorg. Chem. 1984, 23, 501. 16. L. Yu, J. Wang and H. Chen, J. SolidState Chem. 1992, 97, 239. 17. X. Xue-Xiang, Y. Xiao-Zeng and H. Xiao-Ying, Polyhedron 1995, 14, 1815. 18. F. Hoong-Kun, S. Kandasamy, Y. Boon-Chuan, T. YuPeng, D. Chun-Ying, L. Zhong-Lin and Y. Xiao-Zeng, Aeta Cryst. 1995, C51, 2080.