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Do Any ABn Molecules Have Anomalous Shapes v3 of TiF4 and TiF3 and Their Relevance to the Shape of TiF2.

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diene E : A H ? = 64.0, E,,, = 74.3 kcal mol- I, d = 2.8 A, pyramidalizaDo Any AB, Molecules Have Anomalous Shapes?
tion = 17.8". pagodane P: A H ? = 104.1, E>,,= 153.1 kcal m o l - ' (W.-D.
v3 of TiF, and TiF, and Their Relevance to the
Fessner, Dirserfarion. Universitat Freiburg 1986). The formation of such
Shape of TiF,**
monoatomic bridges is apparently only feasible after opening of the pagodane four-membered ring.
By Ian R . Beattie,* Peter J. Jones, and NigelA. Young
[6j H. Prinzbach, R. Pinkos, unpublished.
171 P. R. Spurr, Bulusu A. R. C. Murty, W:D. Fessner, H. Fritz, H. PrinzRecent experimental work suggests that all discrete mobach, Angew. Chem. 99 (1987) 486; Angew. Chem. Inr. Ed. Engl. 26
lecular
first-row transition-element dichlorides are linear
(1987) 455.
in the ground electronic state. We now find that an IR
[Sj R. Pinkos, G. Rihs, H. Prinzbach, Angew. Chem. 101 (1989) 312; Angew.
Chem. Inf. Ed. Engl. 28 (1989) 303.
band previously assigned to matrix-isolated TiF3 is due to
[9] The reactions leading to the dienes 5/13 were carried out o n the gram
TiF,. Further, the band assigned to TiF2is due to TiF3.The
scale, all subsequent reactions thus far on the 25-50 mg scale. The new
reported bond angle of 120" for "TiF2" can thus be excompounds are characterized by spectra ('H NMR (400 MHz), ',C
plained by the presence of trigonal-planar TiF3. "TiF2"
NMR (100.6 MHz). IR, MS) and elemental analyses. For example 21syn-hydroxy-7-oxo-6-oxadodecacyclo~
1 1.9.0.0'~'6.02~".02~20.03~9.03~16.04~19.was a key molecule in the proposals for nonlinearity of
os 17.0n.i~
0 1 o . 1.01n.22
~
.
jdocosane-12-syn-carbonitrile2 : colorless crystals,
AB2 species. We question whether there is unambiguous
m.p. 290°C. IR (KBr): 3=3420,2960, 2225, 1760, 1695 cm-'. 'H NMR
evidence of anomalous shape for any high-temperature
(CDCI,): 6=4.77 (m, 5-H), 4.30 (m, 21a-H), 3.32 (m,8-H), 3.07 (m,12aAB, molecule.
H), 3.03 (m. lo-, 1 I-, 13-, 14-H), 2.81 (m, 18-, 19-H), 2.63 (m, 20-, 22-H),
In 1979 Drake and Rosenblatt"' summarized the experi2.46 (m, 9-, 15-H), 2.41 (m,4-, 17-H). "C NMR (CDCI,): S= 174.0 (C-7),
120.3 (CN), 92.5 (C-5), 81.7 (C-21), 63.9 (C-I, -2)*, 62.1 (C-3, -16)*, 61.2
mental data on the structures of metal dihalide and trihal(C-8), 59.4 (C-10, -l4), 51.5 (C-18, -l9), SI.O(C-20, -22), 48.6 ((2-11, -13).
ide molecules. The dichlorides (MC12) of the first-row tran44.6 (C-4, -l7), 42.1 (C-12), 42.0 (C-9, - 1S).-9,22-Dioxatridecacyclo111 . 1 1.0.01.in,02.20.03.12
. 1 4 , ~ Itetracosane15.~4
sition series and calcium were assigned a linear configura.04.19.~ 5 . 1 1 ~ ~ 6 . 1 2 , ~ 6 . 1 ~ ~ ~ 7 . 1 h , ~ n.017.23
10,21-dione 3: colorless crystals, m.p.z320"C. IR (KBr): L 2 9 6 0 ,
1700 cm-I. ' H NMR (CDCI,): 6=4.93 (m, 8-, 23-H), 3.47 (m, 11-, 20H), 3.22 (m, IS-, 16-H), 3.00 (m,3-, 4-H), 2.70 (m, 7-, 14-, 17-, 24-H), 2.65
(m,2-, 5-, 12-, 19-H). I3C NMR (CDCI,): 6= 173.8 (C-10, -2l), 94.0 (C-8,
-23), 63.9 (C-11, -20). 61.8 ( G I , -6, -13, -18), 59.5 (C-15, -l6), 52.4 (C-3,
-4), 47.1 (C-2, -5, -7, -12, -14, -17, -19, -24).-4,lO,17,23-Tetroxatridecacyc ~ o [ ~ ~ ~ ~ ~ ~ ~ ~ ~ .2 . 1. 2 ~ ~.3 . 5 .~
07.2009.19013.18015.25
3 . .8 ~ 5 .. 2 5 ~.6 , 2 2.016.l8016.21
. Ihexaco-
tion, which is in agreement with recent
For the
difluorides (MF,), those of Ca, Sc, Ti, and V were assigned
as nonlinear, the remainder as linear. For ScF, and VF2
(which are both monoisotopic) the bond angles were estimated['] by analogy with those of neighboring molecules.
Thus CaF,['I and TiFJ6I represent key experimental points
in the assignment of nonlinear structures to these MX2
species.
sane-I 1,24-dione 9 : colorless crystals, m.p. > 320°C. IR (KBr): C= 2940,
1725 cm-'. 'H NMR (CDCI,): 6=4.69 (t. 4-, 22-H, J=7.3 Hz). 3.39 (m,
I-, 14-H), 3.37 (t. 12-, 25-H, J=6.9 Hz), 3.05 (m, 7-, 20-H), 2.97 (m, 6-, 8..
19-, 21-H), 2.93 (m, 2-, 13-, 15, 26-H). "C NMR (CDCI,): S= 170.8 (CI I, -24), 84.0 (C-3, -5, -16, :18), 77.9 (C-9, -22), 66.1 (C-I, -l4), 56.1 (C-7,
-20), 51.3 (C-12, -24), 45.7 ((2-6, -8, -19, -21)*, 44.5 (C-2, -13, -15, -26)*.7,21- Dioxo - 6- oxadodecacyclo[ I 1.9.0.01~16.02~11.02~20.03~9.0'~'6.04~1~.0~~17.
o n . i 5 , 0 ~ o . i.
4018.22
]docosane-l2-syn-carbonitrile 11 : colorless crystals,
m.p.>320"C. 1R (KBr): 5=2965, 2230, 1765, 1695 cm-I. 'H NMR
(CDCI,): 6=4.97 (m, 5-H), 3.39 (m,8-H), 3.18 (m,18-, 19-H), 3.13 (m,
lo-, 14-H), 3.07 (m, 1 I-,13-H), 3.03 (m, 12a-H), 2.68 (m, 4-, 17-H), 2.62
(m, 9-, IS-H), 2.58 (m, 20-, 22-H). I3C NMR (CDCI,): 6=209.7 (C-21),
173.0 (C-7), 119.0 (CN), 90.2 (C-5), 66.4 (C-I, -2)*, 61.4 (C-3, -l6)*, 59.1
(C-10, -l4), 49.5 (C-18, -19), 48.8 (C-8), 46.6 (C-11, -13)*, 46.2 (C-20,
-22)*, 42.8 (C- 15, - 19). 42.4 (C- 12).-5 , I 1-Dioxo-I O-oxadecacyclo11 ~ , ~ , ~ , ~ 2 . 9 , ~ ~ . 7 , ~ 4 . 2 2 ,.o~l 26.,1 b~.~014.21
~ ~ 8 ..015.1
1 7 ~docosa-1(22),17-diene-20syn-carbonitrile 13: colorless crystals, m.p. z 320°C. IR (KBr): 3= 2910,
2240, 1715, 1230 cm-'. 'H NMR (CDCI,): 6=4.52 (t. 9-H, J = 6 . 5 Hz),
3.64 (m, 2H), 3.63 (m. 2H). 3.56 (m, 2-, 8-H), 3.50 (m, 4H). 3.42 (m, 4-,
6-H), 3.03 (t, 12-H, J=6.0 Hz), 2.88 (t, 20-H, J=4.5 Hz). I3C NMR
(CDCI,): 6= 157.2 (C-I, -17)*, 154.9 (C-18, -22)*, 119.2 (CN), 76.2 (C-9),
61.0 (C-14, -15). 54.8 (C-3, -7), 49.3, 48.6, 47.9, 46.7, 45.1, 31.7 (C-20).
a =anti. *: assignment uncertain.
[lo] J.-P. Melder, H. Fritz, H. Prinzbach, Angew. Chem. 101 (1989) 309; Angew. Chem. Inf. Ed. Engl. 28 (1989) 300.
[ I 11 For 5 a first reversible oxidation step with 1.39 V (vs. Ag/AgCI) and a
second irreversible step with ca. 1.7 V were measured cyclovoltametrically (G. Lutz, M. Dietrich, 1. Heinze, H. Prinzbach, unpublished). The
dication is much less stable than the radical cation: ESR (121 and NMR
spectroscopic [I31 characterization of these ions (presumably i , ii) is under way.
+
Ni./4.0
+
+
20
1
15
f,,.cl~lOINm~'l
0
0
1
25
Fig. I . Plot of f M - F versus fM-cI for MX2 molecules in argon matrices
ii
1121 H. Prinzbach, Bulusu A. R. C. Murty, W.-D. Fessner, J. Mortensen, J.
Heinze, G. Gescheidt, F. Gerson, Angew. Chem. 99 (1987) 488; Angew.
Chem. Inf. Ed. Engl. 26 (1987) 457.
1131 G. K. S. Prakash, V. V. Krishnamurthy. R. Herges, R. Bau, H. Yuan, G.
Olah, W.-D. Fessner, H. Prinzbach, J. Am. Chem. SOC. I10 (1988)
7764.
[I41 W.-D. Fessner, G. Sedelmeier, P. R. Spurr, G. Rihs, H. Prinzbach, J. Am.
Chem. SOC.109 (1987) 4626.
[IS] Thanks are due to Dr. K. Schenker and Dr. D. Beck, Ciba-Geigy AG,
Basel, for their kind mediation.
Anqew. Chem. Ini. Ed. Engl. 28 (1989) Nn. 3
-
20
In Figure 1 we plot the Simple Valence Force Field
bond-stretching force constants f M - F and f M - C [ for the
MX2 molecules isolated in argon matrices. The calcula[*] Prof. I. R. Beattie, P. J. Jones, Dr. N. A,-Young
Chemistry Department, Southampton University
Southampton SO9 5NH (UK)
[**I We thank the Scientific and Engineering Research Council for financial
support for this work.
0 V C H Verlugsgeselkchafl mbH. 0-6940 Weinheim, I989
0570-0833/89/0303-0313 $ OZ.S0/0
3 13
tions are based on the reported
values of
v, and assume that the MX2 molecule is linear and symmetrical. If the molecule is nonlinear, our calculation will
yield an apparently lower force constant than that which
would be obtained using the correct molecular geometry.
This rather crude approach to the bonding in these molecules leads to a roughly linear relationship between fM--p
and fM-c-,. The straight line on the graph is based on a
least-squares plot including the origin but omitting the titanium point, which is well removed from the line.
Matrix isolation studies of lower-valent fluorides are
fraught with difficulty (notably the occurrence of I9F in
100% abundance, which makes even the formula of the
species isolated open to question). Figure 1 suggests the
force constant value for TiF, may be in error. Allowing the
molecule to bend to 120" moves TiF, even further from the
line, to the point designated
in Figure 1. In view of the
importance of TiF, in valence theory we have studied the
vapors over heated TiF3 and TiF,.
In our experiment, vaporization of TiF, (prepared from
titanium and fluoride) at ca. 100°C followed by cocondensation of the vapors with argon or neon (Fig. 2) gave IR
spectra almost identical in frequency and intensity pattern
to those assigned to TiF3.Ib1Using a Perkin Elmer 983 G
infrared spectrometer at 0.5-cm-' resolution, we did not
observe any additional bands in the 1000- to 200-cm-' region. Similar results were obtained by heating TiF, (Alfa
Inorganics).
+
I
a)
b)
Abs.
1
I
I
-
I
800
790
vlcrn~']
Fig. 2. Comparison of the 1R spectra of a) TiF4 in neon and b) TiF, in neon
161.
A mass spectrometric study''] has shown that TiF, sublimes unchanged. Further, TiF, was the onZy vapor species
identified from the initial heating of commercial TiF, at
708 K. If the TiF3 was held at 848 K for sufficient time to
avoid "swamping the mass spectrometer with TiF,,"181
some TiF, could be observed. The authors also report univariant vaporization for the two-phase region Ti +TiF2,
again with only TiF, and TiF, identified as vapor species.
3 14
0 VCH Verhgsgesellschaji mbH. D-6940 Weinheim. 1989
We conclude that the band originally assigned to TiF,["
was v3 of TiF,. The reported spectrum of TiF, was generated by heating "commercially available" TiF3 and passing
the vapors (i.e., TiF,) into a cell containing elemental titanium at 940 or 1100°C. By contrast, the mass spectrometric
studied'] show that up to 1025 K (the limit of these experiments) the vapors would contain only TiF, and TiF3. In
our experiment, passing TiF, vapor (from commercial
TiF,) over titanium metal at ca. 80O-85O0C, followed by
matrix isolation in argon, led to an IR spectrum showing a
sharp, intense new band at 740 cm-' (together with the
band at 792 cm-' due to TiF,). There were no other intense
bands in this region of the I R spectrum. The 740-cm - band
was ca. 60% of the intensity of the TiF, band. Under high
resolution this band showed titanium-isotope fine structure, the frequencies agreeing to better than 1 cm-' with
those assigned''] to TiF,. Our results, combined with the earlier mass spectrometric data, identify the 740-cm- ' band as
due to TiF,, not TiF2.
We further find that matrix isolation of the vapors from
recently sublimed TiF, (heated rapidly to ca. 850°C) gave
bands at 740 cm-' (TiF,) and 792 cm-' (TiF,) in roughly
equal proportions. It is thus clear that TiF3 both disproportionates and sublimes unchanged on heating, a not unexpected behavior for halides in this region of the periodic
table.[']
For trigonal-planar TiF3 the isotope intensity and frequency pattern calculated for v3 (neglecting the in-plane
deformation) is identical to that calculated for TiF, with a
bond angle of 120". The angle calculatedrb1for "TiF," in an
argon matrix is 119.5", while in neon, where there are at
least two sites, angles of 125.4" and 123.4" are given.
There are many theories of why certain high-temperature molecules adopt anomalous geometries. However, the
evidence for such distortions is in many cases not definitive. Electron-diffraction molecular-scattering patterns are
averaged over all thermal vibrations and all species in the
vapor; the precise interpretation of electric deflection data
on such molecules is open to question, as is that derived
from ESR measurements in rnatrices."O1 I R isotope shift
data for matrix-isolated species become insensitive as the
mass of the central atom increases. For "TiF?;" the isotope
shift between 46Tiand "Ti in argon was 2.1 cm-' less than
that calculated for a linear molecule (which was why it
represented a key observation). CaF, is another key molecule, but here the difference between the observed isotope
shift (,'Ca, 44Ca in krypton) and the calculated shift for a
linear molecule is less than 1 cm - l . i l s J
Observation of the totally symmetric stretching vibration
in the IR spectrum has been used as a criterion of geometry, notably for compounds of the heavier elements where
the symmetric stretch and the antisymmetric stretch approach one another in frequency. In such cases partial isotopic substitution ('60/180;
35C1/37C1)can lead to unambiguous identification of both v , and v3.["] Even in these
cases, however, great caution is necessary, as may be seen
by reference to elegant papers by Lesiecki and Nibler et
aI.['*'
Where a lowering of symmetry results in the resolution
of a degeneracy (Td to any lower symmetry; D3h, with loss
of the C3 axis, e.g., to C,,),the observation of additional
barids coupled with partial isotopic substitution can lead
to assignment of the point group. However, Beattie et al.f'31
produced evidence that ThCI, had Td symmetry in neon,
but a lower symmetry in krypton, illustrating the possibility that matrix gases may cause a change of geometry. In
one could imagine a trigonalthe case of T-shaped uo3r'4i
OS70-0833/89/0303-0314 $ 02.50/0
'
Angew. Chem. I n ! . Ed. Engl. 28 (1989) No. 3
planar gas-phase molecule being distorted along a coordinate towards UO:Q020in a matrix.
There are many careful and very difficult experiments in
the literature. The purpose of this communication is to
question how many of the results on high-temperature
molecules lead to unambiguous determination of the shape
of the free molecule.
Received: July 14, 1988;
revised version: November 10, 1988 [ Z 2858 IE]
German version: Angew. Chem. 101 (1989) 322
tion of 3 as the LiBr adduct of a P-P ylide took into account the "P NMR spectroscopic data, which were consistent with multiple bond character for the P2-P3 bond, and
the increased coordination number at P3.
(fBu2P),PLi
+ Br-CH2-CH,-Br
---f
2
1
tBuzP'-PZ=P3BrfBu2.LiBr
a P,(PfBu2),
3
[I1 M. C. Drake, G. M. Rosenblatc, J. Electrochem. SOC.126 (1979) 1387.
121 I. R. Beattie, P. J. Jones. A. D. Willson, N. A. Young, High Temp. Sci., in
press.
[3] J. S . Ogden, R. S. Wyatt, J. Chem. SOC.Dalton Trans. 1987, 859.
[4] J. W. Hastie, R. H. Hauge, J. L. Margrave, Chem. Commun. 1969, 1452;
High Temp. Sci. I (1969) 76.
[5I V. Calder, D. E. Mann, K. S. Seshadri, M. Allavena, D. White, J. Chem.
Phys. 51 (1969) 2093.
161 J. W. Hastie, R. H. Hauge, J. L. Margrave, J. Chem. Phys. 51 (1969)
2648.
171 J. W. Hastie, R. H. Hauge, J. L. Margrave, High Temp. Sci. 3 (1971) 257;
D. White, G. V. Caider, S. Hemple, D. E. Mann, J. Chem. Phys. 59
(1973) 6645; C. W. De Kock, D. A. Van Leirsberg, J. Am. Chem. SOC.94
(1972) 3235; J . Phys. Chem. 78 (1974) 134; D. W. Green, D. P. McDermott, A. Bergman, J. Mol. Spectrosc. 98 (1983) 111; A. Snelson, J. Phys.
Chem. 70(1966) 3208; R. S . Wyatt, Ph. D. Theszs, Southampton University 1983; K. R. Millington, Ph. D. Thesis. Southampton University
1987; K. R. Thompson, K. D. Carlson, J . Chem. Phys. 49 (1968) 4379.
[81 N. D. Potter, M. H. Boyer, F. Ju, D. L. Hildenhrand, E. Murad: Thermodynamic Properties of Propellant Combustion Products, U. s. Clearinghouse Fed. Sci. Tech. Inform. AD, No. 715567 (1971).
191 P. Ehrlich, G. Pietzka, 2. Anorg. Afig. Chem. 275 (1954) 121.
[lo] ESR work on TiF2: T. C. De Vore, W. Weltner, J. Am. Chem. Soc. 99
(1 977) 4700.
1111 See, for example: I. R. Beattie, J. S. Ogden, R. S. Wyatt, J. Chem. SOC.
Dalton 1983, 2343; S . D. Gabelnick, G. T. Reedy, M. G. Chasanov,
J. Chem. Phys. 60(1974) 1167; D. W. Green, K. M. Ervin, J. Mol. Spectrosc. 89 (1981) 145.
[I21 M. L. Lesiecki, J. W. Nibler, J. Chem. Phys. 64 (1976) 871; M. Lesiecki,
J. W. Nihler, C. W. De Kock, ibid. 57 (1972) 1352.
[I31 I. R. Beattie, P. J. Jones, K. R. Millington, A. D. Willson, J . Chem. SOC.
Dalton 1988 2159.
[141 See, for example: S. D. Gabelnick, G. T. Reedy, M. G. Chasanov, J.
Chem. Phys. 59 (1973) 6397.
1151 All calculations neglect anharmonicity.
e
By Gerhard Fritz,* Tilo Vaahs, Holm Fleischer, and
Eberh ard Ma tern
Although complexes having terminal phosphanediyl
(phosphinidene) ligands-formed via phosphole complexes-are well-known,"' all efforts to isolate a free phosphinidene have been unsuccessful up to now. Thus, for example, free phosphinidenes could not be detected in the thermolysis of 7-phosphanorbornadienes or of (PMe),.''' Attempts to form free phosphinidenes via decomplexation of
terminal phosphinidene complexes have also failed.''' Apparently, what is lacking is a suitable precursor, from
which phosphinidenes can be generated at sufficiently low
temperatures.
We have now found that the reaction of l I 3 l with 2 affords yellow, toluene-soluble crystals of 3.l4]The formula[*] Prof. Dr. G. Fritz, Dr. T. Vaahs, Dipl.-Chem. H. Fleischer,
Dr. E. Matern
Institut fur Anorganische Chemie der Universitat
Engesserstrasse, D-7500 Karlsruhe (FRG)
Angew. Chem. Int. Ed. Engl. 28 (1989) No. 3
e
The LiX adduct of a C-P ylide Ph3P-CRR'- . .LiX can be
understood in analogous terms.1513 resembles the lithiated
ylides (R2CLi-PR3)X of H . Schmidbaur and W. Tronichfbl
and the 1,1,3,3-tetraphenyl-lh5,2h3,3h5-triphosphenyl
cationis and triphosphenium ions"] described by A . Schrnidpeter et al. A crystal structure analysis of 3 was, until now,
not possible.
Compound 3 decomposes upon warming to 20°C with
quantitative formation of tBuzPBr, LiBr, and the cyclophosphanes 4 (n=3) and 5 (n=4).191 The formation of
these compounds suggests that 2,2-di-tert-butyl-l,I-diphosphanediyl, 6, is the intermediate in this reaction. Therefore, we attempted to obtain evidence for the intermediacy
of 6 by trapping reactions. Decomposition of 3 in 2,3rBu2P-P
6
dimethyl- 1,3-butadiene at ambient temperature gives rise
to the compounds 7 and 8 ; the cyclophosphanes 4 and 5
are no longer formed. The formation of 7 is favored with respect to 6 and suggests the presence of tBu2P-P=P-PtBu2
as a reactive
The decomposition of 3 in
cyclohexene led to 9!'01 but in this case, the major products were the cyclophosphanes 4 and 5 .
7
tBu2P-P=PBrrBu2. LiBr
and the Formation of tBu2P-P
435
8
9
The reaction of 3 with dimethylbutadiene to give 8 is
analogous to the conversion of terminal phosphinidene
complexes to vinylphosphirane complexes.E'l The formation of 9 from 3 and cyclohexene is directly comparable to
the reaction of phosphinidene complexes with olefins."]
Received: July 21, 1988;
revised: November 24, 1988 [ Z 2876 IE]
German version: Angew. Chem. 101 (1989) 324
CAS Registry numbers:
1, 118201-82-4;2, 106-93-4; 3,11863I-50-8;4, 118281-67-7; 5, 118281-66-6;6,
118655-68-8; 7, 118631-51-9; 8, 118631-52-0; 9, 118631-53-1; 2.3-dimethyl1,3-butadiene, 513-81-5; cyclohexene, 110-63-8.
[I] Review: F. Mathey, Angew. Chem. 99 (1987) 285; Angew. Cfiern. Int. Ed.
Engl. 26 (1987) 275.
121 K. C. Caster, L. D. Quin, Tefrahedron Lett. 24 (1983) 5831.
(31 G. Fritz, T. Vaahs, Z. Anorg. Allg. Chem. 552 (1987) 18.
[4] 1.3 g (3.2 mmol) of 1.THF was stirred in 15 mL of THF and treated at
0°C with 0.6g (3.2 mmol) of 2. After the evolution of gas (C,H.) had
ceased, the solution was stirred for 2 h at -40°C; during this time the
color changed from orange to yellow. The solution was cooled to
-78°C. After 2 d, 3 precipitated as a yellow, microcrystalline powder,
which was recrystallized from toluene. Yield: 0.5 g (31%). "P NMR:
0 VCH Verlagsgeselischaji mbH. 0-6940 Weinheim, 1989
0.570-0833/89/0303-0315 $ 02.50/0
3I 5
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