close

Вход

Забыли?

вход по аккаунту

?

Crystal and Molecular Structure of[Li(tmen)]3[Er(CH3)6].

код для вставкиСкачать
Table 1. NMR spectroscopic data of the complexes ( I ) ; 6 values, in C,D,. measured relative to benzene and converted with reference to TMS external. &( 'H,,,,,,,)
~('2Ch,n,c,c)= 129 la].
CH,
CIH~
C&
C(CH1h
CHIC(CH3),
CH,Si(CH,),
CHLH5
C6H4-CH,-p
flat
(Ibj
(rci
(14
(le)
m
I
(Ig)
(lh)
(C5H5)2LuC1
+ LiR
-0.62 s
0.16 q
0.15 m
-
1.77 t
c--- 1.27 m
-
70-80
90-100
100--110
100-1 10
-
-
110-120
7.93 d.
( J = 7 Hz)
1.51 s
0.55 s
t7.45 m, 7 37 m. 7.17 m7.39 d
249s
THF
-78°C
___f
1.39 s
0.27 s
-0.63 s
1.97 s
= 7.27.
38.6
37.6
28.3
48.6
184.2
36.8
62.6
-
128 9
142.2
38.3
5.9
125.7
129.7
118.4
134.3
22.6
sidue; (le) yields, via p-elimination, isobutane and isobutylene in equimolar amounts, whereas tetramethylsilane is
formed from ( I J . Above 300°C the remaining (C5H&Lu
fragments comproportionate with formation of (C,H5)3Lu
which sublimes at this temperature.
(CSHS)2L~R.THF
+ LiCl
(14-(IN
The X-ray structure analysis of the trimethylsilylmethyl
derivative (In (Fig. 1) shows that the lutetium is surrounded
by a distorted tetrahedral array of the methylene carbon C1,
the oxygen of the THF, and the centers of the two cyclopentadienyl ligands. The distance between lutetium and C1 is
only about if pm shorter than the Yb-C distance in dimeric dicyclopentadienyl(methyl)ytterbium, in which the methyl
group bridges two ytterbium atomsf3].The surprisingly large
bond angle of 131 "C at C1 is determined by the spatial requirement of the trimethylsilyl group bound to the same Catom, and the cyclopentadienyl and T H F ligands around the
lutetium.
Procedure
A solution of LuC& (3.3 g, 11.8 mmol) in THF (50 cm') is
treated at room temperature with 9.5 cm' of a 2.58 M solution
of NaC5H5 in THF and the mixture stirred for f h. After
cooling to -78"C, 16 cm3 of a 0 . 7 5 6 ~ solution of
LiCH2Si(CH3)3in pentane is added dropwise and the reaction mixture stirred for 2 h at - 78 "C and 6 h at 25 "C. The
solvent is removed and the residue dried at room temperature and extracted with toluene (3 x 200 cm'). The residue is
dissolved in pentane/diethyl ether (20: 1) and cooled within
2 days to - 30 "C; yield 4.4 g (81%) yellow needles.
Received- August 5, 1980 [Z 682a IE]
German version: Angew. Chem. Y3, 126 (1981)
\
CAS Registry numbers:
(la), 76207-05-1; (Ib), 76207-06-2; (lcj. 76207-07-3; (Id), 76207-08-4; (lei,
76207-09-5; (In, 76207-10-8; ( l g ) , 76207-1 1-9 (Ih), 76207-12-0: Cp2LuC1,
76207-13-1; LiCH,, 917-54-4 LiC,H5, 81 1-49-4; LiCIH9. 109-72-8; LiCfCH,).,,
594-19-4 LiCHIC(CH2)2. 7412-67-1; LiCHZSi(CH,),, 1822-00-0; LiCH2C6H,,
766-04-1 ; LiC,H,-CH ,p, 24 17-95-0
c
2
4
c
c10
c3
[ I ] H. Schumann in T. J. Marks. R. D. Fischer: Organometallics of the f-Ele-
rnents. Reidel, Dordrecht 1979, p. 81 ff.
121 N . M. Ely. M. Tsutsui,Inorg. Chem. 14. 2680 (1975).
[31 J. Holten, M . F. Lappert. D. G. H Buliard, R. Peorce, J. L. Alwood, W. E.
Hunter, J. Chem. SOC.Chem. Commun. 1976, 480.
Fig. 1. Structure of (CsH&LuCHZSi(CH3),.THF (18; orthorhombic, space
groupP2,2,2,, Z=4,a=1738.1(8). b=l226.8(3),~=917.0(3)pm,V=1.955 x 10'
pm', pE= 1.58 g/cm'; 2735 independent reflections; Syntex P2, four-circle diffractometer Rz0.058. Important bond lengths and angles: Lu-C1 238, Lu-0
229, Lu-Ring1
235. Lu-Ring11 234, Si-C1
183 pm; Lu-Cl-Si
131,
106, RingI-Lu-Ring11
130, RingI1-Lu-C1
CI-Lu-0
96, 0-Lu-Ring1
111. 0-Lu-Ring11
104, RingI-Lu-CI
105"
The new compounds (la)-(lh) are extremely sensitive towards moisture and oxygen. On hydrolysis all the ligands are
removed from the lutetium with formation of Lu(OH)~.( I f )
forms stoichiometric amounts of cyclopentadiene, tetramethylsilane and THF. With 12, on the other hand, only the
alkyl moiety is removed; reaction of (lJ>and Iz leads to
(C5H5)2LuI.THF and (CH3)3SiCH21.In the thermolysis of
(Ze) and (lfl,which commences at 100°C, THF is first removed and then at 130 "C [(le)]or 180 "C [(ffl] the alkyl re-
120
0 Verlag Chemie, GmbH, 6940 Weinheim, 1981
Crystal and Molecular Structure of
[Li(tmen)]3[Er(CH3)61[**J
By Herbert Schumann, Joachim Pickardt, and
Norbert Bruncks"'
Dedicated to Professor Wilhelm Klemm on the occasion
of his 85th birthday
By using N,N,N',N'-tetramethylethylenediamine (tmen) as
a stabilizing base we have succeeded for the first time in syn['I
["I
Prof. Dr. H. Schumann, Doz. Dr. J. Pickardt, DipLChem. N. Bruncks
Institut fur Anorganische und Analytische Chemie der Technischen Universitat Berlin
Strasse des 17. Juni 135, D-1000 Berlin 12 (Germany)
Organometallic Compounds of the Lanthanoids. Part 9. This work was supported by the Fonds der Chemischen lndustrie and by the Senator fur Wirtschaft des Landes Berlin (ERP grant, Project 2327).-Part 8: 151.
0570-0833/81/0101-0120
$02.50/0
Angew. Chem. Int. Ed. Engl. 20 (lY81) No. I
thesizing peralkylated lanthanoid complexes'l1. However, the
extreme sensitivity of the isolated permethylated erbium and
lutetium complexes ( I ) and (2), and the fact that interpretable 'H-NMR spectra could only be obtained for the diamagnetic lutetium compound, have so far precluded concrete
data on the structure being obtained.
We report here on the X-ray structure analysis of the title
compound (1). Single crystals were obtained by slowly cooling a solution of (1) in diethyl ether to -30°C under argon.
The structure analysis shows that lanthanoids can form organometallic compounds in which all coordination sites on
the metal are occupied by carbon atoms of monohaptobonded alkyl groups. In the crystal the erbium is surrounded
by the 6 methyl groups in a slightly distorted octahedral arrangement. All the Er-C bonds are of equal length, and the
methyl groups are bridged pairwise by lithium atoms, resulting in a slight widening of the corresponding Me-Er-Me
angles to 93". The lithium atoms are each located at the centers of tetrahedra made up of two methyl groups and the two
nitrogen atoms of a tmen ligand. Thus, an octahedron results
that is coupled via three corners, which are not linked with
each other, to three tetrahedra (Fig. 1). Since both N atoms
**
Qcl
c3
C'Q
c2
c2
138iLl
152151
no bridging function: in (q5-C5H5)2L~CH2Si(CH3)3.THF[51
d(Lu-C) = 238 pm.
In order to test the validity of this structural principle in
the series of the hexamethyl complexes of the lanthanoids,
we prepared the complexes (3)-(7) in the same way as (1)
and (2).
MCI,
Et,O
+ 6LiCH3 + 3tmen -[Li(trnen)],[M(CH,),J
-78°C
+ 3 LiCl
( 1 ~ 7 )
tmen = (CH,),NCH,CH,N(CH,),
Cpd.
M
Color
Thermal behavior
(3)
Pr
Nd
Sm
Er
Tm
Yb
Lu
green
blue
yellow
pink
white
white
white
dec. pt.
dec. pt.
dec. pt.
m.p.
m.p.
m p.
m.p.
(4)
15)
( 1 ) I11
(6)
(7)
(2) 111
59-62 "C
78-83 "C
85-88 "C
138--139°C
109-1 14 "C
141--142°C
141-142"C
The compounds (1)-(7), which have been completely
characterized by elemental analyses, are extremely sensitive
towards moisture and atmospheric oxygen; some of them
even ignite spontaneously. A notable feature is the enhanced
thermal stability of the complexes with increasing atomic
weight of the lanthanoid.
Received: August 11. 1980 [ Z 682b I€]
German version: Angew. Chem. 93, 127 (1981)
CAS Registry numbers:
(1). 66862-11-1; (3). 76206-86-5; (4), 76206-88-7; (5). 76206-90-1; (6). 76206-92-3;
(7). 76206-94-5
[ I ] H. Schumann, J. Miiller. Angew. Chem. 90, 307 (1978); Angew. Chem. Int
Ed. Engl. 17. 276 (1978).
[21 J. Krausse, G. Marx. J. Organomet. Chem 65,215 (1974).
131 J. Holfen. M. F Lapperf. D. G. H. Buflard, R. Pearce. J. L. Alwood. W. E.
Hunter, J . Chem. SOC.Chem. Commun. 1976, 480.
141 J . Hohen, M. F. Lapperl, G. R. Scollary. D. G. H. Ballard, R. Pearce. J. L. A l wood. W. E. Hunter, J . Chem. Soc. Chem. Commun. 1976. 425.
H. Schumunn, W Genthe, N Bnmcks, Angew. Chem. 93. 126 (1981); Angew.
Chem. Int. Ed. Engl. 20, 119 (1981)
Structure of the Antibiotic Moenomycin A'"']
Fig. I . Structure of[ L I ( C H , ) ~ N C H ~ C H ~ N ( C H , ) & [ E ~ ( C( IH) ;~rhombohedral.
)~]
space group R3c. 2 = 2 . a=1309(2) pm, 01=79.39(10)", V=2.!39x 10' pm'.
pc= 0.97 g/cm'. f p y k n =0.91 g/cm': R =0.085. Syntex-P2, four-circle diffractometer: bond lengths i n pm.
By Peter Welzel, Franz-Josef Witteler, Dietrich Muller,
and Werner Riernerl'l
Moenomycin A is a major component of flavomycin@,
which is employed in animal nutrition"]. It inhibits the transglycosylation
in the biosynthesis of murein, the rigid
component of the bacterial cell wall. For moenomycin A we
propose structure (1).
It was known from degradation studies that moenomycin
A is built up of parts A-B-C and D-E-F-G-H-If3I. Thus, the
sugar chain in (1) could be cleaved quite selectively at the
glycosidic bonds of the two N-acetylated amino sugars with
of a tmen group are coordinated to a lithium atom, (1) is
monomeric in the crystal. By way of contrast the bidentate
dioxane ligands in [Li(dioxane)13[Cr(CH&] function as
bridges between two hexamethylchromium unitsf2'.
The bond angles at the lanthanoid as well as the Er-C
bond lengths in ( l ) , the first electron-deficient compound
with methyl bridges between lithium and a lanthanoid, are
comparable with those in electron-deficient compounds with
['I Prof. Dr. P Welzel, Dr. F.-J. Witteler, Dr. D Miiller
other metal atoms. Thus, the dimeric [(q5-C5H5)2YbCH3]2,
Ahteilung f u r Chemie der Universitat
which contains a Yb2(CH3)2four-membered ring, also posPostfach 1021 48, D-4630 Bochum (Germany)
sesses an angle of 93" at the ytterbium atomf3].The bond
W. Riemer
Institut fur Strahlenchemie im Max-Planck-Institut fur Kohlenforschung
lengths d(Yb-C) = 254 pm in [(q5-C5H5)2YbCH3]2f3]
and
Stiftstr. 34-36, D-4330 Mulheim/Ruhr (Germany)
two
d(Yb-C) = 253 pm in (q5-C5HS)2Yb(CH3)2A1(CH3)2L41,
["I This work was supported by the Fonds der Chemischen Industrie and
further lanthanoid derivatives with electron deficient bonds,
Hoechst AG. We thank Dr. H.- W. Fehlhaber, Hoechst AG. for recording
correspond to the Er-C bond length of 257 pm. In contrast,
the mass spectra, and Herr K. Hobert and Fraulein A . Ponfy for their valuathe lanthanoid-C distance is shortened if the alkyl group has
ble assistance.
Angew. Chem. Inf. Ed. Engl. 20 (1981) No. 1
0 Verlag Chemie, GmbH, 6940 Weinheim. 1981
OS70-0833/81/0101-#12I
.$ #2.50/#
121
Документ
Категория
Без категории
Просмотров
1
Размер файла
218 Кб
Теги
crystals, structure, molecular, tmen, ch3
1/--страниц
Пожаловаться на содержимое документа