Two sterically encumbered 1,3,2-dioxaphospholanes - Reactions, comparison of crystal structures and computational explanations

Article abstract of DOI:10.1002/zaac.200700514

3,4,5,6-Tetrachlorobenzo-3-(2,4,6-tri-tert-butylphenyl)-1,3, 2-dioxaphospholane (2) and benzo-3-(2,4,6-tri-tert-butylphenyl)-1,3,2- dioxaphospholane (4), in which the reactive PIII-center lies close to the sterically demanding Mes* group (Mes* = 2,4,6-tri-tert-butylphenyl), were prepared from Mes*-Br and the corresponding P-chloro-phospholane. Compounds 2 and 4 reacted with various oxidants, azides, MeSO₃CF ₃ or [(tht)AuCl] (tht = tetrahydrothiophene) to give the expected products. All crystal structures of the products display a strongly distorted Mes* system with a boat conformation of the phenyl ring and appreciable out-of-plane deviations of phosphorus and the ortho-tert-butyl groups to opposite sides of the ring. Quantum chemical calculations at the DFT (density functional theory) level of theory were used in order to discriminate between intra- and intermolecular forces, which are responsible for these distortions.

Full text of DOI:10.1002/zaac.200700514

DOI: 10.1002/zaac.200700514
Two Sterically Encumbered 1,3,2-Dioxaphospholanes ؊ Reactions, Comparison
of Crystal Structures and Computational Explanations
Matthias Freytag, Jörg Grunenberg, Peter G. Jones, and Reinhard Schmutzler*
Braunschweig, Institut für Anorganische und Analytische Chemie der Technischen Universität
Received November 15th, 2007.
Dedicated to Professor Heinrich Nöth on the Occasion of his 80th Birthday
Abstract. 3,4,5,6-Tetrachlorobenzo-3-(2,4,6-tri-tert-butylphenyl)-
1,3,2-dioxaphospholane (2) and benzo-3-(2,4,6-tri-tert-butylphen-
yl)-1,3,2-dioxaphospholane (4), in which the reactive PIII-center lies
close to the sterically demanding Mes* group (Mes* ϭ 2,4,6-tri-
tert-butylphenyl), were prepared from Mes*ϪBr and the corre-
sponding P-chloro-phospholane. Compounds 2 and 4 reacted with
various oxidants, azides, MeSO3CF3 or [(tht)AuCl] (tht ϭ tetra-
hydrothiophene) to give the expected products. All crystal struc-
tures of the products display a strongly distorted Mes* system with
a boat conformation of the phenyl ring and appreciable out-of-
plane deviations of phosphorus and the ortho-tert-butyl groups to
opposite sides of the ring. Quantum chemical calculations at the
DFT (density functional theory) level of theory were used in order
to discriminate between intra- and intermolecular forces, which are
responsible for these distortions.
Keywords: Gold; Phospholanes; 2,4,6-tri-Tri-t-butylphenyl-3,4,5,6-
tetrachlorodioxaphospholane; Crystal structures; Gold complexes;
Quantum chemical calculations
1 Introduction
Recently [1] we reported the reaction of E-(2,4,6-tris-tert-
butylphenyl)-diphosphene (1) with tetrachloro-ortho-benzo-
quinone (TOB), leading via the unexpected cleavage of the
phosphorus-phosphorus double bond to the products
3,4,5,6-tetrachlorobenzo-3-(2,4,6-tri-tert-butylphenyl)-
1,3,2-dioxaphospholane (2) and bis(3,4,5,6-tetrachloro-1,2-
phenylenedioxa)(2,4,6-tri-tert-butylphenyl)phosphorane (3),
depending on the stoichiometry (Equation (1)). We also re-
ported the synthesis of the dioxaphospholanes 2 and 4,
starting from 1-bromo-2,4,6-tert-butyl-benzene (5), which
was lithiated to 6 and allowed to react with the correspond-
ing chlorophosphine derivatives 7 and 8 (Scheme 1). We
further described the oxidation reactions of 4 with the
H2O2-urea adduct to the phosphoryl compound 9, with el-
emental sulfur to the thiophosphoryl compound 10 and
with TOB to the mixed spirophosphorane 11 (Scheme 2).
Finally, the X-ray structures of 2, 3, 4 and 9 were presented.
Further “standard phosphorus reactions” with the phos-
pholanes were expected to be interesting because of the
proximity of the reactive phosphorus(III) center and the
sterically demanding 2,4,6-tris-tert-butylphenyl unit (also
known as supermesitylene, Mes*). Here we present several
such reactions and the structures of a further eight prod-
ucts.
2 Results and Discussion
2.1 Reactions of compound 4
The dioxaphospholane 4 was treated with (tetrahydrothio-
phene)chloridogold(I) [(tht)AuCl] in dichloromethane to
give the chloridogold(I) complex 12 (Scheme 4).
The attempted Staudinger reaction [2] of 4 with para-
nitrobenzoyl azide in toluene was unsuccessful; the 31P
NMR spectrum after 20 h at room temperature showed
* Prof. Dr. R. Schmutzler
Institut für Anorganische und Analytische Chemie der Techni-
schen Universität
Postfach 3329
D-38023 Braunschweig/Germany
FAX:(049)-531-391-5387
e-mail: r.schmutzler@tu-bs.de
1256
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Z. Anorg. Allg. Chem. 2008, 634, 1256Ϫ1266

Two Sterically Encumbered 1,3,2-Dioxaphospholanes
Scheme 1
A further Staudinger reaction of 4 with para-tolylsulfonyl
azide in pentane at room temperature led after 18 h to the
formation of the expected product 15.
The phosphonium salt 16 was formed in the reaction of
4 with methyl triflate in dichloromethane after 1 h.
As previously reported, the diphosphene 1 did not react
with hexafluoroacetone (HFA), probably because of the
sterically demanding Mes* groups. The attempted reaction
of 4 with a thirteenfold excess of HFA in a sealed tube
overnight also showed that the starting compounds were
unchanged. There was no reaction, either when the mixture
was heated to 50 °C for 5 h.
In an attempt to synthesize a difluorophosphorane, an
excess of SF4 was condensed onto a solution of 4 in a sealed
tube, but after warming up to room temperature the reac-
tion mixture immediately became brown, indicating the de-
composition of 4. The decomposition was confirmed by 31
P
NMR spectroscopy.
Further complexation reactions of 4 also failed. The
attempted reaction with the cis-platinum complex
[(COD)PtCl2] in refluxing THF showed only the signal of
the starting material in the 31P NMR spectrum after 5 h,
as did the reaction of 4 with the trans-platinum complex
[(py)2PtCl2] in CHCl3 after 1 d at room temperature. Re-
fluxing for 5 h led to the decomposition of 4, and the same
results were found with [(CO)5W(NCCH3)] after 3 d in di-
chloromethane at room temperature.
Attempts to synthesize rhodium complexes of 4 with 0.25
equivalents of [(H2CCH2)RhCl]2 or [(COD)RhCl]2 in di-
chloromethane at room temperature led in the first case to
decomposition after stirring overnight, in the second case
to a complex mixture with several sets of signals in the 31P
NMR spectrum. The products could not be separated or
characterized.
Scheme 2
only the signal of the starting material, and refluxing for
6 h led to the decomposition of the dioxaphospholane. Re-
peating the reaction in THF at 55 °C for 2 d led to two
products with chemical shifts of 55.8 and 44.0 ppm in a
ratio of 1 : 6 in the 31P NMR spectrum. Crystallization via
slow evaporation of the solvent from a pentane solution
finally gave the hydrolysis product 14, which was presum-
ably formed from the Staudinger product 13 and adven-
titious water.
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M. Freytag, J. Grunenberg, P. G. Jones, R. Schmutzler
Scheme 3
2.2 Reactions of compound 2
not form a complex with the iron carbonyl after stirring for
1 d in toluene. Heating to 60 °C resulted in the decompo-
sition of 2 after 3 h.
The chlorinated phospholane 2 reacted in a manner similar
to 4 with the urea-H2O2 adduct to the phosphoryl com-
pound 17 and with [(tht)AuCl] to the gold complex 18
(Equation (2)).
3 X-Ray structure analyses
The preparation of a Staudinger product of 2 with para-
toluenesulfonyl azide failed after 16 h in toluene at room
temperature, and heating to 60 °C resulted in four products,
with chemical shifts between 45 and 35 ppm in the 31P
NMR spectrum, which could not be separated by chroma-
tographic methods.
3.1 Extended summary of results for previously
determined structures [1]
Not all of these aspects were discussed in detail in ref. [1].
The phenyl ring of the Mes* group was markedly dis-
torted. In all cases, the bonds at the ipso carbon atom were
˚
Although it is known that 1 reacts with [Fe2(CO)9] and
thus no steric hindrance is expected [3], compound 2 did
lengthened to 1.42Ϫ1.44 A, with concomitant and consist-
ent changes in bond angles to ca. 119, 118, 123 and 117°
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Two Sterically Encumbered 1,3,2-Dioxaphospholanes
at Cipso, Cortho, Cmeta and Cpara, respectively. In addition,
compounds 2, 4 and 9 displayed marked out-of-plane dis-
tortions of the ring, with the ipso carbon atom C1 lying
significantly out of the plane of the other five atoms. The
phosphorus atom lies much further out of the plane, and
the ortho carbon substituents C7 and C15 were displaced
out of the plane in the opposite direction, leading to abso-
lute torsion angles PϪCipsoϪCorthoϪCbutyl (PϪC1ϪC2ϪC7
and PϪC1ϪC6ϪC15 in the numbering adopted for all
compounds under discussion) up to ca. 40°. The para car-
bon substituent C11 was generally displaced slightly out of
the plane in the same direction as C1 and P. Surprisingly,
compound 3 showed only minor or insignificant out-of-
plane distortions. It is surprising that the non-chlorinated
phospholane 4 consistently displays the largest distortions
(except for the fold angle, which is however effectively in-
creased by the larger deviation of the phosphorus atom
from the plane of the phospholane ring), whereas the corre-
sponding chlorinated phospholane 2 is less distorted; the
larger deviations might be expected for compound 2 with
the larger catechol substituent. The reason might be sought
in the slightly longer PϪO bonds in 2, or in the intramol-
ecular non-bonded contacts to the oxygen atoms of the
phospholane, which lie between pairs of methyl groups;
these follow the pattern of one long plus one shorter con-
Compounds 3, 11, 12 and 16 crystallize with one inde-
pendent molecule in the asymmetric unit, compound 4 with
four, all other compounds with two. In Table 1 some com-
mon features are listed: deviations from the reference plane,
the fold angle C1ϪPϪX (X ϭ midpoint of the C19ϪC24
bond, opposite the phosphorus atom in the phospholane
ring),
the
torsion
angles
PϪC1ϪC2ϪC7
and
PϪC1ϪC6ϪC15 and the bond lengths PϪC1 and PϪO.
Individual bond lengths and angles in the Mes* rings are
not presented, but follow closely the trends indicated above
(see Deposited Material for details). The minimum and
maximum values for each parameter are given bold italics;
the values for the spirophosphoranes 3 and 11 and the hy-
drolysed Staudinger product 14 are presented at the end of
the Table and are discussed separately, because they cannot
be compared directly with the σ3λ3-P and σ4λ5-P com-
pounds.
For the sake of completeness, we first present the struc-
ture of the starting material 7 (Fig. 1). Bond lengths and
angles may be regarded as normal. As expected from the
benzoannelation, the five-membered ring adopts an envel-
˚
ope conformation with the phosphorus atom 0.27 A out of
the plane. The crystal packing involves several short con-
tacts; six Cl···Cl contacts (full details in the deposited mate-
rial), of which the shortest are Cl1···Cl1 (Ϫx, 2Ϫy, 2Ϫz)
˚
˚
˚
tact in 2 (e.g. O1···H8C 2.51, O1···H10A 2.26 A), but are
3.4631(7) A, and also Cl4···P (1Ϫx, 1Ϫy, 1Ϫz) 3.6183(5) A
˚
˚
more equal in 4 (e.g. O1···H16A 2.43, O1···H18C 2.36 A).
and Cl4···O1 (x, y, Ϫ1ϩz) 3.323(1) A.
Such contacts are usually regarded as “weak” hydrogen
bonds.
A search of the Cambridge Database [4] for the Mes*
fragment with a phosphorus substituent at C1 was conduc-
ted, with the following restrictions: coordination number 3
or 4 at phosphorus, R < 0.1, no metal coordination at the
phosphorus atoms. For 93 hits (103 independent mol-
ecules), the bond lengths C1ϪC2 / C1ϪC6, taken together,
˚
averaged 1.425 A, the angles C2ϪC3ϪC4 / C4ϪC5ϪC6
123.6°, and the mean distances of C1 and P from the plane
˚
C2, C3, C5, C6 were 0.13 and 0.76 A respectively. A few
compounds with very small substituents at phosphorus (H
and/or B) were however scarcely distorted. This search con-
firms the basic features summarised above and presented in
more detail below.
Fig. 1 The structure of compound 7 in the crystal. Ellipsoids
˚
represent 50 % probability levels. Selected bond lengths/A and
3.2 New structures
angles/°: PϪO1 1.657(1), PϪO2 1.661(1), PϪCl1 2.0766(5),
O1ϪPϪO2 93.95(4), O1ϪPϪCl1 99.28(4), O2ϪPϪCl1 99.57(4).
The structures of compounds 7 and 11 (not presented in
the earlier publication), 12, 14, 15, 16, 17 and 18 were deter-
mined unambiguously by X-ray crystallography; their struc-
tures are shown in Figs. 1Ϫ8. In contrast to the previous
discussion, the reference plane of the Mes* ring is defined
by atoms C2, C3, C5 and C6, because the para carbon atom
C4 also deviates slightly, but significantly and consistently,
from this plane, leading to a flattened boat conformation.
The previously determined structures of compounds 2, 3, 4
and 9 [1] will be included for comparison purposes, where
appropriate.
The spirophosphorane 11 (Fig. 2a) displays (as does 3
[1]) a slightly unusual trigonal bipyramidal configuration at
phosphorus; in the presence of two chelating O,OЈ-ligands,
square pyramidal geometry is more usual [5]. Atoms O2
and O3 occupy axial, O1, O4 and C1 equatorial positions.
The axis O2ϪPϪO3 is almost linear at 177.56(11)°, and the
angles between the atoms in the trigonal plane and those at
the apical positions are close to the ideal values of 90°
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M. Freytag, J. Grunenberg, P. G. Jones, R. Schmutzler
of 120°. This observation was also made in the structure of
3 and may reasonably be explained by the steric demand of
the three substituents at phosphorus. The bond length
˚
˚
PϪC1 of 1.854(3) A corresponds well to the 1.852(3) A in
3, but the differences between the PϪOax (1.732(2) and
˚
1.692(2) A) and the PϪOeq bond lengths (1.655(2) and
1.626(2) A) are larger than in the symmetrically substituted
˚
3, the bonds to the chlorinated substituent being longer.
In contrast to the relatively undistorted structure of 3,
the P-Mes* unit is significantly distorted in 11 (Fig. 2b); it
is tempting to suggest that this may be associated with the
less distorted structure of the starting material 2 compared
to 4 (see above), but the trend is not observed in other de-
rivatives (see below). As in the other structures discussed
below, the phenyl ring has a flattened boat conformation
˚
with C2, C3, C5 and C6 coplanar (mean dev.: 0.02 A); C1
˚
˚
and C4 lie 0.11, 0.06 A and P as much as 0.78 A out of
this plane. The torsion angles PϪC1ϪC2ϪC7 and
PϪC1ϪC6ϪC15 are 27.0 and Ϫ21.8°. It is noteworthy that
the phosphorus atom is shifted towards the side of the
smaller, non-chlorinated substituent with respect to the
Mes* plane, apparently forcing the larger chlorinated sub-
stituent to a sterically unfavourable position between the
two ortho-tert-butyl-groups of the Mes* unit. A possible ex-
planation might be that the smaller substituent remains in
the same position as in the starting material 4 without being
able to pass between the two tert-butyl-groups during the
reaction to give the sterically favoured position towards the
larger new substituent. However, a closer inspection reveals
that both catechol substituents in 11 are involved via their
equatorial oxygen atoms in short 1,6-contacts with the tert-
˚
butyl hydrogen atoms: H8B···O1 2.25, H18A···O4 2.16 A,
associated with approximately eclipsed torsion angles
C2ϪC1ϪPϪO1 Ϫ17.4 and C6ϪC1ϪPϪO4 Ϫ6.4°. In 3 the
˚
corresponding contacts are 2.23 and 2.22 A, with
CϪCϪPϪO torsion angles Ϫ4.5 and Ϫ7.9°. The more sym-
metrical nature of 3 is also seen in the conformation of the
ortho tert-butyl groups; each lies with one methyl carbon
approximately synperiplanar to the CmetaϪCortho bond,
with C3ϪC2ϪC7ϪC9 Ϫ4.6° and C5ϪC6ϪC15ϪC17 7.1°.
In 11, the methyl groups with the lowest absolute torsion
angles are rotated appreciably out of the eclipsed position,
with corresponding values Ϫ13.7, 32.4°. Nevertheless, short
intramolecular H···H contacts result in both cases (3:
˚
H5···H17C 1.97; 11: H3···H17C 1.82 A) yet appear to be
tolerable.
Compound 14, the hydrolysis product in which the phos-
pholane ring has been opened, crystallizes with two inde-
pendent molecules in the asymmetric unit; one of these is
shown in Fig. 3. Values for the second molecule are given
in square brackets. The two molecules differ somewhat in
the orientation of the nitrophenyl unit, with torsion angles
N1ϪC25ϪC26ϪC27 of Ϫ19.3(5)° [6.0(5)°], and of the nitro
group, with C28ϪC29ϪN2ϪO4 168.3(4)° [149.3(4)°].
The distortion of the Mes* unit is the largest of any
Fig. 2 a: The structure of compound 11 in the crystal. Ellipsoids
represent 50 % probability levels.
b: Structures of compounds 3 (above) and 11 (below) viewed side
on to the Mes* ring system (H atoms omitted).
(88.13(10) Ϫ 92.37(11)°). The catechol units are signifi-
cantly bent away from the Mes* substituent, as can be seen
from the increase of the angles C1ϪPϪO1 and C1ϪPϪO4
to 129.36(13) and 123.97(12)° and the decrease of
O1ϪPϪO4 to 106.63(11)°, with respect to the ideal value
˚
compound presented here, with C1 lying 0.23 [0.21] A and
˚
P 1.32 [1.26] A out of the reference plane; the largest
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Two Sterically Encumbered 1,3,2-Dioxaphospholanes
Fig. 5 The structure of compound 15 in the crystal (one of two
independent molecules). Ellipsoids represent 50 % probability le-
vels. Bond lengths/A and angles/° at nitrogen: PϪN 1.554(2), SϪN
Fig. 3 The structure of compound 14 in the crystal (one of two
independent molecules). Ellipsoids represent 30 % probability
levels.
˚
1.613(2), PϪNϪS 123.56(14) [second molecule: 1.550(2),
˚
1.611(2) A, 124.09(13)°].
Fig. 6 The structure of compound 16 in the crystal (solvent and
anion omitted). Ellipsoids represent 30 % probability levels.
Fig. 4 The structure of compound 12 in the crystal (solvent omit-
˚
ted). Ellipsoids represent 50 % probability levels. Bond lengths/A
and angles/° at gold: AuϪP 2.2067(7), AuϪCl 2.2724(7),
PϪAuϪCl 179.00(2).
PhϪP(ϪOC)(ϭO)ϪNHϪC found in the Cambridge data-
base [4], the OϭPϪC angle is much narrower, at 113.8°,
with a concomitant increase in OϪPϪC 102.9°.It therefore
seems that in 14 the doubly bonded oxygen atom O2 is ex-
truded from the region between the methyl groups C10 and
absolute PϪC1ϪCorthoϪCbutyl torsion angle is 52.1°. In
contrast to compounds 3 and 11, the t-butyl groups
are so disposed that one methyl carbon is antiperiplanar to
˚
˚
C18 (O2···H10C 2.71, O2···H18B 2.69 A [2.61, 2.73 A] at
the expense of short contacts to O1 (O1···H10A 2.39,
˚
the bond
C
metaϪCortho
;
C3ϪC2ϪC7ϪC10 Ϫ174.0,
O1Ј···H18F 2.32 A). The ring distortions are in such a di-
C5ϪC6ϪC15ϪC18 169.1° [Ϫ172.1, 167.1°]. This latter
configuration is also observed in all other structures of
this paper.
The phosphorus atoms display a strongly distorted tetra-
hedral coordination with angles between 97.84(14)°
[97.71(16)°] (O1ϪPϪC1) and 124.26(16)° [124.26(16)°]
(O2ϪPϪC1). In methyl N-benzoylphenylphosphonamidate
[6], the only other compound with an acyclic grouping
rection as to promote this effect. The PϪN bond lengths of
˚
1.674(3) and 1.677(3) A correspond well with literature val-
˚
ues [7], and the long CϪN bonds of 1.392(4) and 1.377(5) A
˚
are close to the value of 1.393(3) A in the above-mentioned
phosphonamidate [6].
The hydroxy group is involved in an intramolecular hy-
˚
drogen bond O6ϪH6···O3, with H···O 2.01 [2.07] A,
OϪH···O 156° [156°]. The NH groups act as intermolecular
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M. Freytag, J. Grunenberg, P. G. Jones, R. Schmutzler
Fig. 8 The structure of compound 18 in the crystal (one of two
Fig. 7 The structure of compound 17 in the crystal of 17Ј (one of
two independent molecules; tetrachlorocatechol omitted). Ellip-
soids represent 30 % probability levels.
independent molecules; solvent omitted). Ellipsoids represent 30 %
˚
probability levels. Bond lengths/A and angles/° at gold: AuϪP
2.208(3), AuϪCl5 2.273(3), PϪAuϪCl5 179.09(11) [second mole-
˚
cule: 2.210(3), 2.279(3) A, 179.31(12)°].
hydrogen bond donors to the phosphoryl oxygen atom O2
via the inversion centre at 1/2,1/2,0 [0,1/2,1/2], with H···O 2.05
[2.18] A, OϪH···O 160° [163°], and O2 is also acceptor, via
the same operator, in a “weak” but short hydrogen bond
from C27ϪH27, with H···O 2.26 [2.19] A, OϪH···O 152°
˚
˚
Table 1 Comparison of the X-ray structures; maximum and minimum values are given in boldface italics.
˚
˚
Bond lengths (A)
Compound
Deviation from the plane C2/3/5/6(A)
Fold angle
C1ϪPϪX (°)
Phospholane:
deviation of P
Torsion angles(°)
a)
b)
˚
(A)
C1
C4
P
C7
C11
C15
PϪC1ϪC2ϪC7 PϪC1ϪC6ϪC15
PϪC1
PϪO
2 [1]
4 [1]
0.17 0.07 0.82 Ϫ0.30
0.18 0.06 0.88 ؊0.39
0.05 Ϫ0.33
0.01 ؊0.38
99.9
96.3
0.15
0.25
28.8(3)
؊29.6(3)
1.850(2) 1.701(2), 1.702(2)
Ϫ33.9(3)
34.1(3)
1.856(2) 1.701(2), 1.696(2)
0.17 0.09 1.01 Ϫ0.31
0.18 0.08 1.05 Ϫ0.33
0.19 0.11 1.16 Ϫ0.32
0.18 0.09 1.07 Ϫ0.31
0.25 Ϫ0.26
0.18 Ϫ0.35
0.28 Ϫ0.30
0.25 Ϫ0.29
89.6
89.1
88.3
87.8
0.43
0.42
0.45
0.48
35.8(2)
38.2(2)
40.7(3)
Ϫ34.3(3)
Ϫ38.6(2)
؊40.7(3)
36.6(2)
1.860(2) 1.682(2), 1.678(2)
1.859(2) 1.677(2), 1.688(2)
1.860(2) 1.689(2), 1.685(2)
1.864(2) 1.678(2), 1.678(2)
Ϫ37.7(2)
9 [1]
0.15 0.08 0.91 ؊0.16
0.14 0.08 0.92 Ϫ0.25
0.14 Ϫ0.28
0.14 ؊0.20
111.4
110.2
0.00
0.04
29.8(2)
Ϫ32.6(1)
Ϫ33.3(2)
Ϫ31.3(2)
1.807(1) 1.627(1), 1.637(1)
1.804(1) 1.637(1), 1.622(1)
12
15
0.15 0.08 0.96 Ϫ0.23
0.06 Ϫ0.34
100.7
0.30
Ϫ33.4(3)
37.5(3)
1.824(2) 1.636(2), 1.643(2)
0.15 0.07 1.04 Ϫ0.26
0.15 0.07 1.05 Ϫ0.27
0.12 Ϫ0.23
0.11 Ϫ0.27
111.2
110.0
0.09
0.11
38.0(3)
Ϫ39.2(3)
Ϫ36.6(3)
39.2(3)
1.800(2) 1.627(2), 1.624(2)
1.799(2) 1.627(2), 1.625(2)
16
0.13 0.06 0.95 Ϫ0.22
0.05 Ϫ0.23
110.2
0.26
34.9(3)
Ϫ34.7(3)
1.781(2) 1.596(2), 1.598(2)
17Ј
0.14 0.08 0.95 Ϫ0.25
0.15 0.07 0.92 Ϫ0.23
0.23 Ϫ0.29
0.12 Ϫ0.24
118.0
115.8
0.20
0.12
Ϫ35.0(4)
Ϫ32.7(4)
37.0(4)
32.8(4)
1.789(3) 1.640(2), 1.643(2)
1.789(3) 1.633(2), 1.647(2)
18
0.17 0.06 0.94 Ϫ0.24 ؊0.01 Ϫ0.26
108.9
106.7
0.02
0.11
Ϫ31(2)
34(2)
31(1)
Ϫ33(1)
1.816(11) 1.658(8), 1.666(7)
1.812(12) 1.664(8), 1.672(7)
0.17 0.06 0.95 Ϫ0.29
0.01 0.03 0.20 Ϫ0.08
0.11 0.06 0.78 Ϫ0.16
0.12 Ϫ0.26
0.01 Ϫ0.06
0.10 Ϫ0.10
3 [1]
11
8.9(4)
Ϫ4.0(4)
1.852(3)
1.854(3)
27.0(4)
Ϫ21.8(4)
14
0.23 0.14 1.32 Ϫ0.43
0.21 0.09 1.26 Ϫ0.38
0.28 Ϫ0.44
0.18 Ϫ0.35
51.1(5)
48.3(5)
Ϫ52.1(5)
Ϫ46.5(5)
1.796(4)
1.797(4)
a) X is the midpoint of the bond C19ϪC24, opposite the phosphorus atom in the phospholane ring.
b) from plane C19/C24/O1/O2.
1262
www.zaac.wiley-vch.de
© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Z. Anorg. Allg. Chem. 2008, 1256Ϫ1266

Two Sterically Encumbered 1,3,2-Dioxaphospholanes
[171°]. The two independent molecules thereby occupy in-
dependent regions of the unit cell, molecule 1 at z ഠ 1/2 and
molecule 2 at z ഠ 0.1.
Table 2a Details of the X-ray crystal structure determinations for
compounds 7, 11, 12 and 14
Compound
7
11
12·1/2 CH2Cl2
14
The remaining structures 12 and 15Ϫ18 form a reason-
ably homogenous set with similar structural characteristics
(distortions) of the Mes* moiety, as discussed above and
presented numerically in Table 1. In summary, the aromatic
ring has a flattened boat conformation with out-of-plane
distortions as shown by, e.g. the torsion angles
PϪC1ϪC2ϪC7 and PϪC1ϪC6ϪC15 and the deviation of
C1, C4 and P from the best plane of C2, C3, C5 and C6.
This difference between the degree of distortion in the
starting materials 2 (less distorted) and 4 cannot be clearly
identified in the corresponding products 17 and 9 (the phos-
phoryl compounds), or 18 and 12 (the gold complexes). The
phosphoryl compound 17 crystallizes as an adduct 17Ј with
two molecules of 17 (Fig. 7) and one of tetrachlorocatechol.
The latter is disordered, but the major site acts via the two
hydroxyl hydrogen atoms as a hydrogen bond donor to each
of the independent phosphoryl oxygen atoms. In both com-
pounds, 9 and 17, the phospholane ring is symmetrically
disposed with respect to the Mes* ring, with torsion angles
e.g. C6ϪC1ϪPϪO1 Ϫ29.7, C2ϪC1ϪPϪO2 35.6° in the
first molecule of 9. This feature is also common to the other
structures in this subset, and gives rise here to very approxi-
mate local mirror symmetry (through C11, C4, C1, P, O3
and the midpoints of C19ϪC24 and C21ϪC22). The phos-
pholane oxygen atoms are involved in short intramolecular
contacts to t-butyl hydrogen atoms [9: to O1 2.20, O2 2.23,
O1Ј 2.26, O2Ј 2.15; 17: to O1 2.20, O2 2.19, O1Ј 2.23, O2Ј
Formula
Mr
Habit
C6Cl5O2P
312.28
C30H33Cl4O4P C24.5H34AuCl2O2P C31H39N2O6P
630.33
659.22
566.61
colourless prism colourless tablet colourless tablet
colourless prism
0.3ϫ0.12ϫ0.11
monoclinic
P21/c
Crystal size (mm) 0.24ϫ0.11ϫ0.11 0.27ϫ0.22ϫ0.16 0.24ϫ0.12ϫ0.06
Crystal system
Space group
triclinic
orthorhombic
P212121
monoclinic
C2/c
¯
P1
Cell constants:
˚
a (A)
7.6868(6)
7.8055(6)
8.4862(6)
100.837(3)
90.425(3)
91.991(3)
499.73
2
2.075
1.57
304
Ϫ140
10.0701(12)
16.489(2)
18.229(2)
90
17.6993(12)
11.5490(8)
26.2960(16)
90
21.117(2)
15.6646(18)
20.129(2)
90
˚
b (A)
˚
c (A)
α (°)
β (°)
γ (°)
90
90
100.431(3)
90
115.479(6)
90
3
˚
V (A )
3026.9
4
5286.3
8
6010.7
8
Z
Dx (Mg mϪ3
)
1.383
0.48
1.657
5.8
1.252
0.14
μ (mmϪ1
F(000)
T (°C)
2θmax
)
1312
2600
2416
Ϫ140
52.8
Ϫ140
60
Ϫ140
52.8
60
Transmissions
No. of refl.:
measured
independent
Rint
Parameters
Restraints
Flack parameter
wR(F2, all refl.)
R(F, >4σ(F))
S
0.69Ϫ0.89
0.56Ϫ0.89
9020
2884
0.018
127
37338
6193
0.148
374
41536
7731
0.046
285
64509
12288
0.137
749
0
81
66
719
Ϫ0.10(6)
0.104
0.042
1.03
0.060
0.021
1.05
0.045
0.023
0.94
0.181
0.061
0.89
Ϫ3
˚
Max. Δρ (e A
)
0.43
0.46
1.09
0.57
Table 2b Details of the X-ray crystal structure determinations for
compounds 15Ϫ18.
Compound
15
16·CH2Cl2
17Ј
18·11/2 CH2Cl2
˚
2.22 A]. The gold complexes, 12 and 18 (Figs. 4 and 8) dis-
Formula
Mr
Habit
C31H40NO4PS C27H38Cl2F3O5PS C54H60Cl12O8P2 C25.5H30AuCl8O2P
553.67 633.50 1324.36 882.05
colourless tablet colourless prism colourless prism colourless needle
play the expected linear geometry at the gold(I) centres.
Again, the oxygen atoms of the phospholane system are
involved in short intramolecular contacts to t-butyl hydro-
gen atoms [12: to O1 2.29, O2 2.28; 18: to O1 2.24, O2 2.18,
Crystal size (mm) 0.37ϫ0.32ϫ0.22 0.29ϫ0.27ϫ0.22 0.35ϫ0.24ϫ0.14 0.32ϫ0.07ϫ0.03
Crystal system
Space group
monoclinic
Pc
triclinic
P1
monoclinic
P21/n
monoclinic
P21/c
¯
Cell constants:
˚
˚
O1Ј 2.18, O2Ј 2.16 A]. Additionally, several short H···Au
A (A)
16.656(2)
9.9627(14)
18.547(3)
90
103.295(5)
90
2995.3
4
1.228
0.20
9.2934(18)
11.279(2)
15.255(3)
82.962(6)
74.530(6)
86.229(6)
1528.5
2
22.975(2)
10.9816(10)
26.925(2)
90
104.965(3)
90
15.476(3)
14.036(3)
30.194(6)
90
91.982(10)
90
˚
B (A)
˚
contacts are observed [12: three between 2.94 and 2.98 A;
˚
C (A)
˚
18: four between 2.88 and 2.97 A]. Because gold is a rela-
α (°)
β (°)
γ (°)
tively electronegative metal, such contacts have been postu-
lated as a stabilising type of weak hydrogen bond [8]. The
well-ordered dichloromethane molecule in 12 is associated
with an AuϪCl unit in a three-centre interaction, with
3
˚
V (A )
Z
6562.6
4
6552
8
Dx (Mg mϪ3
)
1.376
0.39
1.340
0.60
1.788
5.2
μ (mmϪ1
F(000)
T (°C)
2θmax
)
1184
Ϫ140
60
664
2728
3448
˚
H···Cl 2.92, H···Au 3.06 A, angles 158, 142°.
Ϫ140
52.8
Ϫ140
50
Ϫ140
52.8
The Staudinger product 15 (Fig. 5) displays the expected
geometry at phosphorus and nitrogen. The largest angle at
phosphorus is NϪPϪC1 116.62(11)° [117.95(10)° in the se-
cond molecule], compared to values of ca. 122Ϫ123° for
OϭPϪC1 in phosphoryl derivatives such as 17. The usual
short contacts from the t-butyl hydrogen atoms to the phos-
pholane oxygen atoms are: to O1 2.23, O2 2.29, O1Ј 2.24,
Transmissions
No. of refl.:
measured
independent
Rint
0.65Ϫ0.93
33714
17040
0.083
705
9666
6192
0.075
380
70224
11544
0.065
712
78806
13406
0.141
663
Parameters
Restraints
2
248
39
418
Flack parameter Ϫ0.04(6)
wR(F2, all refl.) 0.131
0.128
0.046
0.97
0.122
0.045
1.06
0.191
0.073
1.01
R(F, >4σ(F))
0.051
0.99
0.47
S
˚
O2Ј 2.39 A. The oxygen atoms of the sulfonyl group are
Ϫ3
˚
Max. Δρ (e A
)
0.36
0.39
2.86
involved in long CϪH···O contacts (the shortest amounts
˚
to O···H 2.57 A) that might be regarded as weak hydrogen
bonds (for details see deposited material).
The methyl trifluoromethylsulfonate adduct 16 (Fig. 6)
again displays a somewhat distorted tetrahedral geometry
at phosphorus; the PϪC25 bond to the newly introduced
˚
methyl group is shorter than PϪC1 [1.761(2), 1.781(2) A],
and the largest angle is C25ϪPϪC1 121.40(10)°. The con-
tacts from the t-butyl hydrogen atoms to the oxygen atoms
˚
of the phospholane system are: to O1 2.19, to O2 2.20 A.
Z. Anorg. Allg. Chem. 2008, 1256Ϫ1266
© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.zaac.wiley-vch.de
1263

M. Freytag, J. Grunenberg, P. G. Jones, R. Schmutzler
Ϫ NMR: The NMR spectra were recorded on Bruker spec-
trometers, Avance 400 or Avance 200 at observation frequencies of
400 MHz (1H) and 81 MHz (31P), respectively, in CDCl3 as a sol-
vent, unless specified otherwise. 1H NMR chemical shift values are
given relative to tetramethylsilane. The 31P NMR chemical shifts
are referenced with respect to the frequencies that have been deter-
mined earlier for external 85 per cent aqueous phosphoric acid in
the appropriate solvents. Ϫ MS: Mass spectra were recorded on a
Finnigan MAT95 double focussing sector field instrument; EI
(70 eV), ion source temperature: 180 °C. Ϫ In vacuo (i. v.) refers to
a pressure of 0.1 Torr at 25 °C r.t. ϭ room temperature.
Fig. 9 B3LYP/6-311G(d) optimized gas phase structure of 2 (left)
and an “undisturbed” isopropyl-substituted model system (right).
Reaction of 2-(2,4,6-tri-tert-butylphenyl)benzo-1,3,2-
dioxaphospholane (4) with [(tht)AuCl]; Synthesis of
12
The triflate anion, which is well-ordered, is involved in sev-
To a solution of 400 mg (1.04 mmol) of 4 in 6 ml of dichlorometh-
ane was added a solution of 333 mg (1.04 mmol) of (tht)AuCl in
4 ml of dichloromethane. The reaction mixture was stirred for 0.5 h
at r.t. The volatile components were removed i. v. and the residue
was recrystallized from 5 ml of dichloromethane at Ϫ10 °C. Yield:
410 mg (69.2 %); mp.: 160 °C.
eral CϪH···O contacts, of which by far the shortest involves
˚
the methyl group C25 (H25C···O4 2.33 A).
4 Quantum chemical calculations
1H-NMR: δ ϭ 1.12 (s, 9H, para-tert-Bu); 1.66 (s, 18H, ortho-tert-Bu); 7.05
In order to study the reasons for the distortion of the Mes*
group in 2 we performed quantum chemical calculations
using the hybrid density functional theory in combination
with a standard double zeta basis set augmented with pola-
rization functions on all heavy atoms (6-311G(d)). Our
main aim was to find out if the appreciable distortion in
Mes* is due to intra- or intermolecular forces. Starting with
the coordinates from the solid state structure we optimized
the geometry of 2 as an isolated gas-phase molecule. Since
the distortion in the Mes* group is also to be found in the
optimised isolated molecule, the forces must be of an intra-
molecular nature. We therefore proceeded to perform com-
pliance constant calculations [9] to identify potential non-
covalent interactions that are strong enough to distort the
Mes* substituent. Scanning all possible non-bonded inter-
actions we found two weak CH···O interactions (com-
4
Ϫ 7.13 (m, 4H, C6H4); 7.20 (d, JPH ϭ 4.6 Hz, 2H, phenyl-H). 13C-NMR:
4
δ ϭ 30.69 (s, 3C, C12 Ϫ C14; 34.59 (d, JPC ϭ 2.9 Hz, 6C, C8 Ϫ C10, C16
Ϫ C18); 40.22 (s, 2C, C7, C15); further signals could not be assigned because
of poor resolution. 31P-NMR: δ ϭ 165.12. EI-MS: m/z (%): 616 (28) [M]ϩ;
560 (10) [Mϩ Ϫ tert-Bu ϩ1]; 384 (88) [Mϩ Ϫ AuCl]; 275 (100) [Mϩ
C6H4O2]; 231 [Mϩ Ϫ C6H2-tert-Bu2CMe2 ϩ 1]; 57 (46) [tert-Bu].
Ϫ
C24H33AuClO2P (616.97)
Reaction of 2-(2,4,6-tri-tert-butylphenyl)benzo-1,3,2-
dioxaphospholane (4) with para-nitrobenzoylazide
and water; Synthesis of 14
A solution of 400 mg (1.04 mmol) of 8 and 190 mg (1.04 mmol) of
para-nitrobenzoylazide in 10 ml of THF was stirred for 6 h at r.t.
Because in the 31P NMR spectrum no new signals could be ob-
served, the reaction mixture was stirred for a further 2 d at 55 °C.
In the 31P NMR spectrum two signals at 55.8 und 44.0 ppm were
now observed in a ratio of 1 : 6. The solvent was removed i.v., and
the residue was extracted with pentane. Crystals suitable for X-ray
analysis and MS were obtained by slow evaporation of the solvent.
pliance constant: 7.40 A mdynϪ1; assisted by a nonbonded
˚
CH···P (compliance constant: 8.81 A mdynϪ1; a lower value
˚
means a stronger interaction) contact between one of the
the ortho-tert-butyl-hydrogens and the catechol group. In a
third step, we re-optimized 2 after changing one of the
methyl groups into hydrogen on both ortho-tert-butyl-
groups, which indeed led to an undistorted isopropyl sub-
stituent (see Figure 9). The distortion of the Mes* groups
is therefore clearly due to intramolecular forces. Crystal
packing effects can be excluded.
EI-MS: m/z (%): 566 (3) [M]ϩ; 509 (5) [Mϩ Ϫ tert-Bu]; 400 (60) [Mϩ
Ϫ
C(:O)C6H4NO2 Ϫ Me ϩ 1]; 385 (66) [Mϩ Ϫ C(:O)C6H4NO2 Ϫ 2Me ϩ 1];
291 (46) [Mes*ϪPϭO ϩ 1]; 244 (62) [Mes*Ϫ1]; 57 (100) [tert-Bu].
C31H39N2O6P (566.72).
Reaction of 2-(2,4,6-tri-tert-butylphenyl)benzo-1,3,2-
dioxaphospholane (4) with para ؊ tolyl؊sulfonyl
azide; Synthesis of 15
A solution of 400 mg (1.04 mmol) of 4 and 250 mg (1.27 mmol) of
para-tolylsulfonyl azide in 5 ml of pentane was stirred for 18 h at
r.t. The formation of a gas and of a yellowish precipitate was ob-
served. The reaction mixture was filtered and the solvent was re-
moved i. v. Compound 15 was recrystallized from toluene at
Ϫ10 °C. Yield: 190 mg (33.0 %); mp.: 185 °C. C31H40NO4PS
(553.26): calc C 67.25, H 7.28, N 2.53, S 5.79 %; found C 65.37, H
6.90, N 3.05, S 5.71 %.
5 Experimental Section
All operations were carried out in standard Schlenk glassware in
an atmosphere of dry nitrogen. Solvents were dried, purified and
stored following common procedures [10]. 1,3,5-Tri-tert-butyl-ben-
zene, mesitylene, [Fe3(CO)12], [Ru3(CO)12], DBU, and BuLi were
commercially available from Fluka or Aldrich.
1H-NMR: δ ϭ 1.21 (s, 9H, para-tert-Bu); 1.54 (s, 18H, ortho-tert-Bu); 2.35
(s, 3H, tolyl-Me); 7.38 (d, JPH ϭ 6.7 Hz, 2H, phenyl-H); 7.55 (d, JHH
Melting points were determined on a Büchi 530 melting point ap-
paratus, using sealed 0.1 mm capillary tubes, and are uncorrected.
4
3
ϭ
1264
www.zaac.wiley-vch.de
© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Z. Anorg. Allg. Chem. 2008, 1256Ϫ1266

Two Sterically Encumbered 1,3,2-Dioxaphospholanes
4
1.47 Hz, 2H, toloyl-H) 7.78 (d, JHH ϭ 1.70 Hz, 2H, tolyl-H). 13C-NMR:
31P-NMR (reaction mixture): δ ϭ 46.12. Because the X-ray analysis
showed that the crystals contained disordered tetrachlorocatechol
and disordered solvent, no further analyses were conducted.
δ ϭ 21.41 (s, 1C, tolyl-Me); 30.66 (s, 3C, C12 Ϫ C14); 33.45 (s, 6C, C8 Ϫ
3
C10, C16 Ϫ C18); 40.40 (d, JPH ϭ 3.67 Hz, 2C, C7, C15); further signals
could not be assigned because of poor resolution. 31P-NMR: δ ϭ 39.76. EI-
MS: m/z (%): 553 (16) [M]ϩ; 538 (14) [Mϩ Ϫ Me]; 496 (100) [Mϩ Ϫ tert-
Bu]; 385 (20) [Mϩ Ϫ Mes*] ; 231 (22) [Mϩ Ϫ C6H2-tert-Bu2CMe2 ϩ 1] ; 155
(8) [MeC6H4SO2]; 57 (22) [tert-Bu].
Reaction of 3-(2,4,6-tri-tert-butylphenyl)-3,4,5,6-
tetrachlorobenzo-1,3,2-dioxaphospholane (2) with
[(tht)AuCl]; Synthesis of 18
Reaction of 2-(2,4,6-tri-tert-butylphenyl)benzo-1,3,2-
dioxaphospholane (4) with methyl
To a solution of 250 mg (0.65 mmol) of 3 in 5 ml of dichlorometh-
ane was added a solution of 208 mg (0.65 mmol) of [(tht)AuCl] in
3 ml of dichloromethane. After stirring for 1 h at r.t., the volatile
components were removed i.v. and the residue was recrystallized
from 4 ml dichloromethane at Ϫ10 °C. Yield: 190 mg (38.5 %); mp.:
163 °C. C24H29AuCl5O2P (754.80): Calc. C 38.19, H 3.88, Cl
23.48 %; Found C 38.22, H 4.03, Cl 22.34 %.
1H-NMR: δ ϭ 1.27 (s, 9H, para-tert-Bu); 1.70 (s, 18H, ortho-tert-Bu); 7.38
(d, 4JPH ϭ 5.1 Hz, 2H, Phenyl-H). 13C-NMR: δ ϭ 30.79 (s, 3C, C12 Ϫ C14);
34.89 (d, 4JPC ϭ 2.9 Hz, 6C, C8 Ϫ C10, C16 Ϫ C18); 40.49 (s, 2C, C7, C15)
125.20 (d, 3JPC ϭ 9.0 Hz, 2C, C7, C15); further signals could not be assigned
because of poor resolution. 31P-NMR: δ ϭ 184.91. A mass spectrum could
not be recorded because of technical problems.
trifluoromethylsulfonate; Synthesis of 16
A solution of 400 mg (1.04 mmol) of 4 and 0.09 ml (1.27 mmol)
of methyl trifluoromethylsulfonate in 6 ml of dichloromethane was
stirred for 1 h at r.t. The volatile components were removed i.v.,
the residue was dissolved in 3 ml of dichloromethane and layered
under 9 ml of pentane in a narrow glass tube. Within 3 d crystals
of 16, suitable for X-ray, analysis were formed. Yield: 160 mg
(30.0 %); mp.: 182 °C. C26H37F3O5PS·CH2Cl2 (538.65·84.93). calc
C 51.11, H 6.19 %; found C 52.66, H 6.21 %.
1H-NMR: δ ϭ 1.23 (s, 9H, para-tert-Bu); 1.61 (s, 18H, ortho-tert-Bu); 3.55
(d, 2JPH ϭ 12.0 Hz, 3H, PϪMe); 7.09 Ϫ 7.18 (m, 4H, C6H4); 7.47 (d, 4JPH ϭ
6.5 Hz, 2H, phenyl-H). 13C-NMR: δ ϭ 30.93 (s, 3C, C12 Ϫ C14); 33.57 (s,
6C, C8 Ϫ C10, C16 Ϫ C18); 40.39 (d, 3JPC ϭ 2.50 Hz, 2C, C7, C15); further
signals could not be assigned because of poor resolution. 31P-NMR: δ ϭ
127.68.
X-Ray Structure Determinations
Numerical data are presented in Table 2. Data were registered using
Mo-Kα radiation on a Bruker SMART 1000 CCD diffractometer.
Absorption corrections for compounds 7, 11 and 18 were based on
multiple scans (program SADABS). Structures were refined aniso-
tropically on F2 (program SHELXL-97, G.M. Sheldrick, University
of Göttingen, Germany). Methyl hydrogen atoms were identified
in difference syntheses and refined as rigid groups allowed to rotate
but not tip; other hydrogen atoms were included using a riding
model. Restraints to displacement parameters (DELU/SIMU) were
employed for compounds 11, 14, 16, 17, 18. Special features / excep-
tions: the para-tert-butyl group in 11 is disordered over two posi-
tions; for the minor position, staggered methyl hydrogen atoms
were assumed. The compound crystallizes in a chiral space group
but the bulk material is a racemate. For compound 14, OH hydro-
gen atoms were identified in difference syntheses and refined as
rigid groups allowed to rotate but not tip; NH hydrogen atoms
were refined freely, but with NϪH distance restraints. In compound
16, the dichloromethane molecule is disordered over two positions.
Compound 17 crystallized with two molecules of 17 and one tetra-
chloro-o-catechol in the asymmetric unit; this adduct is denoted as
17Ј. The catechol was disordered over two positions with relative
occupancy 85 % : 15 %, and a system of similarity restraints was
used to improve refinement stability. A region of poorly defined
electron density, presumably corresponding to disordered solvent
(pentane), was removed mathematically using the program
SQUEEZE (Prof. A. L. Spek, Univ. of Utrecht, Netherlands); this
solvent was not considered in deriving values for formula weight,
density and associated parameters. Compound 18 crystallized with
two independent molecules and three dichloromethane molecules,
one of which was disordered, in the asymmetric unit.
Reaction of 2,4,6-tri-tert-butylphenylbromide (5) with
2-chloro-3,4,5,6-tetrachlorobenzo-1,3,2-
dioxaphospholane (7); Synthesis of 2-(2,4,6-tri-tert-
butylphenyl)-3,4,5,6-tetrachlorobenzo-1,3,2-
dioxaphospholane (2)
A solution of 16.2 ml (26.0 mmol) of nBuli (1.6 M in hexane) was
added dropwise at Ϫ78 °C to a solution of 7.65 g (23.5 mmol) of 5
in 75 ml of THF. After stirring for 10 min at Ϫ78 °C, 7.35 g
(23.5 mmol) of 7 in 20 ml of THF were added dropwise. The reac-
tion mixture was allowed to warm up to r. t. and was then refluxed
for 3 h. After cooling down to r. t., the solvent was removed i.v.
The residue was suspended in 30 ml of dichloromethane and centri-
fuged. The solution of 2 was carefully separated from the lithium
salts and evaporated i. v. The residue was dissolved in 50 ml of
warm pentane and filtered warm. The solvent was removed i. v.,
the residue dissolved in a small amount of dichloromethane, pre-
cipitated with pentane and stored overnight at Ϫ10 °C. The precipi-
tate of 2 was filtered off, and the procedure was repeated 3x with
the solution. Yield: 3.9 g (31.8 %).
Characterisation: see [1].
Reaction of 2-(2,4,6-tri-tert-butylphenyl)-3,4,5,6-
tetrachlorobenzo-1,3,2-dioxaphospholane (2) with
H2O2 ·O؍C(NH3)2; Synthesis of 2-(2,4,6-tri-tert-
butylphenyl)-3,4,5,6-tetrachlorobenzo-1,3,2-
dioxaphospholane-2-oxide (17)
To a solution of 250 mg (0.48 mmol) of 3 in 7 ml of toluene was
given 140 mg (1.45 mmol) of H2O2 ·OϭC(NH3)2. After stirring for
6 h at r. t. the reaction mixture was filtered. The filtrate was washed
3x with 5 ml of water, and the organic layer was separated and
dried over MgSO4. The solvent was removed i.v., and 17 was
recrystallized from pentane at Ϫ10 °C.
Full details of the crystal determinations (except structure factors)
have been deposited under the numbers CCDC-293475 (7), -293476
(11), -293477 (12), -293478 (14), -293479 (15), -293480 (16),
-293555 (17Ј) and -293481 (18) at the Cambridge Crystallographic
Data Centre. Copies may be obtained free of charge from:
www.ccdc.cam.ac.uk/products/csd/request).
Z. Anorg. Allg. Chem. 2008, 1256Ϫ1266
© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.zaac.wiley-vch.de
1265

M. Freytag, J. Grunenberg, P. G. Jones, R. Schmutzler
[6] E. Breuer, A. Schlossmann, M. Safadi, D. Gibson, M. Chorev,
H. Leader, J. Chem. Soc., Perkin Trans. 1 1990, 3263.
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© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Z. Anorg. Allg. Chem. 2008, 1256Ϫ1266