close

Вход

Забыли?

вход по аккаунту

?

Equilibrium between Isocyanide and Carbene Complexes in Coordination Compounds of 2 6-Dihydroxyphenyl Isocyanide.

код для вставкиСкачать
COMMUNICATIONS
c4
C6
,
~
'C7
Fig. 2. Structure of the complexes 4 (left) and Sa (right) iii tlie crystal (ORTEP)
Selected distances [A] and .ingle> [ ] in 4 : Re-SI 2 243(6). Re-S2 2.222(6). Re-S3
2.210(6). Re-P 1.306(7). Re-N 2.lX(2): Sl-Re-S2 120.4(2), SI-Re-S3 119.311).S l Re-P 93.6(2). S I - R e - h 85.2(51. S2-Re-S3 118.3(2). S2-Re-P 95 3 0 ) . S2-Re-N
86.4(5). S3-Re-P Y5.1(2). $3-Re-N 84.3(4). P-Re-N 178.2(5i,i n 5 a : Re-SI 2.231(2).
Re-S2 2.235C). Rc-S3 2.238(2). Re-Nl 2.231(7). Re-C7 1.90519). C7-N2 1.200(12):
Sl-Re-S2 1 IS X7(8). Sl-Re-S3 IlY.31(8). Sl-Re-Nl X5.2(21, SI-Re-C7 96.1(2). S2Re-S3 119.74(8).S2-Re-N1 85.3(2). SZ-Re-C7 94.6(3).Sj-Re-Nl 85.2(2). S3-Re-C7
93.X(3j. NI-Re-C7 178 7(3i. Rc-C7-N2 173.9(8). C7-N2-C8 150.8(9) [Y].
ofthe C7-N2-C8 angle from theexpected linearity[150.8(9)-]
and the length of the C7-N2 bond [1.200(12) A] (expected value
approximately 1 .I 50 A) are particularly noticeable. These indicate. together with the very low wavenumber for the IR absorption of the N C stretching vibration (1940 cm- I ) , a strengthened
back bond to the isocyanide carbon atom from the rhenium
atom, which. due to the coordination by sulfur. is very electronrich. The great extent of the bending of an isocyanide due to
coordination to an electron-rich transition metal has previously
only rarely been observed in such clarity.1141
With the complexes 2, 4, and 5, we present a new type of
neutral, trigonal-bipyramidal. mixed-iigand complex of Tc"'
and Re"'. A similar coordination geometry is only to be found
in the complex [Tc(PS,)(iPrNC)] with the aromatic trithiol tripod
PS,."ohl The complex 5a is of special interest for further investigations. In principle, complexes of this type could be coupled
to molecules with a specific biodistribution by the formation of an
ainide via the ester function. as has already been demonstrated for
the yymTcvOcomplex of the tetradentate ligand 6-p-aminobenzyl-3.3,9,9-tetrarnethyl-4,8-diazaundecane-2.lO-dionedioxime
(PnAO) .I3] The chelate unit in 5 a is less polar than in the squarepyramidal [TcO(PnAO)], however. For radiopharmaceutical
preparations of complexes of the type 5 a starting from MOT
reagents-the reaction conditions would have to be modified. We
are currently investigating the possibility of coupling technetium
and rhenium to biological anchor groups on the basis of the
concept described above.
Received .lanuary 13. 1994 [Z66161E]
Gerin,in \cr\ion A n g m . Chmi1. 1994. 106, 1416
[ I ] S. Jurisson. D. Berning. W. Jia. D. M a . Chrn! K r i . 1993. 93. 1137 -1156.
121 J Burgess. f i . o m i f i o i i Mer. CIirw. 1993. 1X. 43Y 448.
[ i ] P. Koch. H. R. Micke. AnKPii'. C/iwi/. 1992. 104, 1492-1494, Angm C/11,iii
h r . E d EJi,,lp/. 1992. 31. 1507-1509.
[4] a ) E E . Hahn. S. Rupprecht. K H . Moock. J C/irni Soc. Chwii. C ' U I I I I I I I I I I .
1991. 274-225: b) F. E. Hahn. S Rupprecht, C h i i . Bcr. 1991. 124. 481 -486.
[5] Correct elcnicntal analyses for 1 2. 4-5. Selected spectroscopic data for 1
I R ( K B r ) . I [cni-'1 = 2543 ( S H ) . " C j ' H ) N M R (62Y MHz. CDCI,): d =
57 01 (NCH,). 22.81 (HICSH). 2 : ' H NMR (90 MHz. CDCI3i: 6 =7.35 (m.
l 5 H . Ph-H). 2.97 (m. 12H: S-C'H, and N-CH,!: UV.VIS(CHC1,):
im,,(lg i)= 541 (2 7) 510 (sh), 347 (3.4). 290 (4.2) nm 3 . Yield approx. 10%.
The presumed composition result4 froin the integrals i i i the ' H N M R spectrum.
4:Yield 57'!4.darkgrecn nccdlesfrointoluene; ' H NMR(2OO MHz.CD,CI,):
-
6 = 7 2 (m. 1 5 H : Pli-Hi, 2.Y(m. 12H; S-CH, and N-CH,): UV:VIS(CH2Cl2):
;,mAL(lg
i : ) = 598 ( 2 . 5 ) . 461 ( 3 . 2 ) , 334 lsh. 3.4). 306 (4.1). 247 ( 4 3) nm; MS (El.
7 0 e V ) ' J I P : = 643 (2.1+). - S a . yield 86%. brown rhombuses from CH,CI,.
El2(): I R ( K B r ) . v[cm-'] =1940(NC): ' H N M R (90 MHz, CDCI,): 6 = 5.46
(s. 2 H : CH,CO,). 3 81 Is. 3 H . OCH,). 3.02 (m. 12H: S-CH, and N-CH,):
c4
,y(lg~:)= 570(sh.2.31.437(3.1).355(3.0).314(3.8).251
(4.2) ii!ii. - 5 h : yield 64'!4. olive-green platelets iius Ethanol. IR(KBrj:
v[cm-'] = I976 (NC): ' H NMR (90 MHz. CDCI,). d = 2 98 (m. 12H: S-CHI
and Y-CH?), 1.54 (9. Y H: C H , ) : UV'VIS(CH,CI,i: j.m.,x(lg(:I
= 600 (sh. 2.4).
44X (3.11, 350 ( 3 1 ) . 312 (4.0). 250 (4.2) nni.
[GI i i ! J. Y Cauthier. F. Bourdon. R. K . Young. I i w u i i d r n n Lcrr. 1986.27. 15-18:
hi P. A. Bobbio. J. 0i.i'.<'/xvii. 1961. 26. 3023 3024.
[7] G . Bandoli. D A Cleincnte. U . Mazzi. E. Roncari. J. Chrni. So..Dulroii fiuiis
1982. 13131-1384.
[XI R. A. Pearlstein. u' M . Davis, A C . Jones. A. Davison. /iior,q. (%wn 1989.3'.
3332 3334.
[9] Structure a n a l y m red-violet crystals or2 a e r e obtained by ebaporation ofthe
sohent from a benzene methmol solution. Crystals of 4 (crystallized from
toluene) were vei-y thin. air-sensitive platelets. The diffraction data for this
compound here therefore measured at - 100(5) C. After measuring all symmetry-independent intensities in the 20 range of 5.4-40 . crystal dccompositioii w a s observed and the data collectioii had to be interrupted. Only B relativeIysmalldata set \iasthus:ivclilable. For thisreason. only the Re. P. and Satoms
&ere refined with aiiisotropicic thermal parameters in the least-squares procedure. While the q u a l i t y ofthe dil'friiction data doer not allow a detailed discus\ion of the bond lengths and iiiigles in 4. it is sufficient to allow an unequiwcal
determination of the geometry of the molecule. Compound 5 a can be crystallized fi-om CH,CI,, Et,O Structure parameters: 2 [4] ( S a ) : C,,H,,NPS,Tc
.H,-NPReS,] { C , , , H , - N , O
. monoclinic [monoclinic] [monoclinic: .
ce group P 2 , < ' [/?,.ri]
. (I = 8.906(2) [I0 8 5 5 ( 3 ) ] (7.X27(4);.
75.804(6) [16.707(4)] 13.8
c =11.061(4) [15.441(5)] [13.627(6)1 A.
/i= 108.42(2)[9?.62(2i] 193.19(7)1 . V = 2414(2) [2797(2)] (3476(2)1 ,i3.
Z=4
[4] j4).p,,, = I 3 3 11.531 :2.171. jlhC,=1.527 [1.526] /2.157) gcrn-? Mo,,
radiation ( i = 0.71071 A). Jl(Mok3)= 0 1 [46.81 (87.4) crn - ' . 4233 I25921
125x9: Eymmetr!.-independent dar:i measured at ?0(5j [-lOO(5)] ; 2 0 ( 5 ) ) C in
the 20 range 2-50 [5.4401 { ? - S O ) . Structure solution with Patterson methods. refinement 01' the position parameters of all non-hydrogen atoms uith
anisotropicic thermal parameters (in 4 only Re. S. P anisotropicicj All hydrogen atoms on calculated positions [d(C-H) = 0.95 .&] with B,,,,,, = 1.3 B
K = 3.73 [6.51] [4.10:. R , = 4.56[8 931 (6.09; for 2410 [1824] :2350) struc
factors
2 3n(,:')
and 271 [I471 (163; variables, absorption correction for 4
and S a . Further details of the crystal structure investication may be obtained
from the Fachinformationsrentrum Karlsruhe. D-76344 Eggenstein-Leopoldshafen ( F R G ) on quoting tlie depository number CSD-58128. the names o f t h e
citithors. and the journal c i ~ t i o n
a ) H.-J Pietisch. H. Spies, S. Hofcmann. h r x . Chjni. Acra 1990. 168. 7 9: h)
N de Vrics. J. Cook. A C;. Jones. A. Davison. I ~ o r x C/wiii.
.
1991. 30, 26622665.
M. Melnik. J E. van L m . Cooril. Chriii. Rr,i,. 1987. 77. 275 324.
ahn. T. Lugger. unpublished.
I A/>,. C/itii/i.S o ( . 1976. 98. 5729-5731.
. K. Barker. M. Green. J. A . K. Howard. F G. A.
Stone. .I C h i . So( . / M f o n Trfms. 1979. 1001- 1011.
c:
~
Equilibrium between Isocyanide and Carbene
Complexes in Coordination Compounds of
2,6-Dihydroxyphenyl Isocyanide""
F. Ekkehardt Hahn.* Matthias Tamm, and
Thomas Lugger
We reported recently on the reactions of Fe(CO), and M(CO),
complexes (M = Cr, W) of 2-trimethylsiloxyphenyl isocyanide
( l ) . l l l After hydrolysis of the Si-0 bond, these react by intramolecular attack of the hydroxy group on the isocyanide carbon
[*] Prof. Dr. F E. Hahn, Dr M. Tamm. Dip].-Chem. T. Lugger
Institut fur Anorganische und Analytische Chemie der Freien Unwersitiit
Fabeckstrasse 34-36. 0-14195 Berlin ( F R G )
TeleFax: Int. code + (303838.2424
[**I
This work \ b a s supported by the Deutsche Forschungsgemeinschaft and the
Fonds d e r Chemischcn lndustrie We thank the BASF Aktiengesellschaft for a
doctoral grant (1991 1993) for M. T.
COMMUNICATIONS
to form carbene complexes 3 (Scheme 1 ) . [ 2 . 31 The intermediately formed complex 2 could not be isolated. The driving force for
the intramolecular reaction is the stability of the cyclic carbene
ligand in 3. which has a five-membered aromatic heterocycle.
I
I
M(CO)x
M(CO)x
l a , M = Cr, x = 5
Ib, M = W,x= 5
I c , M = Fe, x = 4
2
3b, M = W, x = 5
3c, M = Fe, x = 4
give a mixture containing the isocyanide complex 6 a and the
carbene complex 6br9](Scheme 3). The force constant for the
N-C stretching vibration in 6 a (1723 N m - ' , calculated from
the IR absorption measured in the mixture) indicates strong
back bonding to the isocyanide carbon in 6 a , and explains the
incomplete carbene formation. For comparison : Because of the
weaker (d-p) n back bonding in l c , a force constant of
1791 N m - ' was calculated,[21and complete conversion into the
carbene complex 3c is observed on cleavage of the Si-0 bond.[''
The mixture 6a/6 b can also be characterized quantitatively by
'H N M R spectroscopy.["' In the spectrum, resonances are found
for the N H p r o t o n in 6 b at 6 = 13.68 and for the OH protons in
6 a and 6 b at 6 = 9.57. The amounts of the components in the
mixture were determined from the integrals (59% 6 a and 41 %,
6b).
Scheme I . Reaction of coordinated 2-trimethylsiloxyphenylisocyanide upon cleavage of the S i ~ - Obond
Normally. the intramolecular carbene formation from 2-hydroxyphenyl isocyanide is hindered when the latter is coordinated
to a particularly electron-rich transition metal fragment. The nucleophilic attack of the oxygen atom on the isocyanide carbon
atom is then made difficult, as this is deactivated by (d-p) n
back bonding. In such cases, a mixture of isocyanide (2) and
cdrbene ( 3 )complexes is obtained.[4J The strength of the (d-p)
n back bond, and consequently the position of the equilibrium
betweeu the complexes of types 2 and 3, may be predicted from
the force constant for the N = C triple bond as calculated according to Cotton.[''
We have now investigated the behavior of the doubly trimethylsiloxy-substituted ligand 2,6-bis(trimethylsiloxy)phenyl isocyanide (4) coordinated to Cr(O), after hydrolysis of the Si-0
bonds. In this case. a mixture is obtained in which the isocyanide
(6 a) and the carbene (6 b) complexes are in equilibrium with one
another (cf. Scheme 3). We report here on a new way of shifting
the equilibrium completely to the side of either the isocyanide or
the carbene. without altering the electronic properties of the
metal center.
iDABC
N
111
F
OCN
t,,,,
oc.
bNH2
OH
0-
0-
1
I
a
N
42
=
Me,SiCI
C
4
L O
'Ir'
0
a
Scheme 3. Reaction of a mixture of 6a;6b with weak bases.
HC(0)OH
OH
,OSiMe,
,,,,1
-co
C
7
H,IPd
I
OSiMe,
Scheme 1 Synthesis of the ligand 4
For the synthesis of the ligand 4 (Scheme 2) ,[61 the nitro group
of commercially available nitroresorcinol is first reduced with
Pd/H, and the resulting primary amine converted into 4-hydroxybenzoxazol according to ErIenmeyer et al.''] After double
deprotonation with two equivalents of nBuLi, this reacts regiospecifically with trimethylchlorosilane under 0-silylation, as
is known for benzoxazol.[']
The reaction of 4 with [Cr(CO),(thf)] leads to the isocyanide
complex 5.['] This reacts after cleavage of the Si-0 bonds to
The reaction of isocyanide complexes with alcohols resulting in
the formation of carbene complexes is normally catalyzed by
bases."'] In contrast to this, we found that by selection of
specific bases, a stabilization of the coordinated 2,6-dihydroxyphenyl isocyanide is possible, even against the preferred intramolecular nucleophilic attack.
If two equivalents of triethylamine are added to a solution of
the 6 a / 6 b mixture in dichloromethane, the expected shift in
equilibrium to the carbene side is not observed. After removal of
solvent, a colorless powder is obtained whose infrared spectrum
shows exclusively absorptions for a pentacarbonyl(isocyanide)chromium complex (cf. 7; v(NC) = 21 54 cm ' ) . [ I
The
'H NMR spectrum of this complex contains signals which indicate the formation of a I :2 adduct 6a.2NEt3.The reaction of the
6 a / 6 b mixture with one equivalent of the dibasic ainine 1,4-diazabicyclo[2.2.2]octane (DABCO) proceeds similarly (exclusive
formation of an isocyanide complex 6 a - D A B C O ; cf. 8; v(NC)
= 2149 ern-').[''] The isocyanide complex 6 a is obviously stabilized by the addition of these amine bases to such an extent
that the equilibrium 6 a / 6 b is shifted completely to the side of
~
COMMUNICATIONS
the pentacarbonyl(2,6-dihydroxyphenylisocyanide)chromiumamine adduct.
In order to understand the mechanism of the unusual stabilization of 2.6-dihydroxyphenyl isocyanide complexes by amine
bases, X-ray structure analyses of the triethylaniitie and the
DABCO adducts of 6 a were carried out.[lzlThese show that in
both cases the isocyanide complex is stabilized by the formation
of N . . H hydrogen bridges to the hydroxy protons. In contrast
to the structure i n solution. crystals of the triethylamine adduct
contain only one molecule of triethylamine per molecule 6 a , and
consequently this complex can be formulated as 6 a . N E t 3 (7;
Fig. 1, left).[131Complex 7 crystallizes, polymerized through hydrogen bridges, as shoivii in Scheme 3 . Crystals of the product
of the reaction of 6a,i6b with DABCO consist of hydrogenbridged polymers 6a.DABCO (8, Scheme 3; Fig. 1. right).1131
c
0
;f;
9
10
Fig. 2. Synthesis of the complexes Y and 10 and the structure of 10 in crystals
f O R T E P ) . Selected distances [A] and angles [.I: Cr-C1 2.070(3). C I - 0 1 1.369(4),
C I - N 1.343(4).01-C4 1.379(4). N-C2 1.464(4). N-C3 1.399(4):Cr-C1-01 118.6(2),
Cr-CI-N 135.3(2). 01-C1-N 106.1(3), C 1 - N - U 124.9(3).CI-N-C3 111.0(3), CZ-NC3 124.1(3) [13].
N4
Fig 1 Structuresoftheconiplexes7lleft)and8(right)in thecrystal (ORTEP). The
asqminetric unit of 8 contains two almosI identical inolecules and one acetone
molecule (not shown). Selected distances [A] aiid angle>[ ] for 7: Cr-C1 1.977(12).
CI-N1 I.l64(13), NI-C2 1.396(14). 0 1 - H I 1.28(13). HI . " 2 1.3X(12),01 . N2
2.634(14). 0 1 . 0 2 * 2.525(11): Ci--Cl-NI 1777(10), CI-NI-C2 1728(12]. 01HI . . . N2 164(8). Thc position of the H atom bonded to 0 2 cotilrl not he rletermined. syninierry code (*)x. 1,2-y. I , ? + z; for 8.0.5(C'H,),CO (molecule I . see
[I31 for further data). Ci-I-CI I.OX918). CI-NI l.l45(X). N 1 - U 1 391(X). 0 1 - H I
0.79(6). HI . - . Y 31.93(6),0 1 - . K 3 2.668(7).0 2 - H 1 O.XO(6). HZ...N4*
I.87(6).
0 2 . - N4* 2.667(6): C r l - C I - N l 176 3(6). C I - N I - C 2 l68.7(6). 0 1 - H I - - N 3
170(6). sqniinetric code ( * ) .I.. 1.2 - 1 . 1;2 + z .
154(7). 02-H2L.N4*
The use of weak bases (the pK, values of phenol and the
tertiary amines employed are of the same order of magnitude)
obviously does not lead to deprotonation of the hydroxy groups
and an increase in their nucleophilicity, but rather to the formation of hydrogen bridges and thus to the stabilization of the
isocyanide complexes. A shift of the 6ai6b equilibrium completely to the side of the isocyanide complexes stabilized by
0 - H ' . N hydrogen bonds is thereby achieved.
Attempts to shift the equilibrium to the carbene side must
therefore be carried out with stronger bases which are capable
of completely deprotonating the hydroxy groups. If a mixture of
6 a / 6 b is treated with two equivalents KOtBu. and the dianion
thus formed is then alkylated with two equivalents of methyl
iodide, the N,O-dirnethylated carbene complex 10 can be obtained in good yield (Fig. 2). The N-methylated complex 9
formed as intermediate can be obtained by the addition of only
one equivalent of KOtBu and MeI. After deprotonation. the
phenolic oxygen atom of 6 a is sufficiently nucleophilic to allow
the intramolecular cycloaddition to proceed to completion. The
subsequent alkylation of the anion prevents the reverse reaction
leading to the isocyanide complex, and a complete shift of the
6 a j 6 b equilibrium to the side of the mono- or dimethylated
carbene complex is achieved.[2.'I
With the synthesis of the complexes 7, 8. and 10, we present
a procedure for the selective displacement of the 6 a / 6 b equilibri-
um between the isocyanide and carbene complexes by means of
suitable bases. The complexes 7 and 8 are the first examples for
which the normally preferred intramolecular carbene formation
in coordinated 2-hydroxyphenyl isocyanides could be prevented.[2.31 This is the first time that such isocyanide complexes have
been successfully stabilized without alteration of the electronic
properties or the steric situation at the metal atom. Conversely,
the carbene complexes 9 and 10 can be isolated when the
N-Ccarbenc
atom in a mixture of 6 a / 6 b is alkylated by reaction
with strong bases and MeI.
Received: Jnnuary 28, 19Y4 [Z66521E]
German version: . 4 n g ~ wc'hmi.
.
IY94. 106, 1419
P. JiitLi. U. Gilge. J. Orgmoriwr. Cherii 1983. 346, 159-162.
F. E. Hahn. M.Tamm. J. Chcnr Sorc Chcin. Commriri 1W3. X42-844.
F. E. Hahn. M. Xiinm. J. Oi:qonomrr. ('lieni 1993. 456, Cll-C14.
F E. Hahn. M. Tamin. T. Lugger. unpublished.
F. A . Cotton. C. S. Kraihanzel, .I Aiii Cheii,. SO(. 1962. 84. 4432 443X
4. Correct elemental analysis. For theqnthesi,. 4-hydrox)henzoxa~ol[7](10 g,
74 mmol) w a s dissohed in anhydrous T H F (200 mL) at - 78 C. rzBuLi (60 mL
of a 2 . 5 M solution i n hexane. 150 mmol) \+as added slowly by syringe. The
inonolithiatcd salt started to precipitate during the addition of the first half of
the rzBuLi. Further addition of r~BuLicaused the precipitate to redissolve.
however. After complete addition. stirring was continued for a further 3 h at
-78 C. Mc,SiCI (20 mL. 158 mmol) *as subsequentlq added to the reaction
mixture. and the clear b r m n solution was stirred for about 12 h at r o a n
temperature. All volatile components were then removed under vacuum. rr-hexane (100 niL) w a s added. and the insoluble LiCl filtered off The h r o a n solution in 17-hex;iiie \\:is concentrated by rcmoviiig the sohent under reduced
pi-essure: 4 \\as obtained as a colorless oil by distillation :it 85 ('0 Ohmhnr.
Yield 18.73 g (Y1 "A,). IR (KBr film)- ~ [ c n i - ' ]= 2125 (NC); ' H NMR
(270 MHz. CDCI,): 6 =7.09 (t, 1 H: Ar-H). 6.52 (d. 2H: Ar-H), 0.32 (a. IXH.
CH,); " C ( ' H ; NMR (67 93 MHL. CDCI,). d = 170.3 (NC), 152.4 (Ar-C-0).
129.1 (p-Ar-C). 113.1 (o-Ar-C). 0.1 (Si-C). the signal Ar-C-NC was not ohserved
[7] E. Sorkin, W, Roth. H. Erlenmeyer. HEII..C/I;I)I.
Acru 1952. 35. 1736 1741
[ X I 5: correct elemental analysis. Selected anal)tical data: green oil, yield 8.1 g
(96%): IR(KBr-film). v[cm-'] = 2149 (s. NC), 2060 (s. COj. 1992 (sh. C O ) .
1945 fvs. hr, CO). ' H NMR (270 MHz. CDCI,): 6 =7.06 (t, 1 H : Ar-HI, 6.50
(d, 2 H ; Ar-H). 0.32 (s, 1 8 H ; CH,). "CIIH] NMR (62.90MHz. CDCI,).
(5 = 217.1 (trons-CO). 214.8 (c/s-CO). 174 0 (NC). I 5 2 7 (Ar-C-0). 129.1 ( p
Ar-C), ll3.0(o-Ar-C),0.1 (Si-C).thesignal Ar-C-NC signal wasnot observed:
MS (70 eV): / ? I ; : 471 ( M '. X.O%). 331 ( M - 5 CO. 100).
"4 Mintui-c 6aj6h: For the preparation. 5 (8.1 g. 17 nimol) bas dissolved in anhydrous inethanol (SO m L ) . A small rample of K F (0.2 g) was added, and the
mixture was stiri-ed at iooin tcrnpei-iituic Tor 2 d. All volatile components were
removed under vacuum. and a colorless powder w a s obtained. After chromatographic purification (AI,O,. 4°C H,O. niethano1:diethyl ether 1: 1 ) . a mixture
of 6a.6h (5.3 g. 9 5 % ) was obtained Selected analytical data: 1R (KBrl:
t,[cn-'] = 3526 (m. N H 6b). 3379 Im. OH 6a,b). 2128 (s. NC 6a). the bands
for the CO absorption? could iicithcr be resolbed nor assigned: ' H N M R
[I]
[2]
[3]
[4]
[S]
[6]
~
+
COMMUNICATIONS
[lo]
[I 11
[I21
( 2 5 0 MH7, [D,]acetone): 6 =13.68 (s. hr. 1 H : N H 6 a ) . 9.57 (s. 3 H; OH 6a.
ed in great detail in the past few years.[41 We have recently
6 b ) . 7.25 (d. 2 H : Ar-H 6b). 7.10(t. 1 H : Ar-H 6 a ) . 6.89 (t. 1 H: Ar-H6b). 6.56
extended these studies with investigations on zwitteriouic
( d , ? H : A r - H 6 a ) : '%C/'H) NMR(62.90MHz,[D3COD]:6 = 230.0(carhene(molecular) L5Si-organofluorosiIicates~51
(examples: zwitterions
C ) .222.7 (rruiis-CO 6 b), 21 8.8 (/runs-CO6 a ) , 21 8.2 (cD-CO6 b ) , 216.0 (CIS-CO
l 1 5 a 1 and 2[5d1).We report here on the synthesis and structural
6 a ) . 175 6 ( N C 6 a ) . 155.9,130.7. 107.4. 106.9 (Ar-C 6 a ) . 156.0, 126.1, 114.4.
121.1. 111.6, 102.3 (Ar-C 6b): MS (70eV): m:: 327 ( M i
6a. 6b. 17.0%). 187
characterization of 5.H20,
( , M i - 5 C 0 . 100).
the first zwitterionic L6SiH
a) K H . Dotz. H. Fischer. P. Hofmann. F. R. Kreissl, U. Schuhert. K. Weiss.
organofluorosilicate. The
1 : R = F
~ u i i . ~ i ~ Mrrul
i i ~ i i (hrbanc Compl
VCH. Weinheiin. 1983: b) B. Crociani in
si - CH, -N
zwitterion 5 is the first
2 : R = Me
R r r i ~r i o m of Cuordrnured Ligaird
I (Ed.: P. S . Braterman). Plenum P r e s
F
'
NCH York. 1985.
molecular compound of
Correct elemental analysis for 7-10.7: ' H N M R (250 MHz. [DJacetone. 1:2hexacoordinate silicon with
triethylainine adduct): d =7.02 (m. 3 H ; Ar-H). 2.8X (quart. 12H: NCH,), 1.15
an F,SiC unit and contains a hexacoordinate (formally twofold
( t . 18 H : CH2-CIf3).0-H-Resonance signal was not observed. 1R (KBr. of the
negatively charged) Si atom and two tetracoordinate (formally
crystalline solid 7): ~ [ c m - ' =
] 341X (m. O - H - - . N ) . 2154 (m,NC). 2062 (s.
CO). I Y X X (ah. CO). 1914 (VF br. CO). - 8: ' H NMR (250 MHI. [D,]acetone):
single positively charged) N atoms. The crystal structure analyR = 7 . O X ( m . 3 H : A r - H ) , 2 . 8 9 ( ~ . 12H:NCHI);IR(KBr):v[cm~']=3421(m.sis of 5 . H 2 0 is the first solid-state structural characterization of
O-H...N).2149(m.NC).2061
(s.C0).1990(sh,CO). 1922(vsbr,CO).-IO:
an 2'Si species with an F,SiC unit.
' H NMR (250 MHz. CDCI,): 6 =7.18 (t. 1 H : Ar-H). 6.80(d.ZH;Ar-H). 4.26
The J.'Si-silicate 5 was prepared by the reaction of (chloro(s. 3 H : NCH,). 3.97 (s. 3 H : OCH,); "C:'H) N M R (62.90MHz. CD,CI,):
r) = 271.1 (carbcne-C). 222.3 (/run.~-CO).
217.7 (c.i,v-CO).155.3. 147.2, 126.7.
methy1)triethoxysilane (3)["]with 1 -methylpiperazine to yield
122.6. 107.6. 104.2 (Ar-C), 57.0 (OCH,). 37.4 (NCH,): MS (70cV): rw:z 355
silane 4,which was treated with hydrofluoric acid; the product
( M 4 . 13.O"Q).
was isolated as monohydrate 5 . H 2 0 .
Thc w e and the scattering power of crystals of 7 were very small. For this
reason. only a limited data set with FZ 2 3 o ( F : ) was available for the calculations In order to kcep the number of refinement parameters small. the six
atoms of thc aromatic ring were refined with isotropic thermal parameters.
/
\
Crys~also f 8 contained two almoct identical molecules of 8 and one acetone
OEt
OEt
HN
NMe
molecule (the methyl groups of which were disordered) in the asymmetric
I
U
I
n
unit Structure parametery: 7 [8 . 0.5(CH3),CO] { 10) : C,,H2,CrN20,
Et 0 -S i -C Hz- C I
E t 0 -S i C HZ- NUN
-Me
[C,,, ,HL,,CrN,O, 4 (C,,H,CrNO,j, monoclinic [orthorhombic] [monoI
I
O
E
t
O
E
t
clinic:. space group P2,;r [Pbcn] ( P 2 , ! n J u, = 12.713(8) [18.200(5)] [6.885(3)).
h = 15 .32X(XI [21.691(6)] [13.969(4);. c =11.950(6) [23.700(4)] 115.772(3)) 8.
/) = 117.034) [90.0] [97.83(2); . V = 2058(4) [9356(7)] (1502.8(14)~, f i 3 , Z = 4
IU E
[I61 14;. { i e L P =1.37 [I 321 {1.58;. prrlLd= 1.383 [1.330] 11.570; gem--'. Mo,,
radiation (L = 0.71073 8).~ ( M o , , )= 5.8 [S.?] i7.8) cm-I. 2688 [SX?l] {2641]
byininetry-iodependent data measured at -100(5) [20(5)] { 2 O ( S ) ) 'Cin the 20
rangt. 2 - 45 12- 451 11-50; '. Structure solution with Patterson methods, refineFw F
ment (if the position parameters of all non-hydrogen atoms wlth anisotropicic
5
therinal parameters (ring atoms in 7 isotropic). C-H atomic positions calculated [d(C'-H) = 0.95 A] with
= 1.3BeqlC,:
no hydrogen atoms were calculated r ~ i acetone
r
in 8.0.5(CH3),CO: H 1 in 7 and all 0 - H in 8.0.5(CH3),C0
were found and refined with constant B,, = 4.0 8'. R = 4.90 [6.95] (3.76),
Compound 5 . H 2 0crystallizes in the space group Pi with one
R , = 6.14 [9.06] j4.85) for 901 [3551] (1764; structure factors F:23o(F:)
pair each of crystallographically independent zwitterions and wa[abaurptioii corrcction for 7and8-0.SiCH,)2CO] and 226[559] 1208) variables.
ter molecules in the asymmetric
The crystal structure is
Further d e t a k of the crystal structure investiFation may he obtained from the
Fachinformationszentrum Karlsruhe. D-76344 Eggenstein-Leopoldshafen
dominated by intermolecular N-H . . . F and 0 - H . . . F hydro( F R G ) o n quoting the depository numcalcd CSD-5x127 and the journal citagen bonds. All of the donor functions are involved in the threetion
T@;
R'
"'3
-
-
I
[I31
dimensional hydrogen-bonding network, which has a marked
surplus of acceptor functions (donor/acceptor ratio 8 :34). The
structures of the two independent zwitterions (Fig. I ) are very
similar. The Si-C distances [194.6(1) and 194.3(2) pm] are distinctly greater than those in the zwitterionic i5Si-organofluoro-
Hexacoordinate Silicon in a Compound with an
F,SiC Unit**
Reinhold Tacke* and Mathias Miihleisen
Anions with penta- and hexacoordinate silicon such as
[RSiFJ. [ R S i F J - , and [R,SiF,]'- (R = organic substituent)
have been known for about thirty years."] More recently salts
containing the anions [R,SiF,] ['I and [R,SiF,]-['"~ 31 have
also been reported. Whereas the aforementioned 16Si-organofluorosilicates have not been structurally characterized. the structural chemistry of 1.5Si-organofluorosilicateshas been investigat[*I Prof. Dr. R. Tacke. Dipl.-Chem. M. Muhleisen
Institut fur Anorganische Chemie der Universitat
Engesserstrasse, Geh. 30.45, D-76128 Karlsruhe (FRG)
Tclct"ix: Int. code + (721)608-4290
I""] Thi\ work was supported by the Deutsche Forschungsgemeinschaft and the
Fonds der Chemischen Industrie. We thank Priv.-Doz. Dr. A. Sebald,
Baqrrischer Geoinstitut!Uuiversit~tBayreuth. for the measurement of the "Si
CP,M.4S N M R spectrum.
Fig. 1. Structures of the crYSla~logrdphicd~ly
independent zwitterions in the crystal
of S.H,O. Selected distances [pm] and angles ["I (standard deviations in parentheses): Sil-F1 174.0(1), Sil-F2 168.5(1), Sil-F3 171.6(1). Sil-F4 169.0(1). Sil-FS
170.8(1), Sil -C1 194.6(1): F1-Sil -F2 177.59(5). F l -Sil -F3 X9.27(5), FI -Sil -F4
87.73(5), F1-Sil-F5 87.47(5). FI-Sil-C1 X9.54(5), F2-Sil-F3 91.40(5), F?-Sil-F4
89.97(5). F2-Sil-F5 91.81(5), F2-Sil-Cl 92.79(5). F3-Sil-F4 88.31(5), F3-Sil-FS
176.56(5), F3-Sil-Cl 89.02(5), F4-Sil-FS 90.45(5), F4-Sil-Cl 176.21(5).FS-Sil-C1
92.06(5).-Si2-F6 171.7(1). S12-F7 16X.X(1). Si2-F8 172.9(1), Si2-F9 169.2(1). Si2F10 170.5(1), S Z C 7 194.3(2); F6-Si2-F7 177.87(5), F6-Si2-FX 89.24(5). F6-Si2-F9
88.13(5), F6-Si2-FlO 89.69(5), F6-Si2-C7 X9.33(5), F7-Si2-FX 89.59(5). F7-Si2-F9
90.04(5). F7-Si2-FlO 91.38(5), F7-Si2-C7 92.47(5), FX-Si2-FY X7.X2(5), FX-Si2-Fl0
176.57(5). FX-Si2-C7 91.03(5), F9-Si2-Fl0 88.89(5), F9-Si2-C7 177 23(6), F10-Si2C7 92.21(5)
1359
Документ
Категория
Без категории
Просмотров
2
Размер файла
504 Кб
Теги
compounds, carbene, coordination, dihydroxyphenyl, complexes, equilibrium, isocyanides
1/--страниц
Пожаловаться на содержимое документа