724 Organometallics, Vol. 22, No. 4, 2003
van Belzen et al.
instrument with an 80 mesh column of 25 m. Elemental
analysis were carried out by Dornis und Kolbe, Mikroana-
lytisches Laboratorium, Mu¨lheim a.d. Ruhr, Germany. The
starting materials phenyl-BIP,10 (p-tolyl)-BIAN,9b Pd(DBA)2,11
iodobenzene dichloride,12 and the palladacyclopentadienes 1
and 62 were prepared according to literature procedures.
Syn th esis of 1,4-Dih a lobu ta -1,3-d ien es. (E,E)-1,4-Di-
br om o-1,2,3,4-tetr akis(car bom eth oxy)bu ta-1,3-dien e (2v).
An excess of bromine (0.5 mL) was added to a solution of 100
mg of 1a (0.13 mmol) in dichloromethane (20 mL). After the
mixture was stirred for 10 min at room temperature, the
solvent was removed by evaporation at reduced pressure and
the organic product was extracted with diethyl ether (2 × 20
mL). The recovered (NN)PdBr2 complex and the dibromodiene
2v were obtained in almost quantitative (>98%) yield. Data
for these compounds have been published.2a
(E,E)-1,4-Dich lor o- (2u ) a n d (E,E)-1,4-Diiod o-1,2,3,4-
tetr a k is(ca r bom eth oxy)bu ta -1,3-d ien e (2w ). These 1,4-
dihalo-1,3-dienes were obtained in the same way and in almost
quantitative yield by bubbling through chlorine for 1 min and
immediate workup, or adding a 5-fold excess of iodine to the
solution, followed by stirring at room temperature for 2 h and
consecutive workup as described above. Yields were typically
95%. Data have been published.2a
Syn th esis of (E,E)-{1,2,3,4-Tetr a k is(ca r bom eth oxy)-4-
h a lo-1,3-bu ta d ien yl}p a lla d iu m (II) Ha lid es w ith Bid en -
ta te N-Liga n d s (4a u -4cw ). To a solution of 150 mg of
2,3,4,5-tetrakis(carbomethoxy)palladacyclopentadiene(phenyl-
bip) (1a ; 0.2 mmol) in dichloromethane (10 mL) was added a
solution of 1 equiv of bromine (10 µL) in dichloromethane (10
mL) dropwise at 0 °C. After addition, the solution was warmed
to room temperature, after which the solvent was removed by
evaporation and the product was washed with diethyl ether
(2 × 20 mL) and then air-dried. The yield of 4a v was 175 mg
(0.19 mmol, 94%). The formation of compounds 4bv and 4cv
was carried out similarly using 1b,c, respectively. Chlorides
4a u , 4bu , and 4cu were synthesized by adding a stoichiomet-
ric amount of iodobenzene dichloride to a solution of 1a -c in
dichloromethane at room temperature. Similarly, 4a w , 4bw ,
and 4cw were prepared from the same palladacyclopentadiene
precursors and iodine. The yields of 4a u , 4bu , 4cu , 4bv, 4cv,
4a w , 4bw , and 4cw were all higher than 92%. Crystals of 4cw
were obtained by slow evaporation of a dichloromethane
solution. Exact masses13 found (calcd): 4a u , [M - Cl]•+ 783.059
(783.072); 4bu , [M - Cl]•+ 85.075 (785.088); 4cu , [M + Na]•+
638.948 (638.953), 4bv, [M + Na]•+ 932.948 (932.946); 4cw ,
[M + H]•+ 800.843 (800.842). Anal. Found (calcd) for 4cv: C,
37.46 (37.39); H, 2.78 (2.85); N, 3.88 (3.96). NMR data are
reported in Tables 1 and 2.
Syn th esis of {1,2,3,4-Tetr a k is(tr iflu or om eth yl)-4-h a lo-
1,3-bu ta d ien yl}p a lla d iu m (II) Ha lid es w ith Bid en ta te N-
Liga n d s (7u -7w ). The procedure given above could also be
used to prepare the trifluoromethyl analogues of compounds
4a u -4cw . When an excess of dihalogen was added to a
solution of 100 mg of 2,3,4,5-tetrakis(trifluoromethyl)palla-
dacyclopentadiene(phenyl-BIP) (6; 0.13 mmol) in dichlo-
romethane (20 mL), compounds 7u -7w were formed within
10 min. The solvent was removed and the solid was washed
with diethyl ether, forming the products in almost quantitative
yield. NMR data are reported in Tables 1 and 2.
Syn th esis of {1,2,3,4-Tetr a k is(ca r bom eth oxy)-1,3-p en -
ta d ien yl}p a lla d iu m (II) Tr iflu or om eth a n esu lfon a te w ith
Bid en ta te N-Liga n d s (10bz a n d 10cz). To 100 mg (0.11
mmol) of (1,2,3,4-tetrakis(carbomethoxy)-1,3-pentadienyl)pal-
ladium(II)((p-tolyl)-BIAN) bromide (4bz) in dichloromethane
was added 32 mg (0.12 mmol) of silver triflate. The solution
was stirred for 30 min, after which the silver bromide was
filtered off and the solution was evaporated to dryness, leaving
an orange-brown solid, which was washed with two small
portions of cold diethyl ether. The yield of 10bz was 96%.
Similarly, the compound 10cz was obtained in 97% yield.
Exact masses found (calcd): 10bz, [M - OTf]•+ 765.127
(765.143); 10cz, [M - OTf]•+ 561.049 (561.049). Anal. Found
(calcd) for 10bz: H, 3.77 (3.26); C, 39.68 (40.55); N, 3.93 (3.94);
S, 3.91 (4.51). NMR data are reported in Tables 1 and 2.
Syn th esis of {1,2,3,4-Tetr a k is(ca r bom eth oxy)-1,3-p en -
ta d ien yl}p a lla d iu m (II)(isocya n id e) Tr iflu or om eth a n e-
su lfon a te w ith Bid en ta te N-Liga n d s (11bz, 11cz, a n d
11bz′). To a solution of 100 mg (0.11 mmol) of 10bz in
dichloromethane was added an equivalent amount, 10 µL (0.11
mmol), of tert-butyl isocyanide. An immediate change of color
took place, and the solvent was removed in vacuo after 5 min,
yielding 99 mg (0.10 mmol, 94%) of the product 11b z.
Compounds 11cz and 11bz′ were prepared in a similar way
in yields higher than 90%. Exact masses found (calcd): 11bz,
[M - OTf]•+ 848.193 (848.216); 11bz, [M - OTf]•+ 644.132
(644.122); 11bz′ [M - OTf]•+ 896.1908 (896.2163). NMR data
are reported in Tables 1 and 2.
Com p u ta tion a l Stu d ies. Most of the calculations were
carried out at the DFT-B3LYP level14 with the Gaussian 98
program,15 using as a model the (HNdCH-CHdNH)Pd[C4-
(CN)4] system. The geometries were fully optimized by the
gradient technique, with the following basis set: for Pd the
LANL2DZ basis set is modified following the prescription of
Couty and Hall.16 In this modified basis the innermost core
electrons (up to 3d) are described by the relativistic orbital-
adjusted effective core potential of Hay and Wadt17 and the
remaining outer core and valence electrons by a [341/541/31]
basis set where the two outermost 5p functions of the standard
LANL2DZ basis set have been replaced by a [41] split of the
5p function optimized by Couty and Hall.16 For the Br atoms
the quasi-relativistic energy-adjusted spin-averaged effective
core potential was taken from the work of the Stuttgart group,
together with their [31/31] basis set,18 to which s and p diffuse
functions (with exponents of 0.0493 and 0.0363, respectively),
and a d polarization function (of exponent 0.381) were added,
following Radom et al.19 With this basis set the Br-Br bond
distance in Br2 is computed to be 2.323 Å at the DFT-B3LYP
level and 2.306 Å at the MP2 level. The slight overestimation
with respect to the experimental value (2.278 Å) is a well-
documented feature for the singly polarized split-valence type
(14) (a) Becke, A. D. Phys. Rev. A 1988, 38, 3098. (b) Lee, C.; Yang,
W.; Parr, R. G. Phys. Rev. B 1988, 37, 785. (c) Becke, A. D. J . Chem.
Phys. 1993, 98, 5648.
(15) Frisch, M. J .; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.;
Robb, M. A.; Cheeseman, J . R.; Zakrzewski, V. G.; Montgomery, J . A.,
J r.; Stratmann, R. E.; Burant, J . C.; Dapprich, S.; Millam, J . M.;
Daniels, A. D.; Kudin, K. N.; Strain, M. C.; Farkas, O.; Tomasi, J .;
Barone, V.; Cossi, M.; Cammi, R.; Mennucci, B.; Pomelli, C.; Adamo,
C.; Clifford, S.; Ochterski, J .; Petersson, G. A.; Ayala, P. Y.; Cui, Q.;
Morokuma, K.; Malick, D. K.; Rabuck, A. D.; Raghavachari, K.;
Foresman, J . B.; Cioslowski, J .; Ortiz, J . V.; Stefanov, B. B.; Liu, G.;
Liashenko, A.; Piskorz, P.; Komaromi, I.; Gomperts, R.; Martin, R. L.;
Fox, D. J .; Keith, T.; Al-Laham, M. A.; Peng, C. Y.; Nanayakkara, A.;
Gonzalez, C.; Challacombe, M.; Gill, P. M. W.; J ohnson, B. G.; Chen,
W.; Wong, M. W.; Andres, J . L.; Head-Gordon, M.; Replogle, E. S.;
Pople, J . A. Gaussian 98, revision A.5; Gaussian, Inc.: Pittsburgh, PA,
1998.
(16) Couty, M.; Hall, M. B. J . Comput. Chem. 1996, 17, 1359.
(17) Hay, P. J .; Wadt, W. R. J . Chem. Phys. 1985, 82, 299.
(18) Bergner, A.; Dolg, M.; Ku¨chle, W.; Stoll, H.; Preuss, H. Mol.
Phys. 1993, 80, 1431.
(19) Glukhovtsev, M.; Pross, A.; McGrath, M. P.; Radom, L. J . Chem.
Phys. 1995, 103, 1878.
Syn th esis of {1,2,3,4-Tetr a k is(ca r bom eth oxy)-1,3-p en -
t a d ien yl}p a lla d iu m (II) Br om id e w it h Bid en t a t e N-
Liga n d s (4bz a n d 4cz). These compounds were prepared
from 1b or 1c according to an earlier report.2b
(10) (a) MacPherson, E. J .; Smith, J . G. Tetrahedron Lett. 1971, 27,
2645. (b) van Belzen, R.; Klein, R. A.; Smeets, W. J . J .; Spek, A. L.;
Benedix, R.; Elsevier, C. J . Recl. Trav. Chim. Pays-Bas 1996, 115, 275.
(11) Rettig, M. F.; Maitlis, M. A. Inorg. Synth. 1977, 17, 134.
(12) Vogel, A. I. A Textbook of Practical Organic Chemistry, 3rd ed.;
Longmans: London, 1956.
(13) With corresponding correct isotope patterns.