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E. Szłyk et al. / Polyhedron 22 (2003) 3389–3393
Table 3
The 31P and 13C chemical shifts of dppp and 1–4 (coordination shifts in parentheses)
Compound
P
Cipso
Cortho
Cmeta
Cpara
CH2a
CH2b
Dppp
)16.8a
138.7b
132.7b
128.4b
128.3b
29.7b
22.6b
1
2
3
4
)8.6 (+8.2)
)9.3 (+7.5)
)8.7 (+8.1)
)8.9 (+7.9)
132.9 ()5.8)
133.2 ()5.5)
133.2 ()5.5)
133.2 ()5.5)
132.0 ()0.7)
132.3 ()0.4)
132.3 ()0.4)
132.3 ()0.4)
129.9 (+1.5)
130.3 (+1.9)
130.2 (+1.8)
129.9 (+1.5)
128.5 (+0.2)
128.8 (+0.5)
128.8 (+0.5)
128.5 (+0.2)
27.5 ()2.2)
27.9 ()1.8)
27.9 ()1.8)
27.7 ()2.0)
17.3 ()5.3)
17.6 ()5.0)
17.7 ()4.9)
17.7 ()4.9)
a
31P literature data: from )17.2 to )17.8 ppm [15,16,22,26].
b
13C literature data: CH2a 29.6, CH2b 22.3, Cipso 138.6, Corto 132.6, Cmeta 128.3 and Cpara 128.4 ppm [26].
The 31P and 13C chemical shifts of dppp and 1–4 are
listed in Table 3.
not being available due to their insolubility in CDCl3)
can be regarded as a result of deprotonation.
The 31P NMR spectra reveal a singlet in the range
from )8.6 to )9.3 ppm, shifted ca. 8 ppm to higher
frequency in comparison to free dppp (d ¼ ꢁ16:8). All
phosphorus atoms remain magnetically equivalent
which proves the chelate coordination mode of dppp
molecules. Analogous results were already reported for
[CuI(dppp)2]þClꢁ, [CuI(dppp)2]þIꢁ, [CuI(dppp)2]þBFꢁ4
and [CuI(dppp)2]þPFꢁ6 (d being )13.1, )8.8, )8.5 and
)10 ppm, respectively) [16,18,19]. The observed desh-
ielding of 31P nuclei seems to be typical for
[Cu(dppp)2]þ chelate cations, confirming their presence
in the studied complexes. However, the measured high-
frequency coordination shifts are smaller than those
found for [AgI(dppp)2]þSCNꢁ, [AuI(dppp)2]þClꢁ,
[NiII(dppp)2]2þ(BF4ꢁ)2 and [PdII(dppp)2]2þ(BF4ꢁ)2 (d
being )4.7, )2.7, )7.8 and 0.0 ppm, respectively)
[11,14,15].
In the 13C NMR spectra both Cipso and CH2a, CH2b
nuclei are shielded upon Cu(I) coordination, this effect
being opposite to that noted for 31P. The observed low-
frequency shifts are ca. 5.5, 2 and 5 ppm, respectively,
the CH2b signals being shifted more than CH2a. This
phenomenon can be explained if it is assumed that in
[Cu(dppp)2]þ chelate cations the CH2 groups interact
with Cu atoms along two bond chains. The cumulated
influence of the Cu(I) moiety via three bonds in both
directions (CH2b) is more expressed than that via four
and two bonds (CH2a).
The carboxylic groups are detected at ca. 160 ppm as
sharp triplets (coupling with a-CF2 groups), similar to
those of the respective RCOOH acids, e.g., for 1
d ¼ 160:1 ppm, for C2F5COOH d ¼ 163:4 ppm. Also
the 19F NMR spectra are analogous, e.g., for 1 the b-
CF3 and a-CF2 peaks appear at )4.6 and )41.4 ppm,
whereas for C2F5COOH at )5.6 and )44.9 ppm, re-
spectively. For 2, 3 and 4 the b-CF3 and a-CF2 peaks are
observed at )3.2 and )38.3 ppm; )3.1 and )38.0 ppm;
)3.0 and )38.1 ppm, respectively. Neither for COO
(13C) nor a-CF2 (19F) signals is the quadrupolar
broadening by 63Cu or 65Cu observed, excluding the
possibility of direct binding of perfluorocarboxylic an-
ions to Cu(I). The small chemical shift changes, com-
paring to RCOOH acids (the data for RCOONa salts
The 63Cu resonances appear as broad (m1=2 ca. 8.5
kHz) bands at ca. 230 ppm, similar data being noted
for [CuI(dppp)2]þPF6ꢁ (d ¼ 231 ppm and m1=2 ¼ 4 kHz)
[19]. The high values of 63Cu half-line widths, com-
paring to the reference standard (440 Hz for [Cu
( CH3CN)4]þClOꢁ4 [23]), as well as the lack of 63Cu–31P
couplings are the result of quadrupolar relaxation and
suggest a low symmetry around the central atom. In
ideally tetrahedral [Cu(monophosphine)4]þClꢁ and
[Cu(monophosphite)4]þ Clꢁ complexes, possessing Td
microsymmetry, the 63Cu nuclei were detected as rela-
tively sharp signals with multiplet structures [24]. In
fact, for the discussed bis-chelated [Cu(dppp)2]þ cations
one can assume rather the lower, pseudotetrahedral C2v
geometry. The 31P and 63Cu temperature variable
NMR experiments revealed no interesting phenomena
upon decreasing the temperature, which excluded the
occurrence of dynamic processes involving the
[Cu(dppp)2]þ species.
3.3.2. DppB complexes 5–9
The 1H and 13C NMR spectra are analogous to those
of free dppB, their assignment and coordination shifts
discussion being difficult due to overlapping of phenyl
and phenylene resonances. The 19F signals shift very
slightly, e.g., for 5 the b-CF3 and a-CF2 groups appear
at )6.2 and )43.1 ppm. For 6, 7, 8 and 9 the b-CF3 and
a-CF2 peaks were detected at )4.8 and )40.3 ppm; )4.6
and )39.9 ppm; )4.6 and )39.9 ppm; )4.6 and )39.8
ppm, respectively. Hence the coordination shifts are
between )0.6 and 0.3 ppm.
The 31P NMR spectra reveal a singlet in the range
from 8.3 to 8.6 ppm, shifted ca. 22 ppm to higher
frequency comparing to free dppB, for which we have
found d ¼ ꢁ12:7 ppm (literature data being )13.3 ppm
[25]). As in the case of compounds 1–4, the equivalency
of all phosphorus atoms can be regarded as the proof
for bis-chelated coordination of Cu(I). It is worth
noting that the deshielding effect is evidently larger for
dppB than dppp complexes, this fact being already re-
ported for [CuI(dppB)2]þPFꢁ6 (d ¼ þ9:0 ppm) [19]. No
dynamic processes were observed upon the decreasing
temperature.
Sz?yk, Edward
