Facile access of well-defined stable divalent lead compounds with small organic substituents

Article abstract of DOI:10.1021/om801167c

reaction of 1 equiv of β-diketiminate lithium, LLi · Oet ₂ {L = HC(CMeNAr)₂ (Ar = 2,6-iP₂C ₆H₃), nacnac ligand} with 1 equiv of PbCl₂ in THF afforded the //-diketiminate lead(II) chloride (

Full text of DOI:10.1021/om801167c

Organometallics 2009, 28, 2563–2567
2563
Facile Access of Well-Defined Stable Divalent Lead Compounds with
Small Organic Substituents
Anukul Jana, Sankaranarayana Pillai Sarish, Herbert W. Roesky,* Carola Schulzke,
Alexander Do¨ring, and Michael John
Institut fu¨r Anorganische Chemie, UniVersita¨t Go¨ttingen, Tammannstrasse 4, 37077 Go¨ttingen, Germany
ReceiVed December 9, 2008
The reaction of 1 equiv of ꢀ-diketiminate lithium, LLi · OEt2 {L ) HC(CMeNAr)2 (Ar ) 2,6-iPr2C6H3),
nacnac ligand} with 1 equiv of PbCl2 in THF afforded the ꢀ-diketiminate lead(II) chloride (1) as a yellow
compound. Treatment of 1 with stoichiometric amounts of methyl lithium, phenyl lithium, lithium
phenylacetylide, and silver triflate resulted in the divalent organolead compounds LPb(II)Me (2), LPb(II)Ph
(3), LPb(II)CCPh (4), and LPb(II)OTf (5). Compounds 2 and 3 are the first stable, monomeric lead(II)
derivatives involving small alkyl and aryl groups Me and Ph, respectively, supported by the ꢀ-diketiminate
ligand. Compound 4 is the first alkynyl lead(II) derivative. All compounds (2, 3, 4, 5) were characterized
by microanalysis, X-ray crystallography, and 1H, 13C, and 207Pb NMR spectroscopy. Single-crystal X-ray
structural analyses indicate that compounds 2-4 are monomeric, and the lead center resides in a trigonal-
pyramidal environment, whereas 5 has a polymeric structure. The results demonstrate the effectiveness
of the ꢀ-diketiminate ligand in creating a protected surrounding for the lead atom.
chelating ligand or bulky aryl ligand, and R a small substituent).7,8
The ꢀ-diketiminate ligand is a particularly versatile ligand for
the stabilization of single-site metal centers with low valence
states.9 Recently our group using this ligand reported the
synthesis and structure of some heteroleptic germylene, stan-
nylene, and plumbylene complexes.10 Now we are interested
in the synthesis of heteroleptic plumbylene derivatives contain-
ing small organic substituents. Herein we report on the prepara-
tion and characterization of the monomeric LPb(II)Me (2),
LPb(II)Ph (3), and LPb(II)CCPh (4) and the polymeric LPb(I-
I)OTf (5) (Tf ) SO2CF3).
Introduction
With the resurgence of interest in stable N-heterocyclic
carbenes over the years,1 the chemistry of their heavier
analogues, silylenes, germylenes, stannylenes, and plumbylenes,
has also attracted considerable interest. Organolead chemistry
was primarily investigated with compounds of lead in the formal
oxidation state IV. In contrast the chemistry of Pb(II) tends to
be dominated by compounds with inorganic ligands, and bivalent
organolead compounds are relatively rare and their chemistry
is poorly explored.2,3 In the literature there are reported some
homoleptic plumbylene complexes. The first well-characterized
organolead(II) species was the bent sandwich complex Pb(η5-
C5H5)2,4 and this has been supplemented by a number of related
derivatives that have a variety of substituents at the cyclopen-
tadienyl ring.5 For many years, however, Pb[CH(SiMe3)2]2 was
the only stable σ-bonded organolead(II) compound.6 But
remarkably little is known about the chemistry of smaller
heteroleptic organic derivatives such as L′Pb(II)R (L′ )
Results and Discussion
The ꢀ-diketiminato-substituted chloroplumbylene LPb(II)Cl
(1) was prepared from ꢀ-diketiminate lithium, LLi · OEt2, and
1 equiv of PbCl2 in THF. 1 readily reacts with 1.6 molar equiv
of MeLi in diethyl ether at -78 °C to give a clear orange
solution. The 1H NMR spectroscopic data of the reaction mixture
indicate that the desired methyl-substituted plumbylene complex
LPb(II)Me (2) is formed nearly quantitatively after warming to
* To whom correspondence should be addressed. Fax: +49-551-393373.
E-mail: hroesky@gwdg.de.
(7) (a) Pu, L.; Twamley, B.; Power, P. P. Organometallics 2000, 19,
2874–2881. (b) Hino, S.; Olmstead, M.; Philips, A. D.; Wright, R. J.; Power,
P. P. Inorg. Chem. 2004, 43, 7346–7352.
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Lappert, M. F.; Protchenko, A. V. Dalton. Trans. 2007, 2770–2778. (b)
Yao, S.; Block, S.; Brym, M.; Driess, M. Chem. Commun. 2007, 3844–
3846. (c) Pineda, L. W.; Jancik, V.; Nembenna, S.; Roesky, H. W. Z. Anorg.
Allg. Chem. 2007, 633, 2205–2209. (d) Stasch, A.; Forsyth, C. M.; Jones,
C.; Junk, P. C. New J. Chem. 2008, 32, 829–834.
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Tamm, M. Angew. Chem. 2008, 120, 7538–7542; Angew. Chem., Int. Ed.
2008, 47, 7428-7432. (b) Chase, P. A.; Stephan, D. W. Angew. Chem.
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(5) Jutzi, P.; Burford, N. Chem. ReV. 1999, 99, 969–990.
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1973, 317–322. (b) Davidson, P. J.; Harris, D. H.; Lappert, M. F. J. Chem.
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Cardin, D. J.; Twamley, B.; Zubavichus, Y. Organometallics 1995, 14,
5708–5710. (d) Stu¨rmann, M.; Weidenbruch, M.; Klinkhammer, K. W.;
Lissner, F.; Marsmann, H. Organometallics 1998, 17, 4425–4428.
(9) Nagendran, S.; Roesky, H. W. Organometallics 2008, 27, 457–492.
(10) (a) Ding, Y.; Roesky, H. W.; Noltemeyer, M.; Schmidt, H.-G.;
Power, P. P. Organometallics 2001, 20, 1190–1194. (b) Ding, Y.; Hao, H.;
Roesky, H. W.; Noltemeyer, M.; Schmidt, H.-G. Organometallics 2001,
20, 4806–4811. (c) Ding, Y.; Ma, Q.; Roesky, H. W.; Herbst-Irmer, R.;
Uso´n, I.; Noltemeyer, M.; Schmidt, H.-G. Organometallics 2002, 21, 5216–
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10.1021/om801167c CCC: $40.75
2009 American Chemical Society
Publication on Web 03/24/2009

2564 Organometallics, Vol. 28, No. 8, 2009
Jana et al.
Scheme 1. Synthesis of Compounds 2, 3, 4, and 5
coordination environment of the central Pb atom exhibits the
same distorted trigonal-pyramidal geometry as in compound 2
(Figure 3).
Interestingly it is noted that the shortest C-C bonds (C1-C2
(1.368(8) Å) and C4-C5 (1.362(9) Å) of the phenyl ring are
exactly opposite each other; this may be due to the influence of
the Pb substituent.
Furthermore, we examined the substitution reactions of 1 with
selected nucleophiles in order to prepare other plumbylene
derivatives. Treatment of 1 with PhCCLi and AgSO3CF3 resulted
in the formation of 4 and 5, respectively (Scheme 1). The
addition of PhCCLi to 1 in toluene at -78 °C proceeded
smoothly to provide 4 in high yield. Maintaing an n-hexane
solution of 4 for one day at -32 °C resulted in yellow crystals
suitable for X-ray structural analysis. Compound 4 crystallizes
room temperature and stirring for another 3 h (Scheme 1). After
extraction with n-hexane, compound 2 can be obtained in the
form of yellow crystals in 82% yield. Its composition and
j
in the triclinic space group P1, with one monomer in the
asymmetric unit. The coordination environment of the central
Pb atom exhibits a distorted trigonal-pyramidal geometry (Figure
4). In the 207Pb NMR spectrum the resonance arises at δ ) 1463
ppm, which is different from that of 3 (δ ) 2424 ppm). In the
literature there are no reports on compounds containing Pb(II)
and acetylide linkages, but there are a few known examples
containing Pb(IV) and acetylide substituents.11
The C1-C2 bond distance (1.214(5) Å) of 4 is in the range
of a triple bond; therefore we assume that no additional electron
density is shifted toward the Pb. The bond angle of Pb1-C1-C2
(159.9(3)°) is smaller than 180°, while the bond angle of
C3-C2-C1 (177.0(4)°) is close to linear.
1
constitution are supported by elemental analysis and H, 13C,
and 207Pb NMR spectroscopy. In addition, the structure of 2
has been confirmed by single-crystal X-ray structural analysis
(Table 1, Figure 1). While compound 2 is sensitive to oxygen
and moisture, it is indefinitely stable under dry nitrogen
atmosphere.
Compound 2 represents the first stable ꢀ-diketiminate plum-
bylene complex with the smallest alkyl group. EI-MS of 2
exhibits the monomeric molecular ion peak [M - Me]+. The
1H NMR spectrum of 2 consists of a singlet resonance (0.55
ppm) for Pb-CH3 that is flanked by 207Pb satellite lines
(2J(207Pb-1H) ) 72 Hz). Also the 207Pb NMR spectrum exhibits
a singlet resonance (δ ) 3009 ppm) that is very much different
from the parent compound [HC(CMeNAr)2PbCl] (Ar ) 2,6-
iPr2C6H3) (1), where the lead shows a resonance at δ ) 1413
ppm. This change was expected because of the different
electronic nature of the substituents on the lead atoms. The other
Interestingly, replacement of the chloride group by the triflate
substituent generates compound 5. The triflate anion (OSO2CF3)
has served as an excellent leaving group in nucleophilic
displacement reactions.12 Organoplumbylene triflates may act
as precursors for further reactions. LPb(II)OSO2CF3 (5) was
prepared in toluene solution in high yield as yellow crystals
that are soluble in common organic solvents, such as n-hexane
and toluene.
1
resonances of the H NMR spectrum and elemental analyses
j
Compound 5 crystallizes in the triclinic space group P1
are in accordance with 2 as formulated.
(Figure 5). In the unit cell there are two asymmetric species,
and each consists of four monomers of 5. The structure of 5 is
not identical with those of the related ꢀ-diketiminate germa-
nium(II)13 and tin(II) triflates.10a The coordination polymer of
5 is oriented along the b axis of the crystal. There are also empty
channels present along the b axis being approximately 11 Å in
diameter. Each lead in compound 5 is bound to two oxygen
atoms of different triflate ions. One Pb-O bond is always shorter
than the (av 2.586 Å) other one (av 2.624 Å). Even the short
Pb-O bonds are considerably longer than the sum of the
covalent radii of oxygen and lead (2.19 Å). This suggests that
all lead oxygen bonds, which constitute essentially the building
block of the backbone of the polymeric chain, are based on
electrostatic nature rather than covalency. Interestingly for the
lead atoms there is always one shorter and one longer bond to
oxygen. However this is not the case for the oxygen atoms of
one triflate molecule. O4 and O5 bound to S2 both form Pb-O
bonds to lead (Pb2 and Pb3) with shorter distances (2.589 and
2.582 Å). In contrast O7 and O8 bound to S3 exhibit longer
Pb-O bonds (Pb3 and Pb4), at 2.614 and 2.630 Å. This means
that there is an irregularity of the expected sequence of
Furthermore we observed that the intermolecular Pb-Pb
distance of 4.403 Å (Figure 2) is very much comparable with
the Pb-Pb distance (4.129 Å) of weakly dimerized
Pb[CH(SiMe3)2]2,6d rather than those (Pb-Pb 2.903-3.527 Å)
of the diplumbylenes.7
The well-defined compound LPbPh (3) was obtained in high
yield from the reaction of 1 with 1 equiv of PhLi at -78 °C in
toluene (Scheme 1). Compound 3 is a yellow solid soluble in
benzene, THF, n-hexane, and n-pentane and shows no decom-
position on exposure to air for a short period of time. 3 was
characterized by 1H, 13C, and 207Pb NMR spectroscopy, EI mass
spectrometry, elemental analysis, and X-ray structural analysis.
The 1H NMR spectrum of compound 3 shows a singlet at 4.79
ppm for the γ-CH proton and two septets (3.57, 3.20 ppm)
corresponding to the CH protons of the iPr moieties. The 207Pb
NMR of 3 exhibits a singlet at 2424 ppm. The most abundant
ion peak in the EI mass spectrum appeared at m/z 702 for the
molecular ion [M]+.
Maintaining an n-hexane solution of 3 for three days at -30
°C resulted in slightly yellow single crystals suitable for X-ray
structural analysis. Compound 3 crystallizes in the monoclinic
space group P21/n, with two molecules in the asymmetric unit
(Table 1). There are two independent molecules in a unit that
differ slightly with respect to distances and angles. The
(11) (a) Pant, B. C.; Davidsohn, W. E.; Henry, M. C. J. Organomet.
Chem. 1969, 16, 413–417. (b) Nast, R.; Grouhi, H. J. Organomet. Chem.
1979, 182, 197–202. (c) Van Beelen, D. C.; Wolters, J.; De Vos, D. Main
Group Met. Chem. 1998, 21, 55–64.
(12) Howells, R. D.; McCown, J. D. Chem. ReV. 1977, 77, 69–92.
(13) Yao, S.; Brym, M.; Merz, K.; Driess, M. Organometallics 2008,
27, 3601–3607.

Facile Access of Stable DiValent Lead Compounds
Organometallics, Vol. 28, No. 8, 2009 2565
Table 1. Crystallographic Data for the Structural Analyses of Compounds 2, 3, 4, and 5
empirical formula
CCDC-No.
C30H44N2Pb
711352
C35H46N2Pb
711353
C37H46N2Pb
711354
C30H41F3N2O3PbS
711355
T [K]
133(2)
133(2)
133(2)
133(2)
cryst syst
space group
a [Å]
b [Å]
c [Å]
R [deg]
ꢀ [deg]
γ [deg]
V [Å3]
triclinic
P1
monoclinic
P21/n
10.146(2)
31.930(6)
19.622(4)
90
99.34(3)
90
6273(2)
8
triclinic
P1
triclinic
P1
j
j
j
10.439(2)
11.973(2)
12.424(3)
90.45(3)
107.02(3)
108.52(3)
1399.2(5)
2
8.7602(18)
11.529(2)
16.702(3)
75.20(3)
82.28(3)
87.86(3)
1616.1(5)
2
12.684(3)
24.602(5)
25.044(5)
105.80(3)
100.97(3)
93.75(3)
7325(3)
Z
8
Dcalcd [g cm-3
]
1.519
6.048
640
1.487
5.404
2816
1.492
5.246
728
1.403
4.706
3072
µ [mm-1
F(000)
]
θ range [deg]
reflns collected
1.72-26.96
12 613
1.23-25.86
52 523
1.83-26.95
15 407
1.39-25.89
58 828
indep reflns
6022
12 096
6979
28 118
data/restraints/params
R1, wR2 [I > 2σ(I)]a
R1, wR2 (all data)a
GoF
6022/0/313
0.0283, 0.0781
0.0300, 0.0792
1.037
12 096/0/710
0.0344, 0.0717
0.0508, 0.0759
0.970
6979/0/374
0.0257, 0.0487
0.0345, 0.0502
0.996
28 118/0/1484
0.0525, 0.1022
0.0979, 0.1146
0.890
∆F(max), ∆F(min) [e Å-3
]
2.935, 1.668
2.109, -1.458
0.886, -1.002
1.140, -2.024
a
2
2
R1 ) ∑|Fo| - |Fc|/∑|Fo|. wR2 ) [∑w(Fo - Fc2)2/∑w(Fo )2]0.5
.
alternating short and long bonds. We find instead Pb1-short-
S1-long-Pb2-short-S2-short-Pb3-long-S3-long-Pb4-short-S4-
long-Pb1. Moreover the triflate based on S2 is most tightly
bound to its neighboring lead atoms, while the triflate based on
S3 in comparison is rather weakly bound. The only other
pronounced crystallographic difference between these two triflate
molecules is a different arrangement of weak hydrogen bonds
between two fluorine atoms each to neighboring isopropyl
groups of the nacnac ligands. F8 of the S3 triflate is hydrogen
bound to two isopropyl groups of two different nacnac ligands
on two different lead atoms (Pb3 and Pb4). F9 is only bound to
nacnac isopropyl of Pb4. However, F6 of the S2 triflate is
hydrogen bonded to two methyl groups of the same isopropyl
group of one nacnac ligand on lead Pb3. F4 is again only bound
to one nacnac methyl group of Pb2. F8 of the S3 triflate is
therefore bridging two different nacnac ligands via hydrogen
bonding and its position might be more constrained. This could
be the reason for the longer and accordingly weaker Pb-O
bonds of S3 triflate. For the S1 triflate there are only two
hydrogen bonds present; both involve F2, which is interacting
with two different nacnac ligands on Pb1 and Pb2. The other
two fluorines (F1, F3) show no hydrogen bonds. For the S4
triflate three hydrogen bonds are present involving each of the
three fluorines (F10, F11, F12). To summarize, each of the four
triflate molecules participates in hydrogen bonding with methyl
groups of the nacnac ligand via their fluorine atoms, but each
does it in a different way, which might cause the inconsistency
of the binding to the lead atoms of the polymeric chain. Unlike
1
compounds 2-4, the H NMR spectrum of 5 shows only one
singlet (δ ) 3.26 ppm) and two doublets for the methyl groups
of the iPr substituents. This indicates that either compound 5
rapidly dissociates under formation of the OTf group and
reassociates at the Pb center or OTf has a bridging function
between two lead atoms, as observed in the solid state structure.
In the 207Pb NMR spectrum the resonance arises at δ ) 1334
ppm, which is similar to that of 1 (δ ) 1413 ppm). Also in the
19F NMR spectrum compound 5 exhibits a singlet resonance
(δ ) -76.5 ppm). In Table 2 we have summarized the 207Pb(II)
Figure 1. Molecular structure of 2. Anisotropic displacement
parameters are depicted at the 50% probability level, and all
restrained refined hydrogen atoms are omitted for clarity. Selected
bond lengths [Å] and angles [deg]: Pb1-C1 2.300(4), Pb1-N1
2.345(3);N1-Pb1-C188.33(13),N2-Pb1-C191.04(13),N1-Pb1-N2
81.44(10).
Figure 2. Unit cell of the 2. Isopropyl groups of the phenyl ring
are omitted for clarity.

2566 Organometallics, Vol. 28, No. 8, 2009
Jana et al.
Figure 3. Molecular structure of 3. Anisotropic displacement
parameters are depicted at the 50% probability level, and all
restrained refined hydrogen atoms are omitted for clarity. Selected
bond lengths [Å] and angles [deg]: Pb1-C1 2.300(5), Pb1-N1
2.319(4);N1-Pb1-C191.12(16),N2-Pb1-C195.22(16),N1-Pb1-N2
82.42(14).
Figure 5. Molecular structure of 5. Anisotropic displacement
parameters are depicted at the 50% probability level, and all
restrained refined hydrogen atoms are omitted for clarity. Selected
bond lengths [Å] and angles [deg] are Pb1-O1 2.595(6), Pb1-O11
2.638(6), O1-S1 1.450(7); N1-Pb1-O1 87.7(2), N2-Pb1-O1
102.6(2), N1-Pb1-N2 82.0(3).
Table 2. 207Pb NMR Data of Pb(II) ꢀ-Diketiminate Compounds
compounda
207Pb {1H} NMR (δ, ppm)
LPbCl (1)
LPbMe (2)
1413
3009
LPbPh (3)
LPbCCPh (4)
2424
1463
LPbOTf (5)
1334
LPbOAr1 (Ar1 ) 2,6-tBu2C6H3)
LPbN(SiMe3)2
LPbP(SiMe3)2
Pb[N(SiMe3)2]2
10408b
18248b
-17378b
491614
a L ) HC(CMeNAr)2 (Ar ) 2,6-iPr2C6H3).
MBraun MB 150-GI glovebox. All solvents were dried by an
MBraun solvent purifying system prior to use. All the chemicals
1
were purchased commercially and used as received. H, 13C, 19F,
and 207Pb NMR spectra were recorded on a Bruker Avance 500
MHz instrument and referenced to the deuterated solvent in the
1
case of the H and 13C NMR spectra. 19F and 207Pb NMR spectra
Figure 4. Molecular structure of 4. Anisotropic displacement
parameters are depicted at the 50% probability level, and all
restrained refined hydrogen atoms are omitted for clarity. Selected
bond lengths [Å] and angles [deg]: Pb1-C1 2.276(3), C(1)-C(2)
1.214(5), C(2)-C(3) 1.442(5), Pb1-N1 2.300(3); N1-Pb1C1
89.04(11), N2-Pb1-C1 90.78(11), N1-Pb1-N2 81.82(9).
were referenced to CFCl3 and Pb(Me)4 respectively. Elemental
analyses were performed by the Analytisches Labor des Instituts
fu¨r Anorganische Chemie der Universita¨t Go¨ttingen. EI-MS were
measured on a Finnigan Mat 8230 or a Varian MAT CH5
instrument. UV-vis spectra were recorded on a Varian Cary 50
instrument. Melting points were measured in sealed glass tubes with
a Bu¨chi melting point B 540 instrument and are not corrected.
Synthesis of Compounds 2, 3, and 4. Compounds 2-4 are
prepared in a similar way using different organo-lithium reagents.
2: A solution of MeLi in diethyl ether (0.63 mL, 1.6 M) was
added drop by drop to a stirred solution of 1 (0.66 g, 1 mmol) in
diethyl ether (25 mL) at -78 °C. The reaction mixture was warmed
to room temperature and stirred for an additional 3 h. After removal
of all the volatiles, the residue was extracted with n-hexane (20
mL) and the resulting solution concentrated to about 10 mL and
stored in a -30 °C freezer. Yellow crystals of 2 suitable for X-ray
diffraction analysis are formed after two days. Yield: 0.560 g (88%);
mp 176 °C. 1H NMR (500 MHz, C6D6): δ 7.12-7.15 (m, 6H, Ar-
H), 4.77 (s, 1H, γ-CH), 3.54 (sept, 2H, CH(CH3)2), 3.43 (sept, 2H,
CH(CH3)2), 1.70 (s, 6H, CH3), 1.31 (d, 6H, CH(CH3)2), 1.21 (d,
6H, CH(CH3)2), 1.20 (d, 6H, CH(CH3)2), 1.19 (d, 6H, CH(CH3)2),
0.55 (s, 3H, Pb-CH3) ppm. 13C{1H} NMR (125.75 MHz, C6D6):
δ 164.52 (CN), 144.35, 144.30, 142.71, 126.01, 124.21, 124.20
(Ar-C), 99.67 (γ-C), 76.63 (Pb-CH3), 28.64 (CHMe2), 27.49
NMR data of lead(II) ꢀ-diketiminate compounds including
Pb[N(SiMe3)2]2.14
Summary
In conclusion the results show that small substituents can be
introduced at the lead(II) center in terminal positions. The X-ray
crystal structure of 2 demonstrates that only in the solid state a
weak interaction is observed, whereas compounds 3 and 4 are
monomeric under these conditions. Compound 5 exhibits a
polymeric chain structure in the solid state and is well soluble
in n-hexane and toluene, respectively. Therefore compounds
2-5 are interesting precursors for metathesis reactions. Pre-
liminary results show that 2 and B(C6F5)3 react under salt
formation.
Experimental Section
All manipulations were performed under a dry and oxygen-free
atmosphere (N2) using standard Schlenk techniques or inside an

Facile Access of Stable DiValent Lead Compounds
Organometallics, Vol. 28, No. 8, 2009 2567
(CHMe2), 27.21 (CHMe2), 24.91, 24.76, 24.08, 23.99 (Me) ppm.
207Pb{1H} NMR (104.72 MHz, C6D6): δ 3009 ppm. EI-MS: m/z
(%) 625 (100) [M+ - Me]. UV-vis (hexane): λmax 392 nm. Anal.
Calcd for C30H44N2Pb (639.88): C, 56.31; H, 6.93; N, 4.38. Found:
C, 56.45; H, 7.91; N, 4.40.
3: PhLi (0.52 mL, 1.9 M in di-n-butyl ether) and 1 (0.66 g, 1
1
mmol). Yield: 0.574 g (82%); mp 158 °C. H NMR (500 MHz,
C6D6): δ 8.50 (d, 2H, o-Ph), 7.56 (t, 2H, m-Ph), 7.02-7.15 (m,
7H, Ar-H and p-Ph), 7.15 (dd, 1H, p-Ph), 4.79 (s, 1H, γ-CH), 3.57
(sept, 2H, CH(CH3)2), 3.20 (sept, 2H, CH(CH3)2), 1.75 (s, 6H, CH3),
1.36 (d, 6H, CH(CH3)2), 1.24 (d, 6H, CH(CH3)2), 1.06 (d, 6H,
CH(CH3)2), 0.51 (d, 6H, CH(CH3)2) ppm. 13C{1H} NMR (125.75
MHz, C6D6): δ 164.40(CN), 145.14, 143.92, 142.34, 137.92, 130.43,
127.80, 127.20, 126.26, 124.67, 124.11 (Ar-C), 98.64 (γ-C), 28.70
(CHMe2), 27.65 (CHMe2), 25.32 (CHMe2), 24.91, 24.76, 24.58,
24.03 (Me) ppm. 207Pb{1H} NMR (104.72 MHz, C6D6): δ 2424
ppm. EI-MS: m/z (%) 702 (100) [M+]. UV-vis (hexane): λmax 393
nm. Anal. Calcd for C35H46N2Pb (701.95): C, 59.89; H, 6.61; N,
3.99. Found: C, 59.62; H, 6.60; N, 3.78.
Figure 6. Asymmetric unit of 5. Isopropyl groups of the phenyl
ring are omitted for clarity.
C), 109.57 (γ-C), 28.60 (CHMe2), 27.81 (CHMe2), 26.23 (CHMe2),
24.63 (Me) ppm. 19F{1H} NMR (188.28 MHz, C6D6): δ -76.5 ppm.
207Pb{1H} NMR (104.72 MHz, C6D6): δ 1334 ppm. EI-MS: m/z
(%) 774 (100) [M+]. UV-vis (hexane): λmax 333 nm. Anal. Calcd
for C30H41F3N2O3PbS (774.26): C, 46.56; H, 5.34; N, 3.62; S, 4.14.
Found: C, 46.79; H, 5.42; N, 3.60; S, 4.16.
Crystallographic Details for Compounds 2, 3, 4, and 5.
Suitable crystals of 2, 3, 4, and 5 were mounted on a glass fiber,
and data were collected on an IPDS II Stoe image-plate diffracto-
meter (graphite-monochromated Mo KR radiation, λ ) 0.71073
Å) at 133(2) K. The data were integrated with X-Area. The
structures were solved by direct methods (SHELXS-97)15 and
refined by full-matrix least-squares methods against F2 (SHELXL-
97).15 In 5 there are some toluene molecules. We have omitted the
reflections caused by toluene using the Squeeze routine of the Platon
software.16 Therefore toluene is not refined in the structure since
it is deleted from the reflection file. All non-hydrogen atoms were
refined with anisotropic displacement parameters. Crystallographic
data are presented in Table 1.
4: PhCCLi (1.00 mL, 1.0 M in THF) and 1 (0.66 g, 1 mmol).
1
Yield: 0.615 g (88%); mp 155 °C. H NMR (500 MHz, C6D6): δ
7.59 (d, 2H, o-Ph), 7.05 (t, 2H, m-Ph), 7.03-7.17 (m, 6H, Ar-H),
6.96 (tt, 1H, p-Ph), 4.87 (s, 1H, γ-CH), 4.08 (sept, 2H, CH(CH3)2),
3.32 (sept, 2H, CH(CH3)2), 1.71 (s, 6H, CH3), 1.47 (d, 6H,
CH(CH3)2), 1.30 (d, 6H, CH(CH3)2), 1.22 (d, 6H, CH(CH3)2), 1.16
(d, 6H, CH(CH3)2) ppm. 13C{1H} NMR (125.75 MHz, C6D6): δ
189.25 (CC), 165.01 (CN), 145.42, 143.57, 142.60, 131.93, 126.89,
126.75, 126.47, 124.99, 123.84 (Ar-C), 114.26 (CC), 103.34 (γ-
C), 28.67 (CHMe2), 28.06 (CHMe2), 27.96 (CHMe2), 25.01, 24.55,
24.26, 24.21 (Me) ppm. 207Pb{1H} NMR (104.72 MHz, C6D6): δ
1463 ppm. EI-MS: m/z (%) 726 (100) [M+]. UV-vis (hexane):
λmax 382 nm. Anal. Calcd for C37H46N2Pb (725.97): C, 61.21; H,
6.39; N, 3.86. Found: C, 61.65; H, 6.64; N, 3.86.
Synthesis of [{HC(CMeNAr)2}Pb(II)OSO2CF3] (Ar ) 2,6-
iPr2C6H3) (5). A solution of 1 (0.66 g, 1mmol) in toluene (15 mL)
was added drop by drop to a stirred suspension of AgOSO2CF3
(0.26 g, 1 mmol) in toluene (10 mL) at room remperature. The
solution was stirred for an additional 2 h. After filtration the filtrate
was concentrated to about 10 mL and stored in a -30 °C freezer.
Yellow crystals of 5 suitable for X-ray diffraction analysis are
formed after two days. Yield: 0.690 g (90%); mp 243 °C. 1H NMR
(500 MHz, C6D6): δ 6.99-7.12 (m, 6H, Ar-H), 4.88 (s, 1H, γ-CH),
3.26 (sept, 4H, CH(CH3)2), 1.60 (s, 6H, CH3), 1.26 (d, 12H,
CH(CH3)2), 1.19 (d, 12H, CH(CH3)2) ppm. 13C{1H} NMR (125.75
MHz, C6D6): δ 165.51 (CN), 144.29, 140.93, 127.70, 124.65 (Ar-
Acknowledgment. This work was supported by the
Deutsche Forschungsgemeinschaft.
Supporting Information Available: X-ray data for 2, 3, 4, and
5 (CIF). This material is available free of charge via the Internet at
http://pubs.acs.org.
OM801167C
(14) Wrackmeyer, B. J. Magn. Reson. 1985, 61, 536–539.
(15) Sheldrick, G. M. Acta Crystallogr., Sect. A 2008, 64, 112–122.
(16) Spek, A. L. J. Appl. Crystallogr. 2003, 36, 7–13.