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N-Arylation and N N-Dibenzylation of Coordinated N2 with Organic Halides; Differences in the Reactivity of trans-[Mo(N2)2(Me8[16]aneS4)] and Its Phosphane Analogues.

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benzene gave orange crystals. M.p. 181 -185°C (decomp.); yield: 234.8 mg
(70%).
4: A vigorously stirred solution of l(200 mg, 0.34 mmol) in toluene (10 ml) was
treated with solid [Pt(PPh,),(C,H,),]
(241.9 mg, 0.34 mmol) at 0°C. Upon
addition, the solution immediately turned deep brown. After the solution was
allowed to warm lo 25 "C and stirred for 2 h the solvent was removed in vacuo.
The resulting brown oil was redissolved in benzene (3 ml) and 4 crystallized
after 2-8 h as a yellow solid. M.p. 188-194°C (decomp.); yield: 330.6mg
(74%).
Received: April 25, 1989 [Z 3305 IE]
German version: Angew. Chem. 101 (1989) 1087
N-Arylation and N,N-Dibenzylation of
Coordinated N2 with Organic Halides;
Differences in the Reactivity of
trans-[Mo(N,),(Me, [16]aneS,)]
and Its Phosphane Analogues**
By Toshikatsu Yoshida,* Tomohiro Adachi, Tatsuo Ueda,
Manabu Kaminaka, Nobuyoshi Sasaki, Taiichi Higuchi,
Takayuki Aoshima, Izumi Mega, Yasushi Mizobe, and
Masanobu Hidai *
The direct formation of C-N bonds by reaction of N,,
coordinated to transition metals, with organic compounds
has been the subject of intensive studies aimed at the development of new methods for the synthesis of organonitrogen
compounds." 'I A variety of organic compounds such as
RX (R = alkyl, acyl) and acid anhydrides have been found
to react with Moo-, W'-, and Re'-N,-phosphane complexes
Review: R. West, Angew. Chem. 99 (1987) 1231; Angew. Chem. Int. Ed.
to give organo-diazenido and/or -hydrazido complexes. So
Engl. 26 (1987) 1201; G . R. Gillette, J. Maxka, R. West, ibid. 101 (1989) 90
far, however, no N-arylation or N-benzylation of coordinatand 28 (1989) 54; M. Weidenbruch, B. Flintjer, S. Pohl, W. Saak, ibid. I 0 1
(1989) 89 and 28 (1989) 95.
ed N, with aryIX and PhCH,X has been achievH. B. Yokelson, A. J. Millevolte, B. R. Adams, R. West, J. Am. Chem. SOC.
ed,[2-3]aside from the indirect N-arylation via a diazenido
109 (1987) 4116; M. J. Michalczyk, M. J. Fink, K. J. Haller, R. West, J.
complex [WX(N,H)(dppe),] (dppe = Ph,PCH,CH,PPh,)
Michl, Organometaflics 5 (1986) 531. (Mes,Si),Si and (Mes,Si),Te: G. R.
with the very strong electrophilic aryl fluoride 2,4Gillette, R. West, R. Tan, unpublished results.
D. Cremer, J. Gauss, E. Cremer, J. Mol. Strucr. 169 (1988) 531.
(N0,),C6H,F.[6~'I
1: 'H NMR (200 MHz, C,D,, 300 K): 6 = 2.09 (br. s, 12H, p-Me),
Recently, we have reported on the synthesis of a novel
2.57 (s, 12H, a-Me), 2.80 (s, 12H. o-Me), 6.34 (s, 8 H , C,H,Me,);
molybdenum(0)-dinitrogen
complex trans-[Mo(N,),(Me,
29Si{'H} NMR (71.55 MHz, INEPT-pulse sequence, C,D,); 6 = - 49.50
[16]ane-S,)] 1 containing a quadridentate thio-crown ether
(t, J = 77 Hz); "P{'H} N M R (202.4 MHz, C6D6): 6 = 324.0(s); MS:
calcd. ( M e ) 594.2456, found 594.2453 (23%).
ligand Me, [I 61 an&, , and on its p , electron donor properE. Niecke, R. Ruger, B. Krebs, Angew. Chem. 94 (1982) 553; Angew.
ties,"'] which distinguish it from phosphanes. Compared to
Chem. Inr. Ed. Engl. 21 (1982) 544; R. Appel, B. Niemann, M. M. Nieger,
the phosphane analogues trans-[Mo(N,),(R,PCH,CH,ibid. 100 (1988) 957 and 27 (1988) 957.
PR,),] (R = Et, Ph) 1 is very nucleophilic, as manifested by
M. Baudler, H. Jongebloed, Z . Anorg. ANg. Chem. 458 (1979) 9; K. F.
Tebbe, ibid. 468 (1980) 202; M. Weidenbruch, M. Herrndorf, A. Schaefer,
the facile N,N-dimethylation of the coordinated dinitrogen
K. Peters, H. G. von Schnering. J. Organomet. Chem. 295 (1985) 7; M.
in 1 with MeBr under ambient conditions. We have now
Baudler, Th. Pontzen, Z. Anorg. ANg. Chem. 491 (1982) 27.
found
the first examples of N-arylation and N,N-dibenzyla2:'H NMR(200MHz,C,D6;300K):6 = 1.97(~,6H,p-Me),2.16(~,6H,
tion of the coordinated dinitrogen in 1 with the correspondo-Me), 2.41 (s, 12H, o-Me), 2.73 (br. s, 12 H, o-Me), 6.24 (s, 4 H ,
C,H,Me,), 6.67 (s, 4 H , C,H,Me,); 29Si{'H}NMR (71.55 MHz, INEPTing organic halides to give aryldiazenido and dibenzylhypulse sequence, C,D,);
6 = -39.7
(dd. l'J,29q,
= 80.0 Hz,
, -- ppw, I
drazido complexes, respectively. To clarify the difference in
~ ' J l ~ ~= s34.0Hz);31P{'H}
, ~ p p ~ ~ ~
NMR(202.4 MHz,C,D,):'6 = -278.3
reactivity between 1 and the phosphane analogues further,
(d, PPW, IIJlppll = 106.9 Hz, l ' J l p p , q v ! + 2 J l p p r a t W i l = 285.0 Hz), - 321.0
liberation of NH, and acetone azine from 1 were also exam(d, PPW); MS (FAB, 3-NO2(C,H,)CH,OH matrix): m/Z 987 (27%.
[ M + matrix fragmentIe), 891 (100%. [M-CO + lie); IR: 3(CO) = 1973,
ined.
1951, 1941 crn-'.-3:'H
NMR (200 MHz, C,D,, 300 K): 6 = 1.93 (s,
Reaction of 1 with two molar amounts of PhX in toluene
6 H , p-Me), 2.03 (s, 6 H , p-Me), 2.22 (s, 12H, o-Me), 2.81 (br. s, 12H,
under ambient conditions (no particular irradiation) for 10 h
o-Me), 6.17 (s, 4 H , C,H,Me,), 6.66 (s, 4H. C,H,Me,); 29Si{'H}NMR
gave the phenyldiazenido complexes 2 (17%) and 3
=p l ~
(71.55 MHz, INEPT-pulse sequence, C,D,): 6 = -53.7 (t. ~ ' J l s ~
38.2 Hz); 31P('H) NMR (202.4 MHz, C,D,): 6 = -272.7 (s, ~ ' J l p ~ 8 ~ w l (26%)r1'] together with biphenyl (Scheme 1). When a more
+ 2Jlp,8.,,I= 129.7 Hz); MS (FAB, 3-N0,(C,H4)CH,0H matrix): m / r
activated aryl halide p-IC,H,CO,Me was employed, 4 was
1243 (20%, [M + 1Ie); IR: C(CO) = 1983, 1958. 1 9 4 2 c m - j . 4 :
obtained in a slightly better yield (32%). Formation of the
' H NMR(S00 MHz, C,D,/C,DB, 300 K): 6 = 2.118 (s, 6H,p-Me), 2.332
aryldiazenido complexes was confirmed unequivocally by
(s, 6H, p-Me), 2.761 (s, 12H, o-Me), 2.767 (s, 12H, o-Me), 6.406 (s, 4 H .
C,H,Me,), 6.842 (s, 4H, C,H,Me,), 6.933 (m, 18H, PPh,), 7.008 (m,
transformation of 3 into the hydrazido complex 5 on treat12H, PPh,); "Sij'H} N M R (71.55 MHz, INEPT-pulse sequence, C,D,/
ment with Me1 at room temperature and by a single crystal
C7D8):6 = -27.0 (t. [ ' J p s i . p l l = 65.0 Hz), "P('H) N M R (202.4 MHz):
X-ray structure analysis of 4 (Fig.
6 = - 119.9 (pseudo-t, Si-P-Pt, IzJ~p,pph,,,,l
+ 2Jlp.pph,,r..r~l
= 28.3 Hz,
CAS Registry numbers:
1,121654-87-3; 2,121674-98-4; 3,121674-99-5;4,121675-00-1; [W(CO),THF],
36477-75-5; [Mes,Si,], 80785-72-4; P,, 7723-14-0.
-
+
I'Jlp,191p,11
= 340 Hz),
22.5
(pseudo-t,
PPh,;
I'Jph,p.5~~p,ll
=
2522.6 Hz); MS (FAB, 3-NO,(C,H,)CH2OH matrix): m / z 1346 (loo%,
[ M + matrix fragmentIe).
[8] J. G. Verkade, J. A. Mosbo in J. G. Verkade, L. D. Quin (Eds.): Phosphorus-31 N M R Spectroscopy in Slereochemical Analysis, VCH, New York/
Weinheim 1987, p. 425.
[9] W. W. Schoeller, C. Lerch, Inorg. Chem. 22 (1983) 2992; W. W. Schoeller, V.
Staemmler, P. Rademacher, E. Niecke, ibid. 25 (1986) 4382.
[lo] X-ray structure analysis of 3: orange rhombs from benzene; crystal dimensions: 0.3 x 0.45 x 0.55 mm3, monoclinic, space group C2/c, a = 17.547(4),
h = 14.517(3), c = 20.086(4) A,
= 115.55(3)',
V = 4616.2(17) A3,
Z = 4. eCslLd
= 1.788 gem-,, p = 5.262 mm-' (Mo,.); T = 118 K, 5330
independent reflections (2 B,, = 55.0"), 4602 with IF[ > 2 o(Fj used for
the structure solution (direct methods). R = 0.0413 (R, = 0.0539,
w-' = u p
0.0005 F'). Further details of thecrystal structure investigation are available on request from the Fachinformationszentrum Karlsruhe, Gesellschaft fur wissenschaftlich-technische Information mbH, D7514 Eggenstein-Leopoldshafen 2 (FRG), on quoting for depository
number CSD-53860, the names of the authors, and the journal
citation.
+
1040
6
VCH Erlagsgeself.schafl mhH, 0-6940 Weinheim, 1989
[*I
[**I
Prof. Dr. T. Yoshida, T. Adachi, T. Ueda, M. Kaminaka, N. Sasaki
Department of Chemistry, Faculty of Integrated Arts and Sciences
University of Osaka Prefecture
Sakai, Osaka 591 (Japan)
Prof. Dr. T. Higuchi
Department of Chemistry, Faculty of Science
Osaka City University
Sumiyoshi, Osaka 558 (Japan)
Prof. Dr. M. Hidai, T. Aoshima, 1. Mega, Dr. Y Mizobe
Department of Synthetic Chemistry, Faculty of Engineering
Tokyo University
Hongo, Tokyo 113 (Japan)
This work was supported by a Grant-in-Aid for Scientific Research
(No. 61 125004) from the Japanese Ministry of Education, Science, and
Culture, and by the Asahi Glass Foundation for Industrial Technology
( M . H.). - Me8[16]aneS, = 3,3,7,7,11,11,15,15-octamethyl-1,5,9,13-tetrathiacyclohexadecane
057~-0833~89/0808-/040
S 02.50/0
Angew. Chem. Inl. Ed. Engl. 28 (1989) No. 8
trans-[MoX(N,Aryl)L]
Me1
rrans-[MoI(N,MePh)L]I
5
2, Aryl = Ph, X = Br
3, Aryl = Ph, X = I
4, Aryl
X
= p-C,H,CO,Me,
Me,C=N-N=CMe,
acetone \
MeOH /
J
trans-[Mo(N,),L]
=
I
PhCH,Br
trans-[MoBr{N,(CH,Ph),}L]Br
toluene
1
6
I
NH,
trans-[MoI{N,Me(CH,Ph)}L]I
+
trans-[Mol(N,Me,)L]I
I
8
Scheme I . L = Me,[lh]aneS,
The complex 4 adopts a slightly distorted octahedral geometry with four S atoms in the equatorial plane and with
the p-N,C,H,CO,Me and I ligands in the trans axial sites.
The all-up conformation of Me,[16]aneS4 in I[''] was retained during the N-arylation. The I ligand lies on the same
side as the macrocyclic C atoms with respect to the 4s equatorial plane, while the N,-p-C,H,CO,Me group lies on the
opposite side. The complex has crystallographically imposed
C, symmetry with the Mo, S(1), S(9), I, N(l) and N(2) atoms
and the phenyl ring as well as the CO, group in the symmetry
plane. The bond lengths and angles of the MoN,-pC,H,CO,Me moiety are typical for Mo" and Mo" organodiazenido ~ o r n p l e x e s . 14]
~ ' ~Despite
~
the low yield the observed facile N-arylation is remarkable and contrasts sharply
with the failure of trans-[M(N,),(dppe),J (M = Mo, W) to
react with PhX under similar conditions and with the formation of trans-[MoX,(dppe),] as sole product under forcing
conditions.[' 51
instead trans-[MoBr,(dppe),] and biben~yl.['~I
Rather surprisingly, reaction of 1 with Me1 in toluene under ambientconditions gave the N,N-benzyl(methy1)hydrazido complex
7 together with the expected N,N-dimethylhydrazido complex 8 in a 1 :3 ratio. It should be noted that if similar reaction
carried out in benzene afforded exclusively 8 in quantitative
yield. The formation of 7 may be interpreted in terms of a
radical process similar to that confirmed for the Nmonoalkylation of trans-[M(N,),(dppe),] (M = Mo, W) by
alkyl halides." 51 Accordingly, 7 may be produced via an
intermediate [MoI(N,CH,Ph)Me, [16]aneS,]. A decisive reaction would be an H abstraction from toluene by a methyl
radical formed by an incipient reaction of 1 with Me1 together with [MoI(N,)Me8[16]aneS,]; the latter would be N-benzylated by the benzyl radical thus generated. Apparently the
dinitrogen ligand in 1 is reactive enough to be attacked by
such a stable radical as PhCH; .
The high nucleophilicity of 1 is further demonstrated by
liberation of NH, on treatment with MeOH at 50 "C for 45 h
(0.06mol/Moatom). If acetone is added to the above
system, acetone azine (0.16 mol/Mo atom, 18 h; 0.40 mol/
Mo atom, 40 h) is obtained. Although the generation of
NH, and acetone azine from 1 is not so effective as observed
in the corresponding reactions of cis-[W(N,),(PMe,Ph),]
Me,C=N-N=CMe, 0.88
(NH, 1.01 mol/W
mol/W atom,[171 18 h at 50 "C), molybdenum-dinitrogen
complexes such as trans-[Mo(N,),(dppe),]
and cis[Mo(N,),(PMe,Ph),] are known to be completely inactive
for such generation of nitrogen compounds under similar
conditions.[171The novel reactivity of the coordinated dinitrogen in I, which probably arises from p , electron donor
ability of the crown thioether, seems to provide a basis for
elucidating the role of sulfur ligands in the nitrogenase cofactor.
Received. April 5, 1989 [Z 3276 IE]
German version: Angew. Chem. 101 (1989) 1053
Fig. 1. Crystal structure of4 (ellipsoids at the 50% probability level). Selected
bond distances [A] and angles ["I: M e S ( 1 ) 2.435(4), Mo-S(5) 2.443(3), MoS(9) 2.440(4), Ma-I 2.925(2), Mo-N(1) 1.775(1I), N(l)-N(2) 1.257(15), N(2)C(21) 1.369(17); S(I)-Mo-S(S) 90.0(1). S(5)-Mo-S(9) 90.0(1), I-Mo-N(1)
176.9(4). Mo-N(I)-N(2) 168.6(10), N(ltN(2)-C(21) 117.6(11).
N,N-Dibenzylation of 1 with PhCH,Br also proceeded
readily under ambient conditions in toluene to give 6 in 60 YO
yield. A similar reaction of the dppe analogue again failed to
give the corresponding diazenido or hydrazido complex, but
Angen. Chem. Int. Ed. Engl. 28 (1989) No. 8
[l] J. Chatt, J. R. Dilworth, R. L. Richards, Chem. Rev. 78 (1978) 589.
[2] J. R. Dilworth, J. R. Richards in G. Wilkinson, E G. A. Stone, E. W. Abel
(Eds.): ComprehensiveOrganometallic Chemistry, Vol8, Chap. 60, Pergamon, Oxford 1982.
[3] H. M. Colquhoun, Ace. Chem. Res. 17 (1984) 23.
[4] M. Hidai in S. Spiro (Ed.): Molybdenum Enzymes, John Wiley, 1985,
pp. 285.
151 M. Hidai, Y. Mizobe in P. S. Braterman (Ed.): Reuctions o/Coordinated
Ligands, Vol2, Plenum, London 1988, pp. 53.
[6] H. M. Colquhoun, J. Chem. Res.(S) 1979, 325.
171 Apart from the N-arylation with aryl halides, a nucleophilic N-phenylation
of an electron-poor complex [(qs-C,H,)Mn(CO),(N,)] with PhLi and formation of aniline by reaction of titanium(iv) compounds with PhLi under
high N, pressure are known [8, 91.
181 M. E. Vol'pin, V. B. Shur, R. V. Kudryavster, L. A. Prodayko, Chem.
Commun. 1968, 7038.
[9] D. Sellman. W. Weiss, Angew. Chem. 90(1978) 295; Angew. Chem. Inr. Ed.
Engl. 17 (1978) 269.
[lo] T. Yoshida, T. Adachi, M. Kaminaka, T. Ueda, T. Higuchi, J Am. Chem.
SOC.110 (1988) 4872.
(111 All the new compounds gave satisfactory elemental analyses except 7,
which was characterized by 'HNMR data. Spectroscopic and physical
data: 2: yellow crystals, m.p. 262-263 "C (dec); IR (Nujol mull): J(N = N)
1560cm-I; ' H NMR: 6 = 1.05(s. 12H, Me). 1.21 (s. 12H. Me), 2.60(d,
J = 11.5Hz, 8 H , CH,S), 2.92 (d, J = 11.5Hz. 8 H . CH,S), 7.0-7.3 (m,
5H. Ph). 3: yellow crystals, m.p. 252-254°C (dec); I R (Nujol mull):
J(N = N ) 1560 cm- ; ' H NMR: 6 = 1.06 (s, 12H, Me), 1.20 (s, 12H, Me),
2.61 (d, J = 12.0H2, 8H,CH,S), 2.98 (d, J = 12.0Hz, 8H, CH,S), 7.07.3 (m. 5H. Ph). 4: orange crystals, m.p. 285-287°C (dec); IR (Nujol
mull): v^((N=N) 1540, D(C=O) 1702 cm-'; 'H N M R : 6 = 1.09 (s, 12H.
Me), 1.19 (s, 12H, Me), 2.62 (d, J = 11.3 Hz, XH, CH,S). 2.96 (d,
J = 11.3 Hz, 8 H . CH,S), 3.82 (s, 3H, CO,Me), 7.17 (d. J = 8.8 Hz, 2H,
Ar), 7.19 (d, J = 8.8 Hz, 2H. Ar). 5 : pale browncrystals. m.p. 278-281 "C
(dec):'HNMR:6=1.20(s.24H.Me),2.87(d.J=ll.OHz.8H.CH,S).
0 VCH VerlugsgesellschafimbH, 0-6940 Weinheim. 1989
0S7~-0833j89j0~~8-l041$02.SO/O
1041
3.05( d, J = 11.0Hz,8H,CH2S),3.81(s,3H,NMe),7.1-7.4(m,5H,Ph).
important for the understanding of the electronic structure
6: pink crystals, m.p. 254°C (dec); ’ H N M R : 6 = 1.17 (s, 6H, Me), 1.19
J=11.6Hz,4H,CH2S),2.93(d,J=11.6Hz,4H, of nonclassical carbocations - which establishes the geomet(~,6H,Me),’2.81(d,
rical consequences of the homoaromatic interactions in 4
CH2S),4.56(s,2H,NCH,),7.2-7.4(m,5H,Ph).7:
‘HNMR:6=1.18
(s, 12H. Me), 1.23 (s, 12H. Me). 2.86 (d, J = 11.4Hz, CH,S), 2.98 (d,
and in the related 7-norbornenyl cation 5.
J = 11.4Hz,CH2S), 3.12 (s, 3H, NMe), 4.56(s, 2H, NCH,), 7.15-7.40
(m, 5H, Ph). 8: pink crystals, m.p. 297-299°C (dec); ‘H NMR: 6 = 1.18
(s, 6H, Me), 1.23 (s, 6H, Me), 2.84 (d, J = 11.6 Hz, 4H, CH,S), 2.94 (d,
J = 11.6 Hz, 4H, CH,S), 3.24 (s. 3H, NMe). The ‘H NMR spectra show
that the Me,[lh]aneS, ligand in 2-8 assumes all-up conformation.
[12] Crystal data for 4: C2,H,,N20,S,IMo ’ 2 CH2CI,. M = 964.18, orthorhombic, a = 23.353(4), b = 13.055(3), c = 13.985(4)A, V = 4264(2) A’,
space group Pnani, Z = 4, D, = 1.50 g ~ m - p(MoKe)
~ ,
= 14.86cm-’.
Crystal dimension 0.15 x 0.15 x 0.40 mm; intensity data were collected in
1
2
3
the range 3 5 2 0 5 50” using the 20lw scan technique; intensities were
Q
corrected for Lorentz and polarization effects. The Mo atom was located
by the Patterson map and the other atoms were found by a successive
Fourier method, and refined by block-diagonal least-squares procedures.
One of solvent molecules (CH,CI,) and the methyl group of the ester were
disordered slightly, but could be modeled successfully. At final conver4
5
gence, R(R,) = 0.062(0.063), S, = 1.56 for 2218 unique reflections
(IFol2 3 0 ( F o ) ) and the final difference map showed no feature above
0.72 eA-’. Further details of the crystal structure investigation may be
obtained from the Fachinformationszentrum Karlsruhe, Gesellschaft fur
Of the three structural alternatives considered by Winstein
wissenschaftlich-technische Information mbH, D-7514 Eggensteinfor the cation intermediate 4 a - 4 , the form with the lowest
Leopoldshafen 2 (FRG), on quoting the depository number CSD-53791,
symmetry (CJ, 4 a, was indicated by NMR experiment~.[~]
the names of the authors, and the journal citation.
The preference for a C, geometry can be rationalized based
[13] M.Sato,T.Kodama,M.Hidai,Y.Uchida,J.
Organomet. Chem. 152(1978)
239.
on PMO arguments.[51Tilting C7 toward the C2-C3 double
[14]T.-C. Hsieh, T. Nicholson, J. Zubieta, Inorg. Chem. 27 (1988) 241.
bond results in better overlap and thus higher stabilization
[15] J. Chatt, R. A. Head, G. J. Leigh, C. J. Pickett, J. Chem. Soc. Dalton Trans.
than
simultaneous interaction with both double bonds
1978, 1638.
in a C,, arrangement. Experimentally, the barrier to
[16] J. Chatt, A. J. Pearman, R. L. Richards, J Chem. Soc. DoffonTrans. 1977,
1853.
bridge flipping 4 a g 4 b e 4 a was estimated to be at least
[17] A. Watanabe, T. Takahashi, D.-M. Jin, I. Yokotd, Y. Uchida, M. Hidai, J.
19.6 kcal mol- mbl
Organomet. Chem. 254 (1983) 75.
The 7-Norbornadienyl Cation:
An NMRfIGLO Validation of its
ab initio Structure **
By Matthias Bremer, Karl Schotz, Paul von Rag& Schleyer,*
Ulrich Fleischer, Michael Schindler, Werner Kutzelnigg,
Wolfram Koch, and Peter Pulay
In 1960 Winstein et al.[’] reported a “world record for
anchimeric acceleration”.[21 7-norbornadienyl chloride 1
solvolyzes I O l 4 times faster than 7-norbornyl chloride 2 and
even lo3 times faster than 7-norbornenyl chloride 3. The
exceptional stability of the 7-norbornadienyl cation 4 permitted its preparation (as the BF,” salt) in SO, solution before the days of “super
We now present an ab initiol
IGLO (Individual Gauge for Localized Molecular Orbitals)r41study on the 7-norbornadienyl cation 4 - a system
I*l
““I
Prof. Dr. P. von R. Schleyer, Dr. M. Bremer, Dr. K. Scholz
Institut fur Organische Chemie, Universitat Erlangen-Nurnberg
Henkestr. 42, D-8520 Erlangen (FRG)
Dip].-Chem. U. Fleischer, Dr. M. Schindler, Prof. Dr. W. Kutzelnigg
Lehrstuhl fur Theoretische Chemie, Ruhr-Universitit
Postfach 102148, D-4630 Bochum (FRG)
Dr. W. Koch
IBM Deutschland GmbH, Wissenschdftliches Zentrum Heidelberg
Tiergartenstr. 15, D-6900 Heidelberg (FRG)
Prof. Dr. P. Pulay
Department of Chemistry and Biochemistry, University of Arkansas
Fayetteville, AR 72701 (USA)
Support was provided by the Fonds der Chemischen Industrie, the Deutsche Forschungsgemeinschaft, the Convex Computer Corporation and the
Regionales Rechenzentrum Erlangen. Most ofthe IGLO calculations were
carried out on the Cyber 205 of the Rechenzentrum of the Ruhr Universitit Bochum. We gratefully acknowledge a generous allocation of computer time on the IBM 3090-200 EjVF of the IBM Dusseldorf computer
center. The vectorized IBM version of Gaussian 86 was used [18]. We
thank 7: Lauhe (Zurich) for communicating his results prior to publication.
1042
0 YCH
Verlagsgesellschafi mhH, 0-6940 Weinheim. 1989
Our ab initio calculations (Table 1) confirm these conclusions. The C,, structure 4b is found to be 26.6 kcal mol-’
(MP2-FCf6-31G*/f6-31G*;the “I/”
means “at the geometry
of’) less stable than the C, alternative 4a. The stabilizations
due to the interactions of the double bonds with the positive
charges can be evaluated by isodesmic reactions [Equations (a)-(c)].
6
+ norbornadiene + 4a + norbornane
(9)
6 + norbornene -+ 5
(7)
6 + 9-4b
-20.3
(8)
+8
-15.0
+8
+
8
6
7
8
6.3
A
9
The large values found for 4 a [Eq. (a)] and for 5 [Eq. (b)]
correspond to the solvolysis rate accelerations found experimentally. The situation in 4b is interesting in view of the
qualitative prediction
that “longicyclic” interactions in
0570-0833j89j0808-1042$02.50/0
Angew. Chem. Int. Ed. Engl. 28 (19R9) No. 8
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anes4, differences, phosphane, organiz, halide, coordinated, dibenzylation, reactivity, arylation, transp, me8, analogues
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