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Insertion of ЧCN into the Metal-Carbene Carbon Bond A Route to Methyleneaminocarbene Complexes.

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complexes. Although the enzymatic phosphate transfer requires, in most cases, a divalent metal ion M2 -under
physiological conditions Mg2 - and ternary enzymeM 2 + - A T P complexes are involved in this reaction, no
structure of a ternary ATP complex has previously
been determined. Furthermore, no X-ray structural analysis has been carried out o n a binary metal ion-ATP
complex. On the basis of ' H - N M R studies"] o n the
model systems Cu(ATP)(bpy)'- [bpy = 2,2'-bipyridyl] a n d
M(ATP)(phen)*- [MZf = Mg2+, Zn2+; p h e n = 1,lO-phenanthroline], which are significantly more stable than the
corresponding binary complexes M(ATP)*-, it has been
suggested that these adducts may display a metal ionbridged conformation, which allows a charge transfer interaction between the 2,2'-bipyridyl o r 1 ,lo-phenanthroline
ligands and the adenine base. In this proposed structure,
the metal ion coordinates both the B- and y-phosphate oxygens of the ATP. We have now isolated the ternary complex [Cu(ATP)(phen)], . 7 H 2 0 ( I ) at p H = 2.8 and report
here its molecular structure (Fig.
At this pH, N 1 of the
adenine is p r ~ t o n a t e d [ ~ ] .
+
+
(XCN=69and 39", yoc=66.3 and 48.6"), whereas one ribose
moiety adopts a C3'-endo-, the other a C2'-endeconformationl'].
The crystal structure of ( I ) is stabilized by both intra- and
intermolecular interactions between adenine and phenanthroline systems. The shortest intramolecular distances to the atoms
of a phenanthroline system are observed for C8 of the first adenine [331.7 pm] and C5 of the second adenine [348.5 pm]. The
base planes are not quite parallel to one another [angles =6.7
and 5.8"]. This structure demonstrates that base stacking may
be observed in ternary ATP complexes together with the involvement of all three phosphate functions in the metal coordination (the a-function albeit to a lesser extent) without the
nucleotide being forced to take up an unusual conformation.
In accordance with the observed structures of ternary complexes of nucleotide monophosphates[61,the adenine bases are
not involved in coordination to the metal ions. It can, therefore, be assumed with some degree of certainty that metal ions
preferentially coordinate the phosphate oxygens in enzymemetal ion-ATP complexes.
1,lO-Phenanthroline may be regarded as a simple model for
an enzyme which binds M(ATP)2- more strongly than M Z +or
A T P - alone, e. 9. the system arginine kina~e/Mn(ATP)'-['~.
The present results then suggest that charge transfer interactions may play an important role in the increased stability of
enzyme-M2+-ATPcomplexes.
Experimental
0.28 g (0.5 mmol) ATPNa2 in 3 cm3 H 2 0is added with stirring to a solution of 0.10 g (0.5 mmol) C U ( N O ~and
) ~ 0.10 g
(0.5 mmol) 1,lO-phenanthroline in 6 cm3 H 2 0 at 80°C. The
pH value is adjusted to 2.8 and the temperature held at 80°C
for 30 min. Blue-green prismatic crystals precipitate upon slow
cooling. ( I ) , which is obtained in quantitative yield, is filtered
off and washed with water and methanol.
Received: September 1, 1980 [Z 756 IE]
German version: Angew. Chem. 93,473 (1981)
CAS Registry numbers
(1). 77507-04-1
Fig. I. Molecular structure of [Cu(ATP)(phen)],.
d!P
Both independent Cu atoms in ( I ) display a strongly distorted [4 21-octahedral coordination. In each case a-, p- and
y-phosphate oxygens of an ATP are coordinated by the same
Cu2+ ion. The two phenanthroline N atoms, one ATP p- and
one ATP y-phosphate oxygen provide the equatorial ligands.
The following distances were determined: Cu-Op 194.2(9)
and 197.7(9); Cu-0,
192.5(8) and 191.9(8); (OB-)Cu-N
198.9(10) and 205.0(12); (0,-)Cu-N
201.3(10) and 199.3(11)
pm. The coordination sphere is completed by one a-phosphate
oxygen of the same ATP and one y-phosphate oxygen of the
other ATP. However, the axial Cu-O,(-H)
interaction is
weak [Cu.. .O,(-H) =287.8(9) and 273.0(8) pm]. In contrast,
the axial Cu-0,
distances are 228.4(8) and 227.3(9) pm reinteraction,
spectively. As a result of the weak Cu-O,(-H)
the coordination of the Cu atoms is distorted somewhat in the
direction of a square pyramidal geometry. C u l is displaced 4.4
pm from the best equatorial plane in the direction of the Cu-0, axial bond and Cu2 by 4.3 pm. Both adenosine moieties
display similar nucleotide configurations; the observed values
lie in the typical regions for purine nucleotides. The conforma= 32.3 and
tions at the glycosidic C1'-N9 bond are anti kCN
5.7"), those at the C4'-C5'
bond gauche-gauche (yo== 59.6
and 50.1°)141.The ribose moieties display the C3'-end@conformation. Similar conformations are observed for both independent ATP molecules in the crystal lattice of ATPNa,. 3 H 2 0
+
Angew. Chem. lnt Ed. Engl. 20 (1981) No. 5
[I] C. F. Naumann, H.Sigel, I. Am. Chem. SOC.96, 2750 (1974); P. R. Mirchel. H .
Sigel. ibid. 100, 1564 (1978).
I21 (1). C W H U N M O ~ ~ PH,O,
~ C Ucrystallizes
~.~
monoclinic, P2,, with a= 1180.7(3),
6=2482.4(5), c=1069.3(2) pm, 8-94.98(3)", Z=2,pc,,,=1.73 g crw3. The
structure was refined to R=0.069, Rw-0.067 for 3649 independent reflexions
(28-Z 120". CuK-radiation, F2>2.0u(Fz).Cu, Pand 0 atoms received anisotropic temperature factors. Of the 7 crystal water molecules, 4 are disordered.
131 C. F. Naurnann. B. fibs. K Sigel, Eur. J. Biochem. 41, 209 (1974).
I41 Definitions of ,yCN and vocare given in M. Sundaralingam, Ann. N. Y . Acad.
Sci. 255, 3 (1975).
I51 0. Kennard, N . W.Isaacs. W.D . S. Motherwell, J. C. Coppola, D. L. Wampler.
A. C. Larson. D. G. Watson. Proc. R. SOC.(London) A 325. 401 (1972).
[61 Chaiau-Yu Wei, B. E. Fischer, R. Bau. J. Chem. SOC.Chem. Commun. 1978,
1053; K. Aoki, J. Am. Chem. SOC.100,7106 (1978).
[71 D. H . Bufflaire.M. Cohn, J. Biol. Chem. 249, 5733, 5741 (1974).
Insertion of -CN
into the Metal-Carbene Carbon Bond:
A Route to Methyleneaminocarbene Complexes
By Helmut Fischer and UIrich Schubert"'
Owing t o the polarity of the CN-bond, azomethines
R'-N=CR2R3
react with a wide variety of substrates"].
Complexes formed by replacement of one of the substituents (R', R' o r R3)are therefore especially suited for stu-
[*I Dr. H.Fischer, Dr.
U. Schubert
Anorganisch-chemisches lnstitut der Technischen Universitat Miinchen
Lichtenbergstr. 4, D-8046 Garching (Germany)
0 Verlag Chemie GrnbH, 6940 Weinheim. 1981
0570-0833/81/050S-461$
02.50/0
461
dies on the influence of metal-organic fragments on the
reactivity of organic functional groups. In the case of the
methyleneaminocarbene complexes
(CO)SM-C(R)N=CRZR3
(1)
an additional polarization and thus activation of the N=C
bond could be expected, owing to the large deficiency of
electrons at the carbene-carbon atom.
Compounds of type ( 1 ) are now readily accessible by
reaction of arylcarbene(pentacarbonyl)chromium(o) and
-tungsten(o) (2) with cyanamides. The complexes (2) react
with dimethylcyanamide (3) almost quantitatively in polar
or non-polar solvents, even at room temperature, with insertion of the CN-group into the metal-carbene carbon
bond to give pentacarbonyl[dimethylamino(methyleneamino)carbene]chromium(o) and -tungsten(o) (4)IZ1.
carbon. On the basis of the observed geometry a most unusual nx-px bonding must be assumed for C1-N2. The contribution of the carbonylmetal fragment to the electronic
stabilization of the carbene-carbon is small, owing to the
contribution of the two organic substituents, as is evidenced by the very long Cr-Cl
bond-whose unusual
length is only seldom met with, even in aminocarbene
The 'H-NMR spectrum of (4d)(in hexachlorobutadiene)
does not alter until decomposition of (4d)takes place, with
concomitant change in color to brown. An isomerization of
E to A and/or B or to Cand/or D can therefore not be detected.
The formation of (4) from (2) and (3) is a second-order
reaction. The rate constants k of a series of diphenylcarbene(pentacarbony1)tungsten complexes, in which one of
the two parahydrogen atoms is replaced by a donor group,
or by an acceptor group, show a good positive correlation
with the Hammett o-constants[61.This suggests a nucleophilic attack of the negatively polarized nitrogen of the CN
group of (3) at the 6'-polarized carbene-carbon of (2) in
P
W
OCH,
w
w
C6H,
p-CH3C6H,
The new yellow crystalline products (4), which are stable
under nitrogen at room temperature, are readily soluble
in polar solvents, and only moderately soluble in nonpolar solvents. The position of the vco bands hardly
changes on varying R, whereas the C=N stretching
vibration (KBr mull) is more influenced: 1680 ( 4 4 , 1677
(4b), 1644 (4c), and 1636 (4d) cm-'; cf. 1666
cm-'
(H5C6-N=C(C6HS)OCH3)
and 1611 cm-'
(H5C6-N=C(C6H5)2)'31.
The two singlets observed for the N-CH3 protons in
the 'H-NMR spectra indicate partial double bond character of the CCarb--N(CH3)-bond.Moreover, it follows from
the 'H-NMR spectra that only one isomer (A, B, C, D or E)
is formed.
A.B
R' = C6H5, R" = R
, R" = C6H5
B, D: R'= R
A , C:
(CO),M=C.
E
In all four isomers with parallel n-systems ( A - 0 ) considerable steric interactions are to be expected, either with
the carbonylmetal moiety or, with the amino groups coplanar to the carbene plane in aminocarbene complexes. An
X-ray structure analysis showed the presence of the isomer
E (torsional angle Nl-Cl-N2-C2:
100.6"); indication
of this was already provided by the yellow color of (4).
since in the case of A - D the first absorption maximum
would have been expected at distinctly higher wavelengths. The equal lengths of the Cl-N1 and Cl-N2
bonds (see Fig. 1) prove that there is, nevertheless, n-interaction between the two nitrogen atoms and the carbene-
462
0 Verlag Chemie GmbH. 6940 Weinheim, 1981
Q
Fig. I. Structure of complex (4a).The hydrogen atoms are not shown. Standard deviations: 0.4-0.7 pm, and 0.3-0.4".
the first reaction step. Subsequently, insertion into the
M-Ccarb bond takes place-most likely with intermediary
formation of a metallacycle. A similar mechanism was also
deduced from the results of kinetic studies on the insertion
of ynamines into the metal-carbene carbon bond of carbene
and presumed for the insertion of ethoxyacetylene in the same compounds17b1.
Complexes of type
( I ) were previously only accessible by reaction of pentacarbonyl[methoxy(methyl)carbene]chromium(o) with oximes
or diphenylmethaneimine[8al and of pentacarbonyl[methoxy(phenyl)carbene]chromium(o) with 1-aminoethanolfsb1.
An investigation of the reactivity of these compounds however, was not carried out, mainly owing to the poor yields
(5.7 to 21%). In addition, two complexes amino-substituted
on the methylene group [R2= N(C2H&, R3= C2Hs]could
be obtained by addition of amino(methy1)carbene- or amino(phenyl)carbene(pentacarbonyl)chromium(o)
to N,Ndiethyl- 1-propynylamine[".
Procedure
A solution of (2) (1.0 mmol) and (3) (1.05 to 1.10 mmol)
in ether (3 cm') is stirred at room temperature for one [(2c)
to ten hours [ ( 2 4 . The initial deep-red solution turns
bright yellow. After removal of solvent in a water-jet va-
0570-0833/81/0505-462$ 02.50/0
Angew. Chem. In(. Ed. Engl. 20 (1981) No. 5
cuum the residue is washed with 3 x 5 cm3 of pentane; the
pentane is then decanted off. After several hours' drying in
a water-jet vacuum one obtains analytically pure (4). (4a)(4d): m. p. =69, 79, 130 (dec.), 106°C; yields 85, 75, 80,
81%.
The cis-isomer of (2) could not be detected. In the reaction of (2) with N(C4H9)4Xanalogous to the preparation of
(3) from (1) and tetraalkylammonium halides, however, we
did not obtain trans-tetracarbonyl[diethylamino(halo)car-
Received: March 17, 1980 [Z 718a IE]
German version: Angew. Chem. 93,482 (1981)
[l] Cf. also S . Parair The Chemistry of the Carbon-Nitrogen Double Bond,
Interscience, London 1980.
[Z] The structure of (4) is confirmed by IR, 'H-NMRand mass spectra, elemental analysis, and an X-ray structure analysis [of (4aJ.
[3] J. Fabian, M. Legrand, P. Poirier, Bull. SOC.Chim. Fr. 1956, 1499.
[4] (40). triclinic, space group Pi ( Z = 2 ) , a=837.8(6), b=944.4(10),
c-1230.2(11f pm, a=86.16(8), p=107.24(6), y= 103.37(6)", V=904x lo6
pm'; pcdIc=1.404 g/cm', 3159 independent reflections (2' 5 2 6 5 5 0 " ,
MoKa. graphite monochromator, X= 71.069 pm); 2391 structural factors
(Fo2 4.2 o(Fo)), R= 0.057 ;Syntex €9,
/XTL.
151 E. 0. Fischer, R . B. A . Pardy, U.Schubert, J. Organornet. Chem. 181, 37
(1979), and references cited therein.
161 H. Fischer, J. Organomet. Chem. 197, 303 (1980).
[7] a) H . Fischer, K . H . Dotz, Chem. Ber. 113, 193 (1980); b) C.P. Casey, S.
W. Polichnowski, A . J . Shusterrnan. C. R . Jones, J. Am. Chem. Sac. 101,
7282 (1979).
181 a) L. Knauss, E. 0.Fischer, Chem. Ber. 103,3744 (1970); b) J. Organomet. Chem. 31, C68 (1971).
[9] K . H. Dofz. J. Organomet. Chem. 118, C 13 (1976).
Ligand Mobility in Carbyne Complexes'**'
By Helmut Fischer, Andreas Motsch, Ulrich Schubert,
and Dietmar Neugebauer"'
Pentacarbonyl(ha1ocarbene)metal complexes are of
particular interest as potential intermediates in the synthesis of halo(tetracarbony1)carbynemetal complexes from
carbene complexes and trihalides of main group I11
elements"]. Thus, pentacarbonyl[diethylamino(halo)carbene]chromium(o), (CO),CdC(X)NEt,] (3), X = C1, Br, I,
spontaneously rearranges in solution with loss of CO to
give t r ~ n s - X ( C 0 ) ~ C r C N E(5)IZ1.
t~
Replacement of the
trans-CO group by another neutral ligand should afford
valuable information on the course of this rearrangement
of a carbene complex into a carbyne complex.
Pentacarbonyl(diethy1aminocarbyne)chromium tetrafluoroborate (1)13' reacts with triphenylphosphane in a first-order reaction (half-life 68 s in 1,1,2-trichloroethane at 25 "C)
to give rrans-tetracarbonyl(diethy1aminocarbyne)triphenylphosphanechromium tetrafluoroborate (2) (red-brown crystals, decomposition above 120 C)["'.
co
OC
\
- . :>
(C,H,),P-Cr=C
I
-N(C,H&
'c,
[*] Dr. H. Fischer [ 1' , DipLChem. A. Motsch, Dr. U. Schubert,
Dr. D. Neugebauer
Anorganisch-chemisches
Institut der Technischen UniversitBt
Miinchen
Lichtenbergstr. 4, D-8046 Garching (Germany)
[ '1
[**I
Author to whom correspondence should be addressed.
Kinetic and Mechanistic Investigations of Transition Metal-Complex
Reactions, Part 7.-Part 6: H. Fischer, J. Organomet. Chem. 197, 303
(1980).
Angew Chem. Int. Ed. Engi. 20 (1981) No. 5
-
X
+ NR,BF,
(~0)~~r-c;
N(CZH5)2
(I)
+
X
F, C1. B r , I
NR,X
(3)
=
bene]triphenylphosphanechromium(o), but, surprisingly,
mer-tricarbonyl(diethylaminocarbyne)halo(triphenylphosphane)chromium (4y1.
c- 'co
0
14)
(a), X
=
C1; (h), X = B r ;
(('1,
X
=
I
In (4) the groups originally trans oriented in (2) are in
the cis-position, while the entering ligand (X-)takes up
the trans-position to the carbyne group. No indication
could be found of the formation of trans-tetracarbonyl[diethylamino(halo)carbene]triphenylphosphanechromium or
other isomers of (4). (4) is also accessible from trans-tetracarbonyl(diethy1aminocarbyne)halochromium (5) by CO/
PPh, exchange (first-order reaction, half-life for (5b)-+ (4b)
129s in 1,1,2-trichloroethane at 25 "C).
X-ray structure analyses were carried out on (2) and (4b)
(Fig. l)'"]. Comparison with the structures of the analogous
methylcarbyne complexes
[rrons-Me3P(CO),CdMe]BC14
(6) [5]
and mer-Br(Me3P)(CO),CdMe (7) [6]
showed, first of all, that the amino group could be in resonance with the metal-carbon bond"'. As a result, the
electron density at the metal in the aminocarbyne complexes is greater than in the corresponding methylcarbyne
complexes. This manifests itself almost exclusively in a
shortening of the metal-ligand bond length of the group
frans to the aminocarbyne moiety (Cr-Br in (4b): 257.2
pm, in (7): 260.3 pm; Cr-P in (2): 246.4 pm, in (6): 247.4
pm; it should be remembered that metal-PMe, bond
lengths are shorter than metal-PPh, bond lengths in comparable complexes).
Although the reactions (2)+(4) and (5)4(4) (at least in
the case of X = Br) proceed almost equally rapidly, formation of (4) via the reaction sequence
(2)
+X-
-t
(5)
+ PPh3
+
(4)
+ CO
can be ruled out, since PPh, is not exchanged in (2) in the
presence of excess free triisopropylphosphane but CO is
0 Verlag Chemie GmbH, 6940 Weinheim, 1981
0570-0833/81/0505-463 S 02.50/0
463
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bond, carbene, methyleneaminocarbene, metali, чcn, insertion, complexes, carbon, route
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