Carbosilane Molecules with Mono- And Bis(amino)arylmetal End Groups: Structures of {NiI[C6H2(CH2NMe2) 2-2,6-SiMe3-4]} and Tetranuclear {[CH2Si(Me)2C6H3(CH 2NMe2)-4-(PdCl)-3]2}2

Article abstract of DOI:10.1021/om980758f

A set of model compounds have been designed in order to develop useful synthetic routes to novel dendritic carbosilane molecules functionalized with organometallic complexes derived from the monoanionic [C₆H₃(CH₂NMe₂)₂-2,6] ^- (=NCN) and [C₆H₄(CH₂NMe₂)-2]^- (=CN) ligands. Selective electrophilic palladation of both [C₆H₂(CH₂NMe₂) ₂-2,6-(SiMe₃)₂-1,4] (1) and [C₆H₄(CH₂NMe₂)-4-SiMe₃-1] (6) using Pd(OAc)₂ afforded, after addition of LiCl, [PdCl-(C₆H₂{CH₂NMe₂} ₂-2,6-SiMe₃-4)] (2) and dimeric [PdCl(C₆H₃{CH₂NMe₂}-2-SiMe ₃-5)]₂ (7), respectively, in 98percent and 84percent yield. Lithiation of [C₆H₃(CH₂NMe₂) ₂-3,5SiMe₃-1] followed by transmetalation using 1 equiv of PtCl₂(SEt₂)₂ in THF at room temperature yielded the platinated complex [PtCl(C₆H₂{CH₂NMe₂} ₂-2,6-SiMe₃-4)] (3). Reaction of the iodinated analogue of 1, [IC₆H₂(CH₂NMe₂) ₂-2,6-SiMe₃-4] (4), with an excess of Ni(PPh₃)₄ in THF at room temperature afforded the nickel complex [NiI(C₆H₂{CH₂NMe}₂-2,6-SiMe ₃-4)] (5). Similar synthetic approaches have also been applied to the (N)CN-substituted carbosilane ligand systems [CH₂Si(Me)₂C₆H₃(CH ₂NMe₂)₂-3,5]₂ and [CH₂Si(Me)₂C₆H₄(CH ₂NMe₂)-4]₂ to give the bismetalated species [CH₂Si(Me)₂C₆H₂(CH ₂NMe₂)₂-3,5-(MX)-4]₂ (MX = PdCl (9), PtCl (10), PdI (12)) and [CH₂Si(Me)₂C₆H₃(CH ₂NMe₂)-4-(PdCl)-3]₂ (13) in good yields. The molecular structures of 5 and bispalladated 13 have been determined. The molecular structure of 13 shows this species to be a centrosymmetric dimeric aggregate in the solid state, with the two bis(amino)arylpalladium carbosilane molecules held together via two terminal - terminal chlorine bridging atoms, thus forming a 26-membered macrocyclic ring.

Full text of DOI:10.1021/om980758f

Organometallics 1999, 18, 277-285
277
Ca r bosila n e Molecu les w ith Mon o- a n d
Bis(a m in o)a r ylm eta l En d Gr ou p s: Str u ctu r es of
{NiI[C6H2(CH2NMe2)2-2,6-SiMe3-4]} a n d Tetr a n u clea r
{[CH2Si(Me)2C6H3(CH2NMe2)-4-(P d Cl)-3]2}2
Arjan W. Kleij,† Henk Kleijn,† J ohann T. B. H. J astrzebski,†
Anthony L. Spek,‡,# and Gerard van Koten*,†
Debye Institute, Department of Metal-Mediated Synthesis, Utrecht University, Padualaan 8,
3584 CH Utrecht, The Netherlands, and Bijvoet Center for Biomolecular Research, Department
of Crystal and Structural Chemistry, Utrecht University, Padualaan 8, 3584 CH Utrecht,
The Netherlands
Received September 9, 1998
A set of model compounds have been designed in order to develop useful synthetic routes
to novel dendritic carbosilane molecules functionalized with organometallic complexes derived
from the monoanionic [C6H3(CH2NMe2)2-2,6]- ()NCN) and [C6H4(CH2NMe2)-2]- ()CN)
ligands. Selective electrophilic palladation of both [C6H2(CH2NMe2)2-2,6-(SiMe3)2-1,4] (1) and
[C6H4(CH2NMe2)-4-SiMe3-1] (6) using Pd(OAc)2 afforded, after addition of LiCl, [PdCl-
(C6H2{CH2NMe2}2-2,6-SiMe3-4)] (2) and dimeric [PdCl(C6H3{CH2NMe2}-2-SiMe3-5)]2 (7),
respectively, in 98% and 84% yield. Lithiation of [C6H3(CH2NMe2)2-3,5-SiMe3-1] followed by
transmetalation using 1 equiv of PtCl2(SEt2)2 in THF at room temperature yielded the
platinated complex [PtCl(C6H2{CH2NMe2}2-2,6-SiMe3-4)] (3). Reaction of the iodinated
analogue of 1, [IC6H2(CH2NMe2)2-2,6-SiMe3-4] (4), with an excess of Ni(PPh3)4 in THF at
room temperature afforded the nickel complex [NiI(C6H2{CH2NMe}2-2,6-SiMe3-4)] (5). Similar
synthetic approaches have also been applied to the (N)CN-substituted carbosilane ligand
systems [CH2Si(Me)2C6H3(CH2NMe2)2-3,5]2 and [CH2Si(Me)2C6H4(CH2NMe2)-4]2 to give the
bismetalated species [CH2Si(Me)2C6H2(CH2NMe2)2-3,5-(MX)-4]2 (MX ) PdCl (9), PtCl (10),
PdI (12)) and [CH2Si(Me)2C6H3(CH2NMe2)-4-(PdCl)-3]2 (13) in good yields. The molecular
structures of 5 and bispalladated 13 have been determined. The molecular structure of 13
shows this species to be a centrosymmetric dimeric aggregate in the solid state, with the
two bis(amino)arylpalladium carbosilane molecules held together via two terminal-terminal
chlorine bridging atoms, thus forming a 26-membered macrocyclic ring.
In tr od u ction
examples concerned the introduction of metals on the
periphery via a direct metal-to-carbon bond.7-11 Car-
bosilane dendrimers12 are well-suited for this purpose
because of their relatively easy synthesis and antici-
pated inertness for common organometallic reagents. In
our group the monoanionic [C6H3(CH2NMe2)2-2,6]-
()NCN) and [C6H4(CH2NMe2)-2]- ()CN) ligands have
The incorporation of metals in dendrimers,1 either in
the skeleton or onto the periphery, may provide an
opportunity to generate new macromolecules with in-
teresting catalytic, redox-active, or liquid crystalline
properties. In recent years much attention was focused
on the synthesis of such materials and led to the
preparation of a broad range of metallodendritic species.
In many cases, the metals of choice were complexed on
the dendrimer surface by suitable donor ligands such
as phosphines2-5 or chelating bipyridines,6 but only few
(3) Lange, P.; Schier, A.; Schmidbaur, H. Inorg. Chem. 1996, 35,
637.
(4) Reetz, M. T.; Lohmer, G.; Schwickardi, R. Angew. Chem., Int.
Ed. Engl. 1997, 36, 1526.
(5) Catalano, V. J .; Parodi, N. Inorg. Chem. 1997, 36, 537.
(6) Achar, S.; Vittal, J . J .; Puddephatt, R. J . Organometallics 1996,
15, 43.
* To whom correspondence should be addressed. Tel: +3130
2533120. Fax: +3130 2523615. E-mail: g.vankoten@chem.uu.nl.
† Debye Institute.
(7) Seyferth, D.; Kugita, T. Organometallics 1995, 14, 5362.
(8) Liao, Y. H.; Moss, J . R. Organometallics 1996, 15 (5), 4307.
(9) Lobete, F.; Cuadrado, I.; Casado, C. M.; Alonso, B.; Mora´n, M.;
Losada, J . J . Organomet. Chem. 1996, 509, 109.
(10) Cuadrado, I.; Casado, C. M.; Alonso, B.; Mora´n, M.; Losado, J .;
Belsky, V. J . Am. Chem. Soc. 1997, 119, 7613.
‡ Bijvoet Center for Biomolecular Research.
#Address correspondence pertaining to crystallographic studies to
this author. E-mail: a.l.spek@chem.uu.nl.
(1) For recent reviews on dendritic molecules see: (a) Newkome,
G. R. Advances in Dendritic Macromolecules; J AI: Greenwich, CT,
1994; Vol. 1, 1995; Vol. 2. (b) Tomalia, D. A.; Durst, H. D. Topics in
Current Chemistry; Weber, E., Ed.; Springer-Verlag: Berlin, 1993; Vol.
165, p 193. (c) Issberner. J .; Moors, R.; Vo¨gtle, F. Angew Chem., Int.
Ed. Engl. 1994, 33, 2413. (d) Freˆchet, J . M. Science 1994, 263, 1710.
(e) Tomalia, D. A. Adv. Mater. 1994, 6, 529.
(11) (a) Knapen, J . W. J .; van der Made, A. W.; De Wilde, J . C.; van
Leeuwen, P. W. M. N.; Wijkens, P.; Grove, D. M.; van Koten, G. Nature
1994, 372, 659. (b) Hoare, J . L.; Lorenz, K.; Hovestad, N. J .; Smeets,
W. J . J .; Spek, A. L.; Canty, A. L.; Frey, H.; van Koten, G. Organo-
metallics 1997, 16, 4167.
(12) (a) van der Made, A. W.; van Leeuwen, P. W. M. N.; De Wilde,
J . C.; Brandes, A. C. Adv. Mater. 1993, 5 (6), 466. (b) van der Made,
A. W.; van Leeuwen, P. W. M. N. J . Chem. Soc., Chem. Commun. 1992,
1400.
(2) Bardaj´ı, B.; Kustos, M.; Caminade, A. M.; Majoral, J . P.;
Chaudret, B. Organometallics 1997, 16, 403.
10.1021/om980758f CCC: $18.00 © 1999 American Chemical Society
Publication on Web 12/30/1998

278 Organometallics, Vol. 18, No. 2, 1999
Kleij et al.
methylamino)methyl]benzene16 with excess n-butyl-
lithium at ambient temperature and subsequently
quenching the lithiated derivative in Et2O with an
excess of trimethylsilyl trifluoromethanesulfonate (Me3-
SiOTf)17 afforded after workup the disilylated material
1,4-bis(trimethylsilyl)-2,6-bis[(dimethylamino)methyl]-
benzene (1) as a yellow oil in an almost quantitative
yield (96%). Selective C-Si bond cleavage17 was achieved
by reaction of 1 with Pd(OAc)2/LiCl in MeOH at room
temperature to yield the palladated compound 2 in 98%
yield. The para-positioned trimethylsilyl group was
unaffected in this latter reaction, showing that direct,
regioselective palladation of dendritic analogues of 1
could be feasible. The same selectivity accounts for the
direct palladation of 1-trimethylsilyl-4-[(dimethylami-
no)methyl]benzene (6), which was obtained as a color-
less liquid in 93% yield by reaction of 1-bromo-4-
[(dimethylamino)methyl]benzene with 2 equiv of tert-
butyllithium in THF at -78 °C followed by a quench
reaction of the lithiated species with an excess of
trimethylsilyl chloride. Selective cyclopalladation18 of 6
using 1 equiv of Pd(OAc)2 in MeOH gave the halide-
bridged dimer [PdCl(C6H3{CH2NMe2}-2-SiMe3-5)]2, 7,
in 83% yield as a mixture of cis- and trans-isomers.
Reaction of 7 with an excess of pyridine rapidly leads
to the formation of the mononuclear pyridine adduct
[PdCl(C6H3{CH2NMe2}-2-SiMe3-5)(C5H5N)], 8, which
was obtained quantitatively as a white solid (95%). The
platinated analogue [PtCl(C6H2{CH2NMe2}2-2,6-SiMe3-
4] (3) was prepared in 61% yield by lithiation of
1-trimethylsilyl-3,5-bis[(dimethylamino)methyl]ben-
zene with 1 equiv of n-BuLi in pentane followed by a
transmetalation reaction in THF using a stoichiometric
amount of PtCl2(SEt2)2 (Scheme 1).
Earlier attempts to ortho-halogenate NCN derivatives
quantitatively by reaction of the corresponding ortho-
lithiated species19 with halide sources such as 1,2-
dibromoethane or molecular Br220 failed and led to only
partially halogenated materials. However, we found that
lithiation of 1-trimethylsilyl-3,5-bis[(dimethylamino)-
methyl]benzene with an excess of n-butyllithium in
hexane followed by “titration” of the lithiated species
with molecular I2 dissolved in Et2O selectively gave the
iodine compound [IC6H2(CH2NMe2)2-2,6-SiMe3-4] (4).
Evidence for a full iodination reaction was provided by
1H and 13C{1H} NMR spectroscopy, GC-MS, and mi-
croanalysis. The iodinated compound 4 exhibits a char-
acteristic 13C{1H} NMR upfield-shifted carbon reso-
nance at 109.5 ppm. Oxidative addition of Ni(PPh3)4 to
4 in THF at room temperature gave the nickel species
[NiI(C6H2{CH2NMe2}2-2,6-SiMe3-4)] (5) (Scheme 1, see
also ref 14b). Complex 5 is reasonably soluble in Et2O
at room temperature, and purification of 5 was ac-
complished by repeated crystallizations from Et2O at
-20 °C; as a consequence, the yield of 5 (35%) was low.
F igu r e 1. Schematic representation of the carbosilane
molecules functionalized with the monoanionic (N)CN
ligands.
been studied extensively13 and several metal complexes
were successfully applied as homogeneous catalysts in
organic reactions. For instance, the [NiX{C6H2(CH2-
NMe2)2-2,6-R-4}] compounds (X ) Cl, Br, I; R ) NH2,
MeO, H, Cl, MeC(O)) have proven to be effective catalyst
systems in Kharasch addition chemistry14 and were also
immobilized on the surface of carbosilane dendrimers
by using a carbamate linker.11a Recently we reported
on the more facile synthesis of carbosilane molecules
functionalized with NCN or CN moieties. These new
ligand systems, in which the ligands are directly σ-bond-
ed to the (peripherial) silicon atoms15 (see Figure 1),
were selectively lithiated without any decomposition of
the carbosilane backbone.
Therefore, we have extended our studies, as the
lithiation of these dendritic ligands could give rise to
new and alternative synthetic concepts for the introduc-
tion of metal sites in carbosilane dendrimers. Here we
present the syntheses of metal species derived from the
carbosilanes substituted with CN or NCN ligands (vide
supra), which serve as model compounds for their
metallodendritic analogues. With the dilithiated ligand
systems as the starting point, we have developed
synthetic routes for the introduction of d8-metal sites.
This was accomplished via either oxidative addition,
C-Si bond activation, or a lithiation/transmetalation
sequence. Especially the last procedure provides a
unique way for the introduction of σ-bonded metal
atoms. Furthermore, we will show further evidence for
an intermolecular aggregation between different orga-
nometallic end groups in metallodendrimers with CN-
and NCN-metal end groups. These latter results will
be evaluated and combined with our earlier results in
this area.15
Resu lts a n d Discu ssion
Syn th eses a n d Ch a r a cter iza tion of Mod el Com -
p ou n d s. Treatment of 1-trimethylsilyl-3,5-bis[(di-
(16) Steenwinkel, P.; J ames, S. L.; Grove, D. M.; Veldman, N.; Spek,
A. L.; van Koten, G. Chem. Eur. J . 1996, 2, 1440.
(13) (a) van Koten, G. Pure Appl. Chem. 1989, 61, 1681, and
references therein. (b) Rietveld, M. P. H.; Grove, D. M.; van Koten, G.
New J . Chem. 1997, 21, 751.
(17) It must be noted that Steenwinkel et al. already reported that
trimethylsilyl chloride failed to silylate the bis(ortho-chelated) lithiated
species mentioned here. See: Steenwinkel, P.; J ames, S. l.; Grove, D.
M.; Kooijman, H.; Spek, A. L.; van Koten, G. Organometallics 1997,
16, 513.
(18) (a) Cope, A. C.; Friedrich, E. C. J . Am. Chem. Soc. 1968, 90,
909. (b) Valk, J . M.; Boersma, J .; van Koten, G. Organometallics 1997,
15, 44366.
(14) (a) Grove, D. M.; Verschuuren, A. H. M.; van Beek, J . A. M.;
van Koten, G. J . Organomet. Chem. 1989, 372, C1-C6. (b) van de Kuil,
L. A.; Luitjes, J .; Grove, D. M.; Zwikker, J . W.; van der Linden, J . G.
M.; Roelofsen, A. M.; J enneskens, L. W.; Drenth, W.; van Koten, G.
Organometallics 1994, 13, 468-477.
(15) Kleij, A. W.; Kleijn, H.; J astrzebski, J . T. B. H.; Spek, A. L.;
van Koten, G. Organometallics 1999, 18, 268.
(19) J astrzebski, J . T. B. H.; van Koten, G.; Goubitz, K.; Arlen, C.;
Pfeffer, M. J . Organomet. Chem. 1985, 246, C75.

Carbosilane Molecules with Arylmetal End Groups
Organometallics, Vol. 18, No. 2, 1999 279
Sch em e 1. Rea gen ts a n d Con d ition s: (i) t-Bu Li, P en ta n e; Me3SiOTf, Et2O; (ii) P d OAc2, MeOH; Excess LiCl;
(iii) t-Bu Li, P en ta n e; P tCl2(SEt2)2, THF ; (iv) t-Bu Li, P en ta n e; I2, Et2O; (v) Ni(P P h 3)4, THF ; (vi) 2 equ iv
t-Bu Li, Et2O, -78 °C; Me3SiCl; (vii) Excess P yr id in e, CH2Cl2
Ta ble 1. Selected Bon d Dista n ces (Å) a n d An gles
In general the nickel(II) center in this type of NCN-
(d eg) of th e Or ga n on ick el(II) Com p lex 5 (Resid u e
NiX complexes is particularly sensitive for oxidation,
and the corresponding paramagnetic Ni(III) complexes
give rise to severe line-broadening in their NMR spectra.
Consequently, NMR solutions of 5 were prepared in an
inert atmosphere, while possible line-broadening was
reduced by bubbling CO(g) (reduction of Ni(III) to Ni(II))
through the NMR sample tube.
A) w ith esd ’s in P a r en th eses
Bond Distances
Ni(1)-C(1)
Ni(1)-N(2)
C(4)-Si(1)
C(14)-Si(1)
1.816(8)
1.990(6)
1.897(9)
1.914(14)
Ni(1)-N(1)
Ni(1)-I(1)
C(13)-Si(1)
C(15)-Si(1)
1.989(6)
2.5943(10)
1.826(11)
1.800(11)
Bond Angles
I(1)-Ni(1)-C(1)
C(1)-Ni(1)-N(2)
177.0(2)
81.9(3)
C(1)-Ni(1)-N(1)
N(1)-Ni(1)-N(2)
83.8(3)
165.6(2)
All discussed reactions (vide supra) gave nearly
quantitative conversions, and compounds 1-8 were fully
1
characterized by H and 13C NMR spectroscopy, GC-
Dihedral Angles
Ni(1)-C(1)-C(2)-C(7) -5.0(9) Ni(1)-C(1)-C(6)-C(8) -1.5(9)
C(1)-C(2)-C(7)-N(1) 21.1(9) C(1)-C(6)-C(8)-N(2) 20.9(9)
MS or FAB mass spectrometry, elemental microanaly-
sis, and in the case of 5, X-ray analysis. The synthetic
procedures described for these mononuclear compounds
combined with their spectroscopic data provide a useful
basis for the preparation of their dimetalated carbosi-
lane analogues (vide infra).
C(6)-C(5)-C(4)-Si(1) 179.5(6) C(2)-C(3)-C(4)-Si(1) 178.9(7)
C(1)-C(2)-C(3)-C(4)
C(3)-C(4)-C(5)-C(6)
1.8(12) C(2)-C(3)-C(4)-C(5)
0.5(14)
-2.0(13)
result of these structural features, the nickel center is
somewhat lifted from the plane defined by the aromatic
ring, which is a distortion commonly found for d8-
metal-NCN complexes.12,17,21
Syn th eses of Bism eta la ted Ca r bosila n es. The
syntheses of the ligand systems [CH2Si(Me)2C6H4(CH2-
NMe2)-4]2 and [CH2Si(Me)2C6H3(CH2NMe2)2-3,5]2 have
been described elsewhere.15 The incorporation of metal
atoms was achieved using synthetic approaches similar
to those described for the mononuclear compounds (vide
supra).
The NCN moieties of [CH2Si(Me)2C6H3(CH2NMe2)2-
3,5]2 were functionalized between the two nitrogen
donor arms (i.e., the 4-position in these carbosilane
molecules) by using the dilithiated precursor [CH2Si-
(Me)2C6H2(CH2NMe2)2-3,5-Li-4]2,15 which proved to be
an excellent starting material for the introduction of
Molecu la r Str u ctu r e of 5. The molecular geometry
of 5, as a model for the NCN-metal species present at
the periphery of carbosilane metallodendrimers, was
established by means of X-ray crystal structure deter-
mination (see Experimental Section). The crystal struc-
ture of 5 comprises the packing of eight molecules in
the unit cell. The asymmetric unit contains two crys-
tallographically independent molecules A and B which
are chemically identical, but which differ slightly but
not significantly in structure. An ORTEP drawing of one
of these molecules (A) is depicted in Figure 2 (for B: see
Supporting Information and values between [ ] in the
text, vide infra). Selected bond lengths and angles are
listed in Table 1.
In 5 each nickel atom is coordinated by two nitrogen
donor atoms and Cipso of the para-substituted, monoan-
ionic η3-N,C,N-bonded aryldiamine ligand, while an
iodine atom trans to Cipso completes the ligand array.
The nickel atoms in residues A and B are bonded in an
approximately square-planar manner. Distortions from
this ideal geometry are found for both residues. For 5
the angles N(1)-Ni(1)-N(2) and I(1)-Ni(1)-C(1) are
165.6 (2)° [165.4(2)°] and 177.0 (2)° [176.3(2)°]. As a
(20) Wijkens, P.; van Koten, G. Unpublished results.
(21) (a) Grove, D. M.; van Koten, G.; Ubbels, H. J . C.; Zoet, R.; Spek,
A. L. Organometallics 1984, 3, 1003. (b) van Beek, J . A. M.; van Koten,
G.; Ramp, M. J .; Coenjaarts, N. C.; Grove, D. M.; Goubitz, K.; Zoutberg,
M. C.; Stam, C. H.; Smeets, W. J . J .; Spek, A. L. Inorg. Chem. 1991,
30, 3059. (c) Schimmelpfennig, U. Thesis, Humboldt Universita¨t Berlin,
Germany, 1992. (d) van de Kuil, L.; Veldhuizen, Y. S. J .; Grove, D. M.;
Zwikker, J . W.; J enneskens, L. W.; Drenth, W.; Smeets, W. J . J .; Spek,
A. L.; van Koten, G. Recl. Trav. Chim. Pays-Bas 1994, 113, 267.

280 Organometallics, Vol. 18, No. 2, 1999
Kleij et al.
Sch em e 2. Rea gen ts a n d Con d ition s: (i) 2 equ iv P d OAc2, MeOH; Excess LiCl; (ii) 2 equ iv t-Bu Li, P en ta n e;
2 equ iv P tCl2(SEt2)2, THF ; (iii) 2 equ iv t-Bu Li, P en ta n e; I2, Et2O; (iv) 2 equ iv P d (d ba )2, Ben zen e
Sch em e 3. Rea gen ts a n d Con d ition s: (i) 2 equ iv P d OAc2, MeOH; Excess LiCl; (ii) Excess P yr id in e, CH2Cl2
metals employing the different approaches as illustrated
in Scheme 1. Reaction of this dilithiated precursor with
2 equiv of PtCl2(SEt2)2 affords the diplatinated species
[CH2Si(Me)2C6H2(CH2NMe2)2-3,5-(PtCl)-4]2 (10) in 93%
yield. To our knowledge, this is the first example of
using a (multi)lithiated carbosilane for the introduction
of metals and demonstrates a convenient, direct syn-
thetic pathway to metallocarbosilane dendrimers. Re-
acting the dilithio compound with I2 as described for 4
affords the diiodo compound [CH2Si(Me)2C6H2(CH2-
NMe2)2-3,5-I-4]2, 11.
The direct metalation routes employed for the prepa-
ration of the mononuclear compounds proved also be
applicable in the synthesis of their bismetallic ana-
logues. The bispalladium chloride derivative 9 (Scheme
2) was prepared in 70% yield by a 2:1 molar reaction of
Pd(OAc)2 and disilylated [CH2Si(Me)2C6H2(CH2NMe2)2-
3,5-SiMe3-4]2 in MeOH, whereas the bispalladium iodide
compound 12 (yield 71%) was obtained by reaction of
the diiodide 11 with a slight excess of Pd(dba)2 (dba )
dibenzylideneacetone) in benzene at room temperature
(Scheme 2).
Cyclopalladation of either [CH2Si(Me)2C6H4(CH2-
15
NMe2)-4]2
or the disilylated precursor [CH2Si-
15
(Me)2C6H3(CH2NMe2)-4-SiMe3-3]2 with 2 equiv of
Pd(OAc)2 in MeOH was successfully carried out and
gave the palladated derivative, after treatment with
LiCl, [CH2Si(Me)2C6H3(CH2NMe2)-4-(PdCl)-3]2 (13) (see
Scheme 3) as a shiny, orange solid. Although in principle
the two palladation reactions differ from each other
(C-H vs C-Si bond activation), the crude yields (86 and
98%, respectively) are roughly the same as well as the
selectivities (i.e., isomer ratio, vide infra) observed with
1H NMR spectroscopy.

Carbosilane Molecules with Arylmetal End Groups
Organometallics, Vol. 18, No. 2, 1999 281
F igu r e 2. Displacement ellipsoid plot (ORTEP, 50%
probability) of one of the two crystallographically indepen-
dent molecules of [NiI(C6H2{CH2NMe2}2-2,6-SiMe3-4)] (5)
in the solid state together with the adopted numbering
scheme. For a complete figure, see Supporting Information.
Hydrogen atoms have been omitted for clarity.
The proton NMR spectrum of crude 13 recorded in
CDCl3 shows the presence of more than one species, as
illustrated by the presence of several sets of signals.
When excess pyridine is added, the spectrum collapses
into one new pattern as a result of the chlorine bridge
cleavage to form the dinuclear, bispyridine complex
[CH2Si(Me)2C6H3(CH2NMe2)-4-(PdCl{C6H5N})-3]2 (14)
(Scheme 3), indicating that complete palladation of the
starting material had occurred. Cooling down a satu-
rated solution of 13 in CH2Cl2 at -20 °C afforded yellow
block-shaped crystals which separated from the solution.
The X-ray crystal structure of 13 confirmed its dimeric
structure (vide infra) and unambiguously showed the
presence of CH2Cl2 in the crystal lattice, which is in line
with the microanalyses. Upon standing, this solvent
slowly evaporates to give the solvent-free complex.
F igu r e 3. Displacement ellipsoid plot (ORTEP, 50%
probability) of the molecular structure of complex 13
together with the adopted numbering scheme. Solvent
molecules and hydrogen atoms have been omitted for
clarity.
Ta ble 2. Selected In ter a tom ic Dista n ces (Å) a n d
An gles (d eg) w ith esd ’s in P a r en th eses for th e
Meta l Ca r bosila n e Com p lex 13
Bond Distances
Pd(1)-Cl(1)
Pd(1)-Cl(2)
Pd(1)-C(1)
Pd(2)-C(1A)
2.3154(15)
2.4747(14)
1.971(5)
Pd(2)-Cl(1)
Pd(2)-Cl(2)
Pd(1)-N(1)
Pd(2)-N(1A)
2.3105(14)
2.4732(15)
2.075(5)
Str u ctu r e of 13 in th e Solid Sta te a n d in Solu -
tion . An X-ray crystal structure determination revealed
the structure of 13 to be dimeric (i.e., tetranuclear) in
the solid state with the chlorine atoms acting as
bridging ligands (see Figure 3). Relevant bond distances
and angles are summarized in Table 2. The coordination
plane around each palladium center is approximately
square planar with interatomic distances to carbon,
nitrogen, and both the chlorine atoms (see Table 2)
comparable to those found for similar complexes.22 The
difference in the Pd-Cl bond lengths (see Table 2) can
be explained by the trans influence of a tertiary N-donor
atom vs an (aryl)Cipso. This causes a weakening of the
Pd-Cl bond trans to the Pd-C(σ) bond.
1.977(5)
2.072(5)
Bond Angles
85.54(5)
Cl(1)-Pd(1)-Cl(2)
Cl(2)-Pd(1)-N(1)
98.52(11)
Cl(1)-Pd(1)-N(1) 175.76(10) Cl(2)-Pd(1)-C(1) 178.33(12)
Cl(1)-Pd(1)-C(1)
94.09(16) N(1)-Pd(1)-C(1)
81.89(19)
Dihedral Angles
Cl(2)-Pd(1)-Cl(1)-Pd(2)
27.66(5)
C(1)-Pd(1)-Cl(1)-Pd(2)
Cl(1)-Pd(1)-Cl(2)-Pd(2)
Cl(1)-Pd(1)-C(1)-C(2)
Cl(1)-Pd(1)-C(1)-C(6)
N(1)-Pd(1)-Cl(2)-Pd(2)
Si(1)-C(21)-C(21A)-Si(1A)
-150.71(13)
-25.83(5)
23.2(4)
-158.4(3)
155.41(12)
178.9(2)
Moreover, the structure shows exclusively the cis,cis-
isomer,23 which indicates preferential crystallization of
one of the three possible geometrical isomers. It is
interesting to compare these results with those of, for
example, Barr et al.,22 who studied the molecular
structures of dinuclear [PdCl(C6H3{CH2NMe2}-2-MeO-
y)]2 (y ) 3, 4, or 5) by X-ray crystallography and found
in all cases exclusively the trans-isomers. Most probably
vicinal interactions in the carbosilane backbone of the
dimeric structures of 13 affect the conformational
energies of the cis,cis-, cis,trans-, and trans,trans-isomer
in such a way that the cis,cis-isomer is the most stable
one.
NMR Sp ect r oscop y of t h e Novel Ca r b osila n e
Com p ou n d s. An interesting feature of these novel end
group functionalized carbosilane compounds is that the
metalated (N)CN moieties as well as the SiMe2 and
methylene protons of the carbosilane backbone give rise
to single resonance patterns on the NMR time scale at
room temperature, consistent with only one type of
metal environment. As to be expected, compared to the
mononuclear complexes (see Scheme 1), similar chemi-
cal shifts are found with respect to the dimetallocar-
bosilanes (Schemes 2 and 3). In general, the course of
(22) The prefix cis refers to the relative positions of the NMe2
groupings around the Pd2Cl2 unit.
(23) Barr, N.; Dyke, S. F.; Smith, G.; Kennard, C. H. L.; McKee, V.
J . Organomet. Chem. 1985, 288, 109.

282 Organometallics, Vol. 18, No. 2, 1999
Kleij et al.
Ta ble 3. Selected 1H NMR Da ta for th e
Mon on u clea r Com p ou n d s a n d Bim eta llic
Ca r bosila n es
compound
X
SiMe
CH2N
3.56
NMe2
2.03
ArH
7.67
1c
SiMe3
0.29
0.52
0.22
0.22
0.26
0.29
0.23
2b
3b
4c
5c
7b
PdCl
PtCl
I
NiI
PdCl
4.00
3.08
3.55
3.07
3.91
2.94
4.03
2.16
2.50
2.85
2.87
2.95
3.09
2.15
2.67
2.86
2.96
6.90
6.94
7.66
6.73
7.33d
7.42d
6.86
6.90
7.64
6.87
7.42d
7.63d
9b
10b
11c
12c
13b
PdCl
PtCl
I
PdI
PdCl
0.19
0.20
0.28
0.36
0.19
0.21
4.00
4.03
3.53
3.31
3.92
3.96
a
F igu r e 4. Possible aggregation modes and isomeric forms
for the (CN)PdCl-dimeric units in the dipalladium carbosi-
lane compound 13.
All signals are singlet resonances at room temperature unless
otherwise stated and are given in ppm vs TMS as an external
standard. Recorded in CDCl3. c Recorded in C6D6. Aromatic
ortho-hydrogen.
b
d
metalation can easily be monitored as the resonances
of the aromatic protons of the ligand systems (7.6-7.7
ppm) and CH2N moieties shift to higher field (6.8-6.9
ppm) (Table 3) together with a characteristic downfield
shift for the signal corresponding to the NMe2 frag-
ments.
When crystalline 13 is dissolved in CDCl3 at room
temperature, the 1H NMR spectrum of a mixture of two
species in a nearly 1:3 ratio is obtained. Variable-
temperature 1H NMR measurements of 13 in CDCl3
show an interesting interconversion between the two
species. At low temperature (208 K), this ratio becomes
ca. 1:8, while at high temperature (335 K) the ratio
becomes close to 1:1. Upon mixing crystalline 13 and
F igu r e 5. Newman projections along the C-C axis in the
carbosilane backbone of dilithiated [CH2Si(Me)2C6H3-
(CH2NMe2)-4]2 and 13.
strained. This supports our findings in the crystal-
lographic studies carried out for 13.
Due to the low solubility of 13 in organic solvents
(CHCl3, THF, benzene) suitable for colligative measure-
ments, analysis of the dimer (A4) vs polymeric (A)n
aggregate formation by molecular weight determination
(cryoscopy) was hampered. FAB-MS spectroscopic analy-
sis of 13 (direct inlet in a m-NBA matrix) showed the
presence of both the monomeric unit (M - Cl)+ (m/z 659)
1
frozen CDCl3 directly followed by analysis by H NMR
spectroscopy at -65 °C, mainly the resonance pattern
belonging to one of these species is observed, while the
resonance pattern belonging to the other species is only
present in trace amounts. From this observation it may
be concluded that the predominant resonance pattern
belongs to the cis,cis-isomer as found in the solid state
(vide supra).
and the dimeric units M2 and (M2 - Cl)+ (m/z 1388
+
and 1353, respectively) with isotope patterns consistent
with their calculated ones. Higher oligomers could not
be detected.
There are a few possibilities that can explain the
presence of two sets of resonances found for 13 in
solution. The aggregation process to afford cis,cis-13
probably proceeds via several equilibria as illustrated
in Figure 4. Starting from two monomeric dipalladated
molecules 13 (A in Figure 4), the dimeric species is
generated in two steps. At first, one set of chlorine
The flexible behavior of the carbosilane backbone used
in this work (viz., Me2SiCH2CH2SiMe2) was earlier
illustrated by the solid-state structure of dimeric {[CH2-
Si(Me)2C6H3(CH2NMe2)-4-Li-3]2}2,15 in which the dihe-
dral angle Si-C-C-Si in the alkanedisilyl skeleton is
-161.7(3)°, resulting in a distorted anti conformation
(see Figure 5, A). In this way, the lithiated ligands of
the two monomeric units are brought in close approx-
imity to each other to form a stable Li4-tetrahedron,
which is regarded as the main driving force in the
formation of this tetralithio aggregate. The carbosilane
backbone in the solid-state structure of 13, however,
shows an almost ideal conformation reflected in the
dihedral angle between the bulky Si substituents, Si-
(1)-C(21)-C(21A)-Si(1A), of 178.9(2)° (Figure 5, B).
t
bridges (either cis or trans, A2c and A2 , respectively) is
formed, after which the second set of chlorine bridges
t,t
results in the dimeric molecules A4c,c, A4t,c, and A4
.
Also, the formation of higher oligomers ([A]n) via similar
equilibria could be possible.
A separate, more detailed study is currently carried
out concerning the aggregational behavior of 13 and
related compounds in solution and in the solid state.
Molecular modeling of dimeric 13 using CAChe soft-
ware (at the MM2 level) shows that within the dimeric
t,t
A4t,c and A4 molecules the conformation of the carbosi-
Con clu d in g Rem a r k s
lane backbone is more strained as compared with the
c,c
conformation of this backbone present in the A4
This investigation has led to the isolation and char-
acterization of novel bimetallic compounds derived from
carbosilane molecules functionalized with monoanionic
isomer. Of the A4t,c and A4 isomers, the conformation
t,t
of the carbosilane backbone in the latter is the most

Carbosilane Molecules with Arylmetal End Groups
Organometallics, Vol. 18, No. 2, 1999 283
[P d Cl(C6H2{CH2NMe2}2-2,6-(SiMe3)-4)] (2). Bissilylated
1 (0.53 g, 1.57 mmol) in MeOH (30 mL) was treated with
Pd(OAc)2 (0.35 g, 1.56 mmol). The orange solution was stirred
for 1 h, and subsequently LiCl (0.14 g, 3.30 mmol) was added,
upon which the color of the solution changed to green-yellow.
The solvent was removed in vacuo, and the solid residue was
extracted with CH2Cl2 (100 mL). The organic layer was washed
with H2O (3 × 50 mL) and dried on MgSO4. After filtration
and removal of all volatiles under reduced pressure, a salmon-
colored solid was isolated (0.63 g, 1.55 mmol, 98%). White
needles were obtained by crystallization of the product in
CH2Cl2/Et2O. 1H NMR (CDCl3): δ 6.90 (s, 2H, Ar-H), 4.00 (s,
4H, Ar-CH2), 2.94 (s, 12H, N(CH3)2), 0.22 (s, 9H, Si(CH3)3).
13C{1H} NMR (CDCl3): δ 158.1 (Cipso), 144.7 (Ar-C), 136.0
(Ar-C-Si), 124.4 (Ar-C), 74.8 (Ar-CH2), 53.1 (N(CH3)2), -0.9
(Si(CH3)2). Anal. Calcd for C17H27N2SiPdCl: C 44.45, H 6.71,
N 6.91. Found: C 44.32, H 6.65, N 7.04.
[P tCl(C6H2{CH2NMe2}2-2,6-(SiMe3)-4)] (3). To a solution
of 1-(trimethylsilyl)-3,5-bis[(dimethylamino)methyl]benzene
(0.47 g, 1.78 mmol) in pentane (25 mL) was added n-BuLi (1.2
mL of a 1.4 M solution in pentane, 1.7 mmol) at room
temperature. After stirring the reaction mixture for 16 h, the
solvent was removed in vacuo, and PtCl2(SEt2)2 (0.81 g, 1.81
mmol) in THF (30 mL) was added. The resulting yellow to
brown solution was stirred for 1 h and subsequently the
solvent evacuated under reduced pressure. The solid residue
was washed with Et2O (2 × 40 mL) and then extracted with
CH2Cl2 (60 mL), filtered through Celite, and concentrated to
afford a cream-colored powder (0.54 g, 1.09 mmol, 61%).
Analytically pure 3 was obtained by crystallization in CH2Cl2/
Et2O. 1H NMR (CDCl3): δ 6.94 (s, 2H, Ar-H), 4.03 (s, 4H,
J (Pt-H) ) 46.0 Hz, Ar-CH2), 2.94 (s, 12H, J (Pt-H) ) 37.9
Hz, N(CH3)2), 0.22 (s, 9H, Si(CH3)3). 13C{1H} NMR (CDCl3): δ
146.6 (Cipso), 143.1 (Ar-C), 134.2 (Ar-C-Si), 123.8 (Ar-C,
2J (Pt-C) ) 34.6 Hz), 77.7 (Ar-CH2, 2J (Pt-C) ) 65.9 Hz), 54.4
(N(CH3)2), -0.9 (Si(CH3)2, 1J (Si-C) ) 136 Hz). Anal. Calcd
for C17H27N2SiPtCl: C 36.47, H 5.51, N 5.67, Si 5.69. Found:
C 36.49, H 5.61, N 5.60, Si 5.66.
CN or NCN end groups. We have successfully demon-
strated that the use of these dilithiated carbosilanes
provides new synthetic approaches to (catalytically
active) metal-containing carbosilane dendrimers. In
addition we can state that the carbosilane backbone
used in this work exhibits a flexible, conformational
behavior governed by the aggregation of the organome-
tallic end groups. A further study toward possible
aggregation between different end groups in metallo-
dendritic species will be carried out. In this respect, it
is interesting to see that the use of the SiC6H3(CH2-
NMe2)-4-(PdCl)-3 end groups in 13 leads to the forma-
tion of a stable 26-membered macromolecular ring
structure. Future work will also be focused on both the
application of the presented synthetic concepts in the
generation of metal-centered organosilicon dendrimers
and their utility as homogeneous catalysts.
Exp er im en ta l Section
Gen er a l. All sensitive, organometallic manupilations were
performed under a dry and deoxygenated dinitrogen atmo-
sphere using standard Schlenk techniques unless otherwise
stated. All solvents were carefully dried and distilled prior to
use. All standard chemicals were purchased from Acros
Chimica or Aldrich and used without further purification. The
precursor materials 1-bromo-3,5-[(dimethylamino)methyl]ben-
zene, 1-bromo-[(dimethylamino)methyl]-benzene, 1-trimeth-
ylsilyl-3,5-[(dimethylaminomethyl)]benzene,16 and the carbosi-
lanes [CH2Si(Me)2C6H3(CH2NMe2)2-3,5]2, [CH2Si(Me)2C6H2-
(CH2NMe2)2-3,5-SiMe3-4]2, [CH2Si(Me)2C6H4(CH2NMe2)-4]2, and
15
[CH2Si(Me)2C6H3(CH2NMe2)-4-SiMe3-3]2 were prepared ac-
cording to previously reported procedures. 1H and 13C{1H}
NMR spectra were recorded on a Bruker AC200/AC300 MHz
or a Varian Inova 300 MHz spectrometer. Chemical shifts are
given in ppm using TMS as an external standard. Melting
points are uncorrected. FAB-MS spectra were recorded on two
different machines: (1) a J EOL J MS SX/SX 102A four-sector
mass spectrometer, operated at 10 kV accelerating voltage,
equipped with a J EOL MS-FAB 10 D FAB gun operated at a
5 mA emission current, producing a beam of 6 keV xenon
atoms; (2) a J EOL J MS AX 505 spectrometer, operated at 3
kV accelerating voltage, equipped with a J EOL MS-FAB 10
D FAB gun operated at a 10 mA emission current, producing
a beam of 6 keV xenon. Data acquisition and processing were
accomplished using J EOL Complement software. The spectra
were obtained from the Analytical Chemical Department of
the University of Utrecht. Elemental analyses were performed
by Dornis und Kolbe, Mikroanalytisches Laboratorium, Mu¨l-
heim a.d. Ruhr, Germany.
[IC6H2(CH2NMe2)2-2,6-(SiMe3)-4] (4). t-BuLi (2.5 mL of a
1.5 M solution in pentane, 3.8 mmol) was added to a solution
of 1-trimethylsilyl-3,5-bis[(dimethylamino)methyl]benzene (0.70
g, 2.65 mmol) in pentane (25 mL) at room temperature. The
solution was stirred for 18 h, and then the lithiated material
was titrated with an excess of I2 (1.21 g, 4.77 mmol) in Et2O
(30 mL) until the color of the solution turned dark red-brown.
Then H2O (30 mL) and Na2SO3 were added, and the mixture
was stirred until decolorization was almost complete. The
organic layer was separated, and the H2O was extracted with
hexane (2 × 40 mL). The combined organic layers were dried
on K2CO3, filtered, and concentrated under reduced pressure.
The slightly yellow viscous oil that was obtained solifidied upon
1
standing (0.88 g, 2.25 mmol, 85%). H NMR (C6D6): δ 7.66 (s,
2H, Ar-H), 3.55 (s, 4H, CH2N), 2.16 (s, 12H, N(CH3)2), 0.26
(s, 9H, Si(CH3)3, J ) 6.7 Hz). 13C{1H} NMR (C6D6): δ 141.7
(Ar-C), 139.2 (Ar-C-Si), 134.2 (Ar-C), 109.5 (Ar-C-I), 69.5
(Ar-CH2), 45.5 (N(CH3)2), -1.0 (Si(CH3)2). GC-MS: m/z 263
(M - I)+. Anal. Calcd for C15H27N2SiI: C 46.15, H 6.97, N 7.18,
Si 7.20. Found: C 46.08, H 7.06, N 7.09, Si 7.29.
[NiI(C6H2{CH2NMe2}-2,6-(SiMe3)-4)] (5). To a solution of
4 (0.27 g, 0.69 mmol) in THF (30 mL) was added Ni(PPh3)4
(1.14 g, 1.03 mmol) in THF (20 mL). The brown solution was
stirred for 18 h at room temperature. 1H NMR spectroscopy
showed at this stage that the conversion of 4 into 5 was
complete. The solvent was removed in vacuo, and the crude
product was extracted with Et2O (2 × 25 mL) was added.
Colloidal Ni0 that was formed during the reaction was centri-
fuged off. Then the combined Et2O layers were cooled to -20
°C to afford dark orange to red, needle-shaped crystals (0.11
g, 0.24 mmol, 35%). 1H NMR (C6D6): δ 6.73 (s, 2H, Ar-H),
3.07 (s, 4H, CH2N), 2.50 (s, 12H, N(CH3)2), 0.29 (s, 9H, Si-
(CH3)3). 13C{1H} NMR (C6D6): δ 155.7 (Cipso), 147.1 (Ar-C),
[C6H2(CH2NMe2)2-2,6-(SiMe3)2-1,4] (1). n-BuLi (4 mL, 1.6
M solution in pentane, 6.4 mmol) was added to a solution of
1-trimethylsilyl-3,5-bis[(dimethylamino)methyl]benzene (1.63
g, 6.16 mmol) in pentane (25 mL) at room temperature. The
solution was stirred for 18 h, and then Me3SiOTf (2.2 mL, 11.4
mmol) was added. The solution decolorized immediately, and
after 25 min of additional stirring, all volatiles were removed
in vacuo. Pentane (50 mL) and NaOH pellets were added (to
pH 14), and the organic layer was separated. The water layer
was extracted with pentane (2 × 50 mL), the combined organic
layers were dried on K2CO3 and filtered, and the filtrate was
evaporated to dryness, affording a clear yellow oil (1.99 g, 5.91
mmol, 96%). 1H NMR (C6H6): δ 7.67 (s, 2H, Ar-H), 3.56 (s,
4H, Ar-CH2), 2.03 (s, 12H, N(CH3)2), 0.52 (s, 9H, Si(CH3)3),
0.29 (s, 9H, Si(CH3)3). 13C{1H} NMR (C6H6): δ 146.1 (Ar-C),
140.3, 139.7 (2 × Ar-C-Si), 134.1 (Ar-C), 66.2 (Ar-CH2), 45.1
(N(CH3)2), 3.4 (Si(CH3)3), -1.0 (Si(CH3)3). GC-MS: m/z 322
(M - CH3)+. Anal. Calcd for C18H36N2Si2: C 64.21, H 10.78, N
8.32, Si 16.69. Found: C 64.08, H 10.82, N 8.42, Si 16.55.

284 Organometallics, Vol. 18, No. 2, 1999
Kleij et al.
136.1 (Ar-C-Si), 123.6 (Ar-C), 72.8 (Ar-CH2), 53.2 (N(CH3)2),
-0.7 (Si(CH3)2). FAB-MS: m/z 447.9 (M+), 321.0 (M - I)+.
Anal. Calcd for C15H27N2SiNiI: C 40.12, H 6.06, N 6.24, Si
6.25. Found: C 39.86, H 6.10, N 6.18, Si 6.31.
-(CH2)2-), 0.19 (s, 12H, Si(CH3)2). 13C{1H} NMR (CDCl3): δ
158.2 (Cipso), 144.7 (Ar-C), 135.0 (Ar-C-Si), 124.6 (Ar-C),
74.8 (Ar-CH2), 53.1 (N(CH3)2), 8.0 (-(CH2)2-), -3.4 (Si(CH3)2).
FAB-MS: m/z 807.9 (M+), 772.9 (M - Cl)+. Anal. Calcd for
C
30H52N4Si2Pd2Cl2: C 44.56, H 6.48, N 6.93, Si 6.95. Found:
[C6H4(CH2NMe2)-1-(SiMe3)-4] (6). 1-Bromo-4-bis[(dimethyl-
amino)methyl]benzene (4.43 g, 20.7 mmol) was dissolved in
THF (30 mL) and subsequently cooled to -78 °C. Then t-BuLi
(42 mL of a 1.5 M solution in pentane, 63 mmol) was slowly
added. The clear orange solution was stirred for 10 min, after
which an excess of trimethylsilyl chloride (10 mL, 8.6 g, 79
mmol) was added, affording a clear colorless mixture. The
solution was allowed to reach room temperature, upon which
a white solid precipitated. The suspension was stirred for an
additional 45 min. HCl (4 M) was added until pH 1, and the
organic layer was separated. The H2O layer was extracted with
Et2O (2 × 100 mL), and then NaOH (4 M) was added until pH
14. The H2O layer was extracted with Et2O (2 × 100 mL), and
the combined organic layers were dried on K2CO3 and filtered.
The filtrate was concentrated in vacuo, and after short-path
distillation of the crude product a clear, colorless liquid was
C 44.32, H 6.46, N 6.88, Si 7.01.
[CH2Si(Me)2C6H2(CH2NMe2)2-3,5-(P tCl)-4]2 (10). This com-
pound was prepared in a similar way as described for 3. t-BuLi
(2.0 mL of a 1.5 M solution in pentane, 3.0 mmol) was added
to a solution of [CH2Si(Me)2C6H3(CH2NMe2)2-3,5]2 (0.76 g, 1.44
mmol) in pentane (20 mL) and stirred for 18 h at room
temperature. A cream-colored powder was formed (1.31 g, 1.33
1
mmol, 92%). H NMR (CDCl3): δ 6.90 (s, 4H, Ar-H), 4.03 (s,
8H, Ar-CH2, J (Pt-H) ) 45.3 Hz), 3.09 (s, 24H, N(CH3)2, J (Pt-
H) ) 37.2 Hz), 0.62 (s, 4H, -(CH2)2-), 0.20 (s, 12H, Si(CH3)2).
2
13C{1H} NMR (CDCl3): δ 146.7 (Ar-C), 143.1 (Ar-C, J (Pt-
C) ) 76.2 Hz), 133.3 (Ar-C-Si), 124.2 (Ar-C, J (Pt-C) ) 35.1
Hz), 77.7 (Ar-CH2, J (Pt-C) ) 67.3 Hz), 54.5 (N(CH3)2), 8.1
(-(CH2)2-), -3.4 (Si(CH3)2). Mp > 200 °C. FAB-MS: m/z 986
(M+), 949 (M - Cl)+. Anal. Calcd for C30H52N4Si2Pt2Cl2: C
36.54, H 5.32, N 5.68, Si 5.70. Found: C 36.68, H 5.39, N 5.55,
Si 5.72.
1
isolated (4.00 g, 19.3 mmol, 93%). H NMR (C6D6): δ 7.50 (d,
2H, Ar-H, J ) 7.9 Hz), 7.41 (d, 2H, ArH, J ) 7.9 Hz), 3.30 (s,
2H, CH2N), 2.10 (s, 6H, N(CH3)2), 0.22 (s, 9H, Si(CH3)3, J )
6.56 Hz). 13C{1H} NMR (C6D6): δ 140.7, 138.7, 133.7, 128.7 (4
× Ar-C), 64.6 (Ar-CH2), 45.5 (N(CH3)2), -1.0 (Si(CH3)2). GC-
MS: m/z 207 (M+). Anal. Calcd for C12H21NSi: C 69.50, H
10.21, N 6.75, Si 13.54. Found: C 69.38, H 10.29, N 6.65, Si
13.64.
[P d Cl(C6H3{CH2NMe2}-2-(SiMe3)-5)]2 (7). To a solution
of 6 (0.74 g, 3.57 mmol) in MeOH (20 mL) was added Pd(OAc)2
(0.81 g, 3.61 mmol), and the initial red suspension was stirred
for 18 h. Then excess LiCl (0.26 g, 6.13 mmol) was added to
the solution, and almost immediately a green suspension was
obtained. After stirring the mixture for 1 h, the solvent was
removed by decantation and the solid residue washed with
MeOH (2 × 25 mL). After drying under reduced pressure a
green solid was obtained (1.03 g, 2.96 mmol, 83%). Analytically
pure 7 was obtained by slow diffusion of Et2O into a concen-
trated solution of the product in CH2Cl2 affording yellow-green
plate-shaped crystals. 1H NMR (CDCl3, mixture of isomers):
[CH2Si(Me)2C6H2(CH2NMe2)2-3,5-I-4]2 (11). Experimental
conditions are similar to those described for 4. To a solution
of [CH2Si(Me)2C6H3(CH2NMe2)2-3,5]2 (1.19 g, 2.26 mmol) was
added t-BuLi (3.5 mL of a 1.7 M solution in pentane, 6.0 mmol)
at room temperature. The lithiated species was “titrated” with
I2 (1.64 g, 6.46 mmol) in Et2O (40 mL). The combined organic
extraction layers were washed with saturated Na2SO3 solution
(2 × 50 mL) and H2O (2 × 50 mL). An orange, very viscous
oil, which solidifies after several weeks, was produced (1.50
g, 1.93 mmol, 85%). 1H NMR (C6D6): δ 7.64 (s, 4H, Ar-H),
3.53 (s, 8H, CH2N), 2.15 (s, 24H, N(CH3)2), 0.79 (s, 4H,
-(CH2)2-), 0.28 (s, 12H, Si(CH3)2). 13C{1H} NMR (C6D6): δ
141.7 (Ar-C), 138.1 (Ar-C-Si), 134.6 (Ar-C), 109.6 (Ar-C-
I), 69.5 (Ar-CH2), 45.5 (N(CH3)2), 8.4 (-(CH2)2-), -3.4 (Si-
(CH3)2). FAB-MS: m/z 779 (M + H)+. Anal. Calcd for C30H52N4-
Si2I2: C 46.27, H 6.73, N 7.19, Si 7.21. Found: C 46.18, H
6.67, N 7.26, Si 7.28.
[CH 2Si(Me)2C6H 2(CH 2NMe2)2-3,5-(P d I)-4]2 (12). To a
stirred solution of 11 (0.32 g, 0.41 mmol) in benzene (40 mL)
was added an excess of Pd(dba)2 (0.56 g, 0.97 mmol) at room
temperature. The dark-colored mixture was then stirred until
1H NMR spectroscopy showed the reaction to be complete ()48
h). The reaction mixture was filtered through Celite and the
solvent removed under reduced pressure. The solid residue was
washed with acetone (30 mL), and the first fraction (0.12 g)
was isolated. The acetone layer was then cooled to -20 °C,
and the precipitated solid was isolated by decantation and
dried in vacuo to give a second fraction (0.17 g) of a beige-
colored solid (total yield 0.29 g, 0.29 mmol, 71%). 1H NMR
(C6D6): δ 6.87 (s, 4H, Ar-H), 3.31 (s, 8H, CH2N), 2.67 (s, 24H,
N(CH3)2), 0.87 (s, 4H, -(CH2)2-), 0.36 (s, 12H, Si(CH3)2).
13C{1H} NMR (C6D6): δ 162.3 (Ar-Cipso), 145.7, 134.6, 124.7
(3 × Ar-C), 74.0 (Ar-CH2), 54.7 (N(CH3)2), 8.8 (-(CH2)2-),
-3.1 (Si(CH3)2). FAB-MS: m/z 865 (M - I)+. Anal. Calcd for
δ 7.42 (s, 2H, Ar-Hortho, major isomer), 7.33 (s, 2H, Ar-Hortho
,
minor isomer), 7.11 (d, 2H, ArH, J ) 7.2 Hz), 6.86 (d, 2H, ArH,
J ) 7.2 Hz), 3.91 (s, 4H, CH2N), 2.87 (s, 12H, N(CH3)2, minor
isomer), 2.85 (s, 12H, N(CH3)2, major isomer), 0.23 (s, 18H,
Si(CH3)3). 13C{1H} NMR (CDCl3, mixture of isomers): δ 147.6,
147.5, 143.1, 142.9 (4 × Ar-C), 138.2, 138.0, 137.8, 137.7 (Ar-
C), 129.7 (Ar-C), 121.2 (Ar-C), 73.2 (Ar-CH2), 53.0, 52.7 (2
× N(CH3)2), -0.9, -1.0 (2 × Si(CH3)2). Anal. Calcd for
C
24H40N2Si2Pd2Cl2 (dimer): C 41.39, H 5.79, N 4.02, Si 8.07.
Found: C 41.35, H 5.86, N 3.98, Si 8.04.
[P d Cl(C6H3{CH2NMe2}-2-SiMe3-5)(C5H5N)] (8). Reaction
of 7 (0.25 g, 0.36 mmol) with an excess of pyridine in CH2Cl2
yielded the monomeric complex 8 as a white solid after
evaporation of all volatiles and washing the product with
1
pentane (20 mL) (0.29 g, 0.68 mmol, 95%). H NMR (CDCl3):
δ 8.91 (d, 2H, pyr-H, J ) 6.3 Hz), 7.84 (t, 1H, pyr-H, J ) 7.4
Hz), 7.38 (t, 2H, pyr-H, J ) 6.4 Hz), 7.14 (d, 1H, ArH, J )
7.3 Hz), 6.96 (d, 1H, ArH, J ) 7.2 Hz), 6.06 (s, 1H, Ar-Hortho),
3.96 (s, 2H, CH2N), 2.94 (s, 6H, N(CH3)2), 0.02 (s, 9H, Si(CH3)3).
13C{1H} NMR (CDCl3): δ 153.8, 148.6, 148.2, 137.8, 137.6,
137.0, 129.5, 125.0, 121.1 (Ar-C), 74.0 (Ar-CH2), 52.8 (N(CH3)2),
-1.2 (Si(CH3)2). Anal. Calcd for C17H25N2SiPdCl: C 47.78, H
5.90, N 6.56, Si 6.57. Found: C 47.59, H 5.98, N 6.64, Si 6.46.
[CH2Si(Me)2C6H2(CH2NMe2)2-3,5-(P d Cl)-4]2 (9). Experi-
mental conditions are similar to those described for 2. [CH2Si-
(Me)2C6H2(CH2NMe2)2-3,5-SiMe3-4]2 (0.22 g, 0.33 mmol) was
suspended in MeOH (40 mL), and to this solution was added
Pd(OAc)2 (0.20 g, 0.89 mmol). In addition, the CH2Cl2 solution
of 9 was filtered through Celite. A light brown solid was formed
(0.19 g, 0.23 mmol, 70%). 1H NMR (CDCl3): δ 6.86 (s, 4H, Ar-
H), 4.00 (s, 8H, Ar-CH2), 2.95 (s, 24H, N(CH3)2), 0.60 (s, 4H,
C
30H52N4Si2Pd2I2: C 36.34, H 5.29, N 5.65, Si 5.67. Found: C
36.42, H 5.36, N 5.61, Si 5.79.
[CH2Si(Me)2C6H 3(CH2NMe2)-4-(P d Cl)-3]2 (13). Method
1: [CH2Si(Me)2C6H4(CH2NMe2)-4]2 (0.46 g, 1.11 mmol) in
MeOH (20 mL) was treated with Pd(OAc)2 (0.52 g, 2.32 mmol).
After stirring the red-colored solution for 3 h, excess LiCl (0.15
g, 3.54 mmol) was added to afford a yellow suspension, which
was stirred for 18 h. The solvent was removed in vacuo, and
CH2Cl2 (100 mL) and H2O (100 mL) were added. The organic
layer was separated and the H2O layer extracted with CH2Cl2
(50 mL). The combined organic layers were filtered through
Celite and evaporated to yield a bright orange solid (0.66 g,
0.95 mmol, 86%). Method 2: To a solution of [CH2Si(Me)2C6H3-
(CH2NMe2)-4-SiMe3-3]2 (0.37 g, 0.66 mmol) in MeOH (30 mL)
was added Pd(OAc)2 (0.32 g, 1.43 mmol), which was stirred

Carbosilane Molecules with Arylmetal End Groups
Organometallics, Vol. 18, No. 2, 1999 285
Ta ble 4. Cr ysta l Da ta a n d Deta ils of th e Str u ctu r e
Deter m in a tion for 5 a n d 13
for 1 h, and subsequently LiCl (0.12 g, 2.83 mmol) was added.
After the same purification and isolation sequence described
in method 1, an orange solid was obtained (0.45 g, 98%). The
low solubility of 13 in the common organic solvents hampered
the analysis by 13C{1H} NMR spectroscopy. Yellow block-
shaped crystals suitable for an X-ray analysis were obtained
by cooling a saturated solution of the product in CH2Cl2 to -20
°C. 1H NMR (CDCl3, crystalline material, mixture of iso-
mers): δ 7.63 (s, 2H, Ar-Hortho, minor isomer), 7.42 (s, 2H,
Ar-Hortho, major isomer), 7.11 (d, 2H, ArH, J ) 7.2 Hz, minor
isomer), 7.10 (d, 2H, ArH, J ) 7.2 Hz, major isomer), 6.88 (d,
2H, ArH, J ) 7.2 Hz, minor isomer), 6.86 (d, 2H, ArH, J ) 7.2
Hz, major isomer), 3.96 (s, 4H, CH2N, minor isomer), 3.92 (s,
4H, CH2N, major isomer), 2.96 (s, 12H, N(CH3)2, minor isomer),
2.86 (s, 12H, N(CH3)2, major isomer), 0.91 (s, 4H, -(CH2)2-,
minor isomer), 0.56 (s, 4H, -(CH2)2-, major isomer), 0.21 (s,
18H, Si(CH3)3, minor isomer), 0.19 (s, 18H, Si(CH3)3, major
isomer). FAB-MS: m/z 659 ((M - Cl)+, monomer), 1388 (M+,
dimer) 1353 ((M - Cl)+, dimer). Anal. Calcd for C24H40N2Si2-
Pd2Cl2‚1.5CH2Cl2: C 37.40, H 5.01, N 3.41. Found: C 37.28,
H 5.03, N 3.41.
5
13
empirical formula
C
15H27IN2NiSi
C48H76Cl4N4Pd4Si4,
3(CH2Cl2)
1643.75
fw
449.07
cryst syst
space group
a/Å
b/Å
c/Å
monoclinic
P21/c (No. 14)
10.2695(7)
27.914(2)
13.7232(11)
90
101.171(6)
90
3859.4(5)
8
triclinic
P1 (No. 2)
10.8029(10)
11.5113(7)
14.7454(19)
100.130(8)
105.530
100.963(6)
1683.9(3)
1
R/deg
â/deg
γ/deg
V/Å3
Z
D(calc)/[g/cm3]
F(000)
1.546
1808
2.7
1.621
826
1.6
µ(Mo KR)/mm-1
cryst size/mm
T/K
0.10 × 0.15 × 0.55
0.15 × 0.15 × 0.35
225
150
radiation/Å
θ min., max./deg
scan (type and
range)/deg
dataset
Mo KR 0.71073
1.5, 27.5
0.64 + 0.35 tan(θ)
Mo KR 0.71073
1.5, 27.5
1.02 + 0.35 tan(θ)
[CH2Si(Me)2C6H3(CH2NMe2)-4-{P d Cl(C5H5N)}-3]2 (14).
Reaction of crystalline 13 (0.24 g, 0.29 mmol) with an excess
of pyridine in CH2Cl2 (see synthesis of 8) yielded 14 as a white
solid (0.22 g, 0.26 mmol, 89%). 1H NMR (CDCl3): δ 8.85 (d,
4H, pyr-H, J ) 5.0 Hz), 7.77 (t, 2H, pyr-H, J ) 7.3 Hz), 7.28
(t, 4H, pyr-H, J ) 6.4 Hz), 7.05 (d, 2H, ArH, J ) 7.1 Hz),
6.95 (d, 2H, ArH, J ) 7.2 Hz), 6.00 (s, 2H, Ar-Hortho), 3.94 (s,
4H, CH2N), 2.91 (s, 12H, N(CH3)2), 0.29 (s, 4H, -(CH2)2), -0.08
(s, 12H, Si(CH3)2). 13C NMR (CDCl3): δ 153.7, 148.6, 148.3,
137.8, 137.3, 136.6, 129.8, 125.0, 121.1 (Ar-C), 74.0 (Ar-CH2),
52.9 (N(CH3)2), 7.7 (-(CH2)2), -3.7 (Si(CH3)2). Anal. Calcd for
C34H48N4Si2Pd2Cl2: C 47.89, H 5.67, N 6.57, Si 6.59. Found:
C 47.70, H 5.45, N 6.27, Si 6.70.
-12: 13; 0: 36;
-17: 17
16 105, 8861, 0.048
-14: 13; 0: 14;
-19: 18
8088, 7705, 0.050
no. of tot, unique
data, R(int)
no. of obsd data
[I > 2.0σ(I)]
4408
5568
N
ref, Npar
8861, 375
7705, 351
0.0452, 0.0985, 1.02
R, wR2, Sa
0.0638, 0.1666, 1.02
w-1
σ2(Fo2) + (0.0606P2) + σ2(Fo2) +
1.6816P where
(0.0370P2) +
1.5120P
0.02, 0.00
P ) (Fo + 2Fc2)/3
2
max. and av.
shift/error
0.01, 0.00
-1.17, 2.20
min./max. resd
-0.69, 1.02
Cr ysta l Str u ctu r e Deter m in a tion s for 5 a n d 13. Gen -
er a l. Crystal data collection and refinement parameters are
given in Table 4. X-ray data were collected at low temperature
(inert oil technique) on an Enraf Nonius CAD4T diffractometer
(Rotating Anode, Mo KR radiation, graphite monochromator).
Both structures were refined on F2 by full-matrix least-squares
(SHELXL96).24 All geometrical calculations including the
ORTEP illustrations were done with PLATON.25 For 5: Needle-
shaped orange crystal. The structure was solved by direct
methods using SHELXS86.26 Correction for absorption was
done with a semiempirical ψ-scan-based technique (PLATON/
ABSPSI).25 The monoclinic unit cell contains two similar but
crystallographically independent molecules of 5. A test for
higher symmetry using PLATON/ADDSYM25 was negative
apart from an indication for a pseudotranslation in the b-axis
direction. Most residual density is found near iodine, indicating
some residual absorption artifacts. Molecule A containing Ni1A
contains some unresolved disorder as indicated by a few larger
than usual displacement ellipsoids and residual density near
Si1A. For 13: Block-shaped yellowish crystal. The structure
dens/[e/Å3]
a
2
2
2 2
R ) ∑|Fo| - |Fc|/∑|Fo|, wR2 ) {∑w(|Fo| - |Fc| /∑w|Fo | }-1/2
.
was solved by automated Patterson techniques (DIRDIF).27
Correction for absorption was done with an empirical correc-
tion procedure (PLATON/DELABS).25 One of the CH2Cl2
molecules is disordered over an inversion center.
Ack n ow led gm en t. We wish to thank Anca van der
Kerk and Kees Versluys from the Analytical Chemical
Department for measuring the FAB-MS spectra. This
work was supported in part (A.W.K. and A.L.S.) by The
Netherlands Foundation of Chemical Research (SON)
with financial aid from The Netherlands Organization
for Scientific Research (NWO).
Su p p or tin g In for m a tion Ava ila ble: A listing of tables
of atomic coordinates, bond lengths and angles, and thermal
parameters for 5 and 13 and complete Figure 2 (11 pages).
See any current masthead page for Internet access instructions.
OM980758F
(24) Sheldrick, G. M. SHELXL96, Program for crystal structure
refinement; University of Go¨ttingen, Go¨ttingen, Germany, 1996.
(25) Spek, A. L. Acta Crystallogr. 1990, A46, C-34.
(26) Sheldrick, G. M. SHELXS86, Program for Crystal Structure
Solution; University of Go¨ttingen, Go¨ttingen, Germany, 1986.
(27) Beurskens, P. T.; Admiraal, G.; Beurskens, G.; Bosman, W. P.;
Garc´ıa-Granda, S.; Gould, R. O.; Smits, J . M. M.; Smykalla, C. The
DIRDIF program system, Technical report of the Crystallography
Laboratory; University of Nijmegen: The Netherlands, 1992.