W.-J. Jin et al. / Journal of Molecular Catalysis A: Chemical 337 (2011) 25–32
27
Table 1
Summary of crystallographic data and structure refinements for complexes 4·CH3COCH3, 5·CH3COCH3 and 6·CH3COCH3.
Compound
4·CH3COCH3
5·CH3COCH3
6·CH3COCH3
Empirical formula
Formula weight
Crystal system
Space group
a (Å)
C21H24NiN5O14Sm
C21H24NiN5O14Eu
781.12
Monoclinic
Cc
11.332(3)
26.905(8)
9.174(3)
90
94.125(4)
90
C21H24NiN5O14Tb
788.08
Monoclinic
Cc
11.308(2)
26.879(3)
9.187(1)
90
94.295(1)
90
779.51
Monoclinic
Cc
11.276(2)
26.738(5)
9.177(2)
90
90
90
90
4
b (Å)
c (Å)
◦
˛
( )
◦
ˇ ( )
◦
ꢁ
( )
3
V (Å )
Z
2798.8(15)
4
1.860
2784.6(5)
4
1.880
ꢂ (g cm−3)
T (K)
1.876
293(2)
0.33 × 0.26 × 0.23
2.867
296(2)
296(2)
3
Crystal size (mm )
0.38 × 0.26 × 0.25
0.33 × 0.26 × 0.23
−
1
ꢃ (mm
F (0 0 0)
)
2.979
3.272
1548
1552
1560
Data/restraints/parameters
Quality-of-fit indicator
No. unique reflections
No. observed reflections
3525/2/380
0.827
3525
3776/2/379
1.037
3776
4273/2/379
1.052
4273
7443
7354
6894
[I > 2(I)]
R
wR
0.0520
0.1147
0.0417
0.1123
0.0413
0.1153
2
1
9.94; H, 2.67; N, 9.76%. IR (KBr, cm−1): 3420 (w), 2952 (w), 1628 (s),
561 (w), 1497 (m), 1466 (vs), 1352 (m), 1293 (s), 1235 (m), 1170
CH3COCH3 (6·CH3COCH3) of suitable dimensions were mounted
onto glass fibers for crystallographic analyses, respectively. All
the intensity data were collected at 293(2) K on a Bruker
(
(
m), 1077 (w), 1053 (w), 1028 (m), 963 (w), 856 (w), 814 (w), 785
w), 739 (m), 672 (w), 631 (w), 584 (w), 528 (w), 492 (w), 471 (w),
SMART CCD diffractometer (Mo-K␣ radiation, ꢀ = 0.71073
A˚ ) in
+
4
41 (w). ESI-MS (m/z): 653.29 [M–NO ] . For 4: Yield: 0.147 g (68%).
ꢄ and scan modes. Structure was solved by direct methods
followed by difference Fourier syntheses, and refined by full-
matrix least-squares techniques against F2 using SHELXTL [14]. All
the non-hydrogen atoms were refined with anisotropic thermal
parameters. Absorption corrections were applied using SADABS
[15]. All hydrogen atoms were placed in calculated positions and
refined isotropically using a riding model. Crystallographic data and
refinement parameters for the complex 4·CH3COCH3, 5·CH3COCH3
and 6·CH3COCH3 are presented in Table 1. Selected bond dis-
tances and bond angles for the three complexes are given in
Table 2.
3
Calc. for C18H18N5O13NiSm: C, 29.97; H, 2.51; N, 9.71%; found: C,
2
−1
9.92; H, 2.72; N, 9.66%. IR (KBr, cm ): 3424 (w), 2987 (w), 2847
(
w), 1630 (s), 1561 (w), 1498 (m), 1466 (vs), 1316 (w), 1276 (s),
1
8
235 (m), 1166 (m), 1109 (w), 1080 (m), 1027 (w), 989 (w), 956 (w),
61 (w), 811 (w), 784 (w), 739 (m), 685 (w), 625 (w), 582 (w), 495
+
(
(
w), 437 (w). ESI-MS (m/z): 659.41 [M–NO ] . For 5: Yield: 0.132 g
61%). Calc. for C18H18N5O13NiEu: C, 29.90; H, 2.51; N, 9.69%; found:
3
−1
C, 29.86; H, 2.62; N, 9.67%. IR (KBr, cm ): 3424 (w), 2948 (w),
2
1
527 (w), 1629 (s), 1560 (w), 1497(s), 1467(vs), 1295 (s), 1236 (m),
168 (w), 1107 (w), 1079 (m), 1029 (w), 987 (w), 952 (w), 861
(
5
w), 813 (w), 785 (w), 740 (m), 683 (w), 625 (w), 604 (w), 580 (w),
+
42 (w), 494 (w), 439 (w). ESI-MS (m/z): 661.01 [M–NO ] . For 6:
3
Yield: 0.143 g (65%). Calc. for C18H18N5O13NiTb: C, 29.62; H, 2.49;
−
1
N, 9.59%; found: C, 29.58; H, 2.63; N, 9.56%. IR (KBr, cm ): 3420
w), 2987 (w), 2846 (w), 1629 (s), 1561 (w), 1501 (s), 1469 (vs),
316 (w), 1279 (s), 1235 (m), 1167 (m), 1109 (w), 1080 (m), 1027
w), 990 (w), 956 (w), 861 (w), 811 (w), 784 (w), 740 (m), 685 (w),
2.5. Polymerization experiments
(
1
(
l-Lactide was prepared from l-lactic acid as previously reported
[16]. The crude product was further purified by re-crystallization
three times from dried ethyl acetate, and dried for 24 h in vac-
6
26 (w), 582 (w), 543 (w), 495 (w), 438 (w). ESI-MS (m/z): 667.98
+
◦
[
M–NO ] . For 7: Yield: 0.128 g (58%). Calc. for C18H18N5O13NiHo:
uum at 30 C. Under nitrogen, 1.000 g (6.94 mmol) of the freshly
3
C, 29.38; H, 2.47; N, 9.52%; found: C, 29.34; H, 2.55; N, 9.46%. IR (KBr,
re-crystallized l-lactide monomer and one of the catalysts 1 and
2–8, in a stipulated molar ratio ([M]/[C]), were charged in an
ampoule inside a glove box. The ampoule was put under high
vacuum (about 12 Pa) for one hour, after which, the ampoule
was sealed under vacuum. The polymerizations were performed
−
1
cm ): 3417 (w), 2953 (w), 1628 (s), 1560 (w), 1469 (vs), 1387 (w),
351 (w), 1295 (vs), 1235 (m), 1170 (m), 1120 (w), 1076 (w), 1028
w), 964 (w), 858 (w), 813 (w), 785 (w), 740 (m), 685 (w), 615 (w),
1
(
5
84 (w), 543 (w), 493 (w), 472 (w), 441 (w). ESI-MS (m/z): 673.98
+
◦
[
M–NO ] . For 8: Yield: 0.155 g (70%). Calc. for C18H18N5O13NiTm:
in a thermostatically controlled oil bath at 130 or 160 C for
3
C, 29.22; H, 2.45; N, 9.46%; found: C, 29.17; H, 2.54; N, 9.35%. IR (KBr,
cm ): 3442 (w), 2953 (w), 1628 (s), 1561 (w), 1467 (vs), 1294 (s),
the selected time. Subsequently, the molten reactive polymer
mixture was cooled by immersing the sealed ampoule in liq-
uid nitrogen and terminated by introducing absolute MeOH with
5% (w/w) HCl to stop the polymerization. The resulting poly-
lactide (PLA) polymer was dissolved in absolute acetone and
precipitate in water. The filtered precipitate was dried under vac-
uum to constant weight. Molecular weights (Mw and Mn) and
molecular weight distributions (PDI = Mw/Mn) were determined
by gel permeation chromatography (GPC) with polystyrene as
standard.
−
1
1
8
238 (m), 1197 (w), 1076 (w), 1028 (w), 963 (w), 940 (w), 857 (w),
14 (w), 785 (w), 740 (m), 673 (w), 632 (w), 583 (w), 544 (w), 493
+
(
w), 472 (w), 442 (w). ESI-MS (m/z): 677.99 [M–NO ] .
3
2.4. Structure determination
Single crystals of [Ni(L)Sm(NO ) ]·CH COCH (4·CH COCH ),
3
3
3
3
3
3
[
Ni(L)Eu(NO ) ]·CH COCH (5·CH COCH ) or [Ni(L)Tb(NO ) ]·
3
3
3
3
3
3
3 3