close

Вход

Забыли?

вход по аккаунту

?

Hydroboration and Hydrozirconation of tert-Butylimino-2 2 6 6-tetramethylpiperidinoborane.

код для вставкиСкачать
[lo] Separation of benzophenone by distillation o r rapid
column chromatography on silica gel (hexane/ether 4 : I ) . 5 , b.p. 47-4X°C/5 x lo-' torr;
[a];;= +SO (c= 1.2 in CHC13). IR and NMR spectra are identical to
those of the racemic lactone [I I].
[ I I ] M. Majewski, V. Snieckus, J. Org. Cbern, 49 (1984) 2682, and references
cited therein.
112) Even the reagents used by Burgess and Martin (see [ I I]) met without
success in this case.
1131 H. Gerlach, W. Muller, Helo. Cbirn. Actn 55 (1972) 2277.
[I41 8 , [a],:"=+66.4 ( c = 1.5, benzene); enl-8, [a]$=-66.8 ( c = 1.5. benzene). Optically pure reference compound (Roussel Uclaf):
[a]??=+67.5 ( c = 1.8, benzene).
Hydroboration and Hydrozirconation of
tert-Butylimino-2,2,6,6-tetramethylpiperidinoborane
By Detlef Mannig, Heinrich Noth,* Manfred Schwartz,
Siegfried Weber, and Ulrich Wietelmann
Dedicated to Professor Max Schmidt on the occasion of
his 60th birthday
Whereas the N M R data of 2-4 are consistent with the
proposed structures, the two hydrozirconation products
5a, b obtained according to Eq. (3) (Cp = cyclopentadienyl)'I2I showed "B-NMR signals which are not reconcilable with an N-metalated bis(amin0)borane (5a: 6=21.5;
5b: 6= 16.8; HB(NR&: 6=26-28; RN(NR,)NRLi:
S=25). The IR spectra d o not contain any stretching
modes of terminal BH-bonds. Medium strength bands in
the region 1865-1910 c m - ' suggest the presence of hydride
bridges. The proposed structure A is based on this finding
(for 5b: C1 replaced by H).
Cp2ZrHX
N-EN-fBu
+
-
5
Cp2Zr~Xl-N(fBul-B(HlN
a,X:CL,
b,X=H
5
A
In many respects the chemistry of the i m i n ~ b o r a n e s ~ ' - ~ ~
is similar to that of the isoelectronic alkynes: they oligomerize or polymerize,[21add HX,[" and form complexes with
transition metals.[41However, the polarity of the BN bonds
An X-ray structure analysis of 5a confirms this postulate
confers enhanced reactivity on iminoboranes. This is ex(cf. Fig. 1). The zirconium atom is coordinated in a disemplified by their rapid organoboronation to diborylamtorted trigonal-bipyramidal fashion if one takes into conines according to Eq. (I)."l
sideration the centroids C, and C, of the $-bonded C p
ligands and the atoms H1, CI, and NI. Each C p ring shows
O
b
R-B-N-R'+
BR;'--t RR"B-NR'-BR;'
(1)
two longer and three shorter C C bond distances. The thermal parameters of the C(F)-C(K) ring suggest disorder; its
Alkynes undergo a cis-hydrometalation." We have now
CC bonds are on average shorter (1.352(9) A) and subject
investigated the hydrometalation of iminoboranes using
to larger standard deviations than the CC bonds of the C p
tert-butylimino-2,2,6,6-tetramethylpiperidinoborane
1 as
ring C(A)-C(E) (1.395(4) A).
an example.'"l If H,B.THF (THF= tetrahydrofuran) is
used, the reaction at - 65 "C and high dilution proceeds according to Eq. (2) to give the four-membered ring diborylamine 2 as the main product.I8l In contrast to this, hydroboration with 1,3,2-benzodioxaborole and with 9-borabicyclo[3.3. llnonane leads to the BN chain compounds 3I9l and
4,r'01
respectively, since electronic and (particularly) steric
effects prevent ring closure.
1
2
3
4
Whether the hydroboration of 1, like that of the alkynes,
proceeds stereospecifically by cis-addition, could not be
confirmed in the above three examples by monitoring the
reactions N M R spectroscopically at low temperatures. The
reason for this is that the rotation barrier of the C C double
bond is markedly higher than that of the BN bond of aminoboranes (40-100 kJ/mol).["I For formation of 2, a rotation about the central BN bond of a cis-hydroboration
product is necessary.
[*I
Prof. Dr. H. Niith, Dr. D. Mannig, MSc., Dipl.-Chem. M . Schwartz,
Dr. S. Weber, Dipl.-Chem. U. Wietelmann
lnstitut fur Anorganische Chemie der Universitat
Meiserstr. I,D-8000 Miinchen 2 (FRG)
998
0 VCH Verlagsgesellschafl mbH, 0-6940 Wernheim. 1985
Fig. 1. ORTEP plot of the molecular structure of 5a 113). For clarity, Cbonded hydrogen atoms have been omitted. Selected bond lengths and angles ([A] and ['I, standard deviations in brackets): Zr-CI 2.551(1), Zr-NI
2.211(2), Zr-HI 1.96(2), Zr-B 2.627(2), B-NI 1.360(3), B-N2 1.459(4), B-HI
1.25(2), NI-CI 1.497(3), N2-CIO 1.499(4), N2-Cl4 1.493(4); CI-Zr-HI
146.3(6), CI-Zr-B I19.4(2), CI-Zr-NI 88.7(1), Zr-NI-B 91.5(2), Zr-NI-CI
137.8(2), C I - N I - B 130.5(2), NI-B-N2 140.3(3), NI-B-HI 102.3(9), N2-B-H
117.4(9), B-N2-CIO 115.9(2), B-N2-C14 120.1(3), CIO-N2-C14 117.7(2), BHI-Zr 107.7(12); C,-Zr-CI 99.8, C,-Zr-CI 98.3. C,-Zr-C, 122.3, C,-Zr-N I
114.1, C,-Zr-NI 120.6 (Cx, C,: centroids of the Cp rings).
Characteristic for 5a is a ZrHBN four-membered ring
system. A short BN bond of only 1.360 A is present which
may be regarded ?s a double bond (1.37 A in
The ZrN bond is
(CH3)2NBClr,"411.33 A in (R2N)2B@i['51).
only slightly longer than in compounds of Zr'" with sp2
hybridized N atoms (2.070 A in C1Zr[N(SiR3)J3
(R=CH3),"'] 2.167 A in Cp,Zr(NC,H&, and 2.198
in
0570-0833/85/1111-0998 $ 02.50/0
A
Angew. Chem. Int. Ed. Engl. 24 i l 9 8 S ) No. 11
(3)
[Zr(NC,H4),]'-"7'). Both the BH as well as the ZrH -distances are consistent with H-bridges (1.25 and 1.35 A in
p-aminodiboranes"'] and 1.73-1.88 A in H-bridged Cp,Zrcompoundsl"l). The tetramethylpiperidino group is
strongly twisted towards the four-membered ring plane:
the C 10-N2-C14 plane is inclined at an angle of 77" to the
plane of the four-membered ring. Consistent with this is
the relatively long BN2 bond (1.459 A), indicating single
A
The ZrB distance is only 0.18 longer than would be
expected for a covalent ZrB bond (2.45 A). This finding is
compatible with a Zr-H-B multicenter bonding, and the
resulting ZrB interaction could be responsible for the good
shielding of the boron atoms in the NMR experiment.
5a thus contains a novel bonding system reminiscent of
that of a p-H-metallaborane. However, it differs from the
latter in that the boron atom is only three-coordinated.
Thus, N-metalated aminoboranes, whose structural chernistry promises new and interesting aspects of bonding, are
accessible by hydrometalation of 1 (and presumably also
of other irninoboranes).
(IOH), 1.36 (9H). 1.5-1.0 (18H): 6("B)= 16.8, /i(1/2)=190 Hz (decoupled), 240 Hz (coupled); S("C)= 18.65, 24.9, 31.57, 32.5, 40.90, 51.46,
53.90, 104.14: IR: v = I875 c m - ' (hr).
1131 Single crystals from hexane: a=8.201(2), b=32.I l(12). c=9.511(2)
/I=
108.30(2)', V=2383(1) A', Z=4,pL.,,.= 1.34 g/cm'. P2,/n, crystal dimensions: 0.2 x 0.3 x 0.5 mm, co scan, scan rate 3-29.3"/min, range of
measurement 28: 2-50", f h , k, + I , 7815 measured intensities, 3789
symmetry-independent with I > 3 ~ ( 1 )anisotropic
;
temperature factors
for non-hydrogen atoms; one methyl group refined as rigid group.
Rs0.043, R,=0.034 with l/w~=o(F)+O.O001(F)'.
Number of refined
parameters: 396. Further details of the crystal structure investigation are
available on request from the Fachinformationszentrum Energie, Physik, Mathematik GmbH, 7514 Eggenstein-Leopoldshafen 2, on quoting
the depository number CSD-51403, the names of the authors, and the
full citation of the journal.
[I41 L. S. Bartell, F. B. Clippard, Inorg. Chem. 9 (1970) 2439.
1151 H. Noth, K. Staudigl, H:U. Wagner, Inorg. Chem. 21 (1982) 706.
[I61 C. Airoldi, D. C. Bradley, H . Chudzynska, M. B. Hursthouse, K. M. A.
Malik, P. R. Raithby, J. Chem. Sac. Dalton Trans. 1980. 2010.
[I71 R. yon Bynum, W. E. Hunter, R. D. Rogers, J. L. Atwood, Inorg. Chem.
19 (1980) 2368.
[I81 K. Hedberg, A. J. Stosick, J. A m . Chem. Sac. 74 (1952) 954.
[I91 I Kopf, H. J. Vollmer, W. Kaminsky, Crysr. Srrucl. Commun. 9 (1980)
985; G. P. Pez, C . F. Putnik, S . L. Snib, G. D. Stucky, J. Am. Chem. Soc.
/ 0 / (1979) 6933; S. B. Jones, J. L. Petersen, Inorg. Chem. 20 (1981)
2889.
1201 H. Noth, K. Staudigl, W. Storch, Chem. Ber. 119 (1981) 3025.
A,
Experimental
Bis(i~'-cyclopentadienyl)-~-hydridozirconium-lert-butyl(2,2,6,6-tetramethylpiperidinohory1)amide chloride 5a : A stirred suspension of Cp,ZrHCI
(0.52 g) in toluene ( 5 mL) was treated dropwise with a solution of 1 (0.44 g)
in toluene (4.4 mL) in the absence of light. After 24 h the clear solution
showed "B-NMR signals at 6=30.2, 21.1, and 18.4 in the ratio 15 : 7 0 : 15.
The toluene was removed by distillation and the residue was dissolved in a
small amount or dichloromethane. Hexane was then added to the resulting
solution until it turned turbid. The Cp2ZrHCI which crystallized out on cooling to - 15°C was removed by filtration and the solution concentrated to a
third 0 1 its volume by evaporation. Subsequent cooiing to -78°C afforded
0.4 g of 5a (42%).
Received: May 2, 1985;
revised: June 10, 1985 [Z 1285 IE]
German version: Angew. Chem. 97 (1985) 979
Publication delayed at authors' request
[I1 P. Paetzold, A. Richter, T. Thijssen, S. Wurtenberg, Chem. Ber. I12
(1979) 38 II; P. Paetzold, T. von Benningsen-Mackiewicz, ibid. 114
(1981) 298: P. Paetzold, C. von Plotho, G . Schmid, R. Boese, B. Schrader, D. Bougeard, U. Pfeiffer, R. Gleiter, W. SchBfer, ibid. 117 (1984)
1089.
[2j P. Paetzold, C. von Plotho, Chem. Ber. 7 I S (1982) 28 19.
[3] P. Paetzold, C . von Plotho, H. Schwan, H.-U. Meier, 2. Naturforsch. 8 3 9
(1984) 610; A. Brandl, H. Noth, Chem. Ber. 118 (1985) 3759.
(41 P. Paetzold, private communication 1984.
[S] H. C. Brown, G. Zweifel, J . Am. Chem. Sac. 83 (1961) 3834; G. Zweifel,
H. Arzoumanian, C. C. Whitney, ibid. 89 (1967) 3652; P. C. Wailes, H.
Weigold, A. P. Bell, J . Organomer. Chem. 27 (1971) 373; D. W. Hart, T.
F. Blackburn. J. Schwartz, J . Am. Chem. Sac. 97 (1975) 679.
[6] H. Noth, S . Weber, Z . Naturforsch. 8 3 8 (1983) 1460.
(71 1 can also he hydrosilylated, hydrostannated, and hydroaluminated.
[8] B.p. 57-58"C/IO-2 torr; NMR (CnD6): 6('H)= 1.52-1.08 (6H), 1.38
(6H), 1.29 (6H), 1.27 (9H), 4.40 (BH), 3.47 (BHz); 6("B)=28.8 (d), 4.4
( t ) ( l :1);6("C)=56.6,49.6,37.5,30.8,30.1,25.8, 17.2;1R:2510(v(BN)),
2362, 2350 (v(BH,)), 1580 c m - ' (v(BN)). Also formed are (R,CNBH),?
(6("€3)=37.2), t m p H . BH, (6("B): -20.3, Q) p-tmpB2H, (6("B)=26.2,
doublet of triplets): R=CH3, tmp=tetramethylpiperidino moiety). 2
cannot be completely separated from byproducts by distillation.
[9] M.p. 72-73°C; NMR (C,D6): 6('H)=7.1-6.6 (m, 4H), 1.46 ( s , 9H), 1.42
(s, 12H), 1.6-1.3 (m, 6 H ) ; 6("B)=34.7 (HBN2), h(1/2)=430 Hz: 24.4
(NBOI), b(1/2)=280 HZ ( I :I);6("C)=15.76, 31.26, 33.63, 37.03, 52.97,
55.48, 111.42, 121.66, 149.13; 1R: 2482 c m - ' (v(BH,)).
[lo] M.p. 65-67°C; NMR (C,D6): 6('H)=1.05 (2H), 1.37 (12H), 1.50 (9H),
1.91 (12H); fi("B)=48.8 (NBC2), 35.3 (HBN2) with 'J("B'H)=82 Hz;
6("C)= 15.86, 23.46, 26.45, 32.25, 33.03, 33.17, 33.87, 37.23, 53.57, 55.91;
I R : 1475 c m - ' (v(BH,)).
[ I I ] H. Heall, C. H. Bushweller, Chern. Reu. 73 (1973) 465; Y. F. Beswick, P.
Wisian-Nelson, R. H. Nelson, J. Inorg. Nurl. Chem. 43 (1981) 2639.
(121 5 a : m.p. 135°C (Zers.): N M R (C,D,): 6('H)=5.96 (IOH), 1.57 (9H),
1.6-1.2 (6H), 1.20 (6H). 1.16 (6H); 8("B)=21.5, h(1/2)=250 Hz (decoupled), 330 Hz (coupled): 6("C)= 18.24, 26.39, 32.34, 35.17, 40.73,
51.66,56.72, 112.59; I R : 1909 (sh, w), 1887 (m), 1865 (w); 1597 (w), 1498
c m - ' (s).-Sb: m.p. 180-188°C (decamp.); N M R (C,D,): 6('H)=5.68
Angew. Chem. Inr. Ed. Engl. 24 (1985)
No. 7 1
Synthesis and Structure of a
Diaza-12-phosphanylia-)i5-stannatacyclobutane
By Manuela Burklin, Elisabeth Hanecker, Heinrich Noth, *
and Wolfgang Storch*
Stannazanes are attracting increasing interest as versatile
synthons for main group element-nitrogen compounds,"]
e.g., for the synthesis of phosphazar~es.~'.~~
They are also
suitable, as reported here, for the synthesis of a novel ring
system.
Phosphorus trichloride reacts with the stannazane tertbutylbis(trimethylstannyl)arnine in the molar ratio 1 :2 to
give the diaminochlorophosphane I , which has only been
detected NMR-spectroscopically; 1 decomposes slowly
below 0°C and quantitatively within 5 h at room temperature. Cyclocondensation, which surprisingly involves formation of tetramethyltin, does not, however, lead to the
diazaphosphastannetidine 2 but to the zwitterion diaza-h2phosphanylia-h5-stannatacyclobutane3. In contrast, the
N-silylated diaminophosphane CIP(NCR3SiR&, a homologue of 1, decomposes with elimination of Me3SiC1.[4,51
Compound 3 undergoes substitution at the Sn-bonded
chlorine atom on reaction with organolithium compounds:
The zwitterionic derivatives 4 are formed. By way of contrast, the reaction of 3 with LiBH4 in ether leads to formation of 5 . Apparently a positively charged h3-phosphorus
center is unstable; its expectedly pronounced electrophilicity therefore favors a hydride migration from the tin atom
to the phosphorus atom.[''
The structures of 3-5 follow from the NMR spectra.[71
Thus, the Il9Sn chemical shifts confirm pentacoordinationis]in 3 and 4a and tetracoordination of the tin atom in
5, whose BH, group, according to the BP coupling, is
bound to the P atom. The I4N-nuclei in 5 are better
shielded (A6(I4N)= 130) as compared to those in 3 and
4a. This is not only an indication of trigonal planar coordinated N atoms but is also a strong argument for pro[*] Prof. Dr. H. Noth, Dr. w . Storch, M. Biirklin, Dipl.-Chem. E. Hanecker
lnstitut fur Anorganische Chemie der Universitat
Meiserstr. I , D-8000 Miinchen 2 (FRG)
0 VCH Vertagsgesekhuft mbH, 0-6940 Webiheim. 1985
OS70-0833/85/1111-0999 $ 02.50/0
999
Документ
Категория
Без категории
Просмотров
1
Размер файла
260 Кб
Теги
hydroborations, butylimido, hydrozirconation, tert, tetramethylpiperidinoborane
1/--страниц
Пожаловаться на содержимое документа