[Cr3O(CH3COO)6(H2O)3]NO3⋅HNO3⋅H2O, TRIAQUA-HEXAKIS(µACETATO)-µ3-OXO-TRICHROMIUM(III) NITRATE NITRIC ACID
SOLVATE MONOHYDRATE
Marco Bettinellia,*, Adolfo Speghinia, Gabriele Bocellib, Olesea Ghercoc, Valeriu Mereacred,
Denis Prodiusd, Constantin Turtad
a
Dipartimento Scientifico e Tecnologico,Università di Verona, and INSTM, UdR Verona, Ca’Vignal, Strada Le Grazie 15, I37134 Verona, Italy
b
IMEM-CNR, Parco Area delle Scienze 37a, 43100 Parma, Italy
c
ASM, Institute of Applied Physics, Academiei St. 5, MD-2028 Chisinau, Moldova
d
ASM, Institute of Chemistry, Academiei St. 3, MD-2028 Chisinau, Moldova
*Corresponding author. Tel.: +39-045-8027902; fax: +39-045-8027929;
E-mail: [email protected]
Abstract: Reaction in methanol solution of the trinuclear ‘basic’ chromium(III) acetate with Pr(NO3)3⋅5H2O and
further extraction by chloroform-acetone mixture led to the formation of novel unusual
[Cr3O(CH3COO)6(H2O)3]NO3⋅HNO3⋅H2O (1) cluster with one “free” molecule of nitric acid. Complex 1 crystallizes
in the monoclinic space group P21/c with, at room temperature, a = 13.624(2), b = 15.032(2), c = 15.180(2) Å, β =
112.98(3) °, Z = 4, and V = 2862.09 Å3. The obtained crystalline compound has been synthesized and characterized
by IR and UV/Vis methods.
Keywords: Chromium carboxylate, Polynuclear complex, UV-Vis
1. Introduction
Oxo-centered triangular complexes of the general type [M3O(OOCR)6L3]n+ are particularly valuable as
frameworks for a systematic study of metal-metal interactions in clusters. They have been characterized for a wide
variety of first-row and heavier transition metals, with mixed-metal combinations and with mixed-valence combinations
[1]. ‘Basic’ chromium carboxylates is a general name for a family of chromium(III) complexes in which only RCOOand oxo/hydroxo/aquo ligands are present. For many years, the only representative of this group was the classical oxocentered trinuclear complex [Cr3O(CH3COO)6(H2O)3]+, whose structure was reported almost four decades ago by
Figgis and Robertson [2].
Chromium(III) carboxylates have been used extensively for various applications as polymerization and
oxidation catalysts [3], suitable building block of zeotype polyoxometalate-macrocations for shape-selective adsorption
of water [4], materials in processing of fir bark extract for air fresheners [5], possible DNA-cleaving agents and
nutritional supplements [6] and for many other uses [7-10]. Ever since the discovery of chromium as an essential human
nutrient, Cr(III) acetates containing [Cr3O(CH3COO)6(H2O)3]+ cation have been administered to animals in biological
intake experiments [11], to produce DNA strand breaks in peripheral lymphocytes [12] and in phosphate ester cleavage
reactions [13].
Here, we report the crystal structural determination of a new cationic trinuclear Cr(III) complex, which
represents a new type of ‘basic’ chromium carboxylate.
2. Results and discussion
It needs to be mentioned that this synthetic route for the title compound can be realized only in the presence of
Pr(NO3)3⋅5H2O. Using other lanthanide nitrates (Ln = La, Eu) clusters with other structures have been obtained. The
reasons for this behavior and the nature of these different products are being investigated.
On the basis of the results of elemental analysis, in the first step of our research it has been assumed that the
obtained product is a new ‘Cr(III,III,IV)-acetate’ cluster. But the absence of splitted components A1 and B2 of E´ [1] in
the region 700-500 cm-1 of IR spectrum (Fig.1) and typical profile of the electronic absorption spectra (Fig.2) for such
trichromium(III) complexes [1] confirm that a member of the investigated class of substances of symmetrical
complexes with “CrIII3O”-core has been obtained. Other IR bands are definitely assigned to vibrations of CH3COO-,
NO3- and H2O groups, but do not represent essential interest for the discussion in the present communication.
88
Figure 1. The νas(Cr3O) band of complexes [Cr3O(Ac)6(H2O)3]NO3⋅HNO3⋅H2O (1) and
[Cr3O(CH3COO)6(H2O)3]⋅CH3COO (BCA)
The electronic spectrum of 1 in acetone solution shows the familiar two peaks in the visible (Fig.2, bands I and
II), corresponding to the 4A2g→4T2g and 4A2g→4T1g transitions of Cr(III) in octahedral symmetry.
No spectral features relative to other oxidation states of chromium are present in the UV-Vis-NIR absorption spectra.
Figure 2. Electronic spectra of [Cr3O(Ac)6(H2O)3]NO3⋅HNO3⋅H2O (1) and [Cr3O(CH3COO)6(H2O)3]⋅CH3COO
(BCA), in acetone solution.
X-ray study of 1 showed that the structure consists of three chromium atoms connected together by an oxygen
atom. In addition two acetate groups connect the three chromium atoms to each other. So every chromium atom adopts
a tetrahedral conformation with four atoms of four different acetate groups as base and the common oxygen and a water
molecule in apex positions (Fig.3). Bond distances and angles do not deviate significantly from the normal range. The
atomic coordinates of the heavy atoms are in Table 2 and their anisotropic thermal parameters are in Table 4. Table 3
reports the coordinates of H atoms with isotropic thermal parameters. The geometrical parameters are in Table 5. A
projection of the complex with the labeling scheme is in Fig. 3.
89
Table 2. Atomic fractional coordinates (x104) and Ueq (x104 Å2 )
x/a
CR1
CR2
CR3
O1W
O2W
O3W
O1
C1A
C2A
O3A
O4A
C1B
C2B
O3B
O4B
C1C
C2C
O3C
O4C
C1D
C2D
O3D
O4D
C1E
C2E
O3E
O4E
C1F
C2F
O3F
O4F
N1G
O1G
O2G
O3G
N1H
O1H
O2H
O3H
O4W
8440
6347
8661
9099
4776
9515
7817
5610
6305
7269
5847
6208
6679
6084
7641
6802
7017
7778
6414
10205
9568
9407
9224
11108
10149
9725
9841
7110
7256
8112
6516
2252
3120
1455
2220
3592
3885
4182
2419
11146
y/b
(1)
(1)
(1)
(3)
(2)
(3)
(2)
(5)
(3)
(2)
(2)
(4)
(3)
(2)
(2)
(5)
(3)
(2)
(2)
(4)
(3)
(2)
(2)
(5)
(3)
(2)
(2)
(5)
(3)
(2)
(2)
(3)
(4)
(3)
(5)
(6)
(7)
(6)
(8)
(5)
914
1475
2401
202
1360
3299
1597
1155
1220
1096
1392
4334
3427
2770
3388
-1346
-386
-202
167
3229
2634
2896
1919
419
895
591
1561
1508
1695
2040
1491
1273
1094
1141
1516
1562
1524
1507
1762
-5
z/c
(1)
(1)
(1)
(2)
(2)
(2)
(1)
(5)
(3)
(2)
(2)
(3)
(2)
(2)
(2)
(3)
(2)
(2)
(2)
(4)
(2)
(2)
(2)
(5)
(3)
(2)
(2)
(4)
(2)
(2)
(2)
(3)
(4)
(4)
(5)
(5)
(10)
(7)
(9)
(4)
7170
7614
8825
6412
7367
9866
7869
4624
5670
5916
6221
7510
7792
7477
8336
7642
7558
7340
7709
6982
7342
8065
6910
9825
9133
8310
9445
10634
9725
9790
8958
5554
5549
4918
6284
9199
10241
8841
8569
6885
Ueq
(1)
(1)
(1)
(2)
(3)
(2)
(2)
(3)
(2)
(2)
(2)
(4)
(3)
(2)
(2)
(5)
(2)
(2)
(2)
(4)
(3)
(2)
(2)
(5)
(3)
(2)
(2)
(4)
(2)
(2)
(2)
(3)
(4)
(4)
(4)
(5)
(6)
(5)
(8)
(7)
314
306
305
511
483
484
299
708
394
488
508
529
363
471
475
572
371
486
524
558
362
456
429
643
379
460
473
531
364
478
536
693
1362
1483
1682
1263
3135
2292
2838
1076
(2)
(2)
(2)
(13)
(12)
(13)
(8)
(23)
(14)
(11)
(10)
(20)
(14)
(11)
(11)
(22)
(13)
(12)
(12)
(19)
(13)
(11)
(10)
(21)
(13)
(11)
(10)
(19)
(15)
(11)
(11)
(19)
(27)
(29)
(36)
(38)
(91)
(56)
(76)
(35)
90
Table 3 . Atomic fractional coordinates (x104) and Uiso (x104 Å2 ).
x/a
H1A
H2A
H3A
H1B
H2B
H3B
H1C
H2C
H3C
H1D
H2D
H3D
H1E
H2E
H3E
H1F
H2F
H3F
H1W1
H2W1
H1W2
H2W2
H1W3
H2W3
H1W4
H2W4
H1NH
y/b
568
491
568
560
654
635
615
729
676
999
1058
1047
1158
1119
1105
761
709
663
886
982
439
455
934
1011
1111
1133
4491
(6)
(7)
(5)
(6)
(6)
(5)
(5)
(4)
(6)
(7)
(6)
(6)
(5)
(6)
(5)
(6)
(5)
(6)
(4)
(5)
(5)
(4)
(4)
(5)
(8)
(4)
(5)
z/c
63
113
170
437
466
455
-147
-163
-160
350
345
295
58
43
-14
120
202
135
-10
9
121
145
341
333
-37
-21
802
(5)
(5)
(4)
(4)
(5)
(5)
(3)
(3)
(5)
(6)
(5)
(6)
(5)
(5)
(5)
(4)
(5)
(5)
(3)
(4)
(5)
(3)
(4)
(4)
(7)
(4)
(4)
Uiso
425
444
437
735
802
711
762
801
712
646
739
656
984
1050
969
1104
1095
1051
605
663
693
780
1030
994
636
704
9221
(6)
(5)
(4)
(5)
(6)
(5)
(3)
(3)
(5)
(6)
(5)
(6)
(5)
(6)
(4)
(5)
(5)
(5)
(4)
(4)
(5)
(4)
(4)
(4)
(7)
(4)
(4)
1341
1209
899
1018
1345
1051
663
586
1257
1415
1118
1247
888
1289
1085
960
951
1007
558
778
1021
693
715
690
1638
164
1386
(289)
(262)
(209)
(229)
(288)
(245)
(143)
(149)
(274)
(300)
(276)
(271)
(269)
(264)
(241)
(210)
(217)
(286)
(164)
(172)
(249)
(162)
(178)
(180)
(360)
(130)
(133)
Table 4. Anisotropic thermal parameters (x104 Å2 ).
U22
U11
CR1
CR2
CR3
O1W
O2W
O3W
O1
C1A
C2A
O3A
O4A
C1B
C2B
O3B
O4B
C1C
C2C
O3C
O4C
C1D
294
251
271
448
298
395
271
562
398
384
313
479
398
306
382
499
353
547
425
578
( 3)
( 3)
( 3)
(17)
(14)
(16)
(11)
(31)
(20)
(15)
(13)
(26)
(19)
(13)
(14)
(28)
(18)
(16)
(15)
(28)
314
337
315
553
658
562
292
1127
415
720
850
402
342
368
316
351
331
312
352
627
U33
( 3)
( 3)
( 3)
(19)
(20)
(19)
(12)
(52)
(21)
(19)
(22)
(25)
(19)
(15)
(14)
(24)
(19)
(14)
(14)
(31)
353
326
316
583
479
488
327
337
334
345
322
721
415
687
613
860
393
740
874
514
U23
( 3)
( 3)
( 3)
(18)
(17)
(17)
(11)
(22)
(18)
(13)
(13)
(33)
(19)
(17)
(16)
(37)
(18)
(18)
(21)
(27)
-33
-34
-36
-225
-80
-168
-37
-23
-17
-85
-96
63
1
-29
-84
47
24
-71
-15
-32
U13
( 2)
( 2)
( 2)
(16)
(15)
(13)
( 9)
(27)
(15)
(12)
(13)
(23)
(15)
(13)
(12)
(25)
(15)
(12)
(14)
(24)
149
108
100
256
137
163
110
70
104
126
79
252
229
136
69
259
107
405
338
263
U12
( 2)
( 2)
( 2)
(15)
(14)
(14)
( 9)
(21)
(16)
(11)
(11)
(26)
(17)
(12)
(13)
(27)
(15)
(15)
(15)
(25)
-21
-25
-35
-37
-56
-120
-36
23
-37
-11
1
107
21
14
19
-40
-16
-43
-55
-240
( 2)
( 2)
( 2)
(15)
(13)
(14)
( 9)
(32)
(16)
(13)
(13)
(20)
(15)
(11)
(11)
(21)
(15)
(12)
(12)
(24)
91
C2D
O3D
O4D
C1E
C2E
O3E
O4E
C1F
C2F
O3F
O4F
N1G
O1G
O2G
O3G
N1H
O1H
O2H
O3H
O4W
277
503
443
394
273
399
391
485
403
453
354
422
589
523
1198
1254
1759
1294
1668
673
(16)
(16)
(14)
(26)
(16)
(14)
(14)
(28)
(20)
(15)
(14)
(22)
(27)
(24)
(46)
(55)
(82)
(52)
(85)
(32)
384
468
411
654
415
502
492
726
365
650
912
895
2204
1932
2471
1720
6318
4826
3735
644
(20)
(16)
(16)
(37)
(21)
(16)
(16)
(37)
(19)
(18)
(23)
(32)
(65)
(54)
(82)
(66)
(239)
(154)
(148)
(35)
389
446
490
720
426
449
410
444
362
369
359
639
1182
1467
1271
1077
1226
1151
2688
1995
(18)
(14)
(14)
(36)
(20)
(14)
(14)
(25)
(18)
(13)
(14)
(25)
(38)
(43)
(46)
(46)
(59)
(44)
(111)
(69)
69
-78
-28
157
60
-6
-28
25
-9
-123
-35
-205
-188
-1080
-947
-325
-561
-642
1487
-137
(16)
(12)
(12)
(28)
(16)
(12)
(12)
(23)
(14)
(12)
(14)
(22)
(39)
(41)
(49)
(43)
(89)
(63)
(103)
(36)
92
237
243
42
109
134
21
248
189
201
158
74
225
-184
367
738
471
905
391
611
(15)
(12)
(12)
(24)
(15)
(12)
(12)
(23)
(16)
(12)
(12)
(20)
(25)
(26)
(37)
(45)
(55)
(42)
(76)
(37)
-18
-183
-87
75
-1
136
64
-72
24
-198
-137
13
200
313
-59
-512
-1211
-176
-254
142
(14)
(12)
(12)
(25)
(15)
(12)
(12)
(26)
(15)
(14)
(14)
(21)
(33)
(29)
(46)
(47)
(108)
(67)
(90)
(24)
Table 5. Bond distances (Å) and angles (°).
CR1
CR1
CR1
CR1
CR1
CR1
CR2
CR2
CR2
CR2
CR2
CR2
CR3
CR3
CR3
CR3
CR3
CR3
C1A
C2A
C2A
O4D
O3C
O3C
O3A
O3A
O3A
O1
O1
O1
-
CR1
CR1
CR1
CR1
CR1
CR1
CR1
CR1
CR1
O1W
O1
O3A
O3C
O4D
O3E
O2W
O1
O4A
O3B
O4C
O4F
O3W
O1
O4B
O3D
O4E
O3F
C2A
O3A
O4A
-
2.021
1.898
1.968
1.969
1.977
1.982
2.030
1.894
1.956
1.975
1.970
1.960
2.058
1.894
1.968
1.958
1.971
1.963
1.502
1.231
1.250
O3E
O3E
O4D
O3E
O4D
O3C
O3E
O4D
O3C
90.0
88.3
171.2
169.9
89.8
90.3
94.6
95.3
93.5
(4)
(3)
(2)
(3)
(3)
(2)
(3)
(2)
(3)
(3)
(3)
(3)
(3)
(2)
(3)
(3)
(3)
(3)
(5)
(5)
(5)
(1)
(1)
(1)
(1)
(1)
(1)
(1)
(1)
(1)
C1B
C2B
C2B
C1C
C2C
C2C
C1D
C2D
C2D
C1E
C2E
C2E
C1F
C2F
C2F
N1G
N1G
N1G
N1H
N1H
N1H
-
C2B
O3B
O4B
C2C
O3C
O4C
C2D
O3D
O4D
C2E
O3E
O4E
C2F
O3F
O4F
O1G
O2G
O3G
O1H
O2H
O3H
O3W
O3W
O3W
CR2
CR1
CR1
C1A
C1A
O3A
-
CR3
CR3
CR3
O1
O1
O1
C2A
C2A
C2A
-
1.496
1.249
1.248
1.487
1.237
1.252
1.490
1.262
1.251
1.500
1.242
1.247
1.496
1.244
1.245
1.216
1.155
1.183
1.474
1.135
1.538
(6)
(4)
(4)
(6)
(5)
(5)
(8)
(5)
(4)
(7)
(4)
(5)
(8)
(5)
(4)
(7)
(6)
(9)
(11)
(13)
(12)
O3D
O4B
O1
CR3
CR3
CR2
O4A
O3A
O4A
86.3
84.3
177.4
119.7
120.2
120.1
116.6
117.9
125.5
(1)
(1)
(1)
(1)
(1)
(1)
(3)
(3)
(3)
92
O1
O1W
O1W
O1W
O1W
O1W
O4C
O3B
O3B
O4A
O4A
O4A
O1
O1
O1
O1
O2W
O2W
O2W
O2W
O2W
O4E
O3D
O3D
O4B
O4B
O4B
O1
O1
O1
O1
O3W
O3W
-
CR1
CR1
CR1
CR1
CR1
CR1
CR2
CR2
CR2
CR2
CR2
CR2
CR2
CR2
CR2
CR2
CR2
CR2
CR2
CR2
CR2
CR3
CR3
CR3
CR3
CR3
CR3
CR3
CR3
CR3
CR3
CR3
CR3
-
O3A
O3E
O4D
O3C
O3A
O1
O4F
O4F
O4C
O4F
O4C
O3B
O4F
O4C
O3B
O4A
O4F
O4C
O3B
O4A
O1
O3F
O3F
O4E
O3F
O4E
O3D
O3F
O4E
O3D
O4B
O3F
O4E
95.4
86.0
84.0
87.2
84.0
179.1
87.3
92.3
172.8
167.1
90.1
88.7
95.8
93.8
93.4
96.9
83.2
86.8
86.0
84.1
178.8
86.8
168.9
90.6
94.1
170.7
86.8
95.8
95.4
95.2
93.7
82.8
86.7
(1)
(1)
(1)
(1)
(1)
(1)
(1)
(1)
(1)
(1)
(1)
(1)
(1)
(1)
(1)
(1)
(1)
(1)
(1)
(1)
(1)
(1)
(1)
(1)
(1)
(1)
(1)
(1)
(1)
(1)
(1)
(1)
(1)
CR1
CR2
C1B
C1B
O3B
CR2
CR3
C1C
C1C
O3C
CR1
CR2
C1D
C1D
O3D
CR3
CR1
C1E
C1E
O3E
CR1
CR3
C1F
C1F
O3F
CR3
CR2
O2G
O1G
O1G
O2H
O1H
O1H
-
O3A
O4A
C2B
C2B
C2B
O3B
O4B
C2C
C2C
C2C
O3C
O4C
C2D
C2D
C2D
O3D
O4D
C2E
C2E
C2E
O3E
O4E
C2F
C2F
C2F
O3F
O4F
N1G
N1G
N1G
N1H
N1H
N1H
-
C2A
C2A
O4B
O3B
O4B
C2B
C2B
O4C
O3C
O4C
C2C
C2C
O4D
O3D
O4D
C2D
C2D
O4E
O3E
O4E
C2E
C2E
O4F
O3F
O4F
C2F
C2F
O3G
O3G
O2G
O3H
O3H
O2H
132.9
133.0
117.0
118.0
125.0
132.4
133.6
117.7
117.0
125.3
134.4
131.7
118.4
117.1
124.5
134.4
132.3
116.5
117.7
125.8
133.9
131.7
117.8
117.6
124.7
132.4
134.3
117.9
117.8
123.8
118.3
117.1
124.4
(2)
(2)
(3)
(3)
(3)
(2)
(2)
(4)
(3)
(3)
(2)
(2)
(3)
(3)
(3)
(2)
(2)
(3)
(4)
(3)
(2)
(2)
(4)
(3)
(3)
(2)
(2)
(6)
(5)
(5)
(7)
(7)
(7)
Table 6. Possible H bonds and contcts <2.5 (D= donor, A = acceptor)
D-H (Å)
O1W-H2W1
O2W-H1W2
O2W-H2W2
O1W-H1W1
O3W-H2W3
0.91(7)
0.70(6)
0.83(7)
0.69(5)
0.76(7)
D...A (Å)
O1W...O4W
O2W...O1G
O2W...O2H
O1W...O2Gi
O3W...O2Gii
2.612(8)
2.828(5)
2.670(9)
2.745(7)
2.746(6)
H...A (Å)
H2W1...O4W
H1W2...O1G
H2W2...O2H
H1W1...O2Gi
H2W3...O2Gii
1.71(7)
2.14(6)
1.85(7)
2.07(5)
2.02(7)
D-H...A (°)
O1W-H2W1...O4W
O2W-H1W2...O1G
O2W-H2W2...O2H
O1W-H1W1...O2Gi
O3W-H2W3...O2Gii
171(5)
167(7)
171(5)
164(6)
158(11)
Equivalent positions: i = -x+1,-y,-z+1; ii = x+1,-y+1/2,z+1/2
93
Figure 3. Projection of the complex with arbitrary numbering. The ellipsoids are at 20% probability level.
Fig. 4. Packing of the complex 1.
The single acetate groups are planar and the dihedral angles formed by the couples which connect Cr1 with
Cr2, Cr1 with Cr3 and Cr2 with Cr3 are 88.1(3), 93.5(2) and 103.8(2)°, respectively.
In the solid state the molecules are connected by intermolecular and intramolecular H-bonds (Fig.4).
3. Conclusion
In summary, new basic chromium acetate has been isolated and characterised by spectroscopic techniques.
This novel compound contains the well-known [Cr3O(CH3COO)6(H2O)3]+ triangular cation, but is characterised by the
unusual presence of a "free" HNO3 molecule. This could give rise to differences in the interaction of this compound
with biological molecules, with respect to other basic chromium carboxylates.
Supporting information available: IR data, listing crystallographic parameters in CIF format, atomic
coordinates, bond distances and angles, thermal parameters and hydrogen atom positions for the title complex. This
material is available free of charge from the authors.
94
4. Experimental
General: All chemicals and solvents were used as received. All preparations and manipulations were
performed under aerobic conditions. [Cr3O(CH3COO)6(H2O)3]⋅CH3COO was prepared as previously described [14].
The UV-Visible absorption spectra were measured with a conventional double beam UVIKON 941 plus
spectrophotometer using a resolution of 1 nm. The solvent (acetone) was used as a reference.
The diffuse reflectance spectra in the medium infrared region (4000-400 cm-1) were measured using a Nicolet
Magna 740 FTIR spectrometer. The powders of the samples under investigation were dispersed in KBr in a 1:100 mass
ratio and the spectra were measured using KBr as a reference. All the spectroscopic measurements were performed at
room temperature.
Synthesis of [Cr3O(Ac)6(H2O)3]NO3⋅HNO3⋅H2O (1). Solutions of [Cr3O(CH3COO)6(H2O)3]⋅CH3COO (‘basic’
chromium acetate, 0.8176 g, 1.279 mmol) and Pr(NO3)3⋅5H2O (1.6001 g, 3.836 mmol) in methanol (ca. 10 mL) were
added with continuous stirring (30-45 min.) to 40 mL of acetonitrile – toluene (1 : 3). After 4-5 days the obtained dark
green viscous mass was dissolved in part in a chloroform-acetone mixture (2:1, ca. 25 mL) and filtered off. During the
first 3 days the transparent solution of dark green color was separated constantly until the first crystals have appeared. A
microcrystalline product was obtained, which was recrystallized from a mixture of acetone and toluene (4:1, ca. 15 mL).
After 1 week the resultant dark green crystals were collected by filtration, washed with toluene, and dried in vacuum.
Yield: ~30% (270 mg) Calc. for C12H27N2Cr3O23: C, 19.93; H, 3.76; N, 3.87%. Found: C, 19.99; H, 3.42; N, 3.78%.
Crystallographic data: The structure was solved by direct methods with SIR97 [15]. The refinement was
carried out with SHELX97 [16]. After some full-matrix anisotropic cycles all H atoms were found in a ∆F map and all
refined isotropically. The ORTEP drawings were performed with ORTEP-3 program [17]. Crystallographic data
(excluding structure factors) for the structures in this paper have been deposited with the Cambridge Crystallographic
Data Centre as supplementary publication. CCDC reference number 612714. Copies of the data can be obtained, free of
charge, on application to CCDC, 12 Union Road, Cambridge, CB2 1EZ, UK fax: +44(0)-1223-336033 or e-mail:
[email protected]]. The crystal data and pertinent details of the experimental conditions are summarized in Table
1.
Table 1. Experimental and crystallographic information for 1.
____________________________________________________________________
Formula
(CH3COO)6·O·NO3·HNO3·(H2O)3·Cr3·(H2O)
Formula weight
723.36
Crystal: color
dark green
shape
prismatic
dimensions (mm)
0.19x0.23x0.34
Crystal system
Monoclinic
Space Group
P21/c
Cell Constants: a (Å)
13.624(2)
b (Å)
15.032(2)
c (Å)
15.180(2)
β (º)
112.98(3)
2862.09
Cell volume (Å3)
Formula units
4
Temperature
room
Diffractometer
Bruker AXS
Radiation, wavelength (Å)
MoKα, 0.71069
Reflections measured
27926
6461, 0.055
Unique reflections, Rint
Reflections. observed [I>2σ(I)]
4547
2θ max (º)
56.7
Indices range: h, k, l
-18/17, -19/19, -19/19
No. of refined parameters
465
R
0.048
Rw
0.14
Weights
w=1/[(σ2Fo+0.099P2+0.22P)]
GOF
0.84
-0.57/0.50
∆ρmin/max(e/ Å3)
5. Acknowledgements
The research described in this publication was made possible in part by Award No. BGPIII #MOB-2-3058CS-03 of the Moldovan Research and Development Association (MRDA) - U. S. Civilian Research & Development
Foundation
(CRDF),
and
Italian
Government
Support
for
Moldavian
Young
Scientists
95
(http://www.edu.md/?lng=ro&MenuItem=5&SubMenu0=2). V. Mereacre thanks also the AvH foundation. The authors
gratefully thank Erica Viviani (Univ. Verona) for expert technical assistance.
6. References
[1]
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[2]
Figgis, B. N.; Robertson, G. B. Nature, 1965, 205, 694–695.
[3]
Windholz, M. (10th Ed.), The Merck Index, Merck, Rahray, NJ, 1983.
[4]
Uchida, S.; Mizuno, N. J. Am. Chem. Soc., 2004, 126, 1602–1603.
[5]
Lyandres, G. V.; Raldugin, V. A.; Shpakov, A. Ya.; Igumnova, M. A.; Bushueva, N. Ya. Izobreteniya 1998, 3,
243(Rus).
[6]
Speetjens, J. K.; Parand, A.; Crowder, M. W.; Vincent, J. B.; Woski, S. A. Polyhedron, 1999, 18, 2617–2624.
[7]
Geiger, D. K. Coord. Chem. Rev., 1998, 172, 157–180.
[8]
Eshel, M.; Bino, A. Inorg. Chim. Acta, 2001, 320, 127–132.
[9]
Eshel, M.; Bino, A. Inorg. Chim. Acta, 2002, 329, 45–50.
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Chem. Soc., 2003, 125, 1168–1169.
[11] Board on Agriculture, The Role of Chromium in Animal Nutrition, National Academy Press, Washington, DC,
1997, 64p.
[12] Gao, M.; Binks, S.P.; Chipman, J.K.; Levy, L. S.; Braithwaite, R. A.; Brown, S. S. Hum. Exp. Toxicol., 1992,
11, 77–82.
[13] Parand, A.; Royer, A. C.; Cantrell, T. L.; Weitzel, M.; Memon, N.; Vincent, J. B.; Rowder, M. W. Inorg. Chim.
Acta, 1998, 268, 211–219.
[14] Brauer, G. Handbook of Preparative Inorganic Chemistry, Academic press, London, 1965, 2, 1371-1372.
[15] Altomare, A.; Burla, M. C.; Camalli, M.; Cascarano, G.; Giacovazzo, C.; Guagliardi, A.; Moliterni, A. G. G.;
Polidori, G.; Spagna, R. Acta Cryst., 1999, C52, 115–119.
[16] Sheldrick, G.M. SHELX97. Program for Crystal Structure refinement, Univ. of Göttingen, Germany, 1997.
[17] Farrugia, L. J. ORTEP3 for Windows, Glasgow University, Scotland (U.K), 1997.
96