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Lithium Di-tert-butylmethylsilylhydrazide a Hexamer with Li+ Ions Bound Side-on and End-on.

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degree of energetic stabilization relative to that of their "conventional" isomers with trigonally planar carbon atoms can
easily be approximated by experiment. This should provide
a good basis from which to assess the results of quantum
mechanical calculations carried out on such systems, and
thus help us to obtain a realistic picture of the common
factors which lead to the formation of stable compounds
containing planar-tetracoordinate carbon atoms.
Received: April 14. 1993
Revised version: July 14. 1993 [Z 6006 IE]
German version: Angeii.. C ~ C I 1993.
I I . 105. 1691
G . Erker. R. Zwettler, C . Kruger. R. Noe. S. Werner, J A m . Clicni. Soc.
1990. 112. 9620; G . Erker. M. Albrecht, C. Kruger. S. Werner.
Org(iji0iiiP/uNi(.,s 1991, 10. 3791; M. Albrecht, G. Erker, M. Nolte. C.
Ki-iiger. J. Or,qiiiioiiier. Clierit. 1992, 427. C21; G. Erker. M. Alhrecht. S.
Wernei-. M. Nolte. C. Ki-uger. Clirni. B w . 1992, 125. 1953; G . Erker, M.
Alhrecht. C. KrGger. S. Werner. J. A n i . Chivii. Soi. 1992, 114. 8531; G
Erker. M. Albrecht. C. Kruger. S. Werner, P. Binger, F. Langhauser.
~ r g i i ~ i u ~ ~ i ~1992.
~ / u lIf.
l ; i3517;
~ ~ review: G. Erker. Coniniivm Inorg. Chem.
1992. 13, 11 1: N o d i r . C h m . Techn. Lah. 1992. 40, 1099; M. Alhrecht, G
€1-kcr.
1993. 441
A. D. Horton. A. G . Orpen. Aiigm'. Choii. 1992. 104. 912; A n R w Chrrii
I n / . E d EtigI. 1992. 31. 876.
See also. R. H Cayton, S. T. Chacon. M. H. Chisholm. M. J. HampdonSmith. J. C. Huffman. K. Folting. P. D. Ellis, B. A. Huggins, Angm.
C/iiwi 1989. I O l . 1547: Angeti-. Clicn?.lut. Ed. Engl. 1989. 28. 1523; S T.
Chncon. M. H. Chisholm, K. Folting. J. C. Huffman, M. J. HampdonSmith. Or.Fu,iniiir/o/ii~s1991. 10. 3722: F. A. Cotton. M. J. Millar. J. Am.
C/ic/i?.Soc. 1977. 99. 7886; S. Harder. J. Boersma, L. Brandsma. A. van
Hrteren. J. A. Kanters. W. Bauer. P. von R. Schleyer. ihid. 1988. 110.7802:
S. L. Buchwald, E. A. Lucas. W. M. Davis, ;hid 1989. 111. 397; see also:
T. Berinehelli. G . Ciani. G. DAlfonno. A . Sironi, M . Freni. J. Chrin Soc.
C ' Y w i i . C o i i i i i t i i n . 1985, 978; W. Uhl. M. Layh. W. Massa, Ciierii. B w . 1991.
124. 1511: M. Layh. W. Uhl, PoI~,/iedron1990. 9, 277; F. A. Cotton, M.
Sh;ing. J 4 n i Chwii. Soc. 1990. 112. 1584.
Theoretic;il studies. R. Hoffmann, R. W. Alder, C. F. Wilcox. Jr., J. Ain.
C ' i w i i . S01.. 1970. 92. 4992; R. Hoffmann. Purr Appl. CIiern. 1971. 28. 181:
J. B. Collins. 1. C. Dill. E.D. Jemmis. Y Apeloig, P. von R. Schleyer, R.
S e e p . J. A. Pople. J A m . Chwii. Soi..1976. 98. 5419; P. von R. Schleyer.
A. I . Boldyev. J. C%erti.Soc. C h n . Coriirmii. 1991, 1536, and references
therein: A 1. Boldyrev. P. von R. Schleyer. J A m . C%eiii. Soc. 1991, il3,
9045.
R. Gleiter. 1. Hyla-Ki-yspin, S. Niu. G. Erker, Aiigciv. Ciieiti. 1993. 105.
753. . 4 t i , y m . <'hem. h i t . Ed. Dig/. 1993, 32. 754.
G . Erker. W. FrBmherg. R. Benn. R. Mynott. K. Angermund. C. Kruger.
~ ~ ~ ~ ~ ~ l I l J ~ l 1989.
I P / l ~8/, /91
~ i1.
~ . S
S. L. Borkowaky. R. F. Jordan. G . D. Hinch. O~grr~ioitir~allirs
1991. 10.
12hX: R. F Jordan. A h . Orgrniomr/. C/ieni. 1991. 32. 325.
5b: Reaction of 1 I with 12 (equimolarj at room temperature in hromohenzene. yield 85 "10(230 mg) after recrystallization from dichloromethane,
m.p (DSC) 155 C (decomp): IR(KBr): ? = 2 0 7 0 (CEC). 1580
( C = C ) c m - ' ; ' H N M R (CD'CI,, 360MHz. 200K): 6 = 5.84 (s. 10H.
Cp). 5.70(s. 10H. Cp). 2.48 (s, 3H. C H , at C'), 2.29 (s, 3H. CEC-CH,),
-0.16 (s. 3H. CH, at Cz); " C N M R (CD'CI,, 9 0 M H z . 213K):
6 = 110.4 ( C ' ) . 135.2. 125.7. 121.7 (BPh;). 127.7. 124.3, 110.3 (CSCMe.
C'). 109.8 ('JC,, =168 Hz. Cp). 108.4 ('J,-,, =166 Hz, Cp). 28.9
= 127 Hz. CH, at C ' ) . 10.0 ('Jc,, = 133 Hz, CEC-CH,), -25.6
(I./<.,, =130 H7. C H , at C').
Reference data: 3a. ' H N M R ([DJbenzene): 6 = 5.67 (Cp), 1.91, 1.66,
1.43 (CH,) [I]. Sa. ' H N M R (CD'CI,): 6 = 6.09, 5.92 (Cp), -0.30 (CH,
at C ' ) : "C N M R (CD2Cl,j: 6 = 11 1.2, 107.9 (Cp). 232.5 (C'), - 14.6
( ' J <,, = 128 Hr. CH, at C ' ) [2]. In the crystal, S a shows an agostic interaction between a C - H bond of the methyl group at C' and the neighboring
zirc~niumcenter. Solutions o f 5 b are characterized by a high-field shift of
the ' H I3C NMR resonances of this methyl group. as was similarly observed for Sa. The 'J(C.H) coupling constants associated with this 13C
NMR methyl signal were likewise within the normal range. In the
' H K M R spectrum (360 MHzj of 5b at 173 K, we observe, however, a
pronounced broadening of this CH, signal. whilst all other signals maintain iiormal line widths.
D.S. Stephenson. G . Bintch, D N M R 5 : A Computer Prograin for
Iterarive Analysis of Exchange-Broadened NMR Spectra (Quantum
Clicmislry Program Exchange 1978. 10. 365): G. Binsch. Drn. N u d .
M q y n Kc.so!i. S/wrfimw. 1975. 45. G . Binsch, H. Kessler. Angeir. Clieni.
1980. '22, 445. AII,FCII C/icwi.I n r . Ed. €jig/. 1980. 1Y. 41 1 ; M. L. H. Green.
L.-I.. Wong. A. Sella. OrgunonieruNicr 1992. 11, 2660, and references
theiein.
J. W. Lauher. R. Hoffmann. J. Am. C/iPi77. Soc. 1976. 98. 1729: P. HoFmann. P. Stiiuffert, N. E. Shore. Chwi. Ber. 1982. 115. 2153.
Lithium Di-tevt-butylmethylsilylhydrazide,
a Hexamer with Li+ Ions Bound Side-on
and End-on**
By Sven Dielkus, Christian Drost, Reginr Herbst-Irmer,
and Uwe KlingebieP
The only monosilylhydrazine known is Ph,SiNHNH,, described by Wannagat et al. in 1958. At 90°C it readily condenses to N,N'-bis(silyl)hydrazine, while releasing N,H, . [ ' ]
This class of compounds is better kinetically stabilized by the
use of tert-butylsilyl groups."'
By treating di-rert-butylmethylfluorosilanewith lithiated
hydrazine, we prepared the thermally stable monosilylhydrazine 1, which can be converted into the lithium derivative 2 by nBuLi. When 2 reacted with trifluorosilylbis(trimethylsilyl)amine, we observed the formation of the N,N'o r N,N-bis(sily1)hydrazines 3 and 4,respectively. The N M R
data of these compounds are compiled in Table 1 .
.xid<>!/
tBu
Me-Si-F
tBu
+ LiNHNH, -*
Me-Si-NH-NH,
LIF
tBu
-LIF
2
tBu 1
I_
-
+ BULl
- BuH
2
7
tBu
Me;$:NH-NH-Si-N(SiMe,),
3
+ F,SiN(SiMe,),
F
Me-Si-N-Si-N(SiMe,),
I
tBu
I
N
I
F 4
H2
Tahle 1. N M R data ofcompounds 1-4. All measurements were made at 25 C
with a 250 MHz spectrometer (except I9F N M R : 80 MHz instrument). Standard for 'H. I3C. and "Si N M R : TMS int., for I9F N M R : C,F, ext., for -Li
N M R . LiCl ext.
1 (all measurements in CDCI,): ' H N M R : 6 = - 0.14 (SiMe. 3H). 0.85
(SiCMe,. IXH); "C NMR: 6 = - 9.44 (Sic). 20.23 (SiCC,). 28.25 (SiCC,):
29Si N M R : b = 8.74.
2 (measurements in C,D,/THF):
10.65.
'Li NMR: 6
=
0.55: "Si N M R : 6
= 9.13,
3 (all measurements in CDCI,): ' H N M R : 6 = 0.11 (SiMe. 3H). 0.22 ( t ,
'J(H,F) = 0.8 Hz. SiMe,. 18H). 0.98 (SiCMe,. 18H). 2.98 (t. 'J(H.F) =
3.3 Hz.NH, 1H),2.99(NH, I H ) ; I 3 C N M R : 6 = - 9.40(t, 'J(C,F) =1.2 Hz,
Sic), 3.62(L4J(C.F) = 1.6 Hz,SIC,).20.49(SiCC3),28.27(SiCC,): I9F NMR:
S = 25.82; 29Si N M R : 6 = - 66.12 (t, 'J(Si,Fj = 219.8 Hz. SiF,). 6.27 (t,
'J(Si,F) =1.0 Hz. SiMe,), 10.85 (SiCMe,).
4 (all measurements in CDCI,): 'H N M R - 6 = 0.04 (t, 'J(H,F) = 2.2 HI.
SiMe. 3H). 0.26it. '4H.F) = 0.8 Hz. SiMe,. 18H). 1.07(SiCMe3. 18Hj. 2.68
(NH,, 2H): ',C N M R : 6 = -7.55 (t, 4J(C,F) = 3.9Hz. SIC). 3.74 (t.
4J(C.F) =1.8 H7. SIC,), 21.14 (SiCC,), 28.92 (SiCC,): "F N M R - 6 = 37.04:
*'Si N M R : 6 = - 60.37 (t, 'J(S1.F) = 236.8 Hz, SiF,). 5.93 (I. 'J(Si,F) =
1.4 Hz. SiMe,). 9.22 (t. 'J(Si,F) = 1.5 Hz. SiCMe,).
Formation of the isomers 3 and 4 requires prior coordination of the Li' ion with the two N atoms of the hydrazine
unit. Side-on coordination of Li+ has so far been predicted
[*I
['I
[**I
Prof. Dr. U. Klingebiel. S. Dielkus."' Dr. C. Drost.
Dr. R. Herbst-Irmer"]
Institut fur Anorganische Chemie der Universiiit
Tammannstrasse 4, D-37077 Gottingen (FRG)
Telefax: Int. code + (551)39-3373
Crystal structure analysis
This work was supported by the Fonds der Chemischen Industrie
only by ab initio calculations for lithiated h~drazine.'~'
To
prove our point, we isolated single crystals of 2 and carried
out an X-ray structural anaIy~is.'~]
exhibits two different
The crystal structure of 2 (Fig.
silylhydrazide units I and 11, which are bound by six Li' ions
to form a hexameric entity. The Li' ions are bound to three
Li
Li
A
0
Fable 2. Calculated and measured parameters in Li(HN-NH,) A and 2 (B),
respectively.
B
Bond lengths A
Ipml
~~~
~
N-N
N'-Li
NZ-Li
different structural units: Lil is coordinated with one N
atom and two NH groups, Li2 with one N atom, one N,, and
one NH unit, and Li3 with one NH, one N,, and one NH,
unit. Thus four Lit ions are bound side-on.
Bond angles
A
B
56
49
76
42.5, 42.8
72.2, 68.6
65.3, 68.5
I"]
-
145
161
189
~
149.3; 147.7
200.8, 202.3
210.4, 202.4
N-Li-N
Li-Ni-N2
Li-N2-N'
coordinated equally by both N atoms of the hydrazine. This
phenomenon also accounts for the isomerizations during the
secondary substitutions.
Experimental Procedure
1: N,H, (0.02 mol, 0.64 g) in hexane (50 mL) was metalated with an equimolar
quantity of BuLi (15% in hexane). When release of butane had ceased, T H F
(50 mL) and rBu,MeSiF (0.02 mol, 3.528) were added. After the mixture was
heated to reflux for 36 h the solvent was distilled off, and the residue was heated
to 90'C for 36 h. LiF was removed, and 1 was purified by distillation. Yield:
65%. B.p. 36"C/0.01 mbar; MS (70eV): m/z 188 (M', 6%).
2: To 1 (0.01 mol. 1.88g) in hexane (20 mL) was added BuLi (0.01 mol, 15% in
hexane). The suspended matter was dissolved by addition of T H F at boiling
temperature, and 2 was obtained in a crystalline form by slow cooling to room
temperature. Yield: 95%, m.p. 68 "C (decomp) 3 and 4: 1 (0.01 mol, 1.88 g) in
hexane/THF (50 mL) was lithiated with BuLi (0.01 mol. 1 5 % in hexane). An
equimolar quantity of the fluorosilane was added rapidly to the Li derivative at
-30°C. The reaction mixture was slowly warmed to room temperature and
heated to reflux for 1 h. The crude products were purified by distillation; a
separation of the structural isomers was not accomplished. Yields (according to
integration of the 'H NMR data): 70% (3). 5 % (4). B.p. 79"C/0.01 mbar. MS
(FI): m / i 413 ( M ' . 100%).
Sll
512
1
Fie. 1. Crystal structure c 2 [Me and rBu groups
. were omitte for clarity).
Selected bond lengths [pm] and angles ["I: Lil-N1 199.5(14), Lil-N3 201.6(13),
Lil-N6 201.8(14), Li2-N2 200.8(14), Li2-N6 203.6(13), Li2-N3 [a] 204.0(13),
Li2-NI 210.4(13). Li3-N4 201.3(14), Li3-N6 202.3(13), Li3-N5 202.4(14), Li3N2 [a] 202.7(13), Nl-N2 149.3(8), Sil-Nl 174.4(6), Si2-N3 173.0(6), N3-N4
149.3(9), N5-N6 147.7(8). Si3-N5 174.4(6); N2-Li2-Nl 42.5(3). N6-Li3-N5
42.8(3), N2-Nl-L12 65.3(5), Nl-N2-Li2 72.2(5), N4-N3-Si2 115.4(4), N4-N3Lil 108.4(5), Si2-N3-Lil 112.7(5), N5-N6-Li3 68.6(5), N6-NS-Li3 68.5(5); symmetry transformation for the equivalent atoms [a]: - x + 1, - y + 1, - z.
Unlike unit 11, in the solid state I does not coordinate Li'
ions side-on. The side-on bond lengths for the atoms Li2 and
Li3 were determined to be 192 and 188 pm, respectively. The
angles at N5 and N6, which bind Li3 side-on, are nearly
identical; the angles at N1 and N2, which coordinate Li2,
deviate by 7" (N5-N6-Li3 68.6, N6-NS-Li3 68.5; and N1-N2Li2 72.2, N2-Nl-Li2 65.3"). Thus Li3 is positioned centrosymmetrically above the N - N bond.
As X-ray structural analyses of Li derivatives of silyl-substituted hydrazines had been unknown so far, the structural
analysis of 2 was compared with ab initio calculations for
lithium hydrazide.I3' Fable 2 shows a comparison of the data
for the calculated (NHNH,)Li+ system (A) with that for the
side-on units Nl-N2-Li2 and N5-N6-Li3 (B) in 2, derived
from the X-ray structure determination.
The stuctural analysis confirms the ab initio calculat i o n ~ , ' ~according
'
to which Li+ ions in hydrazides can be
1626 Q
VCH Verlagsgesellschaft mhH. 0-69451 Weinheim, 1993
Received: May 18, 1993 [Z 6090 IE]
German version: Angew. Chem. 1993, 105, 1689
[I] U. Wannagat, W. Liehr, Z . Anorg. Allg. Chem. 1958,297, 129-136.
[2] C. Drost, U. Klingebiel, Chem. Ber. 1993, f26, 1413-1416.
I
Chem. SOC.
[3] J. R. Dilworth, A. Rodriguez, G. L. Leigh, J. N. Murrell, .
Dalton Trans. 1983, 2, 455-461.
[4] Crystal structure of 2: Space group P2,/n, a =1248.1(2), b =1341.3(3),
c = 2327.4(5) pm,
fi = 100.17(2)", V = 3.835(2) nm3, Z = 4, p =
0.147 m m - ' (Mo~.), 6003 measured intensities, 20,,, = 48", structure solution by direct methods IS], 5996 symmetry-independent reflections used
for the refinement according to F 2 [6]. non-H atoms anisotropic, H atoms
at C atoms according to the "riding" model, H atoms at N atoms refined
with distance restraints, 391 parameters, R1 for F 4 4 F ) 0.0873
(Rf = XllFol- l ~ ~ l ~ / ~ l FuR2
o l ) ,for all data 0.2594 (wR2 =
- ~ ) z ] / ~ [ ~ ~ ( F ~ ) zThe
] ] i Jrelatively
z),
high R values are due to a
very weakly diffracting crystal. Further details of the crystal structure investigation may be obtained from the Fachinformationszentrum Karlsruhe,
Gesellschaft fur wissenschaftlich-technische Information mbH, D-76344
Eggenstein-Leopoldshafen (FRG). on quoting the depository number
CSD-57639, the names of the authors, and the journal citation.
[5] G. M. Sheldrick, A d a CrysroNogr. Secr. A 1990, 46, 467.
[6] G. M. Sheldrick. SHELXL-93, Universitat Gottingen, 1993.
[x[u(c
3 10.00+ .25/0
0570-0833/93/1~11-l626
Angeit-. Chem. hi.Ed. EngL 1993, 32, No. If
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end, side, bound, butylmethylsilylhydrazide, tert, ions, hexamer, lithium
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