M. Cazacu et al.
IR data (pellet in KBr), cm-1 : 3449w, 3069m, 2999m,
1693s, 1598m, 1554m, 1499w, 1440vw, 1428s, 1415s,
EDXRF atomic ratio: Fe:Co:Si=2:1:2.9.
{Fe2IIICoIIO(Ipds)3(H2O)3},
μ3-oxo-tri[1,3-Bis(3-
1390m, 1318m, 1284s, 1263sh, 1190m, 1132w, 1108s, trimellitylimidopropyl)–tetramethyldisi-loxane]
1096s, 1019m, 999vw, 917wbr, 848w, 812vw, 763w, - triaqua – cobalt(II) - diiron(III), complex II: A solution
735m, 708s, 698s, 634vw, 532s, 510s, 466vw.
consisting of 0.3 g (0.50 mmol) H2Ipds in 4.5 mL DMF
1H NMR (400.13 MHz, CDCl3), δ, ppm: 8.09−8.11d, was slowly dropped under vigorous stirring into a
7.67-7.69d, 7.54-7.56d, 7.46-7.48d, 7.41-7.43t (aromatic solution formed by 0.1 g (0.17 mmol) {Fe2CoO} cluster
protons); intensity ratio: 2:2:2:1:2.
1 , 3 - B i s ( 3 - t r i m e l l i t y l i m i d o p r o p y l ) mixture became cloudy due to the formation of a very
tetramethyldisiloxane, [HOOC-C6H3(CO)2N(CH2)3- fine precipitate that was separated by filtration, washed
(CH3)2Si]2O, H2Ipds, was prepared by the chemical with DMF, acetone, and diethyl ether and dried.
modification of the aminopropyl groups telechelic Yield 0.27 g (79%); Elem.Anal. %wt., Found: C50.24;
in 8 mL DMF. After about 15 minutes, the reaction
attached to tetramethyldisiloxane. The used method H5.45, N4.57, Fe5.12, Co2.27, Si 7.80/Calculated for
consisted in condensation 1,3-bis(3-aminopropyl) C84H96N6O31CoFe2Si6 (M=2024.84): C49.83; H4.78;
tetramethyldisiloxane (AP0) with trimellitic anhydride N4.15; Fe5.52; Co2.91; Si8.32.
(AT) in excess (molar ratio AP0:AT about 1:2.25) by
IR data (pellet in KBr), cm-1: 3468mbr, 3069w,
refluxing in N,N`-dimethylformamide (sol. 5 molar) for 3 h 2952m, 2899w, 2878w, 1773m, 1719s, 1658m, 1624s,
[28]. The solution was cooled, filtered, and concentrated 1592m, 1482w, 1432m, 1387s, 1361s, 1312sh, 1254m,
in vacuum after which this was added to excess water 1196w, 1090m, 1062m, 1007sh, 970w, 929w, 840m,
to precipitate the formed diacid macromer. The product 789m, 736s, 709m, 613w, 576w, 546w, 469m, 416w.
deposited as a white solid, and was separated by EDXRF atomic ratio: Fe:Co:Si=2:1:5.7.
filtration and dried.
Yield: 80%; Elem. Anal. %wt., Found: C57.90;
H5.41; N4.61; Si10.19. /Calculated for C28H32N2O9Si2
3. Results and discussion
(M=596.73): C56.40; H5.40; N4.70; Si9.40.
IR data (pellet in KBr), cm-1 : 3473wbr, 3072m,
The homo- and heterotrinuclear carboxy-clusters of
2953m, 2928sh, 1776m, 1717vs, 1694vs, 1626w,
1604w, 1485w, 1421m, 1394vs, 1362s, 1301s, 1254vs,
1187m, 1085s, 1060s, 981w, 974w, 865w, 842m, 788m,
757vw, 729s, 703m, 659vw, 636vw, 610w, 530m.
1H NMR (400.13 MHz, Acetone-d6), δ, ppm: 8.41-
8.43t, 8.32s, 7.92-7.94D (3H, aromatic ring), 3.63-3.67t
(2H, -CH2-N<), 1.70-1.78m (2H, -CH2-CH2-CH2-), 0.58-
0.62m (2H, -Si-CH2-), 0.07 (6H, CH3-Si-); intensity ratio:
3:2:2:2:6.
iron(III) are well-known [15,16]. They have the triangular
molecular structure (Fig. 1) in which the metal ions are
placed in the corners of triangle [16,20,29,30]. The oxo
O2- anion situated in the centre is tridentate ligand and
forms donor-acceptor bonds with metal anions. The
carboxylate groups are bidentate bridge ligands and are
coordinated to the neighboring metal ions in the syn-syn
fashion. The monodentate molecule L completes the
coordination number of the complex’ generator to six.
In out-sphere of the coordination cation is situated the
anion. As a rule there are some molecules of solvent.
Preparationofμ3-oxo-hexaacetato-triaqua–cobalt(II)-
diiron(III), {Fe2CoO}, was done according to an already
reported procedure [30], by mixing aqueous solutions of
FeCl3•6H2OandCo(CH3COO)2 atroomtemperature.The
reaction leads to the product with the structure presented
in Fig. 1 where M = Fe2 and Co, R = CH3 and L= H2O. The
IR spectrum of the precursor {Fe2CoO} (supplementary
data) is characterized by intensive absorption bands at
1588 and 1420 cm-1, which are assigned to νas(COO-)
and νs (COO-) vibration, respectively [31]. The moderate
band assigned to the δ(OCO) vibrations at 725 cm-1 is
observed too. As it was demonstrated early [16,20,32],
in μ3-oxo heterotrinuclear iron(III) carboxylates, the
band assigned to νas(Fe3O) at 605 cm-1 disappeared
and two new bands (663 and 563 cm-1) appear as the
result of diminishing of the symmetry of {Fe3O} fragment
{Fe2IIICoIIO(Bcpdps)3(H2O)3},
μ3-oxo-tri[Bis(p-
carboxyphenyl)diphenylsilane]-triaqua–
cobalt(II)-
diiron(III), complex I: A solution consisting of 0.20 g
(0.44 mmol) H2Bcpdps in 4 mL DMF was slowly dropped
under vigorous stirring into a solution formed by 0.08 g
(0.12 mmol) {Fe2CoO} cluster in 6 mL DMF. Reaction
mixture immediately turned into a gelatinous mass that
was filtered after 24 h and washed with DMF, then with
diethyl ether and dried.
Yield 0.23 g (76%); Elem. Anal. %wt., Found:
C59.10; H5.32; Co3.50; Fe8.01; Si 5.30/Calculated for
C78H60O16CoFe2Si3 (M=1508.2) C62.12; H4.01; Co3.91;
Fe7.41; Si5.59.
IR data (pellet in KBr), cm-1: 3412mbr, 3069m,
3050m, 3020m, 2930m, 1662s, 1613s, 1544s, 1497m,
1395s, 1310sh, 1256w, 1107s, 1019m, 998w, 862w,
773s, 721s, 712s, 702s, 663m, 594w, 536w, 536w,
512m, 482m, 418m.
1081