Synthesis and multinuclear NMR investigation on gold-phosphine-catecholato-complexes

Article abstract of DOI:10.1016/j.inoche.2007.02.023

Ag⁺-assisted dechlorination of Gold(I) and Gold(III) phosphine complexes followed by the reaction with catecholes (H₂CA) in the presence of Et₃N gives neutral violet complexes, whereas 1-9, 8a, 14-16 are Gold(I) two coordinate linear complexes and 10-13 are Gold(III) square planar four coordinate complexes. The 17 new complexes are characterised by ESIMS, IR and multinuclear NMR (¹H, ¹³C, ¹⁹F, ³¹P) spectroscopic studies. In addition, dimensional NMR studies like ¹H-¹H COSY permit a complete assignment of the complexes in the solution phase.

Full text of DOI:10.1016/j.inoche.2007.02.023

Inorganic Chemistry Communications 10 (2007) 666–670
www.elsevier.com/locate/inoche
Synthesis and multinuclear NMR investigation on
gold–phosphine–catecholato-complexes
*
P. Byabartta , M. Laguna
Departmento de Quimica Inorganica, Instituto de Ciencia de Materiales de Aragon, Universidad de Zaragoza-CSIC, Zaragoza 50009, Spain
Received 8 November 2006; accepted 24 February 2007
Available online 6 March 2007
Abstract
Ag+-assisted dechlorination of Gold(I) and Gold(III) phosphine complexes followed by the reaction with catecholes (H2CA) in the
presence of Et3N gives neutral violet complexes, whereas 1–9, 8a, 14–16 are Gold(I) two coordinate linear complexes and 10–13 are
Gold(III) square planar four coordinate complexes. The 17 new complexes are characterised by ESIMS, IR and multinuclear NMR
1
(1H, 13C, 19F, 31P) spectroscopic studies. In addition, dimensional NMR studies like H–1H COSY permit a complete assignment of
the complexes in the solution phase.
Ó 2007 Elsevier B.V. All rights reserved.
Keywords: Gold(I); Gold(III); Catechol; Phosphine; 1H; 3C; 19F; 31P; COSY; NMR; ESIMS
The coordination chemistry of quinonoid systems are
important because of their existence in various redox
states, optoelectronic communication, biological model
study, DNA intercalation, etc. [1–8]. A common feature
of the metal-RQ chemistry is delocalization of active elec-
trons between the metal and the quinonoid ligand. In con-
tinuation of the comprehensive studies on chemistry of
catecholato system [1–5] in this article, we describe some
Gold(I) and Gold(III) phosphine complexes of catecho-
lates. The complexes are well characterized by IR, 1H
NMR, 19F(1H) NMR, 31P(1H) NMR, 3C(1H) NMR,
1H–1H COSY NMR and mass spectrometry.
To a series of methanolic suspension of gold–phosphine
complexes, [Au(Cl)(PPh3)2], 1 (0.990 g, 2.00 mmol), [Au
(Cl)(P(Ph-oMe)3)2], 2 (1.074 g, 2.00 mmol), [Au(Cl)(P(Ph-
mMe)3)2], 3 (1.074 g, 2.00 mmol), [Au(Cl)(P(Ph-pMe)3)2],
4 (1.074 g, 2.00 mmol), [Au(Cl)P(Ph2Me)2], 5 (0.866 g,
2.00 mmol), [Au(Cl)P(PhMe2)2], 6 (0.741 g, 2.00 mmol),
[Au(Cl)(P(Cy.hx)3)2], 7 (1.020 g, 2.00 mmol), [Au(Cl)(P-
(NEt2)3)2], 8 (0.955 g, 2.00 mmol), [Au(Cl)(P(NMe2)3)2], 8a
(0.791 g, 2.00 mmol), [Au(Cl)(AsPh3)2], 9 (1.076 g, 2.00
mmol), AgOTf solution (0.514 g, 2.00 mmol) was sepa-
rately added in 2:2 stoichiometric ratio and refluxed for
15 min, AgCl so precipitated was filtered off over a G4
crucible. This solution was kept in Ar-atmosphere. To a
methanolic solution of catechol (0.110 g, 1.00 mmol) two
drops of NEt3 were added and the colour changed to pale
violet in most cases. This solution was then added to the
above solution and the resulting mixture was stirred for
1 h under argon. The solution was then evaporated to half
of its original volume, cooled to room temperature, filtered
and then washed thoroughly with diethyl ether and dried in
vacuo. The yield was 60%. In case of 10–13 complexes the
stoichiometric ratios are [Au(Br)2(C6F5)2]NBu4, 10
(0.933 g, 1.00 mmol), [Au(Br)2(C6F5)(PPh3)], 11 (0.786 g,
1.00 mmol), [Au(Br)2(PPh3)2]ClO4, 12 (0.981 g, 1.00 mmol),
[Au(Br)3(PPh3)], 13 (0.699 g, 1.00 mmol), separately added
AgOTf solution (0.514 g, 2.00 mmol) in 1:2 ratio, then cat-
echol (0.110 g, 1.00 mmol) followed by NEt3, whereas in
[Au2(Cl)2 (dppa)], 14 (0.850 g, 1.00 mmol), [Au2(Cl)2
(dppm)], 15 (0.849 g, 1.00 mmol), [Au2(Cl)2 (dppe)], 16
(0.863 g, 1.00 mmol), separately added AgOTf solution
(0.514 g, 2.00 mmol) in 1:2 ratio and then catechol(0.110 g,
*
Corresponding author. Fax: +34 976761187.
E-mail address: prithwis33@yahoo.com (P. Byabartta).
1387-7003/$ - see front matter Ó 2007 Elsevier B.V. All rights reserved.
doi:10.1016/j.inoche.2007.02.023

P. Byabartta, M. Laguna / Inorganic Chemistry Communications 10 (2007) 666–670
667
for [C22H26P2AuO2], C, 33.8, H, 3.4; IR(nujol, cmꢀ1
)
m(PPh) 1100, 759, m(C@C) 1620 m(C@O) 1528, 1365, 1297,
ESIMS, 778[M+], 31P(1H) NMR(CDCl3), ppm, ꢀ1.03;
anal. for [Au(P(cyclohexane)3)2(CA)], 7, found: C, 49.17,
H, 3.3, calcd. for [C42H32P2AuO2], C, 49.2, H, 3.4, O,
3.2, P, 6.1; IR(nujol, cmꢀ1) m(C@C) 1650 m(C@O) 1525,
1369, 1291, ESIMS, 1026[M+], 31P(1H) NMR (CDCl3),
ppm, 64.614; anal. for [Au(P(NEt2)3)2(CA)], 8, found: C,
26.27, H, 4.3, N, 10.2, calcd. for [C30H64P2AuN6O2], C,
Path I
Ar. Atmos
[Au(Phosphine)Cl] + AgOTf
[Au(Phosphine)(OTf)] + AgCl
Ar
Atmos
Catechol, NEt3
(low yield, 40–45%)
[{Au(Phosphine)}n(cat)]
Path II
Ar. Atmos
NEt3
[Au(Phosphine)n(Catechol)]
(high yield, 70%)
[Au(Phosphine)Cl] + Catechol
26.3, H, 4.4, N, 10.3, O, 3.9, P, 7.6; IR (nujol, cmꢀ1
)
X = PPh3, 1
m(C@C) 1630 m(C@O) 1525, 1369, 1291, ESIMS,
996[M+], 31P(1H) NMR (CDCl3), ppm, 134.14 (singlet);
anal. for [Au(P(NMe2)3)2(CA)], 8a, found: C, 26.1, H,
4.8, N, 10.2, calcd. for [C18H40P2AuN6O2], C, 26.0, H,
4.9, N, 10.3, O, 3.9, P, 7.6, IR(nujol, cmꢀ1) m(C@C) 1630
m(C@O) 1525, 1369, 1291, ESIMS, 828[M+], 31P( 1H)
NMR (CDCl3), ppm, 104.74 (singlet); anal. for
[Au(AsPh3)2(CA)], 9, found: C, 45.27, H, 3.3 calcd. for
a
I
Au
P(Ph-oMe)3, 2
P(Ph-mMe)3, 3
P(Ph-pMe)3, 4
X
X
b
O
O
PPh2Me, 5
I
Au
b´
PPhMe2, 6
a´
a
P(Cyclohexane)3, 7
P[N(Et2)]3, 8
P[N(Me2)]3, 8a
AsPh3, 9
O
[C42H34As2AuO2], C, 45.3, H, 3.4; IR (nujol, cmꢀ1
)
R
b
R=PPh3,
R=PPh3
Q=ClO4
12
R=C6F5,
R=PPh3,
11
R=PPh3,
R=Br
13
III
R=C6F5,
Q=NBu4
Q
Au
m(C@C) 1630 m(C@O) 1525, 1369, 1291, ESIMS,
1114[M+]; anal. for NBu4[AuIII (C6F5)2(CA)], 10, found:
C, 46.3, H, 4.19, N, 1.6, calcd. for [C34H36NF10AuO2], C,
46.2, H, 4.2, N, 1.7; IR (nujol, cmꢀ1) m(C6F5) 1500, 955,
800, m(C@C) 1620 m(C@O) 1525, 1369, ESIMS, 881[M+],
19F(1H) NMR (CDCl3), ppm, 115.2(o-F), 156.2(p-F),
160.2(m-F); anal. for [AuIII(C6F5) (PPh3) (CA)], 11, found:
C, 51.3, H, 2.9, calcd. for [C30H19F5AuO2], C, 51.4, H, 3.0;
IR (nujol, cmꢀ1) m(C6F5) 1530, 955, 800, m(C@C) 1620
m(C@O) 1525, 1369, ESIMS, 703[M+], 19F(1H) NMR
(CDCl3), ppm, 115(o-F), 156(p-F), 160(m-F); anal. for
NBu4[AuIII(PPh3)2(CA)], 12, found: C, 54.3, H, 3.9, calcd.
10
R
b´
O
a´
Ph2
I
a
Au
P
O
O
X=NH(14),
b
CH2(15),
CH2CH2(16)
X
I
P
b´
Au
a´
Ph2
Scheme 1.
1.00 mmol) followed by NEt3. All other complexes were
prepared similarly; yield, 55–60%. anal. for
for C42H34P2AuO2]ClO4, C, 54.2, H, 4.0; IR (nujol, cmꢀ1
)
[Au(PPh3)2(CA)], 1, found: C, 49.17, H, 3.2, calcd. for
[C42H34P2AuO2], C, 49.2, H, 3.3, P, 5.9; IR(nujol,
m(C@C) 1620 m(C@O) 1525, 1369, ESIMS, 929[M+],
31P(1H) NMR (CDCl3), ppm, 46.1 (major), 35 (minor);
anal. for [AuIIIBr(PPh3)(CA)], 13 found: C, 44.7, H, 2.9,
calcd. for [C24H19PBrAuO2], C, 44.6, H, 2.8, O, 4.8, P,
4.9; IR(nujol, cmꢀ1) m(PPh3) 1100, 755, 695, 545, m(C@C)
1620 m(C@O) 1525, 1369, ESIMS, 647[M+], 31P(1H)
cmꢀ1
) m(PPh3) 1100, 755, 695, 545, m(C@C) 1630 m
(C@O) 1525, 1360, 1297, ESIMS, 1026 [M+],
721[Au(PPh3)2], 31P(1H) NMR (CDCl3), ppm, 27.12; anal.
for [Au(P(Ph(o-Me))3)2(CA)], 2, found: C, 50.7, H, 3.6,
calcd. for [C44H38P2AuO2], C, 50.8, H, 3.7, IR(nujol,
NMR(CDCl3), ppm, 35.24(singlet); anal. for ½AuI ðdppaÞ
2
cmꢀ1
)
m(PPh3) 1100, 759, 699, 555, m(C@C) 1620
ðCAÞꢁ, 14, found: C, 40.3, H, 2.9, N, 1.6, calcd. for
[C30H25P2NAu2O2], C, 40.4, H, 2.8, N, 1.7; IR (nujol,
cmꢀ1) m (dppa) 1100, 755, 545, m(C@C) 1629 m(C@O)
1525, 1379, ESIMS, 887[M+], 31P(1H) NMR (CDCl3),
ppm, 82.27 (singlet); anal. for ½AuI2ðdppmÞðCAÞꢁ, 15,
found: C, 41.9, H, 2.9, calcd. for [C31H26P2NAu2O2], C,
42.0, H, 3.0; IR (nujol, cmꢀ1) m(dppm) 1100, 755,
m(C@C) 1629, m(C@O) 1525, 1379, ESIMS, 886[M+]; anal.
for ½AuI2ðdppeÞðCAÞꢁ, 16, found: C, 42.7, H, 3.1, calcd. for
[C32H28P2Au2O2], C, 42.8, H, 3.2; IR (nujol, cmꢀ1) m(dppe)
1120, 755, 540, m(C@C) 1620 m(C@O) 1525, 1369, ESIMS,
900 [M+].
m(C@O) 1528, 1365, 1297, ESIMS, 1054 [M+],
721[Au(PPh3)2], 31P(1H) NMR (CDCl3), ppm, 25.03; anal.
for [Au(P(Ph(m-Me))3)2(CA)], 3, found C, 50.7 (50.5), H,
3.6 (3.5) calcd. for [C44H38P2AuO2], C, 51.0, H, 3.7, IR(nu-
jol, cmꢀ1) m(PPh3) 1100, 759, 699, m(C@C) 1620 m(C@O)
1528, 1365, ESIMS, 1054 [M+], 721[Au(PPh3)2], 31P(1H)
NMR(CDCl3), ppm, 25.23; anal. for [Au(P(Ph(p-
Me))3)2(CA)], 4, found: C, 50.7, H, 3.6 calcd. for
[C44H38P2AuO2], C, 50.9, H, 3.8, IR(nujol, cmꢀ1
) m(PPh3)
1100, 759, 699, m(C@C) 1620 m(C@O) 1528, 1297, ESIMS,
1054 [M+], 721[Au(PPh3)2], 31P(1H) NMR(CDCl3), ppm,
25.16; anal. for [Au(P(Ph2Me))2(CA)], 5, found: C, 42.7,
H, 3.3, calcd. for [C32H30P2AuO2], C, 43.0, H, 3.2, O,
3.7, P, 6.9; IR (nujol, cmꢀ1) m(PPh2) 1100, 759, 699, 555,
m(C@C) 1620 m(C@O) 1528, 1365, 1297, ESIMS, 902
[M+], 31P(1H) NMR(CDCl3), ppm, 13.03; anal. for
[Au(P(PhMe2))2(CA)], 6, found: C, 33.7, H, 3.3, calcd.
Silver+-assisted dechlorination of Gold(I) and Gold(III)
complexes (1–16) in methanol has prepared a solvated spe-
cies and then addition of catechol (H2CA) (one equivalent)
to this solution followed by Et3N (2.5 equivalent) under
stirring condition has synthesized the title compound 1–9,
10–13, 14–16 (Scheme 1). The composition of 1–9, 10–13,

668
P. Byabartta, M. Laguna / Inorganic Chemistry Communications 10 (2007) 666–670
5
ppm (t1)
145.0
140.0
135.0
130.0
125.0
120.0
115.0
ppm(t1)
50.0
45.0
40.0
35.0
ppm(t1)
60
50
40
30
20
145.0
140.0
135.0
130.0
125.0
120.0
115.0
ppm (t1)
ppm(t1)
7.0
6.0
5.0
4.0
3.0
2.0
ppm(t1)
80.0
75.0
70.0
65.0
60.0
ppm(t1)
8.0
7.0
6.0
5.0
4.0
3.0
2.0
1.0
Fig. 1. 19F of 10, 13C and 31P(H) NMR of 13, 31P(H) NMR of 5, 13C of 5, 1H and 31P(H) NMR of 7, 1H NMR of 8.
14–16 were formulated by elemental analyses. Complexes
1–9, 10–13 are soluble in D2O, CHCl3, MeOH which permit
to measure all NMR, ESIMS Exp. But complexes 14–16 are
poorly soluble in D2O, CHCl3, and MeOH. The ESI mass
spectrum of MeCN solution in the positive ion mode is
structurally enlightening, since it displays a series of charac-
teristics singly. The infrared spectra of 1–9, 10–13, 14–16
complexes have been assigned in comparison with the spec-
tra of the precursor chloro complexes and catechol. Impor-
tant part of IR spectra of the complexes, 1–9, 10–13, 14–16
is the disappearance of stretching at 325–330 and 310–
320 cmꢀ1 corresponding to AuCl of the precursors. The
characteristic stretchings at 1000–1200 and 1620–
1630 cmꢀ1 are assigned to m(PPh3) and m(C@N) + m(C@O),
respectively. A broad weak stretch at 3170–3180 cmꢀ1 may
be assigned to the stretching of water. The m (C–O) appears
at 1525, 1360, 1297 cmꢀ1 in the complexes and the free cat-
echol values are 1664, 1630, 1360, 1265 cmꢀ1 31P(1H)
.

P. Byabartta, M. Laguna / Inorganic Chemistry Communications 10 (2007) 666–670
669
Table 1
1H and 13C(1H) NMR spectral data of the complexes 1–16 (in CDCl3)
Compld
1H NMR
a, a0Ha
13C(1H) NMR
a
b, b0-Hb
Phenyl, Cy, dppa/m/e, Me, Et-H
a, a0–C
b, b0–Cb
Phenyl, Me, Et, Cy–Cc
1
2
6.7 (5 Hz)
6.2 (5 Hz)
6.5 (6.5 Hz)
6.31 (6 Hz)
6.31 (9 Hz)
6.31 (6 Hz)
6.31 (6.33 Hz)
6.31 (6.93 Hz)
6.71 (6.93 Hz)
6.61 (6.83 Hz)
6.39 (6.13 Hz)
6.46 (6.30 Hz)
7.0–7.30 (m, 30H)
120.9
120
121
120.8
120
121.9
120
120.9
121.9
120.9
115.6
115.6
113
115.6
116.6
116.6
116.6
116.6
115.3
116.6
129.2–131.6
7.0–7.31 (m, 24H), 1.99 (s, o-Me)
7.0–7.31 (m, 24H), 1.95 (s, m-Me)
7.0–7.39 (m, 24H), 1.92 (s, o-Me)
7.1–7.39 (m, 20H), 1.90 (s, ꢀMe)
7.0–7.39 (m, 20H), 1.91 (s, ꢀMe)
1.1–2.39 (m, Pcy), 1.90 (s, ꢀMe)
1.99 (quartet, 9 Hz) 1.11 (t, 9 Hz)
1.0–1.09 (NMe, 36H),
129–131.8, 31 (o-Me)
128–130.8, 31 (m-Me)
129–131.44, 30 (p-Me)
129–131.44, 27 (Me)
129–132.44, 27 (Me)
39.6,40,41,43.2, 44.6, 45, 46
39.9, 40.39, 27.99
3
6.1 (5.8 Hz)
6.17 (5.9 Hz)
6.1 (5.4 Hz)
6.1 (5.9 Hz)
6.98 (5.0 Hz)
6.8 (5.8 Hz)
6.77 (5.8 Hz)
6.66 (5.0 Hz)
4
5
6
7
8
8a
9
26.68, 30.27 (Me)
7.1–7.39 (m, AsPh3)
128.6 (d,28 Hz), 129, 130,
130.3, 132, 133, 139, 144
137–133.44, (C6F5)
131–137.44, (C6F5)
130–132.44, 27 (Bu)
128 (d, 6 Hz), 129, 132.4, (d, 9 Hz),
132, 134 (d, 9 Hz), 144
128–131.44, (dppa)
10
11
12
13
6.81 (5.0 Hz)
6.44 (5.1 Hz)
6.88 (5.9 Hz)
6.8 (5.8 Hz)
6.61 (6.03 Hz)
6.23 (6.9 Hz)
6.66 (6.93 Hz)
6.91 (6.93 Hz)
2.22, 1.23 (NBu4)
7.1–7.39 (m, PPh3)
7.1–7.39 (m, 30H), 1.90 2.2 (NBu4)
7.1–7.49 (m, 15H),
120.8
123
121.9
120.3
116.6
117.3
117.6
116.8
14
15
16
a
5.19 (5.0 Hz)
6.61 (5.0 Hz)
6.77 (5.4 Hz)
5.09 (5.33 Hz)
6.71 (5.33 Hz)
6.81 (5.33 Hz)
7.1–7.39 (m, 20H), 8.50 (NHꢀ dppa)
7.1–7.39 (m, 20H), 1.65 (dppmMe)
7.1–7.39 (m, 20H), 1.59 (dppeMe)
120.3
120.6
121.6
116.6
116.6
114.6
129–131.44, 27 (dppm)
129–131.44, 27 (dppe)
Doublet.
b
c
Triplet.
Multiplet.
NMR, (Fig. 1, measured in CDCl3) shows a sharp peak at
27.12 for [Au(P)(Ph3)2(CA)], 25.12 for [Au(P(Pho-
Me)3)2(CA)], 25 for [Au(P(Ph-mMe)3)2(CA)], 25.1 for
[Au(P(Ph-pMe)3)2(CA)], 13.12 for [Au(P)(Ph2Me)2(CA)],
ꢀ1.1 for [Au(PPhMe2)2(CA)], 64.62 for [Au(P(Cy3))2(CA)],
134.12 for [Au(P(NEt2)3)2(CA)], 104.72 for [Au(P(N-
Me2)3)2(CA)], 46.12 for [AuIII(PPh3)2(CA)], 35.12 for
[AuIII(PPh3)Br(CA)], 82.27 for [Au2(dppa)(CA)], whereas
the parent chloro complex arises at 33.3 for [Au(Cl)(PPh3)],
31.29 for [Au(Cl)P(Ph-oMe)3], 31 for [Au(Cl)(P)-
(Ph-mMe)3], 17.23 for [Au(Cl)(P)(Ph2Me)], 4.23 for
[Au(Cl)(P)(PhMe2)], 54.55 for [(Cl)Au(P)(Cy)3], 45.03 for
[Au(PPh3)2](ClO4), 31.31 for [Au(Br)3(PPh3)], 41.93 (major,
trans), 31.83 (minor, cis) for [Au(Br)2(PPh3)2](ClO4), 67.27
for [Au2(Cl)2(dppa)], respectively. Fluorine NMR (Fig. 1,
measured in CDCl3) of complexes (10, 11) show three sharp
signals corresponding to ortho, meta and para fluorine
rings and the pi electron delocalization on the aromatic ring
1
system. The COSY spectrum reveals the H–1H coupling
interactions in the molecule (measured in CDCl3). The dou-
blet of the C(a)H and C(b)H protons show coupling
interaction with the multiplets at d = 7.12 ppm and
7.68 ppm [C(Ph)H and C(Ph-Me)H]. In conclusion, in this
work we have synthesised and characterized 17 gold–phos-
phine mixed ligand complexes using catecholate ion
(CA2ꢀ). The CA2ꢀ is a well-known chelating as well as
bridging ligand. In this case, it forms Gold(I) two coordi-
nate linear complexes and Gold(III) square planar four
coordinate complexes with quinonoid end. The complexes
1
are fully characterised by IR, H NMR, 19F(1H) NMR,
1
31P(1H) NMR, 13C(1H) NMR, H–1H COSY NMR and
ESIMS mass spectrometry. 31P(1H) NMR technique helps
to get the correct assignment regarding the new complex
nature.
1
atom, respectively. The H NMR data for the complexes
Acknowledgement
and proton numbering pattern (Fig. 1, Table 1, measured
in CDCl3) are shown in Scheme 1. Protons are assigned
on the basis of spin–spin interaction, effect of substitution
on PPh3 and on comparing with the spectra of precursor
chloro complexes. Catechol protons give two sharp peak
near at 6.6 and 6.7 characteristics of the product with a
broad multiplet at the aromatic region. The 13C(1H)
NMR spectrum shows (Fig. 1, Table 1, measured in CDCl3)
that the non-protonated carbon atoms at C(PPX3, X = Ph,
Cy, NEt2, NMe2, Ph2Me, PhMe2) and C(dppa), are shifted
farthest downfield in the spectrum (d = 140.12 ppm and
138 ppm) effected by the magnetic interaction of two bulky
phenyl rings environment and the methyl substituted phenyl
The authors thank the Ministerio de Ciencia y Techno-
logia (CTQ2005-08099-CO3-01, Grant No. SB2004-0060)
for financial support. Prof. E. Cerrada, F. Mohr, L. Falv-
ello, M. Thomas, S. Sanz, E. Vergara, are thanked for con-
stant help.
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