Tuning the Energy of the NIR Absorption of Dinuclear Triphos

Tuning the Energy of the NIR Absorption of Dinuclear
Triphos-Cobalt-Complexes
Katja Heinze, Gottfried Huttner*, and Laszlo Zsolnai
Department of Inorganic Chemistry, University of Heidelberg,
Im Neuenheimer Feld 270, D-69120 Heidelberg, Germany
* Reprint requests to Prof. Dr. G. Huttner. Fax: (+49) 6221 545707.
E-mail: [email protected]
Z. Naturforsch. 54 b, 1147-1154 (1999); received June 2, 1999
Dinuclear Complexes, NIR Dyes, Cobalt, Tripodal Ligands, Bridging Ligands
Dinuclear Co(III) complexes of the type [(triphos)Co(C 6 X 2 Z' Z2Z3Z4)Co(triphos)]2+ (Z1~4 =
O, NR, S; R = H, Me; X = H, Cl, Br, I; 1 - 62+) have been prepared and characterized by MS,
IR, NMR, cyclovoltammetric and UV/VIS/NIR measurements and by X-ray analyses (12+, 3a2+
and 42+). Their redox behaviour and the energy of their low energy LMCT bands was studied and
compared to the properties of the mononuclear complexes [(triphos)Co(C 6 H4 Z 'Z 2)]+ (Z1-2 =
O, NH, S).
Introduction
Table I. Dinuclear complexes.
Dinuclear metal complexes are of interest be­
cause of their special electronic and magnetic
properties [1]. Recent research has shown that
dinuclear complexes based on the triphos-cobalt
fragment [triphos = l,l,l-tris(diphenylphosphanomethyl)ethane] as building block exhibit antiferro­
magnetic exchange interactions between the two d7
low-spin Co(II) centers, e.g. in chloro [2], 1,4,5,8tetraoxonaphthalino [3] or dicarboxylato bridged
triphos-Co(II) complexes [4], The diamagnetic /_ianilato d6 low-spin Co(III) complexes [(triphos)Co(C 6X 20 4 )Co(triphos)]2+ (X = H, Cl, Br, I, N 0 2, Me,
/Pr, Ph) [5] absorb stronly in the near infrared re­
gion (Amax = 1132 - 1201 nm; emdX = 17110 - 58300
M ~ 1cm - 1) which has been interpreted as being due
to a ligand-to-metal charge transfer. For these com­
plexes the energy of the NIR absorption depends
slightly on the substituent X at the bridging arene
ligand. One-electron reduction of the dications gives
the strongly delocalized class III [lb] mixed valent
complexes [(triphos)Co(C6X204)Co(triphos)]+ [6],
Here we present our efforts in tuning the energy of
the NIR absorption band and the redox behaviour
by varying the donor atoms of the bridging lig­
and in [(triphos)Co(C 6 X 2Z lZ2Z3Z4)Co(triphos)]2+
complexes (O, NR, S; R = H, Me).
Z1
Z2
Z3
Z4
X
1(BF4)2,
l(BPh4h
2(BF4)2
NH
NH
NH
NH
H
S
s
O
NH
S
NH
S
3a(BF4)2,
o
H
H
O
O
O
O
NH
NH
NH
NMe
NH
S
3a(PF6)2
3b(BF4)2
3c(BF4)2
3d(BF4)2
4(BF4)2
5(BF4)2
6(BF4)2
S
O
NH
NH
NH
NMe
NH
O
0
0
0
0
s
s
CI
Br
I
H
H
H
Results and Discussion
The dinuclear complexes 1 - 62+ (Table I) were
prepared according to Scheme 1 either as tetrafluoroborate or hexafluorophosphate salts. Indepen­
dent of the oxidation state of the briging ligand,
C6X2Z2(ZH )2 or C 6 X 2 (ZH) 4 , the complexes were
obtained as the Co(III) derivatives - a phenomenon
which was already observed for mono- [7] and din­
uclear complexes [5] of this type. All compounds
were isolated as deep blue (except 22+: green,
42+: violet), diamagnetic, sparingly soluble, micro­
crystalline powders and characterized by elemental
analyses, NMR-, IR-, UV/VIS/NIR-spectroscopic,
0932-0776/99/0900-1147 $ 06.00 (c) 1999 Verlag der Zeitschrift für Naturforschung, Tübingen • www.znaturforsch.com
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K. Heinze et al. ■NIR Absorption o f Dinuclear Triphos-Cobalt-Complexes
1148
/s l/S
PhjP'
+
2 [Co(H20 ) 6](BF4)2 +
T>Ph,
12*
• z * \ X PPh:
^ Cq\PPh:
Zf
PPh;
PhjP
+
2 [Co(H20 )6]C I2
(X ')2
+
Z<H
SsPPh2
Scheme 1. Syntheses of the complexes.
Table II. MS data of the complexes.
m/z (% ) a
M2+ + X~
M+
1(BF4)2
2(BF4 ) 2
3a(BF4 ) 2
3 a(PF 6 )2
3b(BF 4 ) 2
3c(BF4 ) 2
3d(BF4 ) 2
4(BF4 ) 2
5(BF4 ) 2
6 (BF 4 ) 2
1587 (5)
1655 (15)
1588 (30)
1646(50)
1656(25)
1747 (30)
1840 (36)
1617(52)
1621 (18)
1622(15)
1500 (3)
1568(100)
1502 (52)
1502(100)
1570(100)
1659(100)
1754(100)
1530 (72)
1534(80)
1536 (78)
M = cation, X
= PF6
[(triphos)CoL + Ph + 1]+
[(triphos)CoL]+
895 (10)
817(8)
—
—
897(100)
897(88)
965(30)
1055 (18)
1149(48)
925(100)
929(10)
931(12)
820(18)
820 (48)
8 8 8 (7)
978(4)
1072(8)
847 (70)
851 (15)
853 (18)
m 2+
750(18)
784 (30)
751(34)
751(40)
786(28)
830 (45)
877 (43)
765(72)
767 (6 8 )
768 (12)
for 3 a(PF 6 )2 , else BF4 ; L = bridging ligand.
mass spectrometric and cyclovoltammetric means.
The mass spectra (FAB, positive) confirm the din­
uclear arrangement with typical fragmentation pat­
terns [3 - 6] observed in all cases (Table II). For the
NH-containing complexes 12+, 3a-d2+ and 52+ a sin­
gle sharp band corresponding to the NH stretching
is observed in the IR spectra at 3337, 3321, 3309,
3303, 3284 and 3304 cm -1 , respectively, show­
ing that in each case the NH 2 group is deprotonated to the NH group during complex formation
and indicating the absence of hydrogen bonding.
The wavenumber of the NH stretching band fol­
lows the same trend (12+ > 3a2+ > 52+) as observed
for mononuclear [(triphos)Co(C6H4(NH)Z)]+ com­
plexes [7a]: Z = NH > Z = 0 > Z = S. The heav­
ier the substituents X in 3- and 6-positions of $ e
bridging ligand in the complexes 3a-d2+ the smaller
the wavenumber of the NH stretching band. For all
tetrafluoroborate salts the B-F stretching is observed
Fig. 1. View of the structure of 12+. Phenyl groups are
omitted for clarity.
as a broad band between 1050 and 1069 cm - 1 ; the
absorption band due to the P-F vibration of 3a(PFö)2
occurs at 839 cm - 1 .
In the 'H NMR spectra the N(H) resonances
are found between 6 = 8.3 and 9.4 - similar
to those found for the mononuclear [(triphos)Co(CöH 4 (NH)Z)]+ complexes [7a], Signals due to the
protons of the triphos ligand fall in a typical range,
that of the protons in 3- and 6-position of the bridg­
ing ligand in the complexes 12+, 22+, 3a2+, 42+, 52+
and 62+ appears between 6 = 5.5 and 7.7 and is
K. Heinze et al. ■NIR Absorption o f Dinuclear Triphos-Cobalt-Complexes
1149
Table III. Selected bond lengths and angles for the com­
plexes l(BPh4)2 , 3a(PF6)2 and 4(BF4h.
C ol-Z 1 a
C ol-Z2 a
Col-PI
Col-P2
Co 1-P3
Z'-C42
Z2-C43
C42-C43
C43-C44
C42-C44A
Z2-R b
Col •••Col A
Z 1-Col-Z2
C42-Z'-Col
C43-Z2-Col
Z'-C42-C43
Z2-C43-C42
Pl-Col-P2
Pl-Col-P3
P2-Col-P3
P I-C ol-Z 1
PI-C ol-Z 2
P2-Col-Z'
P2-Col-Z2
P3-Col-Z'
P3-Col-Z2
T,d
T2
T3
<Pl 6
<p2
<£>3
V5
^6
l(BPh4)2
3a(PFfi)2
4(BF4)2
1.888(4)
1.898(4)
2.204( 1)
2.198(2)
2.201(1)
1.351(5)
1.349(5)
1.464(6)
1.398(6)
1.393(6)
1.913(4)
1.891(4)
2.212(2)
2.232(2)
2.201(2)
1.317(6)
1.325(6)
1.465(7)
1.417(7)
1.371(7)
0.94(6)c
7.68
82.4(2)
114.8(3)
116.4(4)
114.2(4)
112.2(4)
89.51(6)
88.08(6)
95.40(6)
89.3(1)
163.6(1)
109.3(1)
106.6(1)
155.1(1)
93.6(1)
34.3
18.9
25.9
-6.5
-86.3
12.0
38.5
11.0
-1.4
1.897(5)
1.935(6)
2.235(2)
2.229(2)
2.239(2)
1.325(8)
1.337(8)
1.462(9)
1.41(1)
1.376(9)
1.483(9)
7.71
82.5(2)
115.6(4)
114.7(5)
114.4(6)
112.8(6)
90.76(8)
88.33(8)
93.79(8)
82.9(2)
163.9(2)
114.6(2)
101.5(2)
150.3(2)
101.0(2)
19.7
11.3
17.2
-7.3
-43.9
25.7
33.8
27.0
2.0
-
7.73
81.6(2)
116.6(3)
116.2(3)
111.9(4)
112.0(4)
92.21(6)
89.67(5)
91.74(5)
92.6(1)
160.9(1)
109.4(1)
106.9(1)
158.7(1)
89.4(1)
14.8
11.6
13.5
21.5
58.2
15.5
45.9
33.3
31.2
a Z 1 = N1 ( 12+), else 01; Z 2 = N2 ( 12+), N\ (3a2+, 42+);
b R = H (3a2+), CH 3 (42+);c H was located in the difference
map and refined isotropically;d r 1 - 3 : C4-Cv-P(-Col; x =
1 - 3 ;e (f i-e are defined with respect to auxiliary vectors
Hzx - Px (x = 1 - 3) orthogonal to the plane spanned by
the three P atoms and pointing towards the observer with
respect to the orientation shown in Fig. 4: Hzv- Pt - Cips0
—Cortho-
partially hidden under the signals of the aromatic
protons of the triphos ligand. In the 31P{'H } NMR
spectra a single resonance is observed for the phos­
phorus nuclei (S = 23 - 34) of the triphos ligand
indicating a fast rotation of the triphos ligand on
the NMR time scale [7]. In some cases this signal
can only be detected at lower temperatures as was
already observed for the [(triphos)Co(C 6 X 2 0 4)Co-
Fig. 2. View of the structure of 3a2+. Phenyl groups are
omitted for clarity.
Fig. 3. View of the structure of 42+. Phenyl groups are
omitted for clarity.
(triphos)]2+ [5] complexes. For 3 a(PFö )2 the septet
of the P nuclei of the counter ions appears at 6 =
-144.2 (Vpp = 713 Hz).
Single crystals of l(BPh4)2, 3a(PF6)2 and
4 (BF 4)2 were obtained by vapor diffusion of Et 2Ü
in CH 2CI2 (12+, 42+) or acetone (3a2+) solutions of
the complexes (Table III, Figs 1 - 3). All complex
cations possess a crystallographic center of symme­
try. The Co -Co distance amounts to 7.7 A, slightly
larger than in the complexes with Z 1 - 4 = O [5], The
local geometry around the Co centers can be de­
scribed as strongly distorted trigonal-bipyramidal
with PI and Z 2 (Z 2 = N2 for 12+, else N l) oc­
cupying axial coordination sites (Figs 1 - 3). The
C ö F L Z 'Z ^ Z 4 core is essentially planar and the
cobalt centers lie 0.3 A above and below this plane,
respectively (12+) or within this plane (3a2+ and 42+).
The angle between the planes spanned by Z 'C o Z 2
and C ö F b Z 'Z -^ Z 4 amounts to 10.9°, 1.6° and 2.3°
for 12+, 3a2+ and 42+, respectively. Co-Z and C-Z
bond lengths are similar to those found in mononu­
clear [(triphos)Co(C 6 H 4 Z 'Z 2)]+ [7] complexes (Ta­
ble III).
Remarkable is the small conformational change
[8 ] within the triphos-cobalt unit (backbone and
phenyl ring torsions r j _ 3 ,
Table III, Fig. 4)
which occurs on methylating the donor nitrogen
atoms of the bridging ligand (complexes 3a2+/42+;
Fig. 4). The largest angular difference concerns the
orientation of the second phenyl ring (Atp 2 = 42°)
which is certainly due to steric interaction of this
phenyl ring with the methyl group.
All complexes can be reduced by one or even two
steps (Table IV). The differences between the two
K. Heinze et al. ■NIR Absorption o f Dinuclear Triphos-Cobalt-Complexes
1150
1(BF4)2
2(BF4)2
3a(BF4)2
3b(BF4)2
3c(BF4)2
3d(BF4)2
4(BF4)2
5(BF4)2
6(BF4)2
Z1
z2
z3
Z4
NH
S
o
0
o
o
o
s
0
NH
s
NH
NH
NH
NH
NMe
NH
S
NH
S
NH
NH
NH
NH
NMe
NH
O
NH
S
0
o
0
0
0
s
s
E | / 2 [mV]
+35 (qrev.)
-175
-470
-285
-300
-310
-530
-128 (qrev.)
-140
(irr.)
-295
-1480
-1338
-1345
-1300
-1490
(irr.)
-810
Kc
—
1.07 x 102
1.19 x 1017
6 .3 3 x l0 17
4 .6 3 x l0 17
5 .4 5 x l0 16
1.69x 1016
-
2.12x10"
Amax [nm](e max [M 1 cm ’])
695 (9940)
616(7320)
739 (25070)
761 (15560)
761 (14030)
760(18050)
725(25400)
604 (6860)
694 (5160)
853 (11300)
794(13510)
933(28080)
949(32010)
950 (28220)
953 (31650)
971 (14360)
908 (9100)
929(16840)
10~3 M in 0.1 M CH3CN/nBu4NPF6 solution at 295 K ;b in CH2C12 at 295 K.
reduction potentials for 3a-d2+ and 42+ (Z 1 = Z4 = O,
Z2 = Z3 = NR; A E \/2 ~ 1 V) are of the same order of
magnitude as those of the complexes with Z 1-4 = O
[5] corresponding to comproportionation constants
[9] between 1.69x 1016 and 6.33x 1017 (Table IV).
This allows a delocalized class III [lb] description
of the corresponding cationic mixed valent com­
pounds similar to the complexes with Z 1~4 = O [6].
Substituents X in 3- and 6-positions of the bridg­
ing ligand in the complexes 3a-d2+ have a small
influence on the reduction potential (Table IV): the
more electron withdrawing X the easier the reduc­
tion as has already been observed for the complexes
with Z i_4 = O [5]. On the other hand methylation
of the nitrogen donor atom of the bridging ligand
(complexes 3a2+/42+) shifts the reduction potentials
by only 60 and 10 mV to more negative poten­
tials (Table IV). Substitution of oxygen by sulfur
[Z1- 4 = O / Z 1 = Z 3 = O, Z2 = Z4 = S (62+) / Z 1“ 4 =
S (22+)] renders the first reduction more difficult
(A E \/2 ~ 35 mV for each substitution step) but fa­
cilitates the second by 360 and 515 mV, so that the
differences between the two reduction potentials be­
come steadily smaller (Table IV): 1065 mV (Z 1-4 =
O [5]), 670 mV (Z 1 = Z3 = O, Z 2 = Z4 = S: 62+)
and 120 mV (Z 1-4 = S: 22+). Probably backbonding mediated by the sulfur atoms plays an important
role in the reduction processes leading to this un­
expected trend. After reduction of the complexes
12+ and 52+ chemical reactions - probably protona­
tion and decomposition - occur, so that only quasiand irreversible redox processes are observed in the
cyclic voltammograms.
In the UV/Vis/NIR spectra intense LMCT ab­
sorption bands are observed which are split in at
least two bands. Compared to the corresponding
K. Heinze et al. • NIR Absorption o f Dinuclear Triphos-Cobalt-Complexes
1151
Table V. Crystal and refinement data for the structure determinations of l(BPh 4 )2 , 3a(PFö)2 and 4(BF4)2-
Formula
Mr [g mol-1 ]
T [K]
Crystal size [mm]
Crystal system
Z
Space group (no.)
a [A]
b[A]
c[ A]
a n
ß[°]
7 [°J
V [A3]
p (calcd) [g cm ]
26 Range [°]
Scan speed [° min-1 ]
rflns measured / unique / observed
No. of parameters
Residual electron Density [e A-1 ]
Ri,Rw[% ]
l(BPh4)2
3a(PF6)2
4(BF4)2 a
CI36 HI24 P6 C 0 2 N4 B2
(4.0 CH 2 CI2 )
2139.8
200
0.30x0.30x0.30
monoclinic
2
P2]/c (14)
13.838(6)
29.83(1)
15.269(5)
90.0(0)
104.51(3)
90.0(0)
6102(4)
1.344
4.1 -50.0
8.0 - 60.0
11207/ 10737/6713
750
0.65
6.2, 14.9
C ssH stPsC otO i N tF ^
(1.0 EbO)
1793.3
200
0.40x0.30x0.20
triclinic
1
PJ (2)
10.402(3)
15.454(4)
15.835(4)
66.81(2)
85.86(2)
87.65(3)
2333(2)
1.329
3.9-52.0
10.0
9393/8883 /5895
569
1.38
6.8, 20.5
C9()H86P6Co-iO->N->BtF8
(4.0 CH 2 CI2 )
1705.0
200
0.20x0.30x0.30
triclinic
1
PI (2)
12.929(3)
14.463(3)
15.415(4)
68.66(2)
97.16(2)
86.98(2)
2643(2)
1.327
2.9-55.8
10.0
10653/ 10157/6627
583
1.78
10.7, 29.7
a The poor agreement factor and the relatively large residual electron density are due to severely disordered solvent
molecules.
Fig. 5. UV/Vis/NIR spectra of 3a2+ and 42+ in CFbCh.
mononuclear complexes [7a] they are shifted to
lower energy by 2000 - 5600 cm -1 . But unexpect­
edly the order of decreasing energy of this absorp­
tion band on changing the donor atoms is different:
Z 1’2 = OO < OS < SS < NS < NO < NN for the
mononuclear and Z 1~ 4 = OOOO < ONNO < OSOS
< SNNS < NNNN < SSSS for the dinuclear com­
plexes pointing to the fact that it is not always pos­
sible to extrapolate properties of mononuclear to
dinuclear complexes. The low-energy shift which
occurs on substituting the hydrogen in the 3- and
6-positions of the bridging ligand by halogen atoms
has been observed for the Z '~ 4 = O complexes [5]
v / cm ' 1
Fig. 6. Sketch of the NIR absorption bands of the com­
plexes.
and also occurs in the series 3a-d2+ with Z 1 = Z4 =
o , Z2 = Z3 = NH.
Methylation at the nitrogen donor atoms of the
bridging ligand (complexes 3a2+/4 2+) induces only
a shift of the low-energy band of 420 cm -1 towards
lower energy (Fig. 5). But the intensity of this band
decreases by about one half and the band is split
into at least two components (shoulder a t « 875 nm)
which might be due to the pertubation of the ligand
symmetry by the methyl groups. The CT band at
higher energy is shifted hypsochromically by some
260 cm “ 1 and retains its intensity.
1152
K. Heinze et al. ■NIR Absorption o f Dinuclear Triphos-Cobalt-Complexes
In varying the type of the ligating atoms Z 1-4
of the co-ligand in [(triphos)Co(C 6 X 2Z 1Z: Z?Z4)Co(triphos)]2+ complexes we were able to change
the energy of the NIR absorption band by more
than 4000 cm -1 (Fig. 6). Fine tuning of the energy
is possible by exploiting smaller substituent effects
either at the bridging arene ligand or at the donor ni­
trogen atoms, so that the frequency range between
10299 and 12594 cm -1 is covered relatively ho­
mogenously while there is still a gap between 8438
and 10299 c m " 1. Furthermore we have shown that
properties of mononuclear complexes cannot gen­
erally be extrapolated to dinuclear complexes.
Experimental Section
All manipulations were carried out under an inert at­
mosphere by means of standard Schlenk techniques. All
solvents were dried by standard methods and distilled
under inert gas. NMR: Bruker AC 200 at 200.13 MHz
( 1H), 81.015 MHz (31P{1H}); chemical shifts (6) in ppm
with respect to CD 2 CI2 ('H: 8 = 5.32) as internal and to
H 3 PO4 (31P: 6 = 0) as external standard. IR: Bruker FTIR
IFS-66, as Csl disks. UV/Vis/NIR: Perkin Elmer Lambda
19. MS (FAB): Finnigan MAT 8230, 4-nitrobenzyl al­
cohol matrix. Elemental analyses: Microanalytical labo­
ratory of the Organisch-Chemisches Institut, Universität
Heidelberg. Melting points: Gallenkamp MFB-595 010,
melting points are not corrected. Cyclic voltammetry:
Metrohm ‘Universal Meß- und Titriergefäß’, Metrohm
GC electrode RDE 628, platinum electrode, SCE elec­
trode, Princeton Applied Research potentiostat Model
273, 10~3 M in 0.1 M nBu4NPF6/CH3CN.
X-ray structure determinations: The measurements
were carried out on a Siemens (Nicolet) R3m/v fourcircle diffractometer with graphite-monochromated MoKa radiation. All calculations were performed using the
SHELXT PLUS software package. The structures were
solved by direct methods with the SHELXS-86 program
and refined with the SHELX93 program [10]. A reflec­
tion was considered observed if its intensity I was larger
than 2cr(I). Intensities were corrected for Lorentz- and
polarisation effects. An absorption correction (t/> scan,
AxJ) = 1 0 °) was applied to all data. Atomic coordinates
and anisotropic thermal parameters of the non-hydrogen
atoms were refined by a full-matrix least-squares calcu­
lation based on F2. R\ = L (IIF0I - IFc11) / £IF0I; Rw [Z h’(F„2 - Fc2)2 / Z w(F02)2]0'5. Hydrogen atoms were
calculated making use of a riding model except for the NH in compound 3a(PFft)2- Graphics were prepared using
XPMA and ZORTEP [11, 12].
Chemicals: The ligands were commercially avail­
able or prepared by published procedures: 1,2,4,5-tetra-
mercaptobenzene C 6 H6 S4 [13], 2,5-diamino-1,4-benzoquinone C6 H6 N 2 O 2 [14], 2,5-diamino-3,6-dichloro-l,4benzoquinone C 6 H4 N2 O 2 CI2 [15], 2,5-diamino-3,6-dibromo-1,4-benzoquinone C 6 H4 N 2 0 2 Br2 [15], 2,5-diamino-3,6-diiodo-l,4-benzoquinone C 6 H 4 N 2 O 2 I2 [15],
2.5-bis(methylamino)-1,4-benzoquinone C 8 H 10 N 2 O 2
[16], 2,5-disulfido-/?-phenylenediamine C 6 H6 N 2 S 2 [17],
4.6-dimercaptoresorcine C 6 H6 O 2 S2 [18], 1,1,1 -tris(diphenylphosphanomethyl)ethane, CH 3 C(CH 2 PPh2 ) 3 [19].
(/i-1,2,4,5-Benzenetetraamidato)bis[{ 1,1,1 -tris(diphenylphosphanomethyl)ethane}cobalt]-bis(tetrafluoroborate)
[ 1 (BF4 )2 ], (ju-1,2,4,5-benzenetetrathiolato)bis[{ 1 , 1 , 1 tris(diphenylphosphanomethyl)ethane}cobalt]-bis(tetrafluoroborate) [2 (BF4 )2 ], (//-3,6-di-X-l,4-benzenedioxo2,5-diamidato)bis[{ 1 , 1 , 1 -tris(diphenylphosphanomethyl)ethane}cobalt]-bis(tetrafluoroborate) [3a-d(BF4)2]
(X = H, Cl, Br, I), {/7.-l, 4 -benzenedioxo-2 ,5 -di(/V-methyl)amidato}bis[{ 1 , 1 , 1 -tris(diphenylphosphanomethyl)ethane}cobalt]-bis(tetrafluoroborate) [4 (BF4 )2 ],
(//-1,4-benzenedithiolato-2,5-diamidato)bis[{ 1,1,1 -tris(diphenylphosphanomethyl)ethane}cobalt]-bis(tetrafluoroborate) [5(BF4)2], (^-l,3-benzenedithiolato-2,6-dioxo)bis[{ 1 , 1 , 1 -tris(diphenylphosphanomethyl)ethane}cobalt]-bis(tetrafluoroborate) [6 (BF4 )2 ]:
To a solution of the triphos ligand (624 mg, 1 mmol)
in THF (15 ml) a solution of Co(BF4 ) 2 • 6 H 2 O (341 mg,
1 mmol) in ethanol (15 ml) was added. Addition of the
co-ligand [ 1 (BF4 )2 : 69 mg, 2 (BF4 )2 : 103 mg, 3 a(BF 4 )2 :
69 mg, 3b(BF4)2: 104 mg, 3 c(BF 4 )2 : 148 mg, 3 d(BF 4 )2 :
195 mg, 4 (BF4 )2 : 83 mg, 5(BF4)2: 85 mg, 6 (BF4 )2 :
87 mg, 0.5 mmol] to the orange-red colored solution
caused an immediate colour change (22+: green, 42+:
violet, else blue). After stirring for 1 h the solvents
were removed in vacuo, the residue washed with diethylether ( 2 x 1 0 ml), cold ethanol ( 2 x 1 0 ml) and
again diethylether ( 2 x 1 0 ml). The compounds were re­
crystallized from methylene chloride/diethylether. Yields:
1(BF4)2: 53%, 2(BF4)2: 89%, 3a(BF4)2: 60%, 3b(BF4)2:
75%, 3c(BF4)2: 79%, 3d(BF4)2: 6 8 %, 4(BF4)2: 65%,
5 (BF4 )2 : 74%, 6 (BF4 )2 : 69%. Crystals suitable for X-ray
crystallographic analyses were obtained by vapor diffu­
sion of diethylether into a dilute solution of the complex
salts [1( BF4)2: methylene chloride covered with a solution
of NaBPh4 in EtOH giving crystals of l(BPh 4 )2 ,4(BF4)2:
methylene chloride].
1(BF4)2: M. p. 280 - 295 °C (dec.). - IR (Csl): v = 3337
cm “ 1 (m, NH), 1058 (br, BF). - 'H-NMR (CD 2 C12): 6 =
1.90 (bs, 3 H, CHi), 2.66 (bs, 6 H, CH2), 5.87 (s, 1 H,
ligand-C//), 7 . 1 -7.3 (m, 30 H, C //ar), 8.3 (br, 1 H, NH). 31 P{ 1 H} (CD 2 CI2 ): b = 33.6 (s, triphos-P).
C 88 H84 P6 N4 Co 2 B2 F 8 (1675.0): 1(BF4 ) 2 • 4.0 CH 2 C12
Calcd C 54.85’ H 4.61 N 2.78%,
Found C 55.09 H5.17 N 3.87%.
K. Heinze et al. • NIR Absorption o f Dinuclear Triphos-Cobalt-Complexes
2(BF4)2: M.p. > 300 °C (dec.). - IR (Csl): v = 1068
(br, BF). - 'H-NMR (CD2C12): b = 2.0 (bs, 3 H, C //3),
3.0 (bs, 6 H, CH2), 7.1 - 7.3 (m, 31 H, C //ar + ligand-C//).
- 3iP{'H} (CD2C12): b = 27.6 (s, triphos-P).
C88H8oP6S4Co2B2Fh (1743.2)
Calcd C 60.64 H 4.63 P 10.66%,
Found C 61.15 H 5.07 P 10.63%.
3a(BF4)2: M.p. 296°C (dec.). - IR (Csl): v =
3321 cm-1 (m, NH), 1050(br, BF). - 'H-NM R(CD2C12):
b = 1.85 (bs, 3 H, C //3), 2.65 (bs, 6 H, C //2), 6.48 (s, 1
H, ligand-C//), 7.2 (bs, 30 H, C //ar), 7.4 (br, 1 H, NH). 3iP{'H} (CD2C12): b = 23 (s, triphos-P) (180 K).
C 88 H 82 P5 O.N 2 CooB.F 8 (1677.0): 3a(BF4)2 • 0.5 CH.Cb
Calcd C 61.82 H4.87 N 1.63%,
Found C 62.10 H 5.34 N 1.73%.
3b(BF4)2: M.p. 298 - 302 °C (dec.). - IR (Csl): v =
3309 cm- 1(m, NH), 1066 (br, BF). - 1H-NMR (CD2C12):
6 = 1.93 (bs, 3 H, C //3), 2.64 (bs, 6 H, C //2), 7.1 - 7.3 (m,
30 H, C //ar), 8.5 (br, 1 H, NH). - 3iP{'H} (CD2C12): 6 =
26 (s, triphos-P) (190 K).
C88H8oP602N2Co2Cl2B2F8 (1745.9):
3b(BF4)2 • 1.0CH2C12
Calcd C 58.39 H4.51 N 1.53 P 10.15%,
Found C 58.59 H 5.34 N 1.38 P9.98%.
3c(BF4)2: M.p. 282 °C (dec.). - IR (Csl): v = 3303
cm "1 (m, NH), 1059 (br, BF). - 'H-NMR (CD2C12): b =
I.93 (bs, 3 H, C //3), 2.63 (bs, 6 H, CH2), 7.0 - 7.3 (m, 30
H, CHar), 8.9 (br, 1 H, N//). - 31P{'H}~ (CD2C12): <5 = 26
(s, triphos-P) (200 K).
C88H8oP602N2Co2Br2B2F8 (1834.8):
3c(BF4)2 • 1.0 CH.Cl->
Calcd C 55.69 H4.31 N 1.46%,
Found C 55.89 H4.86 N 1.20%.
3d(BF4)2: M.p. 250 °C (loss of I2). - IR (Csl): v =
3284 cm "1(m, NH), 1069 (br, B F ) .- 1H-NMR (CD2C12):
b = 1.93 (bs, 3 H, C //3), 2.66 (bs, 6 H, C //2), 7.1 - 7.3 (m,
30 H, C //ar), 8.3 (br, 1 H, NH). - 3iP{'H} (CD2C12): b =
25 (s, triphos-P) (200 K).
C 88 H80 P6 O 2 N 2 C 0 2 I2 B2 F 8 (1928.8):
3c(BF4)2 • 2.0 CH2Cl->
Calcd C 51.51 H4.03 N 1.33%,
Found C 51.16 H4.29 N 1.52%.
4(BF4)2: M.p. 250 °C (dec.). - IR (Csl): v = 1057
(br, BF). - 'H-NMR (CD2C12): b = 1.8 (bs, 6 H, C / / 3 +
N C//3), 2.87 (bs, 6 H, CH2), 7.1 - 7.3 (bs, 31 H, C //ar +
ligand-C//), 7.4 (br, 1 H, NH). - 3 1 P{'H} (CD 2 C12): no
signal at 295 K.
C9 oH86P60.N.Co.B.F8 (1705.0): 4(BF4 ) 2 • 1.0CH 2 C12
Calcd C 61.06 H 4.96 N 1.57%,
Found C 60.75 H 5.29 N 1.74%.
1153
5(BF4)2: M. p. 240 °C (dec.). - IR (Csl): v = 3304 cm " 1
(m, NH), 1061 (br, BF). - 'H-NMR (CD 2 C12): b = 1.96
(bs, 3 H, C //3), 2.77 (bs, 6 H, C //2), 7.1 - 7.6 (m, 31
H, C //ar + ligand-C//), 9.4 (br, 1 H, NH). - 3 1 P{'H}
(CD 2 C12): b = 33 (s, triphos-P).
CssHg.PftS.N.CooB.Fs (1709.1): 5(BF4). • 3.0 CH.C12
Calcd C 55.66 H 4.52 N 1.43%,
Found C 55.79 H5.13 N 1.40%.
6 (BF4)2: M. p. 237 °C. - IR (Csl): v = 1058 (br, BF). ' H-NMR (CD 2 C12): b = 2.00 (bs, 3 H, C //3), 2.75 (bs, 6 H,
CH2), 7 . 1 - 7.2 (m, 30 H, C //ar), 7.86 (s, 1 H, ligand-C//).
- 3 iP{'H} (CD 2 C12): «5 = 31 (s, triphos-P).
C 88 H 80 P6 S .O .C o.B .F 8 (1711.1): 6 (BF4). • 1.0 CH,C12
Calcd C 59.52 H 4.60%,
Found C 59.19 H 4.80%.
(p -1,4-benzenedioxo-2,5-diamidato)bis[{ 1,1,1 -tris(diphenylphosphanomethyl)ethane}cobalt]-bis(hexafluorophosphate) [3 a(PF 6 )2 ]:
To a solution of the triphos ligand (624 mg, 1 mmol)
in THF (15 ml) a solution of CoCl2 (130 mg, 1 mmol)
in ethanol (15 ml) was added. Addition of the co-ligand
(69 mg, 0.5 mmol) to the red colored solution caused an
immediate colour change to dark-blue. After adding solid
NaPFö (168 mg, 1 mmol) in one portion and stirring for
1 h the precipitated complex salt was filtered off, washed
with diethylether (2 x 1 0 ml), cold ethanol (2 x 1 0 ml)
and again diethylether ( 2 x 1 0 ml). The solid residue was
taken up in methylene chloride and undissolved NaCl was
filtered off. Recrystallization from acetone/diethylether
gave 3 a(PFö) 2 in 51% yield. Crystals suitable for X-ray
crystallographic analysis were obtained by vapor diffu­
sion of diethylether into a dilute solution of the complex
salt in acetone.
M.p. 291 °C (dec.). - IR (Csl): P = 3318 cm - 1 (m,
NH), 839 (br, PF). - 'H-NMR (CD 2 C12): b = 1.80 (s, 3
H, C // 3 ), 2.55 (bs, 6 H, CH2), 6.49 (s, 1 H, ligand-C//),
7.1 - 7.4 (m, 30 H, C //ar), 9.2 (br, 1 H, NH). - 3 iP{'H}
(CD 2 CI2 ): b = 30 (bs, triphos-P),-144.2 (sept.,' Jpf = 713
Hz, PF6) (210 K).
C88H8'>P80oN2Co2Fi2 (1793.3): 3a(PFö)2 2.0 acetone
Calcd C 59.13 H 4.96 N 1.47 P 12.98%,
Found C 58.70 H 5.30 N 1.23 P 12.98%.
Acknowledgements
We are indebted to the Deutsche Forschungsgemein­
schaft, the Fonds der Chemischen Industrie and the Volks­
wagenstiftung for the support of this work.
1154
K. Heinze et cd. • NIR Absorption o f Dinuclear Triphos-Cobalt-Complexes
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