Synthesis and crystal structure of [(2,4-C7H11)2LnC=CC6H 5]2 (Ln - Gd, Er)

Article abstract of DOI:10.1016/S0022-328X(99)00124-2

The reaction of (2,4-C₇H₁₁)₃Ln (Ln = Gd, Er) with HC=CC₆H₅ in toluene leads to [(2,4-C₇H₁₁)₂LnC=CC₆H ₅]₂, which crystallizes in the sp

Full text of DOI:10.1016/S0022-328X(99)00124-2

www.elsevier.nl/locate/jorganchem
Journal of Organometallic Chemistry 584 (1999) 135–139
Synthesis and crystal structure of [(2,4-C7H11)2LnCꢀCC6H5]2
(Ln=Gd, Er)
Suobo Zhang a, Xiuli Zhuang b, Jifeng Zhang b, Wenqi Chen b,*, Juzheng Liu a
a Department of chemistry, Jilin Uni6ersity, Changchun 130023, Jilin, People’s Republic of China
b Changchun Institute of Applied Chemistry, Academia Sinica, Changchun 130022, Jilin, People’s Republic of China
Received 31 July 1998; received in revised form 7 February 1999
Abstract
The reaction of (2,4-C7H11)3Ln (Ln=Gd, Er) with HCꢀCC6H5 in toluene leads to [(2,4-C7H11)2LnCꢀCC6H5]2, which
crystallizes in the space group Pabc. The molecule shows the dimer structure, where two (2,4-C7H11)2Gd or Er units are connected
by asymmetrical alkynide bridges. © 1999 Elsevier Science S.A. All rights reserved.
Keywords: Alkynide; Crystal structure; 2,4-Dimethylpentadienyl–lanthanide; Organolanthanide; Synthesis
lutetium trichloride (3:1 reaction stoichiometry) has
been isolated an unusual minor reaction product, [h5–
(CH3)2C5H5]Lu[h5,h3-(CH3)C5H5CH2CH2CH(CH3)
C3H3(CH3)], which contains a dimeric chelate ligand
derived from the end-to-end fusion of two 2,4-
dimethylpentadienyl groups [7]. As part of our investi-
gation of the reactivity of pentadienyl–lanthanide
compounds, we have examined the reaction of tris–
(2,4-dimethylpentadienyl) lanthanide with pheny-
lacetylene. This method is different from the others,
such as the reaction between lanthanide halides and
alkali metal acetylides [8–10], and the reaction of lan-
thanide alkyls [11,12] or divalent lanthanocene [13–15]
with terminal alkyne. We report here the synthesis and
1. Introduction
Since 1980, pentadienyl–lanthanoid chemistry has
been actively investigated, partly because the pentadi-
enyl–lanthanoid complexes possess reasonable thermal
stability as well as chemical and catalytic reactivities.
For lanthanides, the anionic pentadienyl group can be
expected to bond favorably to ionic lanthanide com-
plexes. Indeed, a few pentadienyl–lanthanide com-
plexes, Ln(2,4-C7H11)3, (Ln=Nd [1], Gd [2], Er [3]),
[Nd6(2,4-C7H11)6Cl12 (THF)2] [4] and Sm(C8H8)(2,4-
C7H11)(THF) [5] have recently been synthesized and
characterized by single crystal X-ray diffraction. How-
ever, in contrast to the cyclopentadienyl ligands, ‘open
ring’ pentadienyl–lanthanide compounds are still quite
scarce, and very little is known about their reactions.
Thus, the reaction of cobaltous chloride with two
equivalents of the 2,4-dimethylpentadienyl anion (2,
4-C7H1−1 ) leads to a dimeric complex, in which each
cobalt center is bonded to an h5-2,4-C7H11 ligand and
an h4-diene portion of the 2,4,7,9-tetramethyl-2,4,6,8-
decatetraene bridging unit, which was formed from the
coupling of two pentadienyl units [6]. From the
metathesis of (2,4-dimethylpentadienyl–potassium with
X-ray structure of
a
novel complex [(2,4-
C7H11)2LnCꢀCC6H5]2 (Ln=Gd,Er).
2. Experimental
All manipulations were conducted under dry nitro-
gen using the Schlenk techniques. The THF was
predried with NaOH and distilled from sodium ben-
zophenone ketyl. Anhydrous GdCl3 was prepared by
Taylor’s method [16]. The complex (2,4-C7H11)3Ln
(Ln=Gd or Er) was prepared by a procedure pub-
lished previously [2].
* Corresponding author.
0022-328X/99/$ - see front matter © 1999 Elsevier Science S.A. All rights reserved.
PII: S0022-328X(99)00124-2

136
S. Zhang et al. / Journal of Organometallic Chemistry 584 (1999) 135–139
Metal analysis was carried out by complexometric
titration.
Table 1
Crystal data of Gd and Er complexes
Compound
[(2,4-C7H11)2GdCꢀCC6H5]2 [(2,4-C7H11)2ErCꢀCC6H5]2
2.1. Synthesis of [(2,4-C7H11)2GdCꢀCC5H6]2
Molecular weight 897.5
Crystal size (mm) 0.34×0.28×0.8
Unit cell dimensions
916.4
0.2×0.32×0.4
PhCꢀCH (0.2 g, 1.96 mmol) and (2,4-C7H11)3Gd
(0.85 g, 1.92 mmol) were placed in a Schlenk flask,
and 10 ml of toluene was added. The mixture was
stirred at 60°C for 2 h. The solution was concen-
trated and crystallized at −20°C to give red crystals,
0.55g (yield 60%). M.p. 167°C. Found: C, 58.41; H,
5.84; Gd, 34.65. Anal. Calc. C22H27Gd: C, 58.88; H,
6.0; Gd, 35.03%. The IR absorption peeks of the Gd
complex (cm−1): 3086 m, 2963 m, 2918 m, 2037 m,
1522 s, 1486 m, 1459 s, 1418 m, 1386 s, 1262 w, 1190
w, 1052 w, 1023 w, 848 m, 789 s, 692 s, 623 m, 561
m, 548 m, 493 m, 466 m. The synthesis of the Er
analog is the same as above. The Er complex is red,
yield 55%. Found: Er 36.15. Anal. Calc. 36.32. Er
complex (cm−1): 3082 m, 2962 m, 2923 m, 2037 s,
1513 s, 1468 s, 1443 m, 1382 s, 1262 w, 1190 w, 1070
w, 1023 m, 848 m, 793 m, 757 s, 691 s, 623 m, 530
m, 514 m, 493 m, 434 m. The MS main peaks for Gd
complex (m/z): [2M−C7H11]+ 793(29), [2M−
C8H5]+ 787(77), [2M−C7H11−C8H5]+ 692(2),
M+444(8), [M−C7H11]+ 349(2), [M−C8H11]+
343(9), [C8H5]+ 101(3), [C7H11]+ 95(39).
˚
a (A)
10.515(4)
17.797(8)
20.895(8)
3910(2)
10.473(2)
20.912(4)
17.813(5)
3901(1)
2–5q
˚
b (A)
˚
c (A)
3
˚
V (A )
Scan range 2q (°) 3–5q
Reflections
Reflections for
I\3|(I)
Space group
Z
Dcalc. (f cm−3
R
Rw
F(000)
5896
2609
4325
1839
Pabc
4
Pabc
4
)
1052
0.045
0.046
1784
1.56
0.038
0.035
1815
3. Results and discussion
3.1. The syntheses of (2,4-C7H11)2LnCꢀCC6H5 (Ln=Gd
or Er)
In general, the metathesis between the s-bond
alkyl–lanthanide and phenylacetylene is used to pre-
2.2. Determination of crystal structure
Table 2
4
4
,
Atomic coordinates (10 ) and isotropic thermal parameters (A×10 )
of Gd complex
A crystal was sealed in a thin-walled glass capillary
under nitrogen. The unit cell parameters were deter-
mined and X-ray intensity data were collected on a
Nicolet R3m/E four-circle diffractometer, using
graphite monochromated Mo–Ka radiation (u=
x
y
z
Ua
Gd
723(1)
2230(1)
3046(10)
4296(9)
4745(9)
3926(8)
2654(8)
1781(8)
1023(8)
3447(9)
3156(7)
2324(8)
1727(8)
1780(11)
860(11)
3718(10)
5530(1)
6816(5)
7206(5)
6999(5)
6420(5)
6009(5)
6203(4)
5791(4)
5435(4)
5513(6)
5689(5)
5340(5)
4608(5)
4149(6)
4383(6)
6421(6)
6092(6)
6247(5)
6614(5)
7013(4)
7035(5)
7417(5)
5957(5)
5717(1)
3455(4)
3068(4)
3031(4)
3375(4)
3775(4)
3817(4)
4214(4)
4527(4)
5660(4)
6262(4)
6698(4)
6626(4)
6111(5)
7166(6)
6522(6)
6668(5)
6121(4)
5546(4)
5461(5)
5870(6)
4844(5)
6058(5)
42(1)
61(4)
68(4)
68(4)
67(4)
58(3)
47(3)
46(3)
48(3)
83(4)
62(3)
60(3)
57(3)
91(5)
96(5)
86(4)
80(4)
55(3)
50(3)
56(3)
81(4)
76(4)
70(4)
C(11)
C(12)
C(13)
C(14)
C(15)
C(16)
C(17)
C(18)
C(21)
C(22)
C(23)
C(24)
C(25)
C(26)
C(27)
C(31)
C(32)
C(33)
C(34)
C(35)
C(36)
C(37)
,
0.71069 A) in the ꢀ scan mode. A total of 5896
(4325) reflections were collected within 3B2qB56°
(Gd) [2B2qB50°(Er)]. The intensity of one check
reflection was monitored every 68 reflections. No ob-
vious change was observed in the intensities of the
check reflection. Correction was made for Lorenz and
polarization effects. The crystal data are listed in
Table 1.
Calculations were carried out with the SHELXTL
computer program. The position of the Gd (Er) atom
was determined from a three-dimensional Patterson
map followed by the use of the Fourier technique.
The positions of all the non-hydrogen atoms could be
fixed on different Fourier maps. They were refined by
least squares and, at the final stage, refined anisotrop-
ically. The final agreement factors are R=0.045
(0.0376) and Rw=0.046 (0.0347).
−853(11)
−1493(8)
−1023(7)
118(8)
1130(10)
241(10)
−2844(9)
Atomic coordinates and isotropic thermal parame-
ters selected bond lengths, bond angles and plane
equations are given in Tables 2–5, respectively.
a Equivalent isotropic U defined as one third of the trace of the
orthogonalised Uij tensor.

S. Zhang et al. / Journal of Organometallic Chemistry 584 (1999) 135–139
137
Table 3
Table 5
4
4
,
Atomic coordinates (10 ) and isotropic thermal parameters (A×10 )
of Er complex
,
Bond angles (A) of Gd and Er complexes
C(18)–Gd–C(21)
C(21)–Gd–C(22)
C(21)–Gd–C(23)
C(18)–Gd–C(24)
C(22)–Gd–C(24)
C(18)–Gd–C(25)
C(22)–Gd–C(25)
C(18)–Gd–C(18a)
C(16)–C(17)–C(18) 177.4(9)
C(17)–C(18)–Gda 135.6(7)
C(22)–C(23)–C(24) 126.7(8)
C(21)–Er–C(22)
C(23)–Er–C(24)
C(21)–Er–C(25)
Er–C(18)–Era
Era–C(18)–C(17)
Cent(1)–Er–C(18)
Cent(2)–Er–C(18)
C(21)–C(22)–C(27) 127.3(9)
C(23)–C(22)–C(27) 113.7(9)
C(23)–C(24)–C(25) 125.3(9)
C(25)–C(24)–C(26) 116.6(9)
C(16)–C(17)–C(18) 178.7(9)
80.4(3)
27.1(3)
53.2(3)
126.9(3)
55.0(3)
100.4(3)
67.1(3)
81.2(3)
C(18)–Gd–C(22)
C(18)–Gd–C(23)
C(22)–Gd–C(23)
C(21)–Gd–C(24)
C(23)–Gd–C(24)
C(21)–Gd–C(25)
C(23)–Gd–C(25)
C(15)–C(16)–C(17)
Gd–C(18)–Gda
C(21)–C(22)–C(23)
C(23)–C(24)–C(25)
C(22)–Er–C(23)
C(24)–Er–C(25)
C(18)–Er–C(18a)
Er–C(18)–C(17)
107.1(3)
132.1(3)
29.6(3)
58.6(3)
31.2(3)
67.0(3)
54.4(3)
121.8(7)
98.8(3)
130.5(9)
127.3(8)
30.0(3)
28.0(3)
81.0(3)
126.0(7)
x
y
z
Ua
Er
721(1)
2245(10)
3042(10)
4308(11)
4736(10)
3926(8)
2659(9)
1779(8)
1021(8)
3438(8)
3162(9)
2320(9)
1710(9)
1761(10)
852(11)
3713(10)
5717(1)
3460(5)
3060(5)
3022(5)
3375(6)
3771(5)
3822(4)
4209(4)
4528(4)
5666(5)
6261(5)
6692(5)
6646(5)
6135(5)
7178(6)
6525(6)
6663(5)
6117(5)
5558(4)
5455(5)
5876(5)
4831(5)
6051(6)
4469(1)
3199(5)
2805(6)
3001(6)
3583(6)
3985(5)
3799(5)
4209(5)
4568(5)
4499(6)
4305(6)
4680(5)
5383(5)
5847(6)
5614(7)
3587(6)
3897(6)
3751(5)
3383(5)
2980(5)
2955(5)
2585(6)
4045(6)
41(1)
50(4)
58(4)
60(4)
63(5)
45(4)
35(3)
34(3)
39(3)
58(4)
46(4)
44(4)
46(4)
67(5)
76(5)
68(5)
62(4)
44(4)
38(3)
44(4)
51(4)
62(4)
64(4)
C(11)
C(12)
C(13)
C(14)
C(15)
C(16)
C(17)
C(18)
C(21)
C(22)
C(23)
C(24)
C(25)
C(26)
C(27)
C(31)
C(32)
C(33)
C(34)
C(35)
C(36)
C(37)
27.0(3)
30.2(3)
66.9(3)
99.0(3)
135.0(7)
112.0
Cent(1)–Er–Cent(2) 127.7
Cent(1)–Er–C(18a)
Cent(2)–Er–C(18a)
C(21)–C(22)–C(27)
C(22)–C(23)–C(24)
C(23)–C(24)–C(26)
C(15)–C(16)–C(17)
114.8
102.9
118.9(9)
130.7(9)
117.9(9)
120.0(8)
108.5
−875(10)
−1497(9)
−1034(8)
139(10)
1115(9)
234(11)
The 2,4-dimethylpentadienyl potassium was prepared
according to the literature [18]:
−2862(10)
a Equivalent isotropic U defined as one third of the trace of the
orthogonalised Uij tensor.
pare the titled complexes. In this paper, the metathesis
between the y-bond 2,4-dimethylpentadienyl and phen-
ylacetylene was first adopted. The preparation of 2,4-
dimethylpentadienyl ligand was as follows [17]:
(2)
In order to inhibit the polymerization of 1,3-
dimethylpentadiene triethylamine was added during the
reaction process.
The reaction of GdCl3 or ErCl3 with three equiva-
lents. of (2,4-C7H11)K leads to the formation of a
crystalline compound, (2,4-C7H11)3Gd or (2,4-
C7H11)3Er, respectively which has been isolated and
determined for its structure (Eq. (3)). It reacts with
HCꢀCC6H5 at 1:1 molar ratio in toluene to form [(2,4-
C7H11)2GdCꢀCC6H5]2 or [(2,4-C7H11)2ErCꢀCC6H5]2
(Eq. (4)).
(1)
Table 4
,
Bond lengths (A) of Gd and Er complexes
Gd–C(18)
Gd–C(22)
Gd–C(24)
Gd–Gda
Gd–C(18a)
C(17)–C(18)
C(21)–C(22)
C(22)–C(27)
C(24)–C(25)
Er–C(18)
Er–C(22)
Er–C(24)
Er–Era
C(11)–C(12)
C(17)–C(18)
C(21)–C(22)
C(22)–C(27)
C(24)–C(25)
2.512(8)
2.814(8)
2.723(9)
3.855(1)
2.566(8)
1.210(12)
1.332(13)
1.531(14)
1.352(14)
2.512(9)
2.813(9)
2.738(10)
3.856(1)
1.375(14)
1.218(12)
1.323(15)
1.509(15)
1.351(15)
Gd–C(21)
Gd–C(23)
Gd–C(25)
C(11)–C(12)
C(16)–C(17)
C(18)–Gda
C(22)–C(23)
C(23)–C(24)
C(24)–C(26)
Er–C(21)
2.866(10)
2.673(8)
2.820(10)
1.370(13)
1.438(11)
2.566(8)
1.407(12)
1.453(12)
1.505(15)
2.847(8)
2.665(10)
2.826(10)
2.557(9)
LnCl3+3(2,4-C7H11)KT“HF(2,4-C7H11)3Ln+KCl
(3)
(2,4-C7H11)3Ln
+C6H5CꢀCHTo“luene[(2,4-C7H11)2LnCꢀCC6H5]2
+2,4-C7H12 (Ln=Gd, Er)
(4)
During the reaction period, the color of the solution
gradually changed from yellow to red, and red crystals
of the phenylalkynide compound were obtained after
suitable workup.
The IR spectra of Gd and Er compounds show
strong absorption at 2037cm−1, which is assigned to
the absorption of –CꢀC– bond [15]. The mass spectra
of the complexes did not give a parent molecular ion
(2M), and gave only some fragments, such as [2M−
Er–C(23)
Er–C(25)
Er–C(18a)
C(16)–C(17)
C(18)–Era
C(22)–C(23)
C(23)–C(24)
C(24)–C(26)
1.428(12)
2.557(9)
1.427(14)
1.409(13)
1.488(15)

138
S. Zhang et al. / Journal of Organometallic Chemistry 584 (1999) 135–139
Fig. 3. Conformations of the two 2,4-dimethylpentadienyl ligands.
,
,
C(33), C(33)–C(34), average 1.430(12) A (1.425(13) A).
,
,
The difference of 0.079 A (0.084 A) between internal
and external C–C bond distances is larger than that in
,
(2,4-C7H11)3Gd (0.046 A) [2] or (2,4-C7H11)3Er [3]
,
(0.001A).
It is interesting to note that the Gd–C(2,4-C7H11)
distances fall in two different orders, Gd–C(21,25)
Fig. 1. The structure of [(2,4-C7H11)2GdCꢀCC6H5]2.
,
(2.866(10), 2.802(10) A)\Gd–C(22,24) (2.814(8),
C7H11]+, [2M−C8H5]+, which denote the dimeric
structure for Gd.
,
,
2.723(9) A)\Gd–C(23) (2.673(8) A) and Gd–C(32,
,
34) (2.788(9), 2.867(8) A)\Gd–C(31, 35) (2.773(10),
,
,
2.730(9) A)\Gd–C(33) (2.687(8) A). It might be that
the CꢀCC6H5 ligand is situated against an open edge
(C21–27) of a 2,4-C7H11 ligand, which leads to repul-
sion between CꢀCC6H5 and C31 as well as C35, since it
is situated against the back end (C31–37) of the other
2,4-C7H11 ligand. The Er–C(2,4-C7H11) distances are
essentially consistent with the above mentioned law.
The Gd–C(18) [Er–C(18)] and Gd–C(18a) [Er–
C(18a)] distances are 2.512(8) (2.512(9)) and 2.566(8)
3.2. Molecular structures of the complexes
The structure of [(2,4-C7H11)2LnCꢀCC6H5]2 (Ln=
Gd, Er) (Figs. 1 and 2) was established by single-crystal
X-ray analysis. The complex is an alkynyl-bridged
dimer, both the 2,4-dimethylpentadienyl ligands are
nearly planar with maximum deviation from their least
squares planes of 0.1371 (0.1379) for C(27) and 0.1026
(0.0902) for C(36), which form a dihedral angle of
123.3° (123.7°) between the two planes.
The 2,4-C7H11 ligand adopts the planar U conforma-
tion. The C–C bond distances of Gd compound fall in
two sets, viz. the external C–C bond distances, C(21)–
C(22), C(24)–C(25), C(31)–C(32), C(34)–C(35), aver-
,
(2.557(9) A), respectively, which indicates that the elec-
tron deficient alkynyl bridge is asymmetrical, and the
reason is the same as mentioned above. In the ring-
opened cyclopentadienyl–lanthanide complex, the rela-
tionship between two ligand conformations is
intriguing. The angle between Ln–C(23)–1/2[C(21)+
C(25)] and Ln–C(33)–1/2 [C(31)+C(35)] planes is
defined as the conformation angle when two ligands are
syn-eclipsed the conformation angle is equal to 0°;
when they are anti-eclipsed the conformation angle is
180°. The schemes are shown in Fig. 3.
,
,
age 1.351(14) A (1.341(15) A); and the internal C–C
bond distances, C(22)–C(23), C(23)–C(24), C(32)–
For the transition metal sandwich compounds the
conformation angles of (2,4-C7H11)2M (M=V, Cr, Fe)
are from 59.7 to 89.8° [10,19].
The complexes of Gd and Er have the conformation
angles of 160.9 (Gd) and 157.9°(Er), which are greater
than the transition metal sandwich compounds. Owing
to steric hindrance, the two 2,4-dimethylpentadienyls
adopt anti-eclipsed form (Fig. 3). The Gd–CꢀC [Er–
CꢀC] and Gda–CꢀC [Era–CꢀC] angles are 125.6
(126.0°) and 135.6 (135.0°), respectively. The observed
9–10° difference is similar to that of {[(CH3)N](CH3)-
Be(CꢀCCH3)}[20] (11°), but smaller than that of {[t-
C4H9C5H4)2SmCꢀCC6H5]2 (58.2°) [14] and [(C5H5)2Er-
CꢀCC(CH3)3]2 (34°) [11].
Fig. 2. The structure of [(2,4-C7H11)2ErCꢀCC6H5]2.

S. Zhang et al. / Journal of Organometallic Chemistry 584 (1999) 135–139
[10] C. Qian, Y. Ge, J. Organomet. Chem. 299 (1986) 97.
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