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Monomeric Tris(2-pyrazolato)Lanthanoid Complexes with the Bulky 3 5-Di(tert-butyl)pyrazolato Ligand.

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1,3.5-Tris[diazo(3-(diazo(3-(diazo(phenyl)methyl)phenyl)methyl)phenyl)methyllbenzene (4d): The nonaketone 4 b was converted to the corresponding
nonahydrazone 4 c by the addition of anhydrous hydrazine and hydrazine hydrochloride in dimethyl sulfoxide (DMSO) at 90'C. The nonahydrazone 4c
was then oxidized with HgO in a benzene/CH,CI, mixture in the presence of a
3 M solution of KOH in ethanol. The mixture was stirred for 7 days at room
temperature. Filtration of the reaction mixture followed by concentration of
the filtrate in vacuo left a deep wine-red oil, which was immediately chromatographed on alumina (Woelm neutral, activity IV) at 0 'C with hexane and
benzene. This afforded the nonadiazo compound 4 d as a deep red oil in 6 5 %
yield. 'H NMR (270 MHz, CDCI,, 21 "C): 6 =7.43-6.85 (m): IR(Nuj0l):
C[cm-'] = 2060; UV/VIS(MTHF): >.,,,[nm](&) = 520 (950).
Photolysis and magnetic measurement: A solution of about 20 pg of 4 d in
80 pL of MTHF in a quartz sample basket suspended in a superconducting
solenoid was irradiated with UV light (480 > A > 400 nm). The UV light was
obtained by a combination of a Kenko B-390 band-path filter and an OCLI
type B cold mirror. During the magnetic measurement the field gradient was
kept constant at 5 Teslam-' while the main field was changed from 0 to 7 Tesla.
Received: January 18, 1993 [Z 5816 IE]
German version: Angew. Chem. 1993, 105, 900
(pz)J complexes (Ln = Nd,15' YbI6])have low solubility and
are probably polymeric with only bridging pz groups, whilst
[Nd(Me,pz),(thf)] (Me,pz- = 3,5-dimethylpyrazolate; thf =
tetrahydrofuran) is dimeric with p-Me,pz and q2-Me,pz ligands and, unexpectedly, bridging T H F ligands.['I We now
have used the bulky 3,5-di(tert-butyl)pyrazolato (tBu,pz-)
ligand to give tris(q2-pyrazo1ato)Ianthanoid compounds as
monomeric, petroleum ether-soluble [Ln(q2-tBu2pz),(thf),]
complexes, the first metal complexes of any element with
$-bound pyrazolate ions as the sole anionic ligands. The
X-ray structure of the neodymium complex confirms the
monomeric nature of the compounds.
Reaction of bis(pentafluoropheny1)mercury and 3,5-di(tertbuty1)pyrdzole with an excess of lanthanoid metal in THF at
room temperature gave the air- and water-sensitive complexes 1-4 (Ln = La (l),Nd (2), Gd (3), or Er (4)) in 36-55 O/O
yield [Eq. (a)].
+
-+
2 L n 3[Hg(C,F,),]
6HtBu,pz
(a)
[I] H. C. Longuet-Higgins, J. Chem. Phyx. 1950, fa, 265.
THF
2[Ln(tBu,pz),(thf),]
3Hgi
6C,F,H
[2] E. Wasserman, L. C. Snyder, W. A. Yager, J. Chem. Phjs. 1964, 41, 1763.
1-4
131 G. Kothe, K.-H. Denkel, W. Siimmermann, Angew Chem. 1970, 82, 935:
Angew. Chem. In[. Ed. Engl. 1970, 9. 906.
141 I. Fujita, Y. Teki, T. Takui. T. Kinoshita, K. Itoh, F. Miko, Y Sawaki. H.
The mass spectra of 1-4 show mononuclear [LnIwamura, A. Izuoka, T. Sugawara, J. Am. Chem. Soc. 1990. 112,4074, and
(tBu,pz):] parent ions, in contrast to the [Nd(Me,pz),(thf)]
references therein.
complex,[51 which gives dinuclear ions and no [Nd[5] N. Nakamura, K. Inoue, H. Iwamura, T. Fujioka, Y Sawaki. J. Am. Chem.
Sor. 1992, 114, 1484.
(Me,pz)l]. This result and the high solubility of 1-4 in
[6] 'H NMR data (270 MHz, CDCI,, 21 "C): 6 = 8.41 (s, 3 H . 2,4, 6-H), 8.23
petroleum ether infer monomeric structures, and this was
(L4J(H,H) = 1 . 7 H ~ , 3 H , T - H ) , 8 , 1 4 f t , ~ J ( H , H=1.7
) Hr,3H;2-H).8.03
established by the X-ray crystal structure of 2 (Fig.
(d, 'J(H,H) = 8.1 Hz, 3H: 6-H), 8.00 (d, ,J(H,H) = 8.1 Hz. 3 H : 4 - H ) .
7.97 (d, 3J(H,H) = 8.1 Hz, 6 H ; 4.6"-H), 7.74 (d, 'J(H,H) = 8.1 Hz, 6 H ;
2"',6"-H),7.62(t,3J(H,H)=8.1 H Z . ~ H ; ~ ' - H ) , ~ . ~ ~ ( ~ . ~ J ( H
Hz,
,H)=X,~
@ c20
3 H ; 5"-H), 7.52 (t. 'J(H,H) = 8.1 Hz, 3 H ; 4"-H), 7.41 (t, 'J(H,H) =
8.1 Hz. 6 H ; 3,5"'-H).
+
+
Monomeric Tris(q'-pyrazoIato)Lanthanoid
Complexes with the Bulky
3,5-Di(tert-butyl)pyrazolato Ligand""
By Joanna E. Cosgrlff, Glen B. Deacon*,
Bryan M . Gatehouse, Holger Hemling,
and Herbert Schumann*
Dedicated to Professor Bruce West
on the occasion of'his 65th Birthday
Pyrazolate (pz) ions mainly behave as bridging ligands
owing to the directional characteristics of the lone pairs on
the nitrogen atoms,['I but some f-block complexes have
chelating q2-pyrazolato ligands.['- 51 In all these complexes,
the f-block metal atoms also have either cyclopentadienyl
ligandsr2*
31 or bridging pz ligands.14. 'I No tris($-pyrazolato)
lanthanoid complexes have been reported; the simple [Ln['I
["I
Dr. G. B. Deacon, J. E. Cosgriff, Dr. B. M. Gatehouse
Chemistry Department, Monash University
Clayton, Victoria 3168 (Australia)
Telefax: Int. code +(613)565-4597
Prof. Dr. H. Schumann, Dip].-Chem. H. Hemling
Institut fur Anorganische und Analytische Chemie
der Technischen Universitit
Strasse des 17 Juni 135, D-W-I000 Berlin 12 (FRG)
Organoamido- and Aryloxo-lanthanoids, Part, and Organometallic Lanthanoid Compounds, Part 77. This work was supported by the Australian
Research Council and an Australian Postgraduate Research Award for
J. C., the Fonds der Chemischen Industrie and the Deutsche Forschungsgemeinschaft.-Part 5. G. B. Deacon, T. Feng, P. MacKinnon, R. H.
Newnham, S. Nickel, B. W. Skelton. A. H. White, Ausf.J. Chem., 1993,46,
387. Part 76. H. Schumann, M. Glanz. J. Winterfeld, H. Hemling, J.
Orgunomer. Chem. 1993.445, C1.
874
@J VCH Verlugsgesellsrhufi mhH, W-6940 Weinheim, 1993
Fig. I. Crystal structure of 2 (H atoms omitted for clarity). Selected distances
[pm] and angles ['I (Cen 1, Cen 2, and Cen 3 denote the centers of the bonds
Nl-N2, N3-N4 and NSN6, respectively): Nd-NI 243(1), Nd-N2 246(1), NdN3 241.8(8), Nd-N4 238.1(8), Nd-N5 249.2(9), Nd-N6 247.7(6), Nd-Ol
247.5(6), Nd-02 243.2(8), N1-N2 136(1), N3-N4 138(1), N5-N6 140(1); N1Nd-N2 32.2(3), N3-Nd-N4 33.3(3). N5-Nd-N6 32.7(2), 01-Nd-02 145.2(6),
Cenl-Nd-Cen2 140.3(4), Cen2-Nd-Cen3 109.2(3), Cenl-Nd-Cen3 110.6(4),
Cenl-Nd-01 84.5(3), Cenl-Nd-02 88.0(4), Cen2-Nd-01 81.0(4) Cen2-Nd-02
88.5(3), Cen3-Nd-01 112.0(6). Cen3-Nd-02 102.5(3)
Coordination of three qZ-(tBu,pz) ligands and two THF ligands gives irregular eight coordination for the central Nd
atom. The Nd-N distances (Fig. 1) increase from silimar to
those for qZ-Me,pz to near those for p-Me,pz in [{Nd($-Me,pz),(p-Me,pz)(p-thf)}z] (5).[']Although the elongation can be attributed to the steric demands of three q2tBu,pz- hgdnds, the Nd-0 distances are normal for LnO(thf) lengths.["' A clearer picture of the stereochemistry
around the neodymium center is obtained if the arrangement
of oxygen atoms of the THF ligands and the mid points
(Cen 1-Cen 3) of the N-N bonds is considered.['51This arrangement is intermediate between a trigonal bipyramid
0570-0833!93/0606-0874$10.00+.2510
Angew. Chem. I n f . Ed. EngI. 1993. 32, No. 6
with 0 1 and 0 2 apical, and Cen 1, Cen 2, and Cen 3 in the
equatorial positions (Cen 1, Cen 2, Cen 3, and Nd are coplanar, deviation <0.08(4) pm), and square pyramidal with
Cen 3 apical, and transoid Cen 1, Cen 2, and 0 1 , 0 2 relationships in the square plane (Nd 75.71(2)pm above the
plane). In either case, the skeletal angles (Fig. 1) deviate considerably from those for regular arrangements. Although
tBu,pz is bridging in the only reported complex of this ligand
[ ( N i ( t B ~ , p z ) ( N 0 > } , ] , it
~ *is~ ~sufficiently bulky (cf. pz[', 61
and Me,p~['~),in conjunction with the nondirectional ionic
character of lanthanoid-ligand bonding, to promote formation of monomeric [Ln($-pz),] complexes.
The petroleum ether-soluble compounds 1-4 are potential
synthetic reagents of comparable utility to [Ln{N(SiMe,),),]
species[' in protolytic ligand exchange reactions. To illustrate this, 6 [Odpp- = 2,6-diphenylphenolate; Eq. (b)] has
been readily prepared from 2. The high solubility of 3,5di(terr-buty1)pyrazole in petroleum ether facilitates the separation of products.
[Nd(tBu,pz),(thf),]
+ 3 HOdpp
------t
[Nd(Odpp),(thf),]
+ 3 HtBu,pz
(b)
6
2
Experimental Procedure
Syntheses and characterization. All operations were carried out under a purified N, or Ar atmosphere. 1: La powder (0.80 g, 5.7 mmol), [Hg(C,F,),] [18]
(1.48 g. 2.8 mmol), and HtBu,pz[19](1.00g, 5.5 mmol) werestirred together in
T H F (40 mL) at room temperature for 2 days. The reaction mixture was filtered
and evaporated until solid deposited. Dissolution by warming and cooling to
room temperature gave 1 (0.84 g, 5 5 % ) as a white powder. Correct C,H,La
analyses ' H NMR(200MHz,C6D6):6=1.13(m,8H,P-H(thf)). 1.39(s,54H,
iBu), 3.25 (t, J = 6.5 Hz, 8 H , x-H(thf)), 6.37 (s, 3 H , H4(tBu,pz)). MS (L =
tBu2pz):m;;676(NdL:.0.3%),661 (NdL: - Me,0.3%),497 (NdL:,0.8%),
4x1 (NdL: - MeH, 0.9%), 180 (LH', 20%), 165 (LH' - Me, 300%). IR
(NujoljFluorolube. strong bands only) J[cm-'] = 2948,2895,2858,1456,1430,
1412, 1357. 1250. 1224, 1031, 1016, 993, 875, 787. After analogous preparations, 3 was isolated similarly, and 2 and 4 were obtained by evaporation of the
filtered reaction mixture to dryness and crystallization of the residue from pentaneiTHF at - 10 " C ,The IR spectra of 2-4 were essentially identical with that
of 1. and their mass spectra showed features corresponding with those of 1.
Reaction of 2 with HOdpp: A solution of 2. prepared in situ from Nd powder
(0.68 g. 4.7 mmol), [Hg(C,F,),] (0.74 g, 1.4 mmol), and HtBu,pz (0.50 g,
2.8 mmol) in T H F (40 mL) was filtered onto HOdpp (0.68 g, 2.8 mmol) and
stirred briefly at room temperature. The blue solution was concentrated to
about 8 mL, which resulted in deposition of light blue [Nd(Odpp),(thf),]. After
addition of pentane the mixture was stirred to dissolve any HtBu,pz and the
blue solid was collected (0.78 g, 5 5 % ) . The IR and mass spectra were in agreement with those of the authentic compound [20,21]. Evaporation of the filtrate
gave a white residue of HtBu,pz (IR identification).
Received: January 26, 1993 [Z 5827 IE]
German version: Angew. Chem. 1993, 105, 906
[l]
[2]
[3]
[4]
S.Trolimenko, Chem. Rev. 1972, 72, 497-509.
C. W. Eigenbrot. K. N. Raymond, Inorg. Chem. 1981, 20, 1553-1556.
C. W. Eigenbrot. K. N. Raymond, Inorg. Chem. 1982,21, 2653-2660.
H. Schumann, P. R. Lee, J. Loebel, Angen.. Chem. 1989,101,1073-1075;
Angel,.. Chem. Int. Ed. Engl. 1989, 28. 1033- 1035.
[ S ] G B. Deacon. B. M. Gatehouse, S. Nickel, S. N . Platts, Aust. J. Chem.
1991. 44, 613 -621.
[6] G . Bielang. Doktor des Fachbereiches Chemie Thesis, University of Hamburg. 1979.
[7] 2 - Air-sensitive blue crystals, C,,H,,N,NdO,, M , = 826.3, monoclinic,
=
space group P2,. a = 976.0(1). h =1972.7(3), c =1179.6(2) pm.
98.76(1),, V = 2244.7(5) lo-,' m3, z = 2, p..,., = 1.222 gem--', crystal
0.25 x 0.15 x 0.30 mm'; Enraf-Nonius CAD-4 four-circle diffractometer,
Mo,, radiation 71.069 pm, graphite monochromator, (a-26) scan, 1 s 28
5 49 . at 165 K, 3671 independent reflections, 3265 observed (F, >
6n(F0))used in the refinement (SDP software package (data reduction) [XI,
SHELX76 [91). 450 refined parameters. R = 0.0398, data corrected for
Lorentz and polarization effects [lo]. Non-hydrogen atoms refined with
anisotropic thermal parameters. H positions calculated and refined
isotropically with a common displacement factor (U,,*," = 0.111(8) A').
Further details of the crystal structure investigations may be obtained
from the Fachinformationszentrum, Karlsruhe, Gesellschaft fur wissenschafthch-teclinische Information mbH, D-W-7514 Eggenstein-Leo-
Angew. Chcm. I t i f . Ed. E n d . 1993, 32, N o . 6
6 VCH VerlagsgeseltschufimbH.
poldshafen 2 (FRG) on quoting the depository number CSD-57054, the
names of the authors and the journal citation.
[S] B. A. Frenz, Enraf, SDP-Plus Structure Determination Package, Version 3.0, Enraf-Nonius Delft, 1985.
[9] G . M. Sheldrick, SHELX 76, Program for Crystal Structure Determination, University of Cambridge, 1976.
[lo] D. Walker, D. Stewart, Acta Crysrallogr. Sect. A 1968, 24, 321-324.
[ l l ] Subtraction of an ionic radius [I21 of an eight-coordinate Nd3' ion from
the Nd-O distance gives 134 pm. This corresponds closely to the difference
( I 34(5) pm) derived from Ln-O(thf) distances of organolanthanoid-THF
complexes with coordination numbers 7-10 [13] and contrasts to the differences (149- 159 pm) for THF complexes of bulky lanthanoid aryloxides
~41.
[12] R. D. Shannon. Actu Cr,vstullogr.Sect. A 1976, 32, 751--767.
1131 G . B. Deacon, P. I. MacKinnon, T. W. Hambley, J. C. Taylor. J. Orgunumet. Chem. 1983,259,91-91.
[14] G. B. Deacon, T. Feng, S. Nickel, M. I. Ogden, A. H. White, Aust. J
Chem. 1992, 45, 671 -683.
[15] In qz-pyrazolato-Ln coordination, the bond can be viewed as a nondirectional and ionic interaction between the N-N bond and the Ln3+ center.
[16] K. S. Chong, S. J. Rettig, A. Storr, J. Trotter, Can. J. Chem. 1979, 57,
3090- 3098.
[17] For example: P. B. Hitchcock, M. F. Lappert, A. Singh, J Chem. Soc.
Chem. Commun. 1983, 1499-1501.
I181 G. B. Deacon, R. N. M. Smith, J. Org. Chem. USSR (Engl. Trunsl.) 1982,
18, 1854-1855.
[19] J. Elguero, E. Gonzalez, R. Jacquier, Bull. Soc. Chrm. Fr. 1968, 707-713.
[20] G. B. Deacon, S. Nickel, P. MacKinnon, E. R. T. Tiekink, Aust. J. Chem
1990,43, 1245-1257.
[21] A band at 1069(s)cm-' was inadvertently omitted from the reported
spectrum [20].
Delocalization of Electrons in the Dodecahedrane
Cage-A D,,-Symmetrical 4c-3e Radical Cation
as a Structural Borderline Case**
By Klaus Weber, Horst Prinzbach,* Reto Schmidlin,
Fabian Gerson, and Georg GescheidP
Dedicated to Projessor Herbert Zimmermann
on the occasion of his 651h birthday
The very special architecture of cage dienes 1 (7,8;12,19bisseco-I ,I 6-dodecahedradiene, pagodadiene) and 2 (1,16dodecahedradiene)",
with their perfect syn-periplanar,
parallel C = C bonds account for notable gradations in structure and energy:I3] the transannular distance d between the
two x bonds (a,xdistance) increases from 2.62 to 3.52 A, the
pyramidalization angle q5 of the olefinic centers from 9.9 to
42.9", and the diene strain (MM2) from 25.3 to
36.3 kcal mol-'.[' - 3 1
Remarkable consequences of these differences are: 1 undergoes photochemical [2 + 21 cycloaddition, homoconjugate addition of bromine,"] and, above all, facile one- and
['I Prof. Dr. H. Prinzbach, DipLChem. K. Weber
Chemisches Laboratorium der Universitat
Institut fur Organische Chemie und Biochemie
Albertstrasse 21, D-W-7800 Freiburg (FRG)
Telefax: Int. code (761) 203-2815
Dr. G. Gescheidt, DipLChem. R. Schmidlin, Prof. Dr. F. Gerson
lnstitut fur Physikalische Chemie der Universitdt
Klingelbergstrasse 80, CH-4056 Base1 (Switzerland)
['*I Applications of ENDOR Spectroscopy to Radical Cations in Freon Matrixes, Part l l . This research was supported by the Deutsche Forschungsgemeinschaft, the Fonds der Chemischen Industrie, BASF AG, and the
Schweizerische Nationalfonds zur Forderung der wissenschaftlichen
Forschung. We thank Prof. Dr. E. Haselbach and Prof. Dr. T. Bally,
Universitdt Fribourg, Switzerland, for their help with the experiments with
'OCo irradiation, and Dr. P. Such, Bruker Analytische Messtechnik.
Rheinstetten, for measuring ENDOR spectra above 35 MHz. -Part 10: A.
Arnold, U. Burger, F. Gerson, E. Kloster-Jensen, S. P. Schmiedlin. J. Am.
Chem. Soc.. in press.
+
W-6940 Weinherm, 1993
0570-0833/93j0606-0875$ 10.00 + .25jO
875
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butyl, monomeric, lanthanoids, tert, trish, complexes, pyrazolates, ligand, bulka
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