Reactions of amino-imino-boranes with transition metal halides and substituted transition metal halides

Article abstract of DOI:10.1515/znb-2001-0714

The aminoiminoborane tmp-B≡NCMe₃ (1) adds to TiBr₄ or ZrCl₄ in a 1:1 ratio while PdCl₂ adds 1 in a 1:2 ratio. In these new compounds the NBN unit is almost linear and the configuration corresponds to an allene. On the other hand 1 and Ti(OR)4 compounds and Ti(NMe₂)₄ give N metallated diaminoboranes tmp-B(X)-NCMe₃EX₃ (X = OR, NMe₂). Mixed compounds Ti(OR)_3-nX_n lead to diaminoboranes with BOR groups while the TiCl bond inserts into the B≡N bond of 1 to produce tmp-BNMe₂-NCMe₃TiCl₃. Hydrolysis of this compound leads to a spirocyclic dititanoxane with a short linear Ti-O-Ti bond and pentacoordinated Ti centers carrying two Cl atoms each. Spirocycles with a BN₂E (E = Ti, Nb, Ta, Pd) unit are formed when 1 is allowed to react with TiCl₄, NbCl₅, TaCl₅ and PdCl₂. The palladium compound 16 is dimeric, and dimerization occurs via Pd-Cl bridges. The aminoiminoborane tmp-B=NC₆H_3-2,6-iPr₂ reacts with the titanium compounds in the same manner as 1, however without formation of spirocycles.

Full text of DOI:10.1515/znb-2001-0714

Reactions ofAmino-imino-boranes with Transition Metal Halides
and Substituted Transition Metal Halides
Barbara Böck, Heinrich Nöth, and Ulrich Wietelmann
Department of Chemistry, University of Munich,
Butenandtstr. 5-13, D-81 377 München, Germany
Reprint requests to Prof. Dr. H. Nöth. E-mail H.Noeth@lrz.uni-muenchen.de
Dedicated to Professor Dr. H. P. Fritz
Z. Naturforsch. 56 b, 659-670 (2001); received May 3, 2001
Adducts of Aminoimino Boranes, Metallated Diaminoboranes, Titanium
The aminoiminoborane tmp-B=NCMe3(1) adds to TiBr4or ZrCL in a 1:1 ratio while PdCh
adds 1in a 1:2ratio. In thesenewcompounds theNBN unit isalmost linearandtheconfiguration
corresponds to an allene. On the other hand 1 and Ti(OR)4 compounds and Ti(NMe2)4 give
N metallated diaminoboranes tmp-B(X)-NCMe3EX3 (X = OR, NMe2). Mixed compounds
Ti(OR)3_„X„ lead to diaminoboranes with BOR groups while the TiCl bond inserts into the
B=N bond of 1to produce tmp-BNMe2-NCMe3TiCl3. Hydrolysis of this compound leads to
a spirocyclic dititanoxane with a short linear Ti-O-Ti bond and pentacoordinated Ti centers
carrying two Cl atoms each. Spirocycles with a BN2E (E = Ti, Nb, Ta, Pd) unit are formed
when 1is allowed to react with TiCU, NbCls, TaCls and PdCh. The palladium compound 16is
dimeric, and dimerization occurs via Pd-Cl bridges.
The aminoiminoborane tmp-B=NC6H3-2,6-/Pr2 reacts with the titanium compounds in the
same manner as 1, however without formation of spirocycles.
Introduction
ily formed with covalent EX„ molecules. Type A
adducts are best known for metal carbonyls [4],
Iminoboranes RN=BR' [2] and aminoiminobo-
ranes R2N-B=NR' [3] are highly unsaturated and
therefore very reactive compounds due to the pres-
ence of dicoordinated boron and nitrogen atoms
linked by a triple bond. Therefore, only members of
these family of compounds are known where bulky
substituents R, R' and R2N provide kinetic stabil-
ity. Nevertheless, thesecompounds react easily with
a large variety of inorganic, metal organic and or-
ganic compounds at the BN triple bond. In case
of aminoiminoboranes, the presence of the amino
group adds an additional reactive center. Many of
itsreactions have been summarized in two extensive
reviews [2, 3].
Three types of reactions between electrophiles
EX„ with aminoiminoboranes A have so far been
observed: i) the formation of simple adducts A;
ii) insertion of the BN triple bond into an E-X
bond to produce diaminoboranes B, and iii) inser-
tion followed by the formation of a heterocycle C
by establishing an intramolecular E-N bond. These
heterocycles result for strongly Lewis acidic EX„_i
fragments while diaminoboranes oftype B are read-
-Ph
B— N
In this report we describe reactions of two
aminoiminoboranes with various transition metal
0932-0776/01/0700-0659 $ 06.00 (c) 2001 Verlag der Zeitschrift für Naturforschung, Tübingen • www.znaturforsch.com
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660
B. Böck et al. ■Reactions of Amino-imino-boranes
halides, alkoxides, dimethylamides and mixed aminoiminoborane 1. The results are summarized
species in order to explore relative migratory ap-
titudes of these substituents, particularly for tita-
nium(IV) compounds.
in eq. (2).
Finally, the formation of heterocycles of type C
were observed in reactions of 1 with TiCU, NbCl5,
TaCIs and PdCl2 as described by eq. (3). PdCl2
gives two different products in its reaction with 1.
Moreover, an additional compound, 23, was iso-
lated in small amounts from the reaction of 1 with
TiCl3NMe2, obviously aresult ofhydrolysis. Due to
its small yield compound 23was only characterized
by an X-ray structure determination (v. i.).
Reaction
At ambient temperature no reaction of
the aminoiminoborane
1
was observed with
CpTiCl3, Cp2TiCl2, Cp2ZrCl2, (Ph3P)AuCl and
(Ph3P)Ru(CO)Cl. However, adduct formation to
give compounds of type A was noted in case of
TiBr4, ZrCL* and PdCl2, while the aminoiminobo-
rane 2 did not react with TiBr4 and ZrCU (PdCl2
has not been tested).
17
20
21
OiPr Cl
OBu Cl NMe2
22
18
19
X
Y
Cl
Br OiPr OBu
Cl Br OiPr
NMR Spectra
The 11B NMR spectra should allow the assign-
ment of the structures of the new compounds.
In adducts of type A the boron atom is two-
coordinated. As these adducts are isoelectronic with
cations of type (R2N=B=NR2)+[5] which are char-
acterized by signals in the range of 30 to 35 ppm
and fairly large line widths one may expect similar
features for the 11B NMR signals of type A com-
pounds. On the other hand, diaminoboranes show
resonances in theregion of20 to 30 ppm, depending
of the nature of the third substituent [6]. Therefore,
the resonances for type B compounds should fall
into this range. Compounds of type B and C have
three-coordinated boron atoms which are bonded to
only one three-coordinated N atom which allows
for BN-tt bonding. Consequently, its boron atoms
should be less well shielded as compared with com-
pounds of type A. Table 1summarizes the 11B NMR
data.
7
9
10 11
12
6
8
Ti
Ti
Ti
Ti
Ti Ti
Ti
OBu
OBu
OiPr
OiPr
NMe2 OiPr NMe2 Cl
X3
Y
OEt
OEt
Cl OiPr
NMe2
NMe2
ci
Cln-1
_________
(3)
13 14 15 16
Ti
E
n
Nb Ta Pd
4
5
5
2
Many of the investigated transition metal com-
pounds give bis(amino)boranes of type B. These
results are summarized in eq. (2). For the titanium
compounds the scale for reactivity is Cl > OR >
NMe2, a trend that is not surprising. The same
kind of behavior was also noted for the reaction
Compounds 3 to 5 show broad signals, two of
which are in the expected range while the 11B atom
of the aminoiminoborane 2with TiCl3NMe2. How- of the palladium dichloride adduct is much better
ever, it is one isopropoxy groups of ClTi(OiPr)3 that shielded. Most likely this is due to astronger param-
binds to the boron atom, a behavior that is differ- agnetic contribution to the shielding resulting from
ent compared with the same reaction involving the the Pd atom. The basic structural skeleton of these
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B. Böck et al. •Reactions of Amino-imino-boranes
661
Table 1. 11B NMR data for compounds of types A, B, and C;
6
in ppm, half widths given in parentheses (in Hz).
3 = TiBr4• 1
34.4
640
5 = PdCl2•2(1)
25.2
750
4 = ZrCl4• 1
35.9
580
6
UB (ppm)
hi/2 (Hz)
7 = Ti(0/Pr)4 1
6 = Ti(OEt)4• 1
8 = Ti(OfBu)4• 1
9 = Ti(NMe2)4• 1
<5UB (ppm) 24.8
520
26.1
370
26.8
370
29.5
260
h,/2 (Hz)
10 = TiCl(0/Pr)3• 1 11 = Ti(0/PrhNMe2• 1 12 = Ti(NMe2)Cl3• 1 14 = Ti(0/Pr)3N(SiMe3)2• 1
6
UB (ppm) 25.5
520
28.4
300
32.1
310
hi/2 (Hz)
(18 = PdCl?- 1)2
23.8
270
15 = TiCU • 1
<5nB (ppm) 36.2
16 = NbCl5
30.3
170
1
17 = TaClg • 1
30.5
260
180
h,/2 (Hz)
20 = TiBr4•2
34.2
740
21 = Ti(0/Pr)4•2
25.0
410
19 = TiCl4 •2
<5nB (ppm) 37.2
440
hi/2 (Hz)
21 = Ti(OBu)4 •2
23 = TiCl3NMe2•2
36.6
490
22 = TiCl(OiPr), •2
23.2
430
8
UB (ppm) 25.7
580
hi/2 (Hz)
Table 2. 1H NMR data for compounds of types A, B, and C. Numbering as given in eq. (1 -3);
constants 7(H,H) in Hz.
6
1H in ppm, coupling
H2,3,4
H6,6', H7,7'
1.2 (br.)
C(CH3)3
1.44
1.38
1.25
1.21
1.24
1.49
1.46
1.45
1.06
1.62
1.41
1.43
BOR/BNMe2
-
TiOR/Ti(NMe2)
-
1.1 -1.7 m
1.3 -1.6 m
1.01 -1.46
1.06- 1.39
0.84- 1.43
1.32- 1.67
1,16- 1.18
1.20- 1.70
1.23 -1.30
1.3 -1.7
1.9 br
1.91 br
1.80 br
1.33- 1.41
1.12- 1.46
0.94- 1.32
0.90- 1.40
1.01 -1.59
1.20- 1.43
3
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
-
-
1.45, 1.56
1.10 (br)
1.10 (br)
1.37 (br)
1.35, 1.38
1.22 (br)
1.33, 1.41
1.45
1.28, 1.52
1.63 br
1.62 br
1.43, 1.44
1.60 br
1.78 br
1.11 t,38.7 q (7.08)
1.09 d, 4.49 se (6.1)
1.07 m, 4.1 m
2.59 s
1.27 t, 4.29 q (7.3)
1.19 d, 4.45 se (6.1)
0.88 m, 4.3 m
3.15
1.27 d, 4.86 se (6.1)
1.60 d, 5.16 s
4.93 s, 1.64,2.67
1.46, 10.4 d
1.76
1.20 d 1.41 d
1.34 d, 1.57 d
1.33, 1.37
1.05, 1.20
1.34, 1.36
1.25, 1.49
1.74, 1.84
1.52, 1.59
1.52, 1.79
0.76, 1.13
0.93 d, 3.94 se (6.6)
3.13 br
087 d, 3.88 se (7.11)
1.14 d, 4.68 se (6.0)
3.95 t, J = 6.35
1.29 d, 4.87 se (6.3)
2.39 s
three compounds should show the geometry of al- trum revealed a broad signal for the methyl carbon
lenes, i. e. the C2N atoms of the tmp group and the atoms. At -40 °C this broad signal splits into two
NC(E) plane should be (more or less) perpendicular signals. On the other hand no reliable data could
to one another. This would make the Me groups of be observed for the ZrCU compound 4 due to rapid
tmp substituent inequivalent; and two setsof signals decomposition in CD2CI2 solution.
for the four methyl groups should be present in the
!H and 13C NMR spectra. These have indeed been
observed for the palladium complex 5. In case of
the TiBr4 adduct 3 only a single signal was found
in the 'H NMR spectrum while the 13C NMR spec-
The barrier to rotation in compound 5 was de-
termined as zAG* = 68±3 kJ/mol. This value is
10 kJ/mol less than found for bis(dialkylamino)-
boron cations [7]. The rotational barrier for com-
pound 3 was even lower with zAG* = 62±3 kJ/mol.
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662
B. Böck et al. ■Reactions of Amino-imino-boranes
in ppm.
BORa
Table 3. 13C NMR data of for compounds of types A, B, and C;
6
C3
C2,4
C6,7
TiORaNMe2
Cl,5
CMe
3
CMe3
64.0
31.3 br
38.62 31.54, 28.83
3
5
6
7
8
9
16.75 57.95 37.20
16.93 54.42
19.09 50.88 39.38
19.02 50.65
32.0
54.32 34.2
54 br 34.42 20.24, 59.72
48.43 32.15 19.02, 32.15
30.25,32.31
32.2 br
16.25,70.66
27.71,76.22
41.28
19.18 50.99 39.36 30.48, 32.22 54.73 34.43 14.57, 19.86, 36.34, 65.65 14.43, 19.69, 37.13,75.1
19.12
40.01
24.10, 68.62
34.72 23.00, 64.89
47.23
53.00 40.46 32.03, 33.63
57.73 35.35
38.04
30.50, 32.29
37.91 30.69, 32.48
31.93, 32.48 54.07 32.40
39.61
55.7
-
35.7, 81.76
46.47
46.19
10 10.03 51.13
11 18.94 51.40
12 18.19 66.35
34.49
13 17.03 61.37 37.75 32.39, 31.50 65.05 30.57
14 16.07
15 16.12
16 17.55 61.6,
61.5
59.87
60.72
33.29, 33.29, 54.9
32.16, 32.34
65.89 36.21 26.47,31.16
36.21 26.45,31.62
30.73
30.69
32.79
65.89
36.7,
36.8
17
18 17.51 57.77 36.96 31.35, 31.89
19 18.6 55.17 36.96 30.36, 33.60
20 18.33 55.56 33.45 29.19, 32.22
21 17.67 57.25 38.35
22 15.43 54.39 37.53 31.92, 33.25
59.87 37.67 30.67, 33.16
16.08
29.29, 33.75
C8 CIO C ll C12
C9
C13/13'
BOR
TiOR/NMe2
17
18 145.80 125.29 131.60 124.42 29.35 24.38,25.52
19 151.54 123.24 28.07 24.24,25.07 24.01,64.99
13.77, 19.65,33.45,63.92
160.83 128.18 138.82 124.10 29.03 24.02,25.11
26.4, 78.20
125.88 140.96
20 150.20 123.51 140.78 122.95 28.09 24.41,24.41
14.03, 19.37, 36.35,75.56
25.42, 83.2
48.20
21
22
157.75 124.28 140.38 123.19 29-38 24.23,25.28 24,99, 65.97
157.20 127.59 238.61 124.61 29.35 24.42,26.21
R
as given in the formula number.
6 to 8) leads to <5n B = 24.8 to 26.8. The reaction
Although the NMR data are consistent with the sug-
gested structures the most convincing argument for of 1 with Ti(NMe2)4 produces a tris(amino)borane,
their structures is provided by IR data: two strong and compound 9 gives rise to an n B NMR signal
at 29.5 ppm which is typial for tris(dialkylamino)-
bands for all three compounds were observed in
the region 1887 to 1757 cm-1 which we assign to boranes [6]. Therefore, the n B NMR signal for 10
at 25.5 fits to the (R2N)2BOR series of compounds.
On the other hand, the 11B NMR signal at 32.1 ppm
for compound 12 is in accord with the presence of a
B-Cl bond. These conclusions are supported by 'H
and 13C NMR data. For compounds 6 to 8 two sets
of signals for the OR groups are observed (in a 1:3
the antisymmetric and symmetric stretching modes
of the BN2 unit in agreement with IR data ob-
served for the isoelectronic bis(dialkylamino)boron
cations [5]. It is interesting to note that the pal-
ladium complex shows the highest wave numbers
(1887 and 1824 cm"1) demonstrating particularly
strong BN-7r-bonding.
ratio for the
resonances). A single resonance is
found for the methyl groups of the tmp substituent
indicating free rotation about the respective B-N
bond at ambient temperature. This rotation is, how-
ever, hindered in compound 9 as there are two sig-
nals both in the ]H and 13C NMR spectrum for the
tmp methyl groups. On the other hand only single
signals were observed for BNMe2 and Ti(NMe2)3
groups.
In case of type Bcompounds the 11B NMR spec-
traallow adecision which substitutuent ofthemixed
titanium compounds has migrated from the titanium
atom to the boron atom because the shielding of
the boron atom in compounds of type (R2N)2BX
depends primarily on X and increases in the or-
der Cl < NR2 < OR. Inspection of Table 1 shows
that an OR group at the boron atom (compounds
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B. Böck et al. ■Reactions of Amino-imino-boranes
663
The presence ofaBO/Pr group in compound 10is
manifested by two sets of resonances belonging to
the boron and titanium bonded isopropoxo groups.
Only one signal for the Me2N groups in compound
11 and one set of signals for the O/Pr group demon-
strate that the OR group has moved to the boron
atom as deduced also from the 1'B NMR spectrum.
Finally, a fairly strongly deshielded 13C NMR sig-
nal for the Me2N group in 12 is not compatible with
the presence of a BNMe2 unit.
The formation of the heterocycles of type C can-
not be unequivocally deduced from the 11B NMR
spectra since the shielding of the boron atoms is
not distinctly different from those of type C: This
had to be expected for compounds with a tricoor-
dinated boron atom. However, they can be readily
recognized by a considerable deshielding of the 13C
resonance of the quaternary C atoms of the tmp sub-
stitutents whose N atom becomes tetracoordinated
and adopts an ammonium type character on ring
formation.
Fig. 1. Schematic drawing of the structure of the dimer of
compound 16. The tmp rings are drawn in two different
configurations.
tem while TiBr4 produces an adduct. The titanium
tetraalkoxides react with formation of diaminobo-
ranes and the same kind of migration behavior is
observed with the mixed compounds ClTi(0 /Pr)3
and Cl3TiNMe2 for 1 .
Molecular Structures
As compounds C are spirocycles their suggested
molecular structure should lead to two sets of
methyl groups of the tmp substituent, and this has
indeed been observed. All other NMR data arecom-
patible with the spirocyclic structure. Moreover, in
case of the palladium compound 16 two 14N NMR
signals were observed at -250 and -35 ppm. The
high field signal is assigned to the ammonium type
N atom while the broad signal at -250 ppm repre-
sents the tree-coordinated N atom [8],
Single crystals were obtained of the byproduct
of the TiC^NMe? reaction as well as of the two
palladium complexes. The byproduct proved to be
One further observation on compound 16 needs a
comment. Its molecular structure as determined by
X-ray structure analysis shows that the compound is
present as a centrosymmetric chloro bridged dimer.
Only two chemically different tmp methyl groups
(C6, C l) were expected. While the *H-NMR spec-
trum shows only a single fairly broad signal for the
methyl hydrogen atoms we find in the l3C NMR
spectrum two pairs of signals for these methyl car-
bon atoms, and also two signals for atoms Cl/5
and C2/4. We take this as evidence that in solution
there is ring inversion. This should also result in two
signals for the C3 atom, but this has not been ob-
served.
Fig. 2. Molecular structure of 23. Thermal ellip-
soids are drawn on a 50% probability scale. Hydro-
gen atoms omitted for clarity. Selected bond lengths
(in A) and bond angles (in0): Ti-Cll 2.260(2), Ti-C12
2.2081(2), Ti-0 1.805(1), Ti-Nl 1.93(3), Ti-N3 2.330(3),
Ti-B 2.563(4), Nl-B 1.433(4), N2-B 1.460(4), N3-
B 1.505(3), Nl-Cl 1.497(3), N3-C6 1.84.7(4), N3-C5
184.5(4); Cl 1-Ti-C1294.1(1), Cl 1-Ti-0 102.5(1), C12-Ti-
O 108.8(1), Ti-O-Ti(a) 180, Cll-Ti-Nl 97.1(1), C12-Ti-
N1 134.9(l),0-Ti-Nl 111.1(3), Cl1-Ti-N3 150.1(1), C12-
Ti-N3 84.5(1), 0-Ti-N3 106.3(1), N1-Ti-N3 64.9(1), Bl-
B-N3 103.7(2), N1-B-N2 130.9(2), N1-B-N3 103.7(2),
N3-B-N2 124.9(2).
The boron atom of the aminoiminoborane 2 is
sterically more strongly shielded than the boron
atom in 1. We therefore expected that additions
product of type A would be favored. This, however,
is not the case. TiCU gives rise to a spirocyclic sys-
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664
B. Böck et al. •Reactions of Amino-imino-boranes
the titanoxane 23 (see Fig. 2). The bordeaux red
compound crystallized in the triclinic space group
P\ (#2) with Z = 1. Its oxygen atom resides on an
inversion center. Consequently, the Ti-O-Ti bond
angle is 180°. The Ti atoms are pentacoordinated
by one oxygen atom, two nitrogen atoms and two
Cl atoms, and the geometry around the Ti atoms
is best described as distorted trigonal bipyramidal
with atoms C12 and N3 occupying the axial posi-
tions as demonstrated by an N-Ti-Cl bond angle of
150(1)°.The sum of bond angles between the equa-
torial atoms O, C12 and N 1is 354° with a very open
C12-Ti-Nl bond angle of 134.9(1)°.
The four-membered T i^B ring is folded as
shown by the sum of bond angles of 347.4°, the
smallest angle being 64.9(1)° for Nl-Ti-N3, the
widest 103.7(2)° for N1-B-N3. One notes that the
tmp group is not involved in ring formation.
Fig. 3. Molecular structure of compound (16)2. Arbitrary
atom sizes. Selected bond lengths (in A) and bond an-
gles: Pd-Cll 2.398(2), Pd-Cl+2.350(2), Pd-B 2.453(8),
Pd-Nl 2.135(5), Pd-N2 2.005(5), B-C12 1.809(8), B-Nl
1.50(1), B-N2 1.338(9); Cl 1+-Pd-Cll 80.5(1), Pd+Cll-Pd
99.5(1), Nl-Pd-N2 70.0(2), N1-B-N2 112.4(6), B-nl-Pd
83.8(3), B-N2-Pd 93.8(4), C10-N2-B 138.1(6), C10-N2-
Pd 128.1(4)C12-B-N1 120.1(5), C12-B N2 127.5(6), Cl-
N1-C5 115.5(5).
Two significantly different Ti-Cl bond lengths
(2.260(2) and 2.281(2) A) are compatible with the
distorted trigonal bipyramidal geometry. Moreover,
they are longer than e. g. in TiCU (2.17 Ä) [9] and
similar to those in (TiCl3NMe2)2 with penta-coord-
inated Ti atoms [10]. This also holds for the rather
long axial Ti-N3 distance of 2.330(3) A which is
0.257 A longer than the equatorial Ti-Nl bond of
1.933(3) A. Taking these data into account it is not
surprising that there are three significantly differ-
ent B-N bond lengths: B-Nl of 1.434(4), B1-N2
of 1.460(4) and B1-N3 of 1.505(3) Ä, the longest
falling into the range for BN single bonds with tetra-
coordinated nitrogen atoms [11]. The shortest B-N
bond results from the three-coordinated N atom N 1
which resides in a planar environment and allows
for BN 7r-bonding with the boron atom because the
C2N unit of the tmp ligand is almost perpendicular
to the BN2 ring unit preventing 7r-bonding. In con-
trast to many four membered diazadiboretidines,
which normally feature a planar ring system [12],
the diazatitanaboretidine unit in 23 is folded.
The two Pd-Cl bonds are slightly but significantly
different. This, however, is not unusual for chloro
bridged dimeric palladium complexes [14]. While
the Cl-Pd-Cl bond angles are 80.5°, the Pd-Cl-Pd
bond angles are wide with 99.5°. The P d^B rings
are planar with a sum of inner ring bond angles
of 360°. They have a trapezoidal shape due to the
long Pd-N bonds and short B-N bonds. There is a
very acute Nl-Pd-N2 bond angle of only 70.0(2)°
in contrast to the wider N1-B1-N2 bond angle of
112.4(6)°. As expected the Pd-N1 as well as the
Nl-B bond lengths are longer than the Pd-N2 and
B-N2 bond lengths because the atom N1 is tetra-
coordinated. The average Pd-N bond in 16 is falls
in the range observed for pyridine complexes of
Pd(II), e.g. [ClPd(NC5H4Me)PPh3]2 [14]. Accord-
ing to the B-N2 distance of 1.338(9) A we have to
assign double bond character to this bond; more-
over, the sum of bond angles at atom N2 is 360°.
Therefore, this B-N bond is a double bond. The
Pd-B distance in the P d^B ring is 2.483 Ä, only
10% longer than expected for a Pd-B single bond
(2.25 A) [15]. This may be the reason for the effi-
cient shielding of the boron nuclei as observed in
the NMR spectra.
The spirocyclic structure of the palladium com-
plex 16 as deduced from NMR data has been ascer-
tained by an X-ray structure analysis as depicted in
Fig. 3. The space group is R3 (# 148) with Z = 9
for the hexagonal setting. The asymmetric unit is
Cl-Pd-NCMe3-BCl-tmp which dimerizes via PdCl
bridges. The generated Pd2Cl2 four membered ring
incorporates an inversion center. The Pd-Pd dis-
Compound 5 was difficult to crystallize because
tance is 3.624 A. Therefore there is no metal-metal crystals obtained from toluene became powders on
storing. Single crystals were obtained, however,
interaction as present in [^-(CO)2Cl4Pd2]2_ [13].
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B. Böck et al. ■Reactions of Amino-imino-boranes
665
tion [5] as expected for an adduct structure A. Both
N atoms exhibit a planar geometry.
Discussion
Thereactionsofaminoiminoboranes with various
transition metal halides, and alkoxo and dimethyl-
amino titanium compounds show that the forma-
tion of the four membered heterocycles C proceeds
stepwise: the first step involves the adducts of type
A, followed by the insertion reaction to give com-
pounds of type B which may transform into the
isomeric heterocycles C provided that the EX/;_i
fragment is sufficiently Lewis-acidic to form a co-
ordinative EN bond with the tmp ligand.
Fig. 4. Molecular structure of the PdCL adduct 5. Ar-
bitrary atom sizes. Hydrogen atoms are omitted. Se-
lected bond lengths (in A) and bond angles (in °): Pd-
Cll 2.312(3), Pd-C12 2.297(3), Pd-N2 2.082(9), Pd-N2A
2.054(9), B-Nl 1.378(2), B(A)-N1(A) 1.33(2), B-N2
1.29(2), B(A)-N2(A) 1.35(2); Cll-Pd-C12 177.8(2), N2-
Pd-N2(A) 179.0, Cll-Pd-N2 89.3(3), C12-Pd-N2 89.8(3),
N2(A)-Pd-Cll 91.2(3), N2(A)-Pd-C12 89.2(3), N2-B-N1
Adduct formation is favored for sterically de-
manding transition metal halides such as TiBr4
and NbCIs (both having comparable E-X- bond
lengths). PdCb is an exception because it forms an
178.6(8), Cl 1-N2-Pd 123.0(7),Cl 1-N2-B 133(1), Pd-N2- adduct in a 1:2ratio. However, it also reacts with 1to
B 104.5(8), B-N1-C6 118.3(9), B-N1-C2 119(1), Cl-Nl-
C6 121.6(9).
the dimeric heterocycle 16in a 1:1 ratio. Obviously,
the palladized diaminoborane tmp-B(Cl)-NCMe3-
PdCl is an intermediate, and two monomeric cyclic
species 16 with tricoordinated Pd atoms dimerize
via Cl bridges to give the final product.
from cyclohexane. Elemental analysis ofcompound
5 pointed to an 1:2 addition product as supported
by IR and NMR data. This was ascertained by the
result of the X-ray structure determination. Fig-
ure 4 depicts the molecular structure of the com-
plex. The compound crystallizes in the monoclinic
Systems that can be compared with the behav-
ior of PdCl2 are the mercury halides [20]. 1 reacts
with HgCh to the mercurized diaminoborane tmp-
space group P2iIn. The asymmetric unit contains B(Cl)-NCMe3-HgCl while HgBr2 and Hgl2 react
only according to step one [20]. On the other hand
TiCl4,ZrCl4 and NbCIs can be compared with BCI3
[21], A1C13, GaCl3 [22] and SnCl4 [23], Only BC13
finally forms a heterocyclic compound of type C
while the others are involved only in the first step
of the reaction sequence. It has not been tested yet
if the adducts 3 to 5 rearrange on heating to give
compounds of types B or C (it should be noted
that the zirconium compound decomposes quickly
in methylenechloride solution). Particularly stable
addition products of 1 are generated by introduction
of the fragments M(CO)s (M = Cr, W) [4].
half a molecule. The Pd atom sits on a twofold
axis. Because no absorption correction was possi-
ble (due to a failure of the instrument) the R value
converged at only
R = 8.66%. Therefore, we will
discuss only some relevant features of the structure.
The Cl 1-Pd-C12bond angle is 177.8(2)° andtheN2-
Pd-N2A bond angle is 179.0(3)°. Consequently, the
N-Pd-Cl angles are only slightly different at 89.3
and 89.8(3)°, respectively. The Pd-Cl bond lengths
are compatible with known data [16], trans-PdCl2
(NC7H]])2 [17]. While the Pd-N bonds are essen-
tially equal, and also correspond to known distances
[18], the B-N bond lengths are different. The shorter
bonds involved the Me3CN group (aver. 1.287 A)
while the B-N bond to the tmp substituents (aver.
1.351 A) are longer. This corresponds with data
for differently substituted diaminoboron cations [5].
Average B-N bond lengths in these are 1.334 A [19].
LinearN-B-Narrays(178.2 and 178.6°) andtheper-
pendicular arrangement of the C-N-Pd an C-N-C
planes are in accord with an allene type configura-
Titanium tetraalkoxides react to compounds of
type B because the Ti(OR)3 fragment is not suf-
ficiently Lewis acidic to allow the formation of a
coordinative Ti-N bond. This bond, however, forms
on hydrolysis ofcompound 12 which requires arear-
rangment of substituents; moreover it is not the tmp
ligand but the Me2N group which forms the coordi-
native Ti-Nbond, because the dimethylamino group
is sterically less demanding than the tmp ligand. A
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666
B. Böck et al. ■Reactions of Amino-imino-boranes
similar behavior is noted for reactions of the ti-
tanium compounds with the aminoiminoborane 2,
but in case of the reaction with Cl3TiNMe2 no het-
erocycle is formed.
Butoxoftris(butoxotitanium)-tert-butylamino]-2.2.6.6-
tetramethylpiperidino-borane (8)
Prepared in analogy to 6 from Ti(OBu)4 (1.24 g,
3.64 mmol) and an equivalent amount of a0.5 M solution
of 1 in hexane. Colorless, fairly mobile oil, 6nB = 26.8.
Yield: 1.77g(86%). IR (cm“ 1): region 2800- 1650freeof
bands, 1457 (st, //BN2), 1302 (//BO). - C29H6304N2BTi
Aminoiminoboranes of type (R3Si)2N-B=N-
SiR3 which have not yet been synthesized except
(Me3Si)(Me3C)N-B=N-CMe3 [22] may be useful
precursors for generating EvBvNj ceramic materi- (562.57): calcd. C 61.92, H 11.29, N 4.98; found C 61.59,
H 11.41,N4.71.
als, and this may be an interesting area to explore
in the future.
B-Dimethylamino[tris(dimethylaminotitanium)-tert-
butylamino]-2.2.6.6-tetramethylpiperidino-borane (9)
Experimental
Ti(NMe2)4 [24] (0.65 g, 2.9 mmol) was dissolved
in hexane (10 ml) and the solution cooled to -20 °C.
Added to this stirred solution was a hexane solution of
1 (2.9 mmol in 15.8 ml of hexane). After the deep or-
ange colored reaction mixture had attained ambient tem-
perature no aminoiminoborane could be detected by 11B
NMR. About 60% of the hexane was removed in vacuo
and the remaining solution cooled to -78 °C. Orange
crystals formed within 12 h. Yield: 0.604 g (47%), m. p.
All experiments wereperformedeitherunder ablanket
of dry dinitrogen gas or in a vacuum using Schlenk tech-
niques. Consequently all solvents were made anhydrous
and stored under nitrogen gas. The aminoiminoboranes
usedwereprepared by literature methods [5,22, 23], and,
if not otherwise stated, the reagents used were commer-
cially available.
NMR: JEOL 270 EM ('H, 13C), Bruker WP 200 (‘H,
nB, 14N); IR: Perkin-Elmer325 (Nujol/Hostaflon mulls)
or as liquids between CsBr plates; MS: Atlas CH7, 70
eV; X-ray diffraction: Siemens P4 diffractometer, MoKa
radiation, graphite monochromator. Elemental analyses
were performed in the microanalytical laboratory of the
former Institute of Inorganic Chemistry.
64 -66 °C,
8UB = 29.5. C2iH5]N6BTi (446.42): calcd.
C 56.51, H 11.56, N 18.83; found C 56.72, H 10.78, N
15.59.
Isopropoxo[chloro-bis(isopropoxo)titanium]-tert-butyl-
amino]-2.2.6.6-tetramethylpiperidino-borane (10)
To a stirred solution of 1 (3 mmol) in hexane (6 ml)
was added a 1.0 M solution of ClTi(OiC3Hv)3 in hexane
(3 ml diluted with 10ml ofhexane). Within afew minutes
the colorless solution turned orange. The reaction was
complete after 3 h (nB NMR). All volatile components
were removed in vacuo. An orange oil remained. Yield:
Ethoxo(triethoxotitanium)-tert-butylamino]-2.2.6.6-
tetramethylpiperidino-borane (6)
A solution of tetraethoxotitanium (680 mg, 3 mmol)
in hexane (15 ml) was cooled to -30 °C. To this stirred
solution was added dropwise a 0.5 M hexane solution
of r-butylimino-2.2.6.6-tetramethylpiperidino-borane (1)
(6ml). A deepyellow solution formed which wasallowed
to attain ambient temperature. After stirring for 12 h all
volatile components were removed in vacuo leaving be-
hind aviscous yellowish liquid which proved tobepure6,
<5nB = 24.8. IR(cm_1): noband intheregion2800-1500;
1467 (i/BN2) 1298 (//BO). - C2iH47N204BTi (450.33):
calcd. C 56.01, H 10.52, N 6.22; found C 55.89, H 9.71,
N 5.74.
1.23 g (78%); 6UB = 25.5; IR (cm“1): 1462 vst (//BN2),
1298 vst (//BO). - C24H48N2BClTi (482.81): calcd. C
54.73, H 10.02, N 5.80, Cl 7.34; found C 51.50, H 9.73,
N 5.49, Cl 8.0.
Isopropoxo[tris(dimethylamino)titanium]-tert-butyl-
amino]-2.2.6.6-tetramethylpiperidino-borane (11)
(Me2N)3TiO/Pr [24] (0.61 g, 2.1 mmol) was dissolved
inhexane(10ml) and thesolutioncooledto-78 °C. While
stirring a solution of 4.16 mmol of 1 in 16 ml of hexane
was slowly added. A yellow solution resulted which was
reduced in volume to appr. 9 ml. A yellow precipitate
formed within a short time. It was isolated at -78 °C and
dried in vacuo. Yield: 0.7 g (1.5 mmol, 72%), m. p. 81
-83 °C, IR (cm-1): no band in the region 2800 - 1600,
1462(st, //BN2);«5nB =29.6). -C24H52N5OBTi (461.36):
Isopropoxo[tris(isopropoxo)titanium]-tert-butylamino-
2.2.6.6-tetramethylpiperidino-borane (1)
Prepared in analogy to 6 from Ti(0/Pr)4 (0.95 g,
3.29 mmol) and 6.6 ml of a 0.5 M hexane solution of 1.
Yield: 1.38 g (83%) of 7 as a light yellow oil. IR (cm'1):
no band in the 2800 -1634 region, 1460 (st, //BN2, 1302
(st, //BO). - C25H55N20 4BTi (506.44): calcd. C 59.29, H calcd. C 57.27, H 11.36, N 15.18; found C 56.84, H 11.44,
10.95, N 5.53; found C 61.18, H 11.10, N 5.17.
N 14.2.
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B. Böck et al. ■Reactions of Amino-imino-boranes
667
Isopropoxo-(triisoproxotitanium)-2,6-diisopropylphe-
1-Chloro-2-tert-butyl-3-dimethylamino-3,3-dichloro-
5,5,9,9-tetramethyl-2-aza-4-azonia-3-titanata-spiro-
[3,5]nonane (12) and 1,1-Bis(2-tert-butyl-4-dimethyl-
amino-3-(2',2',6',6'-tetramethylpiperidino)-l-dichloro-
2-aza-4-azonia-3-boratitanium)oxide (23)
nylamino)-2',2',6',6 '-tetramethylpiperidino-borane (19)
As described for 7,Ti(0/Pr)4 (0.82 g, 2.88 mmol) dis-
solved in toluene (10 ml) was allowed to react with 2
(0.96 g, 2.9 mmol, 15 ml toluene). Yield: 0.7 g (40%),
m.p. 140 - 244 °C, 6UB = 25.0, IR (cm-1): 1460 (st,
i/BN2), 1280 (st, i/BO). - C33H63N2B 04Ti (610.59):
calcd. C 64.92, H 10.40, N 4.59; found C 67.58, H 11.05,
N 4.36.
0.27 g of freshly sublimed Cl3TiNMe2 (1.36 mmol)
was suspended in hexane (5 ml). A solution of 1 in hex-
ane (3.5 ml, 0.5 M) was added. The deep green suspension
turned almost spontaneously red brown. Stirring was con-
tinued over night and the suspension then kept for 6 h at
-20 °C. The insoluble 12 was isolated by filtration and
dried in vacuo, Yield; 0.426 g (75 %), m. p. 82 - 86 °C,
<§'1B 32.1; IR (cm- 1): no bands in the region 2800 to 1600,
1452 (st, v BN2), 420, 390 (i/TiCl2). - Ci5H33N3BCl3Ti
(420.52): calcd. C 42.84, H 7.91, N 9.99 Cl 24.6; found
C 42.56, H 8.46, N 9.78, Cl 21.9.
Butoxo(tributoxotitanium)-2,6-diisopropyphenylamino-
2',2',6',6'-tetramethylpiperidino-borane (20)
At -35 °C a solution of Ti(OBu)4 (1.1 ml, 3.2 mmol)
in hexane (15 ml) was added to a solution of 2 (1.025 g,
3.14 mmol) in hexane (15 ml). After warning to room
temperature all volatiles were removed in vacuo. Com-
pound 20 remained as a yellow oil which could not be
crystallized. £n B = 25.7; IR (cm-1): 1460 (st, ^BN2),
1318 (st, v BO). - C37H7iN2B04Ti (666.70): calcd. C
66.66, H 10.73, N 4.20; found: C 66.50, H 11.01, N 4.06.
From the filtrate settled some purple single crystals
which proved to be compound 23 by X-ray diffraction.
The compound was not characterized further due to the
small amount.
Chloro-(trichlorotitanium)-2,6-diisopropylphenylamino-
2',2',6\6'-tetramethylpiperidino-borane (17)
Isopropoxy-(chloro-diisopropoxotitanium)-2,6-diiso-
propylphenylamino-2',2',6',6'-tetramethylpiperidino-
borane (21)
A
solution of freshly distilled TiCl4 (0.89 g,
4.54 mmol) in 15 ml of hexane was dropped into a stirred
solution of 1.34 g of 2 (4.1 mmol) in hexane (25 ml). The
mixture turned red immediately and voluminous yellow
flakes formed. Warming the suspension to ambient tem-
perature produced a deep red solution containing some
yellow flakes. These were removed by filtration. The fil-
trate was cooled to -78 °C. A deep purple precipitate
formed within 2 d. Yield: 0.92 g (44%), m. p. 126 -127 °C,
IR (cm-1: no bands in the region 2800 to 1580; 1453 (st,
i/BN2), 388, 420 (uTiCh). - C2,H35N2BCl4Ti (516.05):
calcd. C 48.88, H 6.84, N 5.43, Cl 27.3; found C 48.93,
H 7.17, N 5.19, Cl 27.5.
In analogy to 10 compound 2 (1.21 g, 3.7 mmol) was
dissolved in hexane (20 ml) and allowed to react with
ClTi(0/'Pr)3 (3.7 mmol) dissolved in hexane (15 ml). A
greenish yellow solution formed. The volume was re-
duced by 50%. At -78 °C a yellow powder separated.
Yield: 1.34 g, 62%, m.p. 153 - 155 °C, <5n B = 23.3, IR
(cm-1): 1460 (st, t/BN2), - C 30 H56N2BC103Ti (586,96):
calcd. C 61.39, H 9.62, N 5.11, Cl 16.0; found: C 60.65,
H 9.53, N 4.84, Cl 16.0.
Chloro-(dimethylamino-dichloro-titanium)-2,6-diiso-
propylphenylamino-2 ',2',6',6'-tetramethylpiperidino-
borane (22)
Bromo-(tribromotitanium)-2,6-diisopropyphenylamino-
2',2',6',6'-tetramethylpiperidino-borane (18)
TiBr4 (1.1 g, 2.7 mmol) was dissolved in toluene
(10 ml) and cooled to -40 °C. While stirring, a solution of
At -20 °C a solution of 2(1.13 g, 3.45 mmol) in toluene
(15 ml) was allowed to react with a suspension of freshly
2 (0.905 g, 2.78 mmol) in 1ml of toluene was added. After sublimed Cl3TiNMe2(0.65 g, 3.3 mmol dissolved in 10 ml
the mixture had attained ambient temperature toluene was of toluene). After stirring for 3 d at ambient temperature
removed in vacuo. A dark brown oil remained. This was a brown suspension had formed. Insoluble material was
treated with hexane (10 ml). The resulting solution was removed by filtration and the filtrate reduced by 50% of
cooled to -78 °C whereupon a red brown solid precipi- its volume. The brown solution was stored at -20 °C. 22
tated. The precipitate was isolated by filtration and dried separated as a brown powder. Yield: 0.70 g (41%), m. p.
in vacuo. Yield: 1.04 g (55%), m. p. 95 °C, <5UB = 34.7;
IR (cm-1): 1449 (i/BN2). - C2iH36N2BBr4Ti (693.88):
calcd. C 36.35, H 5.05, N 4.04; found C 34.81, H 5.78, N
3.73.
145 °C; 6UB = 32.6, IR (cm-1): 1468 (st, i/BN2), 382,
428 (st, uTiCh). - C23H4]N3BCl3Ti (524.67): calcd. C
52.65, H 7.88, N 8.01, Cl 20.2; found C 53.59, H 6.05, N
7.77, Cl 21.9.
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668
B. Böck et al. • Reactions of Amino-imino-boranes
l-Chloro-2-tert-butyl-3,3,3-trichloro-5,5,9,9-
tetramethyl-2-aza-4-azonia-1-bora-3-titanata-
spiro[3,5]nonane (13)
(580.40): calcd. C 26.90, H 4.69, N 4.83; found C 18.41,
H 3.43,N 3.63.
trans-(Di-p-3,3'-dichloro-l,l'-dichloro-2,2'-di-tert-bu-
tyl-5,5,9,9,5',5',9',9 '-tetramethyl-2,2 '-diaza-4,4 '-diazo-
nia-3,3'-dipalladata-borane-dispiro[3,5,3',5']dinonane
(16) and trans-[dichloro-bis[tert-butyl-(2,2,6,6-tetrame-
thylpiperidinoboryl)amido]palladium (5)
10 ml of a hexane solution containing 3.1 mmol of
1 was cooled with dry ice. While stirring, a solution of
TiCl4 (0.59 g, 3.1 mmol) in hexane (10 ml) was slowly
added. A yellow precipitate formed immediately. Stir-
ring was continued for 10 min before the suspension was
allowed to reach ambient temperature. Then the suspen-
sion was warmed to 35 °C until all the solid had dissolved.
Yellow needles separated on cooling the solution to dry
ice temperature. These were collected with a cooled glass
frit (G3). Yield: 0.92 g (74%), dec. 46 °C (red). Mol. mass:
found: 406.8 (cryoscopic in benzene). - Ci3H2yN2BCl4Ti
(411.90): calcd. C 37.91, H 6.61, N 6.80; found C 37.86,
H 7.11, N 6.18.
A suspension of PdCl2 • 2 PhCN (1.01 g, 2.72 mmol)
in toluene (10 ml) was allowed to react with 1 (5.5 mmol)
in toluene (10 ml). A red solution formed, the 11B NMR
spectrum of which revealed a comparatively sharp signal
at 24.2 ppm sitting on a broad signal centered at 24 ppm.
All volatile components were removed at 10~3 torr, and
the residue treated with 30 ml of boiling hexane. From
the solution separated 0.65 g of 5 (39%) as yellow-orange
crystals, m. p. 138 °C (dec). The filtrate was reduced in
vacuo to 4 ml. This solution was cooled to -78 °C. 0.53 g
of 16 separated on standing at -78 °C within a few days
as dark red, air stable crystals, dec. 145 °C.
16: IR (cm“ 1): 297 st (vPdCl2); 6 14N (CDC13): -250,
-365. - C26H54N4B2Cl4Pd2 (798.98): calcd. C 39.09, H
6.81, N 7.01; found C 41.34, H 7.70, N 6.83.
5: Mol. mass: found 680 (cryoscopic. in benzene). IR
(cm-1, in toluene): 1883 st, 1845 sh, 1824 (i/BN2), 331
st (^PdClterm). - C26H54N4B2Cl2Pd (621.67): calcd. C
46.37, H 8.69, N 9.01; found C 50.12, H 8.81, N 8.73.
1-Chloro-2-tert-butyl-3,3,3,3-tetrachloro-5,5,9,9-
tetramethyl-2-aza-4-azonia-1-bora-3-niobata-
spiro[3,5]nonane (14)
Freshly sublimed NbCls (0.93 g, 3.44 mmol) was sus-
pended in dichloromethane (10 ml).While stirring, a so-
lution of 3.44 mmol of 2 in a mixture of toluene and
dichloromethane (5 + 6 ml) was added with stirring within
1 h. This resulted in the formation of a slightly brown
solution. After warming to ambient temperature some in-
soluble material was removed by filtration. The solution
showed only a single n B NMR signal at 30.3 ppm. An
oil remained on removing all volatiles from the filtrate. It
was dissolved in dichloromethane (10 ml) and the solu-
tion layered with hexane (15 ml): After several hours light
yellow crystals had separated. Yield: 0.84 g (49%), m. p.
138 °C(dec.). The compound is hydrolytically sensitive
(which may be the reason for an unsatisfactory elemental
analysis). - Ci3H27N2BCl5Nb (492.36): calcd. C 31.71,
H 5.53., N 5.69; found C 25.44; H 5.27, N 4.79.
[tert-Butylimino-2,2,6,6-tetramethylpiperidino-borane]-
titaniumtetrabromide (3)
A suspension of TiBr4 (1.47 g, 4.0 mmol) in hexane
(5 ml) was cooled to -55 °C. To the stirred suspension
was added a solution of 4.0 mmol of 1 in hexane (7 ml).
A dark red solution formed which was allowed to attain
ambient temperature. Toluene was added until a clear
solution resulted (about 25 ml). On cooling the solution
to -20 °C 2.1 g (89%) of the adduct 3 separated as a
red crystalline powder; m. p. 79 °C, dec. The compound
dissolved in hydrocarbons. On air it hydrolyses rapidly to
give a white powder. - IR (cm-1, Nujol): 1770, sh, 1757
(vs {vas N=B=N). - C]3H27N2BBr4Ti (589.70): calcd. C
26.48, H 4.62, N 4.75; found C 26.08, H 4.85, N 4.42.
l-Chloro-2-tert-butyl-3,3,3,3-trichloro-5,5,9,9-
tetramethyl-2-aza-4-azonia-1-bora-3-tantalata-
spiro[3,5]nonane (15)
A stirred solution of TaCls (1.04 g, 2.90 mmol) in
toluene (5 ml) was allowed to react at -78 °C with a so-
lution of 2.90 mmol of 1 in 5 ml of toluene. On warming
a yellow suspension formed. The solid had a sticky ap-
pearance. Only a single "B NMR signal at 29 ppm was
[tert-Butylimino-2,2,6,6-tetramethylpiperidino-borane]-
zirconiumtetrachloride (4)
Freshly sublimed ZrCl4 (0.77 g, 3.3 mmol) was sus-
observed for the solution. After all volatiles had been re- pended in toluene (10 ml) and treated at 0 °C with an
moved in vacuo an oil remained. Dichloromethane (15 ml) equimolar amount of 1 dissolved in 6 ml of toluene. After
was added to the oil. Insoluble material (0.5 g) was fil- stirring for 2 h the mixture was cooled to -15 °C and
tered off and the filtrate layered with pentane (15 ml).
Within 1 week 0.54 g of 15 (32%) had separated as light
yellow crystals, m. p. 96 - 98 °C (dec. to a black material).
a colorless powder of 4 (1.34 g, 89%) was isolated by
filtration, m. p. 132 - 134 °C, dec. The compound is insol-
uble in hydrocarbons and decomposes (reacts) on contact
The compound is moisture sensitive. - Ci3H27N2BCl5Ta with dichloromethane or chloroform. IR (cm-1, Nujol):
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B. Böck et al. ■Reactions of Amino-imino-boranes
669
Table 4. Crystallographic data and data referring to data collection and structure solution.
Compound
23
16
5
Chemical formula
Molecular weight
Crystal size
Crystal color
* (A)
b(A )
C26H54N4B2Cl4Pd2
798.98
0.22 x 0.15 x 0.14
yellow
12.650(6)
19.2748(8)
14.2189(5)
90
109.135(6)
90
C3oH660N6B2Cl4Ti2
C26H54N4B2Cl2Pd
621.67
0.25 x 0.2 x 0.18
bordeaux red
25.13(1)
25.163(8)
15.098(6)
90
90
120
8278.9
3671
758.09
0.3 x 0.24 x 0.2
red
7.676(2)
9.378(3)
15.370(5)
81.56(3)
84.66(3)
67.84(2)
1012.5(5)
404
c (A)
Q(°)
3 0
7 O
V (A )
3275.0
1312
F(000)
Space group
Z
p (cm-1)
P\
1
0.69
P2\/c
4
7.43
R3
18
12.79
26 Range (°)
h, k, I Ranges
Refl. collected
Refl. unique
Refl. observ. (4a)
2.68 - 48.0
0,-10,-16 to 8, 10, 16
4017
3614
2955
0.0413
0.0996
1.052
2.2 - 47.6
0, 0,-18 to 30, 30, 18
2.3-48.4
0, 0,-16 to 13,21, 15
8214
5620
3865
0.086
0.0863
4.482
3262
3036
2602
0.0629
0.0588
1.86
Ri
Ri
GOOF o
0.245
1.02
0.65
emax (e/A' )
1812 st, 1730 sh, 1754 vst {yN=B=N). Ci3H27N2BCl4Zr data collection employing a graphite monochromator and
(455.22): calcd. C 34.30, H 5.98, N 6.15; found C 32.78,
H 6.02, N 5.33.
M o-K q radiation. An empiric absorption correction was
applied on the data based on 10 sets of ip scans of se-
lected reflections (in case of compound 16 absorption
correction could not be applied due to an instrument
failure). Lorentz and polarization correction was also
applied. The structures were solved by direct methods
(compound 23) or Patterson methods (for the two Pd
compounds) using the program SHELX [26]]. Non hy-
drogen atoms were refined by least squares methods on
F0 with anisotropic displacement parameters, while hy-
drogen atoms were placed in calculated positions and
refined isotropically with fixed Ui values. A summary of
the crystallographic data and data referring to structure
solution and refinement is given in Table 4. Further data
on the crystal structure analysis are deposited as sup-
plemental material with the Cambridge Crystallographic
Data Centre and may be obtained free of charge on appli-
cation to the Director, Cambridge CB2 J1EZ, UK Lens-
field Road by quoting the CCDC number 162960. E-mail:
deposit@ccdc.cam.ac.uk
[tert-Butylimino-2,2,6,6-tetramethylpiperidino-borane]-
vanadium trichloride
To 0.33 g of VCI3 (2.1 mmol) was added a solution
of 2.1 mmol of 1 in dichloromethane (20 ml). The mix-
ture was kept under reflux for 3 d. A deep violet solu-
tion formed. Its volume was reduced in vacuo to appr.
10 ml. This solution was layered with hexane (20 ml).
Within 2 d violet, extremely air sensitive crystals could
be isolated. Yield: 0.65 g (82%). - IR(cm-1): no bands
in the 2800 - 2500 region. MS (70 eV): m/e = 243
(tmpB(Cl)NHCMe3+ - Me; correct isotope pattern). -
C13H27N2BCI3V (379.48): calcd. C41.15, H 7.17, N7.38;
found C 41.46, H 7.47, N 7.36.
X-ray structure analysis
Selected single crystals were mounted under argon in
glass capillaries. A Nicolet R3 diffractometer was used for
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670
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