Novel sterically congested monoorganobismuth(iii) compounds: synthesis, structure, and bismuth-arene π interaction in ArBiXY (X, Y = Br, I, OH, 2,6-Mes2-4-t-Bu-C6H2PHO2) 2,6-Mes2-4-t-Bu-C6H

Article abstract of DOI:10.1021/om800934c

Four novel sterically congested terphenyl-substituted bismuth dihalides of the type [2,6-Mes₂-4-R- C₆H₂BiX ₂]₂ (1, R = t-Bu, X = Cl, Br; 2, R = H, X = Br; 3, R = t-Bu, X = Br; 4, R = H, X = I) were sy

Full text of DOI:10.1021/om800934c

1202
Organometallics 2009, 28, 1202–1211
Novel Sterically Congested Monoorganobismuth(III) Compounds:
Synthesis, Structure, and Bismuth-Arene π Interaction in ArBiXY
(X, Y ) Br, I, OH, 2,6-Mes2-4-t-Bu-C6H2PHO2)
Hans J. Breunig, Nawja Haddad,§ Enno Lork, Michael Mehring,*,† Clemens Mu¨gge,§
Christof Nolde,‡ Ciprian I. Ra¸t, and Markus Schu¨rmann‡
Institut fu¨r Chemie, Technische UniVersita¨t Chemnitz, Strasse der Nationen 62, 09111 Chemnitz, Germany,
Technische UniVersita¨t Dortmund, Anorganische Chemie II, Otto-Hahn-Strasse 6, 44221 Dortmund, Germany,
Institut fu¨r Chemie, Humboldt-UniVersita¨t zu Berlin, Brook-Taylor-Strasse 2, 12489 Berlin, Germany, and
Institut fu¨r Anorganische and Physikalische Chemie, UniVersita¨t Bremen, Postfach 330 440,
28334 Bremen, Germany
ReceiVed September 26, 2008
Four novel sterically congested terphenyl-substituted bismuth dihalides of the type [2,6-Mes2-4-R-
C6H2BiX2]2 (1, R ) t-Bu, X ) Cl, Br; 2, R ) H, X ) Br; 3, R ) t-Bu, X ) Br; 4, R ) H, X ) I) were
synthesized and structurally characterized including single-crystal X-ray diffraction analyses. Whereas
the compounds 1-3 are dimeric in the solid state, the organobismuth diiodide 4 is a one-dimensional
coordination polymer. Upon hydrolysis of compound 3, the first structurally characterized monoorga-
nobismuth halide hydroxide, [2,6-Mes2-4-t-Bu-C6H2BiBr(OH)]2 (5), was isolated instead of the expected
monoorganobismuth dihydroxide. Stability of compound 5 toward further hydrolysis might be interpreted
to be the result of both intramolecular bismuth-arene π interaction and intramolecular OH-arene π
interaction. Reaction of compound 5 with the sterically congested phosphinic acid 2,6-Mes2-4-t-Bu-
C6H2PH(O)(OH) gave the organobismuth phosphinate ArBiBrO(O)HPAr (Ar ) 2,6-Mes2-4-t-Bu-C6H2)
(6). The single-crystal X-ray structure analysis of compound 6 reveals unusual 2-fold intramolecular
bismuth-arene coordination. Compounds 3, 5, and 6 were studied in detail by temperature-dependent
NMR spectroscopy in solution in order to get information on the Menshutkin-like bismuth-arene π
interaction. Whereas for compounds 3 and 5 only qualitative information was obtained showing that the
dimeric structures most likely are not preserved in solution, more distinct information was available for
compound 6. Four distinct intramolecular processes were observed. The energy barriers for the dislocation
of the arene ligands in compound 6 by rotation of the terphenyl ligand around the Bi-C bond was
estimated to be approximately 54 kJ mol-1. This energy barrier results from a combination of both steric
hindrance for the rotation and intramolecular bismuth-arene π complexation.
not only provide steric protection but additionally stabilize
organobismuth derivatives by intramolecular bismuth-arene π
coordination, as was shown previously for [Ar1BiCl2]2 (Ar1 )
2,6-Mes2-C6H3)5 and [2,4,6-Ph3-C6H2BiCl2]2.20 Hydrolysis of
such compounds is expected to give arylbismuth dihydroxides.
However, so far only the formation of diorganobismuth
Introduction
In comparison to other main group metals the organometallic
chemistry of bismuth developed slowly, a possible result of the
labile bismuth carbon bond.1 However, it is well known that
the stability of organometallic bismuth compounds is signifi-
cantly increased by the use of either intramolecular donor ligands
or bulky organic ligands, which was demonstrated recently by
the isolation of intriguing examples, e.g., with BidE (E ) P,
As, Sb, Bi) bonds.2-19 Bulky arene ligands such as m-terphenyl
(8) Balazs, L.; Breunig, H. J.; Lork, E.; Soran, A.; Silvestru, C. Inorg.
Chem. 2006, 45, 2341.
(9) Breunig, H. J.; Balazs, L. Organometallics 2004, 23, 304.
(10) Soran, A. P.; Silvestru, C.; Breunig, H. J.; Balazs, G.; Green, J. C.
Organometallics 2007, 26, 1196.
(11) Linti, G.; Kostler, W.; Pritzkow, H. Eur. J. Inorg. Chem. 2002,
2643.
(12) Breunig, H. J.; Königsmann, L.; Lork, E.; Nema, M.; Philipp, N.;
Silvestru, C.; Soran, A.; Varga, R. A.; Wagner, R. Dalton Trans. 2008,
1831.
* Corresponding author. E-mail: michael.mehring@chemie.tu-chemnitz.de.
† Technische Universität Chemnitz.
‡ Technische Universita¨t Dortmund.
§ Humboldt-Universita¨t zu Berlin.
Universita¨t Bremen.
(1) Suzuki, H.; Matano, Y. Organobismuth Chemistry; Elsevier: Am-
sterdam, 2001.
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1999, 44, 1.
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78.
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Ruzicka, A.; Cisarova, I.; Holecek, J. J. Organomet. Chem. 2007, 692, 3969.
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R.; Holecek, J. Organometallics 2007, 26, 2911.
(6) Balazs, G.; Breunig, H. J.; Lork, E. Organometallics 2002, 21, 2584.
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Holecek, J. Organometallics 2006, 25, 4366.
10.1021/om800934c CCC: $40.75
2009 American Chemical Society
Publication on Web 01/22/2009

Monoorganobismuth(III) Compounds
Organometallics, Vol. 28, No. 4, 2009 1203
hydroxides was claimed in some early publications21,22 and was
only recently evidenced by single crystal structure analyses of
(o-tolyl)2BiOH,23 [2-(Me2NCH2)C6H4]2BiOH,12 and 6-tert-butyl-
12-hydroxo-5,6,7,12-tetrahydrodibenz[c,f][1,5]azabismocine.24
Here we report on a series of novel sterically congested
arylbismuth halides of the type [2,6-Mes2-4-R-C6H2BiX2]2 (1,
R ) t-Bu, X ) Cl, Br; 2, R ) H, X ) Br; 3, R ) t-Bu, X )
Br; 4, R ) H, X ) I) and present the first structurally
characterized examples of an arylbismuth halide hydroxide,
[Ar2BiBr(OH)]2 (5), and an arylbismuth phosphinate,
Ar2BiBrO(O)HPAr2 (Ar2 ) 2,6-Mes2-4-t-Bu-C6H2) (6). The
single-crystal X-ray structure analysis of compound 6 reveals
unusual 2-fold bismuth-arene coordination, which was ad-
ditionally studied by NMR spectroscopy in solution in order to
get information on the strength of this type of weak interaction.
According to a recent review by H. Schmidbaur and A. Schier,
so far no experimental and only sparse theoretical25-27 data for
the strength of the bismuth-arene π interaction are available.28
Scheme 1. Synthesis of Arylbismuth Compounds 1-6
Results and Discussion
Synthesis. Arylbismuth dichlorides with terphenyl substitu-
ents as bulky, sterically demanding ligands in compounds such
as 2,4,6-Ph3-C6H2BiCl2 (7), Ar1BiCl2 (8), and 2,6-[2,6-(i-Pr2-
C6H3)]2-C6H3BiCl2 (9) have been reported.4,5,20 These com-
pounds were prepared starting from the corresponding aryl
bromides or -iodides, which were converted into the aryl lithium
compounds by metal-halogen exchange.29-31 Subsequent reac-
tion with BiCl3 gave the arylbismuth dichlorides 7-9 with yields
between 20% and 65%. We did observe that in the case of Ar2Br
(Ar2 ) 2,6-Mes2-4-t-Bu-C6H2) metal-halogen exchange with
1 equiv of n-BuLi did not exceed 50%, and to maximize the
yield, a 2-fold excess of n-BuLi had to be used. However, the
high solubility of Ar2Li (10) even in diethyl ether and n-hexane
(in contrast to Ar1Li) prevented its isolation, and we changed
to t-BuLi for the in situ preparation of the lithium organyl 10.
Subsequent reaction with BiCl3 produced an oil containing
organobismuth dibromide Ar2BiBr2 is accessible via metathesis
reaction of the corresponding Grignard reagent Ar2MgBr with
BiBr3 (Scheme 1). The pure and crystalline material of Ar2BiBr2
(3) was obtained upon crystallization from n-hexane with a yield
of 19%.
Starting from the organobismuth dibromide Ar1BiBr2 (2) the
corresponding diiodide Ar1BiI2 (4) was prepared by halogen
exchange using potassium iodide in ethanol following a recently
published synthetic procedure.10,19
Noteworthy, the arylbismuth dihalides 1-4 are stable toward
moisture, and we had to add either water and an amine or NaOH
to the reaction mixture in order to prepare Ar2BiBr(OH) (5).
Attempts to prepare the corresponding dihydroxide Ar2Bi(OH)2
failed. A prominent byproduct is 2,6-Mes2-4-t-Bu-C6H3, which
results from bismuth-carbon bond cleavage. Surprisingly,
compound 5 did not give the product of homocondensation, as
was observed recently for (2,4,6-Me3-C6H2)2BiOH32 and 6-tert-
butyl-12-hydroxo-5,6,7,12-tetrahydrodibenz[c,f][1,5]azabismoc-
ine24 as well as for the related organotin compound Ar2-
SnMe2OH,33 but reaction with Ar2PH(O)OH34 at room tempera-
ture quantitatively gave the heterocondensation product
Ar2BiBrO(O)HPAr2 (6). The latter compound was crystallized
from CH2Cl2 to give a crystalline compound that reveals two
types of intramolecular bismuth-arene π complexation. The
dynamic behavior of this type of interaction in solution was
studied by detailed NMR investigations.
1
Ar2BiCl2, as evidenced by H NMR spectroscopy and electro-
spray ionization mass spectrometry (ESI-MS), but isolation of
the pure crystalline solid failed. The use of the Grignard reagent
Ar2MgBr, which forms easily in THF from Ar2Br and Mg,
seemed to be more convenient, but metathesis reaction with
BiCl3 gave the crystalline, mixed organobismuth dihalide
Ar2BiBrxCl2-x (1), as was shown by ESI-MS and X-ray single-
crystal structure analysis. In contrast, the reaction of Ar1MgBr
with BiCl3 gave the pure organobismuth dibromide Ar1BiBr2
(2) with a yield of 38% after crystallization. The corresponding
(20) Avtomonov, E. V.; Li, X.-W.; Lorberth, J. J. Organomet. Chem.
1997, 530, 71.
(21) Davies, A. G.; Hook, S. C. W. J. Chem. Soc. C 1971, 1660.
(22) Hartmann, H.; Habenicht, G.; Reiss, W. Z. Anorg. Allg. Chem. 1962,
317, 54.
(23) Roggan, S.; Limberg, C.; Ziemer, B.; Siemons, M.; Simon, U. Inorg.
Chem. 2006, 45, 9020.
(24) Yin, S. F.; Maruyama, J.; Yamashita, T.; Shimada, S. Angew.
Chem., Int. Ed. 2008, 47, 6590.
(25) Turner, L. E.; Davidson, M. G.; Jones, M. D.; Ott, H.; Schulz, V. S.;
Wilson, P. J. Inorg. Chem. 2006, 45, 6123.
(26) Dikarev, E. V.; Bo, L.; Rogachev, A. Y.; Haitao, Z.; Petrukhina,
M. A. Organometallics 2008, 27, 3728.
Molecular Structures of Compounds 1-6 in the Solid
State. Molecular structures of the arylbismuth halides 1-6 were
determined by single-crystal X-ray diffraction analysis. Crystal-
lographic data are given in Table 1. Selected bond lengths and
angles are given in Table 2 for 1-4 and in the corresponding
figure captions for 5 and 6. In the past decade several
monoorganobismuth dihalides were structurally characterized
including monomeric species such as the sterically congested
(27) Konietzny, S. Doctoral thesis, Unversity of Kaiserslautern, 2003.
(28) Schmidbaur, H.; Schier, A. Organometallics 2008, 27, 2361. A
summary of the state of theoretical treatment of the bonding phenomena in
arene complexes of EX3 (E ) As, Sb, Bi) is presented in this review.
(29) Ruhlandt-Senge, K.; Ellison, J. J.; Wehmschulte, R. J.; Pauer, F.;
Power, P. P. J. Am. Chem. Soc. 1993, 115, 11353.
(32) Breunig, H. J.; Ebert, K. H.; Schulz, R. E.; Wieber, M.; Sauer, I.
Z. Naturforsch. (B) 1995, 50b, 735.
(33) Mehring, M.; Nolde, C.; Schu¨rmann, M. Inorg. Chim. Acta, in press,
doi:10.1016/j.ica.2008.04.003.
(34) Nolde, C.; Schu¨rmann, M.; Mehring, M. Z. Anorg. Allg. Chem.
2007, 633, 142.
(30) Schiemenz, B.; Power, P. P. Organometallics 1996, 15, 958.
(31) Rivard, E.; Power, P. P. Inorg. Chem. 2007, 46, 10047.

1204 Organometallics, Vol. 28, No. 4, 2009
Breunig et al.
Table 1. Crystallographic Data for Compounds 1-6
1
2
3
4
5
6
empirical formula
C28H33BiBr1.12Cl0.88
CH2Cl2
784.15
·
C24H25BiBr2
0.25 C6H14
768.42
monoclinic
P2(1)/n
11.201(2)
17.161(4)
14.047(3)
90
95.250(10)
90
2688.8(10)
1
·
C56H66Bi2Br4
C24H25BiI2
C28H34BiBrO
C56H67BiBrO2P
Mr
cryst syst
space group
a/Å
b/Å
c/Å
1476.69
triclinic
776.22
orthorhombic
P212121
8.300(1)
15.035(2)
19.512(4)
90
90
90
2434.9(7)
4
675.44
1091.96
monoclinic
P2(1)/c
15.3197(3)
26.2909(6)
13.7661(3)
90
110.9350(10)
90
5178.54(19)
4
triclinic
monoclinic
P2(1)/n
9.1994(2)
26.5238(6)
11.1646(2)
90
106.7899(11)
90
2608.06(9)
2
j
j
P1
P1
8.9213(3)
13.0022(6)
14.2868(6)
107.120(2)
91.579(2)
104.401(2)
1524.91(11)
2
8.9597(3)
11.1881(3)
14.1175(6)
92.1152(12)
95.2567(13)
106.5419(14)
1347.94(8)
1
R/deg
ꢀ/deg
γ/deg
V/Å3
Z
λ/Å
0.71073
7.516
0.71073
9.536
0.71073
9.517
0.71073
9.783
0.71073
8.309
0.71073
4.245
µ/mm-1
cryst size/mm
cryst color
calcd density/mg m-3
0.08 × 0.05 × 0.05
0.60 × 0.40 × 0.10 0.08 × 0.05 × 0.05 0.70 × 0.40 × 0.30 0.20 × 0.20 × 0.16 0.14 × 0.12 × 0.10
yellow
yellow
yellow
orange
yellow
colorless
1.401
1.708
1.712
1.819
2.117
1.720
θ range for data collection 3.27 to 27.44
2.53 to 25.01
10 885
4742
3.37 to 25.00
9742
4545
2.67 to 27.51
4094
3730
2.97 to 27.46
18 082
5764
2.92 to 25.33
37 836
9463
no. of reflns collected
no. of unique reflns
13 792
6824
[Rint ) 0.049]
[Rint ) 0.072]
[Rint ) 0.041]
[Rint ) 0.044]
[Rint ) 0.040]
[Rint ) 0.071]
completeness to 2θ [%]
GOOF
97.9
99.7
95.6
99.5
96.8
99.8
0.959
1.012
1.011
1.062
0.954
0.637
max. and min. transmn
R1 [I > 2σ(I)]
wR2 (all data)
0.705 and 0.538
0.0384
0.0675
0.449 and 0.069
0.0661
0.1810
0.648 and 0.550
0.0469
0.0833
0.157 and 0.056
0.0479
0.1249
0.345 and 0.212
0.0515
0.1371
0.676 and 0.588
0.0343
0.0523
largest diff peak and
1.225/-0.994
3.068/-1.882
1.967/-0.842
2.296/-2.299
1.409/-2.638
0.543/-0.554
hole/e/Å3
C6H4BiCl2]2 and [(t-BuOCH2)2C6H3BiX2]2 (X ) Cl, I),10,19
whereas (MeOCH2)2C6H3BiX2 (X Cl, I) and 2,6-
Table 2. Selected Bond Distances [Å] and Angles [deg] for
Compounds 1-4
)
(Me2NCH2)2C6H3BiX2 (X ) Cl, Br, I)19 crystallize as doubly
bridged polymeric chains with asymmetrical bismuth-halide
coordination. Similarly, one-dimensional structures with sym-
metric bismuth-halide coordination are observed for compounds
of the type RBiI2 (R ) Me, Et, n-Bu),37,38 whereas MeBiCl2
forms a layered structure.39 Polymeric chains with asymmetric
bismuth halide bridges of the type Bi-X · · · Bi were also
reported, e.g., for compounds with bulky substituents such as
MesBiBr240 and (Me3Si)2CHBiCl2.41 The mixed organobismuth
dihalide [Ar2BiBrxCl2-x]2 (1) and [2,6-Mes2-4-R-C6H2BiBr2]2 (2,
R ) H; 3, R ) t-Bu) form similar dimeric structures with
intramolecular bismuth-arene π coordination (Figures 1, S1,
and S2), which resemble those of compounds 7 and 8.5,20 Single
crystals of the mixed organobismuth dihalide Ar2BiBrxCl2-x (1)
were obtained from CH2Cl2 at -20 °C, and the elemental
analysis of the crystalline material corresponds to the formula
C28H33BiCl1.5Br0.5. However, refinement of the crystal data gave
[Ar2BiCl0.88Br1.22]2 (1), showing a higher bromide content than
expected from elemental analysis. We conclude that a con-
glomerate of crystals with a different degree of Cl/Br substitution
was obtained, which is confirmed by the ESI-MS(-) spectrum
showing the following anions and relative intensities:
[Ar2BiCl3]- (683.4, 80%), [Ar2BiCl2Br]- (729.6, 100%),
[Ar2BiClBr2]- (775.5, 62%), [Ar2BiBr3]- (819.0, 15%). Note-
worthy, in the solid state the disorder for terminal Cl(1)/Br(1)
ligands and for bridging ligands Cl(2)/Br(2) differ significantly,
showing ratios of 0.715/0.285 and 0.405/0.595, respectively.
There is a preference for chloride in terminal and bromide in
bridging position in accordance with Pearson‘s concept of hard
compound
1, X ) Br, 2, X )
3, X )
Y ) Br
4, X )
Y ) I
Y ) Cl
Y ) Br
Bi(1)-C(1)
2.264(4)
2.56(2)
2.57(3)
3.15(3)
2.259(14) 2.269(8)
2.286(11)
Bi(1)-X(1)
2.6401(18) 2.6626(9) 2.8649(10)
2.6642(14) 2.6629(10) 2.8302(10)
3.3223(17) 3.2707(9) 4.097(1)
4.005(1)
Bi(1)-X(2)
Bi(1)-X(2′)
Bi(1)-X(2′′)
Bi(1)-Y(1)
2.647(4)
2.643(17)
3.205(16)
3.490
Bi(1)-Y(2)
Bi(1)-Y(2′)
Bi(1)-Arcent
3.527
3.703
4.678
90.47(3)
169.29(3)
3.571
4.591
101.26(3)
Bi(1)-Ar′cent
4.698
4.706
X(1)-Bi(1)-X(2)
X(1)-Bi(1)-X(2′)
X(1)-Bi(1)-X(2′′)
X(1′)-Bi(1)-X(2)
X(1′)-Bi(1)-X(2′′)
X(1)-Bi(1)-C(1)
X(2)-Bi(1)-C(1)
X(2)-Bi(1)-X(2’)
C(1)-Bi(1)-X(2′)
Y(1)-Bi(1)-Y(2)
Y(1)-Bi(1)-Y(2′)
Y(1)-Bi(1)-C(1)
Y(2)-Bi(1)-C(1)
C(1)-Bi(1)-Y(2′)
88.8(3)
167.4(3)
89.58(5)
165.2(1)
77.4(1)
76.1(2)
63.9(1)
102.4(3)
99.1(3)
99.22(12) 94.5(4)
100.7(2)
102.6(2)
79.72(3)
85.8(2)
103.7(3)
79.2(4)
87.3(2)
87.7(8)
163.4(8)
95.1(4)
99.7(5)
90.7(4)
103.6(3)
79.67(4)
97.9(3)
C(2)-C(1)-Bi(1) (a1) 108.3(3)
131.4(9)
109.5(9)
21.9
108.5(5)
132.1(6)
23.6
132.4(8)
108.7(8)
23.7
C(6)-C(1)-Bi(1) (a2) 131.2(3)
∆(a1 - a2)
22.9
triptBiCl2 (tript ) 9-tryptycenyl)35 and Ar1BiCl2 (8).5 The latter
is additionally stabilized by “Menshutkin-like”28,36 intramo-
lecular bismuth-arene π interaction. However, crystallization
of compound 8 from Et2O instead of benzene results in a dimeric
structure with asymmetrical bismuth-halide coordination5
similar to [2,4,6-Ph3-C6H2BiCl2]2 (7).20 Other examples of
dimeric structures are intramolecular coordinated [2-(Me2NCH2)-
(37) Wang, S. M.; Mitzi, D. B.; Landrum, G. A.; Genin, H.; Hoffmann,
R. J. Am. Chem. Soc. 1997, 119, 724.
(38) Mitzi, D. B. Inorg. Chem. 1996, 35, 7614.
(39) Althaus, H.; Breunig, H. J.; Lork, E. Organometallics 2001, 20,
586.
(40) Becker, G.; Egner, J.; Meiser, M.; Mundt, O.; Weidlein, J. Z. Anorg.
Allg. Chem. 1997, 623, 941.
(41) Althaus, H.; Breunig, H. J.; Ro¨sler, R.; Lork, E. Organometallics
1999, 18, 328.
(35) Baker, R. J.; Brym, M.; Jones, C.; Waugh, M. J. Organomet. Chem.
2004, 689, 781.
(36) Menshutkin, B. N. J. Russ. Phys. Chem. Soc. 1911, 43, 395.

Monoorganobismuth(III) Compounds
Organometallics, Vol. 28, No. 4, 2009 1205
Figure 1. Thermal ellipsoid representation (30%) of the molecular structure of [2,6-Mes2-C6H3BiBr2]2 (2). Hydrogen atoms were omitted
for clarity.
and weak Lewis acids and bases. The Bi-Clterminal, Bi-Clbridging
(primary bonds), and Bi · · · Clbridging (secondary bonds) bond
lengths amount to 2.56(2), 2.57(3), and 3.15(3) Å, which is
comparable with bond lengths reported for [2,4,6-Ph3-
C6H2BiCl2]2 (7)20 and [Ar1BiCl2]2 (8).5 The corresponding
Bi-Brterminal, Bi-Brbridging, and Bi · · · Brbridging bond lengths
amount to 2.647(4), 2.643(17), and 3.205(16) Å. Only slightly
different values were found in [2,6-Mes2-4-R-C6H2BiBr2]2 (2,
R ) H; 3, R ) t-Bu) for the bismuth bromide bond lengths
(Table 2). However, both compounds 2 and 3 show an
elongation of the Bi · · · Brbridging bond (2, 3.3223(17) Å; 3,
3.2707(9) Å), as compared with compound 1, indicating a
slightly weaker secondary interaction. In comparison, the one-
dimensional polymers 2,6-(Me2NCH2)2C6H3BiBr2 (11),10 Mes-
BiBr2 (12),40 and PhBiBr2 (13)42 show bismuth bromide
coordination ranging from highly asymmetric in 11 (2.8404(9),
3.818(1) Å) via slightly asymmetric in 12 (2.607(3), 2.619(3),
2.808(3), 2.818(1) Å), to almost symmetric in 13 (2.8801(9),
2.9253(11) Å).
Apparently, steric effects and/or the “Menshutkin”-like
bismuth-arene π complexation in compounds 2 and 3 influence
the secondary Bi · · · Br interaction but do not significantly alter
theprimaryBi-Brbondlength.Thestrengthofthisbismuth-arene
π interaction is most often indicated by the distance of the
bismuth atom from the ring centroid of the coordinated aryl
ligand28 but was also expressed as a difference ∆ in the
Bi(1)-C(1)-C(2) and Bi(1)-C(1)-C(6) bond angles including
the ipso- and the ortho-carbon atoms of the bismuth-bonded
aryl ligand.5 Thus, a short Bi-arene distance should correspond
to a large difference ∆. However, a comparison including
compounds 1-8 (Table S1) shows that there is no direct
correlation between these data; for example, 2, Bi-arylcentroid
3.527 Å, ∆ ) 21.9°; 3, Bi-arylcentroid 3.703 Å, ∆ ) 23.6°.
If the bismuth-arene coordination is taken into account for
compounds 1-3, the geometry at bismuth is best described as
tetragonal pyramidal with the covalently bonded carbon atom
in apical position. Although the organobismuth diiodide Ar1BiI2
(4) also shows the typical bismuth-arene π complexation with
a Bi-arylcentroid distance of 3.571 Å, the coordination geometry
and the arrangement of the molecules in the crystal lattice differ
significantly from those of the other dihalides. The molecules
arrange in one-dimensional chains through weak secondary
Bi · · · I interactions with adjacent bulky aryl ligands situated in
trans position (Figure 2). The related organobismuth diiodides
RBiI2 (R ) Me, Et, Bu)37,38 show a cis configuration of similar
polymeric chains with almost symmetric bismuth iodide coor-
dination and bond lengths in the range 3.087 to 3.134 Å. The
iodide ligands in 4 are not lying in a plane as observed for RBiI2
(R ) Me, Et, Bu) and are asymmetrically coordinated to the
bismuth atom as shown by the bond lengths Bi(1)-I(1)
2.8649(10) Å, Bi(2)-I(2) 2.8302(10) Å, Bi(1) · · · I(1′) 4.097(1)
Å, and Bi(1) · · · I(2′′) 4.005(1) Å. The lengths of the secondary
Bi · · · I bonds are shorter than the sum of the van der Waals
radii of bismuth and iodine (rvdW(Bi) ) 2.40 Å; rvdW(I) )
1.95-2.12 Å),43 but the bond strength is assumed to be relatively
weak.
A similar bonding situation was observed in
(ROCH2)2C6H3BiI2 (R ) Me, t-Bu) and 2,6-(Me2NCH2)2-
(42) Clegg, W.; Errington, R. J.; Fisher, G. A.; Hockless, D. C. R.;
Norman, N. C.; Orpen, A. G.; Stratford, S. E. J. Chem. Soc., Dalton Trans.
1992, 1967.
(43) Bondi, A. J. Phys. Chem. 1964, 68, 441.

1206 Organometallics, Vol. 28, No. 4, 2009
Breunig et al.
Figure 2. Thermal ellipsoid representation (30%) of a section of the polymeric structure of Ar1BiI2 (4). Hydrogen atoms were omitted for
clarity.
C6H3BiI2, both showing a polymeric bismuth iodide chain with
organic ligands in a sort of zigzag arrangement.10,19 The primary
and secondary bismuth iodide bond lengths range from 3.010
to 3.105 Å and from 3.973 to 4.278 Å, respectively, and thus
are comparable with those in compound 4. However, the primary
bismuth iodide bonds are located in trans position, whereas in
compound 4 these are in cis position.
(Figure 4). The coordination geometry at the bismuth atom is
best described as distorted octahedral with two Bi-O bonds as
a result of the asymmetrically chelating phosphinate ligand
(Bi(1)-O(1) 2.204(3) Å, Bi(1)-O(2) 2.640(3) Å; P(1)-O(1)
1.548(3) Å; P(1)-O(2) 1.503(3) Å), a Bi-Br bond with a bond
length of 2.6658(7) Å, a Bi-C bond (Bi(1)-C(41) 2.271(5)
Å), and two bismuth-arene π contacts. The bismuth-arene
centroid distance to the phosphorus-bonded terphenyl ligand
[C(21)-C(26)] is 3.376 Å, whereas the distance to the bismuth-
bonded terphenyl ligand [C(51)-C(56)] amounts to 3.522 Å.
The bond angles Bi(1)-C(41)-C(42) and Bi(1)-C(41)-C(46)
are 109.6(4)° and 132.2(4)° (∆ ) 22.6°), respectively, compa-
rable to those of compounds 1-5, and thus indicating a
significant bismuth-arene interaction of both π ligands. The
dynamic behavior of this interaction in solution was studied in
detail by NMR spectroscopy (see below).
The hydrolysis product of [Ar2BiBr2]2 (3) was obtained as a
colorless crystalline material that was stable in air for several
months and analyzed to [Ar2BiBr(OH)]2 (5). The molecular
structure of 5 is comparable with that of the dimeric terphenyl-
substituted bismuth dihalides (Figure 3). It is a centrosymmetric
dimer with asymmetrically bridging OH groups and terminal
Bi-Br bonds and displays the following bond lengths:
Bi(1)-O(1)2.138(6)Å,Bi(1)-O(1A)2.533(6)Å,andBi(1)-Br(1)
2.670(2) Å and a bismuth-aryl ring centroid distance of 3.662
Å. Although this indicates a stronger bismuth-arene π interac-
tion than, for example, in compound 3 (Table S1), the difference
between the Bi(1)-C(1)-C(2) and Bi(1)-C(1)-C(6) angles
of ∆ ) 21.5° is smaller than in compound 3.
NMR Studies in solution. In the solid state compounds 1-6
show a bismuth-arene π coordination leading to a nonsym-
metrical arrangement of the terphenyl substituents. However,
in solution at room temperature exclusively the NMR data of
compound 6 indicate that its molecular structure observed in
the solid state is retained in solution. However, all compounds
including 6 show broadening of their NMR signals, which might
be interpreted to be the result of dynamic coordination behavior.
Thus, we have selected compounds 3, 5, and 6 in order to study
their dynamic behavior by variable-temperature NMR. The
phosphinic acid Ar2PH(O)OH was included in this study for
Noteworthy, a short oxygen-aryl ring centroid distance of
3.408 Å was observed in 5, which compares well with OH-aryl
distances reported previously44 and might be indicative of a
weak metal-OH-arene
π interaction as observed in
Ar1 M(OH)2 (M ) Ge, Sn).45 However, further description of
2
the OH-arene interaction was not possible since the position
of the OH hydrogen atom could not be refined unambiguously.
The aryl bismuth phosphinate Ar2BiBrO(O)HPAr2 (6) is
monomeric in the solid state, which is a result of the shielding
of the bismuth atom by 2-fold bismuth-arene coordination
1
comparison, but did not show any change of its H NMR
spectrum at 203 K in comparison to the spectrum at 293 K,
which indicates free rotation of the terphenyl ligand. Similarly,
1
Ar2BiBr2 (3) did not show significant changes of its H NMR
(44) Desiraju, G. R.; Steiner, T. The Weak Hydrogen Bond in Structural
Chemistry and Biology; Oxford University Press: Oxford, 1999.
(45) Pu, L. H.; Hardman, N. J.; Power, P. P. Organometallics 2001,
20, 5105.
spectrum at low temperature and is assumed to be monomeric
in solution with free rotation of the terphenyl ligand. In contrast
to compound 3 the terphenyl ligands of the arylbismuth bromide

Monoorganobismuth(III) Compounds
Organometallics, Vol. 28, No. 4, 2009 1207
Figure 3. Thermal ellipsoid representation (30%) of the molecular structure of [Ar2Bi(OH)Br]2 (5). Hydrogen atoms except H(1) were
omitted. Selected bond lengths [Å] and angles [deg]: Bi(1)-C(1) 2.267(8), Bi(1)-Br(1) 2.670(2), Bi(1)-O(1) 2.138(6), Bi(1)-O(1A) 2.533(6),
Bi(1)-Arcent[C(11)-C(16)] 3.662; O(1)-Arcent[C(21)-C(26)] 3.408; Br(1)-Bi(1)-O(1) 87.3(2), Br(1)-Bi(1)-O(1A) 155.84(14), Br(1)-Bi(1)-C(1)
98.9(2), O(1)-Bi(1)-C(1) 100.1(3), O(1)-Bi(1)-O(1A) 69.4(2), C(1)-Bi(1)-O(1A) 91.6(2), C(2)-C(1)-Bi(1) 109.3(6), C(6)-C(1)-Bi(1)
130.8(6); ∆ [C(2)-C(1)-Bi(1), C(6)-C(1)-Bi(1)] ) 21.5°.
hydroxide 5 show a splitting of their five 1H NMR signals (2 ×
CH, 2 × CH3, 1 × t-Bu; room temperature) to give 13 1H NMR
signals at 203 K (6 × CH, 6 × CH3, 1 × t-Bu) (Figure S3).
Thus, we assume that rotation of the terphenyl ligand is stopped
and the monomer-dimer equilibrium is shifted quantitatively
toward the hydroxy-bridged dimer [Ar2Bi(OH)Br]2 (5) as
observed in the solid state. The assumption of a monomer-dimer
equilibrium is supported by IR spectroscopy, showing one sharp
OH band at 3550 cm-1 in the solid state and two bands centered
at 3531 and 3575 cm-1 in CH2Cl2 solution (Figure S4).
Additionally, a peak assigned to the dimeric anion [{Ar2-
BiBr(OH)}2OH]- was observed by ESI(-) MS. Compound 6
shows 11 distinct 1H NMR resonances and 25 13C NMR
resonances at room temperature (Tables S1 and S3). In
comparison to the phosphinic acid Ar2PH(O)OH only minor
pairs of signals merge into one signal. Interestingly, in the
temperature range from 203 to 243 K only those signals assigned
to the Ar2PHO2 moiety show coalescence, whereas broadening
of the signals assigned to the Ar2BiBr moiety is observed at
temperatures above 243 K (Figure 5).
A detailed analysis using 2D-EXSY spectroscopy at 203, 220,
247, and 297 K revealed four different rotational processes,
R1-R4, which are shown in Figure 6. At 203 K NOE contacts
and cross-peaks for the exchange between pairs of hydrogen
atoms H13/H25, H15/H23, H17/H29, and H19/H27 are ob-
served, which is indicative of an exchange of the mesityl groups
of the 2,6-Mes2-4-t-Bu-C6H2-PHO2-moiety by rotation around
the P-C(1) bond (process R2). The coalescence effects allow
the calculation of the energy barrier for the rotation R2, which
amounts to 49.8 ( 1.8 kJ/mol. The rotation of the mesityl groups
within the 2,6-Mes2-4-t-Bu-C6H2-PHO2 moiety (process R4, R4′)
is observed at higher temperature, as indicated by exchange
cross-peaks of low intensity at 220 K (Table S6). At this
temperature the rotation of the 2,6-Mes2-4-t-Bu-C6H2-BiBr
moiety around the Bi-C(41) is also observed, as indicated in
the ROESY spectrum by cross-peaks between H32/H53, H34/
H55, H36/H57, H37/H58, H38/H57, and H43/H45 (process R1).
The one-dimensional proton NMR at 247 K shows that at this
temperature the signals assigned to the 2,6-Mes2-4-t-Bu-C6H2-
PHO2 moiety are merged into one set of broad signals (2 ×
CH; 2 × CH3; 1 × t-Bu; 1 × PH). The remaining peaks are
suitable to identify the process R3/R3′. The ROESY spectrum
shows exchange cross-peaks for the following pairs of signals,
H32/H34, H34/H53, H34/H55, H36/H38, H38/H57, and H38/
H59. This is indicative for the rotation R3/R3′ around the
1
differences are observed in the H NMR spectrum, with an
exception being the P-H resonance, which is shifted from 6.31
ppm in the phosphinic acid to 7.24 ppm in the phosphinate 6.
Noteworthy, a characteristic feature of the 13C NMR spectrum
of compound 6 is the resonance at 221.9 ppm, which is assigned
to the carbon atom C(41) bound to bismuth. Although it is
known that the bismuth atom causes a low-field shift for the
ipso-carbon atom,5 to the best of our knowledge, such a strong
shift was not reported before and is indicative for a low electron
density at the carbon atom.
The 1H NMR signals of compound 6 observed at room
temperature split into 27 distinct signals (12 × CH; 12 × CH3;
2 × t-Bu; 1 × PH) at 203 K, which shows that the molecular
structure observed in the solid state is frozen at low temperature
in solution (Table S3). Upon increasing the temperature, several

1208 Organometallics, Vol. 28, No. 4, 2009
Breunig et al.
these reported values it seems to be reasonable that in compound
6 the process of rotation and the metal-arene coordination
almost equally contribute to the energy barrier of approximately
50 kJ mol-1 for the dynamic processes R1 and R2. A more
detailed theoretical investigation is currently in progress.
Conclusion
Four novel terphenyl-substituted arylbismuth dihalides have
been structurally characterized, and their bismuth-arene π
interaction was analyzed. It is demonstrated that the hydrolysis
of these sterically congested compounds is difficult to control,
and attempts to prepare an arylbismuth dihydroxide failed.
Instead [2,6-Mes2-4-t-Bu-C6H3BiBr(OH)]2 (5) was isolated,
which represents the first fully characterized example of a
monoorganobismuth halide hydroxide. In compound 5 the
Bi-Br bond is remarkably stable toward hydrolysis and the
Bi-OH bond is stable toward homocondensation. We assume
both effects to result from both steric constraints and stabilization
by weak intramolecular Bi–OH-arene interaction. However,
heterocondensation with more acidic E-OH groups takes place,
as was demonstrated upon reaction of compound 5 with
Ar2PHO2H. The isolated product, Ar2BiBrO(O)HPAr2 (6), is a
rare example of an organobismuth compound showing 2-fold
intramolecular bismuth-arene coordination. The energy barriers
for the dislocation of the arene ligands away from the bismuth
atom by rotation of the terphenyl ligand were determined by
NMR techniques to be approximately 50 kJ mol-1. This energy
barrier results from a combination of steric hindrance for the
rotation and intramolecular bismuth-arene coordination. These
results show that compound 6 might be a suitable model
compound to investigate the nature and strength of bismuth-arene
π complexation using a combined theoretical and experimental
approach, which is currently under investigation.
Figure 4. Thermal ellipsoid representation (30%) of the molecular
structure of Ar2BiBrO(O)HPAr2 (6). Hydrogen atoms except H(1)
were omitted. Selected bond lengths [Å] and angles [deg]:
Bi(1)-C(41) 2.271(5), Bi(1)-Br(1) 2.6658(7), Bi(1)-O(1) 2.204(3),
Bi(1)-O(2) 2.640(3), Bi(1)-Arcent[C(51)-C(56)] 3.522, Bi(1)-
Arcent[C(21)-C(26)] 3.376;Br(1)-Bi(1)-O(1)90.67(8),Br(1)-Bi(1)-O(2)
151.33(7), Br(1)-Bi(1)-C(41) 97.59(12), O(1)-Bi(1)-O(2)
61.00(11), O(1)-Bi(1)-C(41) 101.55(16), O(2)-Bi(1)-C(41)
84.89(14), C(42)-C(41)-Bi(1) 109.6(4), C(46)-C(41)-Bi(1)
132.2(4).
C(42)-C(51) bond and the C(30)-C(46) bond. The rotation
process R1 is associated with an energy barrier of 53.8 ( 1.0
kJ/mol, which is slightly higher than the energy barrier for the
rotation process R2. Thus, there is no correlation of the energy
barrier for rotation and the Bi-arene distance (Bi(1)-
Arcent[C(51)-C(56)] 3.522 Å, Bi(1)-Arcent[C(21)-C(26)] 3.376 Å) ob-
served in the solid state. It is interesting to note that in
Yb(SAr*)2 (Ar* ) 2,6-Trip2C6H3; Trip ) 2,4,6-iPr3C6H2) a
similar intramolecular metal-arene π complexation was found
and that the dynamic character of the metal-arene coordination
is associated with an energy barrier of 54.3 kJ mol-1 based on
variable-temperature NMR studies in methylcyclohexane solu-
tion.46 Theoretical studies on the model system Yb(SH)2(C6H6)2
gave a value of 31.5 kJ mol-1 (B3LYP) for benzene dissociation.
However strong dependence on the method used for the
3. Experimental Section
3.1. General Comments. All reactions were performed using
standard Schlenk techniques under an atmosphere of nitrogen or
argon. All solvents were distilled from appropriate drying agents
immediately prior to use (sodium-benzophenone for THF, P4O10
for CH2Cl2, and sodium for hexane and toluene). Bismuth(III)
bromide was obtained commercially and used without further
purification. BiCl3 was sublimed and stored under an atmosphere
of argon before use. 2,6-Mes2-C6H3MgBr,49 1-bromo-2,6-dimesityl-
4-tert-butylbenzene,50 and 2,6-Mes2-4-t-Bu-C6H2PH(O)OH34 were
prepared according to previously described procedures.
1H, 13C, and 31P NMR spectra were recorded in CDCl3 or CD2Cl2
solution by using a Bruker DPX 200, a Bruker DRX 400, a Bruker
AV 400, or a Varian Inova 600 spectrometer. The signals are
indicated using the usual abbreviations: s (singlet), d (doublet), t
(triplet), m (multiplet). The following abbreviations were used to
assign the atoms of the aromatic rings: i (ipso), m (meta), o (ortho),
p (para).
calculation was reported, and MP2 calculations gave a value
46
of 73.9 kJ mol-1
.
In the case of bismuth only DFT methods
have been used to calculate the energy of bonding for the
bismuth-arene interaction in model compounds such as
[Bi2(O2CCF3)4 · · · C16H10]26 and [Bi{OC6H2-(CH2)-2}3N} · · ·
IR spectra were recorded as KBr plates on a Bruker IFS 28
spectrometer.
C6H6]25 with bonding energies of 31 and 13 kJ mol-1
,
Electrospray ionization mass spectrometric analyses (ESI-MS)
were recorded in the positive and the negative mode on a
Thermoquest-Finnigan instrument using CH3CN as the mobile
phase. The compounds were dissolved in CH3CN and than diluted
with the mobile phase to give solutions of approximate concentra-
tion 0.1 mM. The samples were introduced via a syringe pump
operating at 10 µL/min. The capillary voltage was kept at 4.5 kV,
respectively. These values are of the same order of magnitude
as calculated for the model complex [AsCl3 · · · C6H6] (31 kJ
mol-1 as determined by DFT)47 and reported for complexes of
antimony trichloride with aromatic hydrocarbons such as
[(SbCl3)2 · · · C6H6] or [(SbCl3)2 · · · C6Me6] (23 and 31 kJ mol-1
,
respectively, as determined by calorimetry).48 On the basis of
(46) Niemeyer, M. Eur. J. Inorg. Chem. 2001, 1969.
(47) Vickaryous, W. J.; Herges, R.; Jonson, D. Angew. Chem., Int. Ed.
2004, 43, 5831.
(48) Perkampus, H. H.; Sondern, C. Z. Z. Naturforsch.(B) 1981, 36a,
362.
(49) Du, C.-J. F.; Hart, H.; Ng, K.-K. D. J. Org. Chem. 1986, 51, 3162.

Monoorganobismuth(III) Compounds
Organometallics, Vol. 28, No. 4, 2009 1209
1
Figure 5. Temperature-dependent H NMR of compound 6 showing the region for aromatic protons including the numbering scheme as
used in Figure 6.
Mass spectra were recorded on a Finnigan MAT 95 (EI) or
Finnigan MAT 8230 (FAB) spectrometer. The pattern of bismuth-
containing ions was compared with theoretical values.
The C and H elemental analyses were performed by the
Mikroanalytisches Laboratorium Beller in Go¨ttingen and at the TU
Dortmund using a Leco CHNS-932 analyzer.
Synthesis of [2,6-Mes2-4-t-Bu-C6H2BiBrxCl2-x]2 (1). A solution
of 1-BrMg-2,6-Mes2-4-t-BuC6H2 in THF, prepared from 3.5 g (7.8
mmol) of 1-Br-2,6-Mes2-4-t-BuC6H2 and 1.5 g (62 mmol) of Mg
in 50 mL of THF, was added dropwise to a solution of 3.6 g (11
mmol) of BiCl3 in 20 mL of THF and heated at reflux for 1 h. The
solvent was removed under vacuum, and the resulting solid was
extracted three times with 40 mL of toluene. Evaporation of the
solvent and subsequent crystallization of the solid material from
CH2Cl2 at -20 °C gave 1.8 g (ca. 35%) of [Ar2BiBrxCl2-x]2 (1)
with a mp of 205-208 °C.
Anal. Calcd for C28H33BiBr0.5Cl1.5 (671.69): C 50.07; H 4.95.
1
Found: C 50.40; H 5.00. H NMR (200 MHz, CDCl3): δ 1.32 (s,
9H, C(CH3)3), 2.13 (s, 12H, o-CH3), 2.35 (s, 6H, p-CH3), 7.00 (s,
4H, m-Mes), 7.80 (s, 2H, m-C6H2). ESI-MS(-) m/z (relative
intensity %): 664.4 (15) [Ar2BiCl2(OH)]-, 683.4 (80) [Ar2BiCl3]-,
729.6 (100) [Ar2BiCl2Br]-, 775.5 (62) [Ar2BiClBr2]-, 819.0 (15)
[Ar2BiBr3]-.
Figure 6. Dynamic behavior of compound 6 showing rotation
Synthesis of [2,6-Mes2-C6H3BiBr2]2 (2). A solution of 2,6-Mes2-
R1-R4 and partial numbering scheme.
C6H3MgBr prepared from 7.96 g (40 mmol) of MesBr, 1.44 g of
Mg (60 mmol), 1.88 g (20 mmol) of 1,3-Cl2C6H4, and 12.5 mL
(20 mmol) of n-BuLi was added dropwise to a solution of 6.31 g
(20 mmol) of sublimed BiCl3 in 50 mL of THF. The solvent was
removed under vacuum, and the resulting solid was washed with
while the cone-skimmer voltage was varied in the positive mode
between 20 and 80 V and in the negative mode between -40 and
-80 V. The extraction cone voltages were in the range from 0 to
-5 V (positive mode) and from 0 to 5 V (negative mode). The ion
200 mL of toluene and crystallized from hexane to give 5.29 g
(38%) of [Ar1BiBr]2 (2) with a mp of 185-186 °C.
source temperature was kept at 250 °C. The m/z values reported
correspond to that of the most intense peaks in the corresponding
Anal. Calcd for C24H25BiBr2 · 0.25 C6H14 (703.93): C 43.52; H
isotope pattern.
4.08. Found: C 43.54; H 4.65. 1H NMR (200 MHz, C6D6): δ 2.14
(s, 18H, o- and p-CH3), 6.80 (s, 4H, m-Mes), 7.23 (t, 1H, p-C6H3),
7.39 (d, 2H, m-C6H3). 13C{1H} NMR (50 MHz, C6D6): δ 21.2 (p-
CH3), 21.7 (o-CH3), 129.1 (m-Mes), 130.3 (p-C6H3), 134.6 (m-
(50) Mehring, M.; Löw, C.; Vrasidas, I.; Schu¨rmann, M.; Jurkschat, K.
Phosphorus Sulfur 1999, 151, 311.

1210 Organometallics, Vol. 28, No. 4, 2009
Breunig et al.
C6H3), 136.5 (p-Mes), 137.2 (o-Mes), 138.6 (i-Mes), 150.4 (o-C6H3),
(i-C6H3 not observed). MS (EI, 70 eV) m/z (relative intensity %):
680 (7.6) [Ar1BiBr2]+, 601 (100) [Ar1BiBr]+, 522 (7.0) [Ar1Bi]+,
312 (24.3) [Ar1H]+, 209 (8.8) [Bi]+.
MHz, CD2Cl2): δ 1.25 (s, 9H, C(CH3)3), 2.04 (s, 12H, o-CH3), 2.33
(s, 6H, p-CH3), 6.92 (s, 4H, m-Mes), 7.10 (s, 1H, OH), 7.43 (s,
2H, m-C6H2). 13C NMR (150 MHz, CDCl3): δ 21.5 (p-CH3), 21.8
(o-CH3), 31.4 (C(CH3)3), 35.3 (C(CH3)3), 128.3 (m-Mes), 132.1 (m-
C6H2), 136.6 (p-Mes), 136.1 (o-Mes), 139.7 (i-Mes), 148.0 (vbr,
o-C6H2), 152.6 (p-C6H2), 204.7 (i-C6H2). 13C NMR (100 MHz,
CD2Cl2): δ 20.9 (p-Mes), 21.4 (o-CH3), 31.2 (C(CH3)3), 35.3
(C(CH3)3), 128.2 (m-Mes), 130-138 (br o-C6H2, i-Mes, m-Mes),
132.2 (m-C6H2), 138.2 (p-Mes), 152.7 (p-C6H2), 204.0 (i-C6H2).
FAB-MS m/z (relative intensity %): 657 (65) [Ar2BiBr]+, 578 (85)
[Ar2Bi]+. ESI-MS(-) m/z (relative intensity %): 755.0 (30)
[Ar2BiBr2OH]-, 773.2 (25) [Ar2BiBr2Cl]-, 816.6 (90) [Ar2BiBr3]-,
1368.1 (30) [{Ar2BiBrOH}2OH]-, 1412.0 (100) [{Ar2BiBr}2OBr]-,
1493.0 (25) [{Ar2BiBr2}2OH]-. IR (ν cm-1): 3548m, 2964st,
2916m, 1611w, 1579w, 1537vw, 1479m, 1435m, 1382w, 1362w,
1243w, 1113vw, 1041m, 883w, 852m, 734vw, 464m.
Synthesis of [2,6-Mes2-4-t-Bu-C6H2BiBr2]2 (3). A solution of
1-BrMg-2,6-Mes2-4-t-BuC6H2 in THF, prepared from 9.0 g (20
mmol) of 1-Br-2,6-Mes2-4-t-BuC6H2 and 1.9 g (78 mmol) of Mg
in 90 mL of THF, was added dropwise to a solution of 7.6 g (17
mmol) of BiBr3 in 20 mL of THF at 0 °C. The resulting pale reddish
suspension was stirred for 1 h, and the solvent was removed under
reduced pressure (20 mbar). The brown residue was dissolved in
80 mL of toluene and filtered over Celite, and the solvent was
removed under reduced pressure to give a yellow residue. Crystal-
lization from 120 mL of hexane at 5 °C gave 2.13 g (19%) of yellow
crystals of [Ar2BiBr2]2 (3) with a mp of 210-212 °C.
Anal. Calcd for C28H33BiBr2 (738.35): C 45.55; H 4.50. Found:
1
C 45.90; H 4.70. H NMR (400 MHz, CDCl3): δ 1.30 (s, 9H,
3.4. Synthesis of 2,6-Mes2-4-t-Bu-C6H2P(O)(H)OBi(Br)C6H2-
2,6-Mes2-4-t-Bu (6). A solution of 0.32 g (0.74 mmol) of 2,6-Mes2-
4-t-Bu-C6H2PH(O)OH in 30 mL of CH2Cl2 was added at room
temperature to a solution of 0.50 g (0.74 mmol) of 5 in 30 mL of
CH2Cl2. The solvent was removed under vacuum, and crystalliza-
tion from hexane quantitatively gave colorless crystals of
Ar2BiBrO(O)HPAr2 (6) with a mp of 248-249 °C.
C(CH3)3), 2.12 (s, 12H, o-CH3), 2.33 (s, 6H, p-CH3), 6.98 (s, 4H,
1
m-Mes), 7.71 (s, 2H, m-C6H2). H NMR (400 MHz, CD2Cl2): δ
1.33 (s, 9H, C(CH3)3), 2.13 (s, 12H, o-CH3), 2.34 (s, 6H, p-CH3),
7.00 (s, 4H, m-Mes), 7.75 (s, 2H, m-C6H2). 13C NMR (150 MHz,
CDCl3): δ 21.4 (p-CH3), 21.7 (o-CH3), 31.4 (C(CH3)3), 35.7
(C(CH3)3), 128.9 (m-Mes), 131.8 (m-C6H2), 136.7 (i-Mes), 137.5
(o-Mes), 138.9 (p-Mes), 149.7 (o-C6H2), 154.3 (p-C6H2), 200.9 (i-
C6H2). 13C NMR (100 MHz, CD2Cl2): δ 21.2 (p-CH3), 21.6 (o-
CH3), 31.2 (C(CH3)3), 35.6 (C(CH3)3), 128.8 (m-Mes), 132.2 (m-
C6H2), 137.7 (i-Mes), 138.9 (o-Mes), 149.8 (p-Mes), 136.8 (o-C6H2),
154.0 (p-C6H2), 202.0 (i-C6H2). FAB-MS m/z (relative intensity %):
657 (30) [Ar2BiBr]+, 578 (10) [Ar2Bi]+, 370 (30) [Ar2]+. IR (ν
cm-1): 2964vst, 2914st, 2861m, 2731vw, 1610m, 1577w, 1541w,
1478st, 1439st, 1378st, 1362m, 1243m, 1203vw, 1166vw, 1131vw,
1113vw, 1041w, 925vw, 882m, 850vst, 785vw, 744w, 730w, 656w,
604w, 573w, 547w, 457vw.
Synthesis of 2,6-Mes2-C6H3BiI2 (4). To a solution of 0.36 g
(0.53 mmol) of 2 in 40 mL of ethanol was added 0.35 g (2.13
mmol) of KI. The reaction mixture was stirred at ambient
temperature for 3 days. The ethanol was removed under reduced
pressure, and 40 mL of toluene was added to the yellow solid.
Filtration followed by solvent removal under reduced pressure
afforded 0.31 g (74%) of Ar1BiI2 (4) as a deep orange solid with
a mp of 183-184 °C.
Anal. Calcd for C24H25BiI2 (776.24): C 37.14; H 3.25. Found C
37.17; H 3.25. 1H NMR (200 MHz, C6D6): δ 2.16 (s, 6H, p-CH3),
2.17 (s, 12H, o-CH3), 6.81 (s, 4H, m-Mes), 7.20-7.33 (m, 3H, m-
and p-C6H3). 13C{1H} NMR (50 MHz, C6D6): δ 21.3 (p-CH3), 22.0
(o-CH3), 129.3 (m-Mes), 130.3 (p-C6H3), 133.1 (m-C6H3), 137.0
(p-Mes), 137.5 (o-Mes), 138.7 (i-Mes), 150.6 (o-C6H3). MS (EI,
70 eV) m/z (relative intensity %): 649 (100) [Ar1BiI]+, 522 (43.4)
[Ar1Bi]+, 440 (13.4) [Ar1I]+, 314 (16.8) [Ar1]+, 209 (8.75) [Bi]+.
Synthesis of [2,6-Mes2-4-t-Bu-C6H2BiBr(OH)]2 (5). (a) To a
suspension of 0.16 g (4 mmol) of NaOH in 10 mL of toluene was
added a solution of 0.74 g (1 mmol) of 3 in 20 mL of toluene
within 10 min. The solvent was removed under vacuum and the
residue dissolved in 7 mL of hexane and filtered through Celite.
Crystallization at -30 °C gave 99 mg (15%) of compound 5 as
yellow solid with a mp of 246-250 °C.
(b) A solution of 0.2 g of Et3N, 15 mL of methanol, and 1 mL
of water was added dropwise at room temperature to a solution of
0.6 g (0.8 mmol) of 3 in 15 mL of CH2Cl2. After 2 h the amount
of solvent was reduced to about the half to give a suspension. After
filtration the colorless precipitate was dried under vacuum. Crystal-
lization from CH2Cl2/EtOH gave 80 mg (14%) of [Ar2BiBr(OH)]2
(5) as yellow crystals with a mp of 245-250 °C.
Anal. Calcd for C55H65BiBrO2P (1077.96): C 61.28, H 6.08.
1
Found: C 60.80; H 5.80. H NMR (400 MHz, CD2Cl2): δ 1.24 (s,
9H, C(CH3)3), 1.26 (s, 9H, C(CH3)3), 1.93 (s, 12H, o-CH3), 2.12
(s, 12H, o-CH3), 2.25 (s, 6H, p-CH3), 2.38 (s, 6H, p-CH3), 6.83 (s,
4H, m-Mes), 6.93 (s, 4H, m-Mes), 6.97 (s, 2H, m-C6H2), 7.24 (d,
1JP-H ) 585.8 Hz, 1H, P-H), 7.55 (s, 2H, m-C6H2). 13C NMR (100
MHz, CD2Cl2): δ 20.86 (o-CH3), 20.90 (p-CH3), 21.1 (p-CH3), 21.2
(o-CH3), 31.1 (C(CH3)3), 31.2 (C(CH3)3), 35.2 (C(CH3)3), 35.4
(C(CH3)3), 126.7 (m-C6H2, 3JC-P ) 10.2 Hz), 126.9 (i-C6H2, 1JC-P
) 143.3 Hz), 127.6 (m-Mes), 128.1 (br, m-Mes), 128.1 (m-Mes),
128.2 (m-Mes), 132.3 (br, m-C6H2), 136-138 (br, i-C6H2, o-C6H2,
2
p-C6H2, i-Mes, o-Mes, p-Mes), 144.0 (o-C6H2, JC-P )12.9 Hz),
4
152.5 (p-C6H2), 156.0 (p-C6H2, JC-P ) 2.1 Hz), 221.9 (i-C6H2).
31P{1H} NMR (162 MHz, CDCl3): 34.4. ESI-MS(-) m/z (relative
intensity %): 755.0 (15) [Ar2BiBr2OH]-, 817.2 (100) [Ar2BiBr3]-.
ESI-MS(+) m/z (relative intensity %): 657.2 (60) [Ar2BiBr]+,
723.2 (30) [Ar2BiBrOP(H)O]+, 1011.6 (100) [Ar2BiOP(H)(O)Ar2]+,
1093.5 (40) [Ar2BiBrOP(H)(OH)Ar2]+, 1115.6 (30) [Ar2BiBr-
OP(H)(O)Ar2+Na]+, 1131.5 (40) [Ar2BiBr-OP(H)(O)Ar2+K]+. IR
(ν cm-1): 2962vst, 2916st, 2428w, 1610m, 1589m, 1546m, 1479m,
1442m, 1383st, 1262m, 1243m, 1163m, 1113vst, 1075st, 1039st,
971vst, 956st, 882m, 847vst, 802m, 562m, 480w, 448w, 409m.
X-ray Crystallographic Studies. The intensity data sets for the
compounds 1, 3, 5, and 6 were collected on a Nonius KappaCCD
diffractometer, and those of the compounds 2 and 4 on a Siemens
P4 four-circle diffractometer using graphite-monochromated Mo
KR radiation (λ ) 0.71073 Å). For this purpose the crystals were
attached with either Kel-F oil or Paratron oil to a glass fiber and
cooled in a nitrogen stream to 173 K. The structures were solved
by direct methods with SHELXS-97 (1, 3, 5, and 6) or Patterson
methods (2 and 4) and refined using SHELXL-9751,52 as included
in the WinGX software package.53 All non-hydrogen atoms were
refined with anisotropic thermal parameters. The hydrogen atoms
were calculated in riding positions with isotropic temperature factors
set at 1.2 times those of the carbon atoms where they are attached
to aromatic hydrogen atoms and 1.5 for the methyl groups. The
position of the hydrogen atom assigned to the OH group in
compound 5 was isotropically refined with constraint isotropic
temperature factors at 1.5 times U(eq) of the carrier atom. However,
the hydrogen atom is located close to the oxygen atom, which we
Anal. Calcd for C28H34BiBrO (675.45): C 49.79, H 5.07. Found:
C 50.20; H 5.30. H NMR (400 MHz, CDCl3): δ 1.22 (s, 9H,
(51) Sheldrick, G. M. Acta Crystallogr. 1990, A46, 467.
(52) Sheldrick, G. M. SHELXL-97: Program for the Refinement of
Crystal Structures; University of Go¨ttingen: Go¨ttingen, 1997.
(53) Farrugia, L. J. J. Appl. Crystallogr. 1999, 32, 837.
1
C(CH3)3), 2.06 (s, 12H, o-CH3), 2.32 (s, 6H, p-CH3), 6.91 (s, 4H,
1
m-Mes), 7.41 (s, 2H, m-C6H2), (OH not observed). H NMR (400

Monoorganobismuth(III) Compounds
Organometallics, Vol. 28, No. 4, 2009 1211
assign to the high residual electron density at bismuth. We could
not refine the H atom in a more appropriate position. For the
hydrogen atom attached to phosphorus in compound 6 the x,y,z
values were refined and isotropic temperature factors were set at
1.2 times those of the P(1) atom. Atomic scattering factors for
neutral atoms and real and imaginary dispersion terms were taken
from International Tables for X-ray Crystallography.54,55 The ring
centroidsandangleswerecalculatedusingthePLATONsoftware,56,57
according to the description of Cremer.58 The drawings were created
by SHELXTL59 and the Diamond program package.60
considered it to be a crystallization solvent molecule (hexane). The
carbon atoms of the disordered solvent were refined isotropically
with a site occupation factor of 0.25. The distances between
neighboring carbon atoms were constrained to be 1.5 Å for the
bond and 2.4 Å for the closest in space.
CCDC reference numbers are 702236 (1), 702237 (2), 702238
(3), 702239 (4), 702240 (5) and 702241 (6).
Acknowledgment. Financial support by the Deutsche
Forschungsgemeinschaft is gratefully acknowledged (M.M.,
C.N., H.J.B., C.I.R.).
In the crystal structure of [2,6-Mes2-C6H3BiBr2]2 (2) there is a
disordered solvent molecule occupying a special position. We
(54) Farrugia, L. J. WINGX, MS-Windows System of Programs for
SolVing, Refining and Analysing Single Crystal X-ray Diffraction Data for
Small Molecules; Universiy of Glasgow: Scotland, 2005.
(55) International Tables for Crystallography; Kluwer Academic Pub-
lishers: Dordrecht, 1992; Vol. C.
(56) Spek, A. L. Platon: Multipurpose Crystallographic Tool; Utrecht
University: Utrecht Netherlands, 2000.
(57) Spek, A. L. J. Appl. Crystallogr. 2003, 36, 7.
(58) Cremer, D. Acta Crystallogr., Sect. B: Struct. Sci. 1984, 40, 498.
(59) Sheldrick, G. M. Release 5.1 Reference Manual, Bruker AXS, Inc.:
Madison, WI, 1997.
(60) Brandenburg, K. Diamond, Version 3.1f; Crystal Impact GbR:
Bonn, Germany, 2008.
Supporting Information Available: For compounds 1-6 details
of structure determination, atomic coordinates, bond lengths and
angles, and displacement parameters in CIF format. Molecular
figures of 1 and 3 in Figures S1 and S2. Selected structural data of
1
compounds 1-8 (Table S1). IR and VT H NMR spectra of 5.
Detailed NMR data for compounds 3, 5, and 6 (Tables S2-S6).
This material is available free of charge via the Internet at
http://pubs.acs.org.
OM800934C