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

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[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
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).
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
BR;'--t RR"B-NR'-BR;'
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
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
respectively, since electronic and (particularly) steric
effects prevent ring closure.
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.
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)
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
0570-0833/85/1111-0998 $ 02.50/0
Angew. Chem. Int. Ed. Engl. 24 i l 9 8 S ) No. 11
[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
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)
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)
1201 H. Noth, K. Staudigl, W. Storch, Chem. Ber. 119 (1981) 3025.
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)
[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
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
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
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hydroborations, butylimido, hydrozirconation, tert, tetramethylpiperidinoborane
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