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Laser Photolysis of the Bisazoalkane 7-syn 7-anti-Bis-2 3-diazabicyclo[2.2

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tetrahydrofuran (THF) via 3, which cannot be detected
spectroscopically, to give tricarbonyl( 1,3-diphosphaal1yl)cobalt 4 (correct elemental analysis): in the process,
NaCl is eliminated and C O evolved.
According to the X-ray structure determination (Fig. l),
4 can be described best as a square pyramid having two P
atoms and two C O ligands at the base and a third carbonyl
group at the apex, with the ally1 C atom below the basal
plane pointing towards the C o center. The N M R data[31
(magnetic equivalence of the two aryl-P units) are in accord with this description.
Fig. 1. Stereograph of the crystal structure of 4
Laser Photolysis of the Bisazoalkane
By Waldemar Adam, * Klaus Hannemann.
Eva-Maria Peters, Karl Peters, Hans Georg von Schnering,
and R . Marshall Wilson
Recently the synthesis of the tetraradical 2 by denitrogenation of the bisazoalkane 1 was reported.[’I We have
now synthesized the bisazoalkane 3, from which we
wanted to generate the tetraradical 4 by laser photolysis.
Although other suitable bisazoalkanes such as the bisazoalkane 512] are known, no formation of tetraradicals
4 be formed, then it
could hitherto be ~ b s e r v e d . ’ Should
could react further with intramolecular coupling to give
the known[41hydrocarbon 6 ; that is, its formation would
be an indication of the intermediary occurrence of the tetray1 4 . By stepwise cleavage of N2, the formation of the
novel hydrazine 7 would be possible by intramolecular
trapping reaction‘51 of the diyl with the remaining azo
The following findings support the classification of 4 as
a 1,3-diphosphaallyl c ~ m p l e x : ‘all
~ ’ three atoms of the PCP
triad are bonded to the Co atom; the C1 atoms of the aryl
moieties and the PCHP skeleton form a plane; the PC distances within the ligands are the same and lie between a
PC single bond and a PC double bond, in contrast to the
starting material.
Experimental procedure
A solution of octacarbonyldicobalt (0.85 g, 2.5 mmol) in T H F (SO mL) is added to 13 g of I % sodium amalgam. After stirring overnight at room temperature, the supernatant is decanted and treated with 1 (3.0 g, 5 mmolj, then
heated at 45°C for 4 h, during which time the solution undergoes a color
change from yellow to rust-brown. The solvent is removed and the residue
extracted three times with 20 m L of hexane. The extracts are combined; 3
crystallizes out as orangish brown prisms. Yield: 1.9 g (83910), m.p.= 163°C
Received: January 30, 1988;
revised: March 4, 1985 [Z I149 IE]
German version: Angew. Chem. 97 (1988) 421
CAS Registry numbers:
1, 96164-77-1: 2, 14878-28-5; 4, 96193-91-8.
a) T. C. Kleebach, R. Lourens, F. Bickelhaupt, J. Organornet. Chem. 210
(1981j 2 I I ; b) S . 1. Al-Resayes, S . 1. Klein, H. W. Kroto, M. F. Meidine, J.
F. Nixon. J. Chem. SOC.Chem. Commun. 1983, 930; c j A. H. Cowley, R.
A. Jones, L. A. Stewart, A. L. Stuart, J . Am. Chem. SOC.105 (1983) 3737;
d j R. Appel, C. Casser, M. Immenkeppel, F. Knoch, Angew. Chem. 96
(1984) 908; Angew. Chem. I n f . Ed. Engl. 23 (1984) 895.
a) V. Earth, Dissertation, Universitat Bonn 1983; b) H. H. Karsch, F. H.
Koehler, H. U. Reisacher, Tetruhedron L e f f .25 (1984) 3687.
Selected NMR data: ”P-NMR (32.2 MHz, H,PO, ext., C,D,): 6=34.4 (d,
J(PCH)=7.0 Hz). ‘H-NMR (90 MHz, TMS int., C6D6j: 6=0.8 (s, 18H,
CH,), 1.3 ( s , 36H, CH,), 5.8 (t, 1 H, CH), 7.0 (br., 4 H , aromat. H). I3CNMR (20 MHz, C6D,): 6=31.1 (s, p-CHl), 34.5 (t, o-CH,). 34.6 (5, p CCH,). 39.3 (s, o-CCH3), 90.6 (t, J(PCj=86 Hz, CH), 123.2 ( s , aromat.
C 3 ) , 135.8 (“t”, J(CP+CPP)=82 Hz, aromat. CI), 150.0 ( s , aromat. C-4),
157.1 (m, aromat. CZ), 201 (hr., CO).
X-ray analysis of 1 : P2,/c: u = 1732.1(6), b = 1008.8(4), c=2387.5(9) pm,
= 1.15 g/cm3, Z = 4 . Direct methp=93.38(3jn. Y=4100.0. lo6 pm3,pc.,lCd
ods (SHELXTLj, 4631 reflections, R=0.082 (R,=0.066 for disorder of
the tBu groups). Important bond distances [pm] and bond angles [“I
(standard deviations in parentheses): Co-P 238.2(2)/239.5(2). P-C(a1lyl)
176.9(7), 179.1(7), Co-C(ally1) 203.4(7), Co-C(carbony1, basal) 179( I ) /
181(1). C‘o-C(carbony1,apical) 184(1): PCP l01.8(4), PCH 129 (H atoms
from a difference Fourier synthesis; dihedral angle PCP/PCoP 102. Further detail$ of the crystal structure investigation are available on request
from the Fdchinformationszentrurn Energie Physik Mathematik, D-7514
Eggenstein-Leopoldshafen 2, on quoting the depository number CSD
51 232. the names of the authors, and the journal citation.
Angew. Chrm. Int. Ed. Enyl. 24 (1985) No. 5
The bisazoalkane 3I6l was prepared from the known bis~ r a z o l e , [ which
is formed upon double cycloaddition of
4-phenyl-4H- 1,2,4-triazole-3,5-dione(PTAD) to 9,lO-dihydrofulvalene, by catalytic hydrogenation and subsequent
oxidative hydrolysis. The X-ray structure analysis of the
bis-azoalkane 3 (Fig. I , top) showed that the double PTAD
cycloaddition led to the syn,antr-product.[*’
Both the direct as well as the triplet-sensitized laser phot o l y ~ i s of
[ ~ the
~ bisazoalkane 3 gave, besides unreacted 3,
small amounts (ca. 15%) of the four possible monoazoalkanes Sa, d (major products) and Sb, c (minor products).
Cleavage of N2 from the “upper” azo group led to the
isomers Sa, b , while cleavage of NZ from the ‘‘lower’’ azo
group furnished the isomers Sc, d . All the isomers could
be completely characterized on the basis of their spectral
data and could be recovered in pure form by column and
gas chromatography. The X-ray structure analysis of SC
(Fig. 1, bottom)[81proved to be a valuable aid for the stereochemical assignment of all isomers. The isomeric com-
[*] Prof. Dr. W. Adam, Dr. K. Hannemann
lnstitut fur Organische Chemie der Universitat
Am Hubland, D-8700 Wurzburg (FRG)
E.-M. Peters, Dr. K. Peters, Prof. Dr. H. G . von Schnering
Max-Planck-Institut fur Festkorperforschung
Heisenbergstr. I , D-7000 Stuttgart 80 (FRG)
Prof. Dr. R. M. Wilson
Department of Chemistry, University of Cincinnati
Cincinnati, O H 45221 (USA)
0 VCH Verlagsgesellschaji mbH. D-6940 Weinheim. 1985
0570-0833/85/0505-0421$ 02.50/0
42 1
though “two-photon processes” have been observed during pulsed laser irradiation,[”J no cases of a simultaneous
double N2-cleavage leading to a tetraradical has hitherto
been reported. Even 2, which should be favored by stereoelectronic factors such as ring strain and spiroconjugation, is not formed upon photolysis of the bisazo compound. Here too, instead of the required simultaneous
double N,-cleavage, a stepwise process takes
generation and detection of polyradicals still remain a
Received: November 26, 1984;
revised: February 1, 1985 (2 1092 IE]
German version: Angew. Chem. 97 (1985) 417
Fig. I . Stereoviews of the crystal structures of 3 (top) and 8c (bottom) 181;
0 N, 0 C .
position depended on the irradiation conditions (direct or
sensitized); even at optimal intensity (focused laser beam
at maximum power) no further products could be detected
by capillary gas chromatography.
The complete photolysis (direct as well as sensitized) of
the bisazo compound 3 yielded the three possible bi-5,5’bicyclo[2.1.0]pentanes 9a -9c in roughly statistic amounts.
Synthesis, Structure, and Reactivity of
q3-l-Azaallylmolybdenum Complexes**
The pure monoazoalkane isomers 8 each afforded a pair
of the isomers 9, namely in the photolysis of Sa, d a mixture of 9b, c , whereas in the case of 8b, c the isomers 9a, b
were formed. All bi(bicyc1opentane) isomers 9 could be
characterized on the basis of their spectroscopic data. The
isomers 9b, c could be isolated in pure form by preparative gas chromatography. The photoproducts can be explained, if it is assumed that the cyclization of the 1,3-diyl
intermediate proceeds with retention or double inversion;
an analogous process was formulated for the photochemical decomposition of 2,3-diazabicycl0[2.2.l]hept-2-ene.~’~~
For the formation of 4, two photons have to be successively absorbed (one by each azo chromophore)
( 3 % 3* % 3**) within the lifetime of a n np*-excited
state (ca. 1 ns), so as to ensure a double Nz-cleavage. Al422
[ I ] a) L. McElwee-White, W. A. Goddard 111, D. A. Dougherty, J. Am.
Chem. Soc. 106 (1984) 3461; b) L. McElwee-White, D. A. Dougherty,
ibid. 106 (1984) 3466.
121 W. Adam, 0. De Lucchi, Angew. Chem. 92 (1980) 815; Angew. Chem.
Int. Ed. Engl. 19 (1980) 762.
131 R. J. Bushby, S. Mann, Tetrahedron Leu. 24 (1983) 4743.
141 L. A. Paquette, R. F. Davis, D. R. James, Tetrahedron Lerr. 1974. 1615.
IS] a) R. D. Little, G. W. Muller, J . Am. Chem. SOC.I01 (1979) 7219; b) R.
D. Little, K. J . Stone, ibid. 105 (1983) 6976.
[6] M.p. 190°C (decomp.), recrystallized from ethanol.- ‘H-NMR (CDCI,;
4 0 0 M H z ) : 6 = 0 . 8 7 ( b r . d , J = l l Hr; IH,7’-H),0.90-1.03(m;4H,H,),
1.19 (d, J = l l Hz; I H , ?-H), 1.47-1.63 (m; 4 H , HJ, 4.82 (br. s ; 2H,
l‘,4’-H), 5.03 (br. s ; ZH, 1,4-H).-”C-NMR (CDCI,: 100 MHr):
6 = 17.96 (t), 20.89 (t), 46.87 (d), 51.19 (d), 77.95 (d), 79.53 (d).-Correct
elemental analysis.
171 L. A. Paquette, M. J. Wyvratt, H. C. Berk, R. E. Moerck, J. Am. Chem.
Soc. I00 (1978) 5845.
IS] Further details of the crystal structure investigations of 3 and 8c are
available on request from the Fachinformationszentrum Energie Physik
Mathematik, D-75 14 Eggenstein-Leopoldshafen 2, on quoting the depository number C S D 51 219, the names of the authors, and the full citation of the journal.
In the direct photolysis (COHERENT supergraphite-argon ion laser; total power ca. 3 W for the 334, 351, and 364nm UV lines) [3]=0.01 h.( in
benzene, and in the triplet-sensitized photolysis additionally (benzophenone]=0.1 M were used.
W. R. Roth, M. Martin, Justus Liebigs Ann. Chem. 702 (1967) I ; Tetrahedron Lett. 1967. 4695.
a) V. S. Letokhov, Nature /London) 305 (1983) 103: b) T. R. Evans (Ed.):
Applications q’ Lasers to Chemical Prohlems irechniqurs of Chemistcv,
Vol. XVII). Wiley, New York 1982; c) J. S. Steinfeld (Ed.): Laser-induced Chemical Processes. Plenum, New York 1981 ; d) J. C. Scaiano, P.
J. Wagner, J . Am. Chem. SOC.106 (1984) 4626.
0 VCH Verlugsgesellrchafl mbH. D-6940 Weinheim, 1985
By Michael Green,* Richard J. Mercer,
Carolyn E. Morton, and A . Guy Orpen
Dedicated to Professor F. G. A . Stone on the occasion
of his 60th birthday
Although the ubiquitous q3-allyl ligand has been shown
to play an important role in many transition metal mediated reactions,”] little is known about the chemistry of
q3-l-azaallyl complexes121where a terminal CH2 group of
the ally1 fragment is replaced by an N H group. Such compounds can be formed on reaction of the 2-substituted
azirinesl3] 1 and 2 with the unsaturated dimolybdenum
species [ M O ~ ( C O ) ~ ( ~ - C ~InH toluene
~ ) ~ ] . at room temperature, the initial red-brown color becomes dark green, and
column chromatography on alumina afforded orange crys[*] Dr. M. Green, R. J. Mercer, Dr. C. E. Morton, Dr. A. G. Orpen
Department of Inorganic Chemistry, University of Bristol
Cantock’s Close, Bristol BS8 ITS (England)
This work was supported by the Science and Engineering Research
Council, Great Britain.
0570-0833/8S/0505-0422 $ 02.50/0
Angew. Chem. Int. Ed. Engl. 24 (198s) No. 5
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photolysis, diazabicyclo, syn, bisazoalkane, anti, bis, laser
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