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V.V. Shatunov et al. / Journal of Organometallic Chemistry 696 (2011) 2238e2251
Table 3
1O and 31R NMR shifts of initial compounds and their complexes in S6D6.
No.
Compound
dH, ppm
dP, ppm
MR3
Phosphine
Alkyl
Aryl
e
Ph3P
e
e
7.44 (m, 6H); 7.01 (m, 9H)
7.44 (m, 6H); 7.01 (m, 9H)
7.43 (m, 8H); 7.10 (m, 12H)
e
ꢃ6.26
ꢃ17.68
ꢃ16.35
e
1
2
Ph2Pe(CH2)3ePPh2
Ph2Pe(CH2)5ePPh2
AlMe3
AlEt3
GaMe3
GaEt3
InMe3
InEt3
Ph3P$AlMe3
Ph3P$AlEt3
Ph3P$GaMe3
Ph3P$GaEt3
Ph3P$InMe3
e
2.12 (m, 4O); 1.72 (m, 2O)
1.98 (m, 4O); 1.51 (m, 4O); 1.45 (m, 2O)
e
4a
4b
5a
5b
6a
6b
7a
7b
7c
7d
7e
7f
8a
8b
8c
8d
8e
8f
ꢃ0.35 (s, 9O)
e
1.16 (t, 9H); 0.35 (q, 6O)
ꢃ0.10 (s, 9O)
e
e
e
e
e
e
1.26 (t, 9H); 0.57 (q, 6O)
ꢃ0.18 (s, 9O)
e
e
e
e
e
e
1.48 (t, 9H); 0,6 (q, 6O)
ꢃ0.07 (s, 9O)
e
e
e
e
7.52 (m, 8H); 7.17 (m, 12H)
7.49 (m, 6H); 7.08 (m, 9H)
7.50 (m, 6H); 7.05 (m, 9H)
7.49 (m, 6H); 7.04 (m, 9H)
7.52 (m, 6H); 7.05 (m, 9H)
7.48 (m, 6H); 7.10 (m, 9H)
7.52 (m, 6H); 7.12 (m, 9H)
7.42 (m, 8H); 7.07 (m, 12H)
7.35 (m, 8H); 7.05 (m, 12H)
7.42 (m, 8H); 7.11 (m, 12H)
7.37 (m, 8H); 7.08 (m, 12H)
7.43 (m, 8H); 7.11 (m, 12H)
7.44 (m, 8H); 7.14 (m, 12H)
7.45 (m, 8H); 7.10 (m, 12H)
7.47 (m, 8H); 7.10 (m, 12H)
7.44 (m, 8H); 7.05 (m, 12H)
7.43 (m, 8H); 7.10 (m, 12H)
ꢃ5.21
ꢃ5.25
ꢃ5.25
ꢃ4.35
ꢃ6.72
ꢃ6.13
ꢃ18.56
ꢃ15.29
ꢃ12.58
ꢃ12.34
ꢃ17.68
ꢃ15.86
ꢃ15.82
ꢃ14.40
ꢃ14.26
ꢃ13.14
ꢃ14.75
1.52 (t, 9H); 0.60 (q, 6O)
0.29 (s, 9O)
e
e
1.55 (t, 9H); 0.96 (q, 6O)
0.24 (s, 9O)
e
e
Ph3P$InEt3
1.71 (t, 9H); 1.06 (q, 6O)
ꢃ0.05 (s, 9O)
e
(SH2)3(PPh2$AlMe3)2
(SH2)3(PPh2$AlEt3)2
(SH2)3(PPh2$GaMe3)2
(SH2)3(PPh2$GaEt3)2
(SH2)3(PPh2$InMe3)2
(SH2)3(PPh2$InEt3)2
(SH2)5(PPh2$AlMe3)2
(SH2)5(PPh2$AlEt3)2
(SH2)5(PPh2$GaMe3)2
(SH2)5(PPh2$GaEt3)2
(SH2)5(PPh2$InEt3)2
2.10 (q, 4O); 1.54 (m, 2O)
1.97 (q, 4O); 1.57 (m, 2O)
2.01 (q, 4O); 1.70 (m, 2O)
2.03 (q, 4O); 1.60 (m, 2O)
2.07 (q, 4O); 1.71 (m, 2O)
2.08 (q, 4O); 1.71 (m, 2O)
1.95 (q, 4O); 1.45 (m, 4O); 1.25 (m, 2O)
2.03 (q, 4O); 1.42 (m, 4O); 1.25 (m, 2O)
1.97 (q, 4O); 1.43 (m, 4O); 1.23 (m, 2O)
2.00 (q, 4O); 1.43 (m, 4O); 1.23 (m, 2O)
2.03 (q, 4O); 1.47 (m, 4O); 1.28 (m, 2O)
1.32 (t, 9H); 0.32 (q, 6O)
0.08 (s, 9O)
1.35 (t, 9H); 0.68 (q, 6O)
0.10 (s, 9O)
1.60 (t, 9H); 0.85 (q, 6O)
ꢃ0.1 (s, 9O)
9a
9b
9c
9d
9f
1.23 (t, 9H); 0.38 (q, 6O)
0.2 (s, 9O)
1.54 (t, 9H); 0.87 (q, 6O)
1.67 (t, 9H); 0.98 (q, 6O)
diphenylphosphine substituents as a result of complexation. This
effect is decreased, when an alkyl chain is extended in compounds
9aef. Phosphorus resonance shifts for most adducts downfield on
31P NMR spectra due to complexation.
(7d) in benzene under atmospheric oxygen using NMR spectrom-
etry in a sealed vial with a liquidegas interface. It has been estab-
lished that the oxidation starts with the formation of
ethoxydiethylgallium and small quantities of triethoxygallium.
Their generation is detected by 1H NMR studies from the signals of
It should be noted that downfield shifts DdO for alkyl substitu-
ents bound to the metal atom for the studied complexes 7e9 which
are determined as the difference of dO values of a coordinate and
a free metal trialkyl, change in the following order PPh3 ꢄ 2 ꢄ 1
depending on the phosphine nature. An ability of the phosphorus
atom defined by the nature of its substituents to form complexes
should theoretically change in the following order 2 ꢄ 1 > PPh3.
Hence, the value of chemical shifts dO in complexes 7e9 does not
correlate with the strength of the MeP bond which is apparently
caused by the donor properties of the phosphine groups different in
direction and the steric repulsion of alkyl groups bound to the
metal atom and the substituents bound to the phosphorus atom
[30]. The same conclusion can be made from the absence of the
correlation between phosphorus chemical shifts DdR for the studied
complexes 7e9 and the nature of metal trialkyl. The values of
DdR are determined as a difference of dR values of a coordinate and
a free phosphine, with the nature of metal trialkyl. In this case
values of DdP can correlate only with a steric branching of phos-
phine. This has been previously shown by the example of
complexes of AlMe3 with various phosphines [31].
It should be noted that in diluted solutions of complexes 7e9 in
benzene and chloroform the above compounds have not dissoci-
ated during both long stay at room temperature and long heating to
60 ꢀC. A slow dissociation of the complexes occurs only at
temperatures above 65 ꢀC.
Complexes 7e9 are far more resistant to atmospheric oxygen as
compared with the original metal trialkyls. No spontaneous
inflammation in the air has been observed; the white smoke
indicative of an active stage of oxidation for most complexes has
appeared after staying in the air for 5e10 min. The oxidative
stability of the synthesized adducts 7e9 has been studied on a 5%
solution of the complex of triethylgallium with triphenylphosphine
OeCH2 fragments as quadruplets with
d 3.56 and 3.95 ppm.
However, as one ethyl group of GaEt3 has converted by 10% into an
ethoxy group, a gradual dissociation of complex 7d into GaEt3 and
PPh3 has been observed and shown in the spectra as resonances of
free GaEt3 with
d 0.63 and 1.33 ppm. The isolated PPh3 is oxidized
by atmospheric oxygen into triphenylphosphineoxide that is clearly
seen in the spectra by the appearance and the intensification of the
resonance of protons in the position 2 and 6 of the phenyl
substituents of the Ph3PO molecule as quadruplet with d 7.78 ppm.
Besides, as a result of autocatalytic oxidation processes of the
phosphine moiety of complex 7d, the speed of the Ph3PO formation
becomes higher than the speed of the GaeC oxidation that leads to
an increase of the triphenylphosphineoxide concentration. The
oxidation process finally results in a mixture of complexes of tri-
phenylphosphineoxide with ethoxydiethylgallium (10), trie-
thylgallium (11) and triethoxygallium (12) in mole ratio 1:1:0.2
(Scheme 9).
Dative bond O:/Ga is obviously less stable than P:/Ga that
leads to a lower downfield shift during the complexation with
triphenylphosphineoxide. Therefore the resultant 1H NMR spectra
of the mixture that forms after the oxidation of complex 7d contain
characteristic resonances of protons of complex 10 in the form of
triplets at
from the ethoxy group) and quadruplets of CH2 and OCH2-groups at
0.8 and 3.2 ppm. As regards the complex 11, the signals of CH2-
groups are observed as triplet at 1.44 ppm and quadruplet at
0.75 ppm. Triethoxygallium complex 12 is represented in the 1H
NMR spectra by signals of ethoxy groups in the form of quadruplet
at 3.62 ppm and triplet at 1.16 ppm. Resonances of aromatic
substituents are registered in the form of multiplet at 7.15 ppm
and quadrulet at 7.81 ppm. Meanwhile, mass spectra of a mixture
d 1.56 (SO3 from the ethyl group) and 1.16 ppm (SO3
d
d
d
d
d
d
d