Organoplatinum(IV) complexes with hydrogen bonds: From monomers to polymers

Article abstract of DOI:10.1021/om990942g

A series of organoplatinum(IV) complexes has been prepared, in which one of the alkyl groups contains a functional group that is capable of taking part in hydrogen bonding. These complexes are formed by oxidative addition of reagents RCH₂X to [PtMe₂(bu₂bipy)] (1; bu₂bipy = 4,4′-di-tert-butyl-2,2′-bipyridine) and have the formula [PtXMe₂(CH₂R)(bu₂bipy)] (2, R = CO₂H, X = Br; 3, R = 4-C₆H₄CO₂H, X = Br; 4, R = 4-C₆H₄CH₂CO₂H, X = Br; 5, R = C₄N₂H₃O₂, X = Cl; 6, R = 4-C₆H₄NHCO₂Me, X = Cl; 7, R = 2,4-C₆H₃(NHCO₂Me)₂, X = Cl). These complexes may form dimers through OH···O or NH···O hydrogen bonding or polymers through NH···X hydrogen bonding. Further derivatives were prepared by reaction of the above complexes with AgBF₄ in the presence of nicotinic acid or 4,4′-bipyridyl (bipy): namely, [PtMe₂(CH₂C₆H₄CO₂H)(4-NC₅H₄CO₂H) (bu₂bipy)][BF₄] (8) and [{PtMe₂(CH₂R)(bu₂bipy)}₂(μ-bipy) ][BF₄]₂ (9a, R = C₆H₄CO₂H; 10a, R = C₆H₄CH₂CO₂H) Complex 9a forms a polymer by OH···O hydrogen bonding, whereas 8 and 10a undergo hydrogen bonding with the solvent and/or the counterion. This work shows that extended structures can be designed with hydrogen bonding in organoplatinum compounds and that there is a fine balance between formation of dimers or polymers through OH···O, NH···O, or NH···Cl bonding forms and formation of simpler structures arising from hydrogen bonding to solvent molecules or counterions.

Full text of DOI:10.1021/om990942g

Organometallics 2000, 19, 1635-1642
1635
Or ga n op la tin u m (IV) Com p lexes w ith Hyd r ogen Bon d s:
F r om Mon om er s to P olym er s
Christopher S. A. Fraser, Hilary A. J enkins, Michael C. J ennings, and
Richard J . Puddephatt*
Department of Chemistry, University of Western Ontario, London, Canada N6A 5B7
Received November 30, 1999
A series of organoplatinum(IV) complexes has been prepared, in which one of the alkyl
groups contains a functional group that is capable of taking part in hydrogen bonding. These
complexes are formed by oxidative addition of reagents RCH2X to [PtMe2(bu2bipy)] (1; bu2-
bipy ) 4,4′-di-tert-butyl-2,2′-bipyridine) and have the formula [PtXMe2(CH2R)(bu2bipy)] (2,
R ) CO2H, X ) Br; 3, R ) 4-C6H4CO2H, X ) Br; 4, R ) 4-C6H4CH2CO2H, X ) Br; 5, R )
C4N2H3O2, X ) Cl; 6, R ) 4-C6H4NHCO2Me, X ) Cl; 7, R ) 2,4-C6H3(NHCO2Me)2, X ) Cl).
These complexes may form dimers through OH‚‚‚O or NH‚‚‚O hydrogen bonding or polymers
through NH‚‚‚X hydrogen bonding. Further derivatives were prepared by reaction of the
above complexes with AgBF4 in the presence of nicotinic acid or 4,4′-bipyridyl (bipy): namely,
[PtMe2(CH2C6H4CO2H)(4-NC5H4CO2H)(bu2bipy)][BF4] (8) and [{PtMe2(CH2R)(bu2bipy)}2(µ-
bipy)][BF4]2 (9a , R ) C6H4CO2H; 10a , R ) C6H4CH2CO2H) Complex 9a forms a polymer by
OH‚‚‚O hydrogen bonding, whereas 8 and 10a undergo hydrogen bonding with the solvent
and/or the counterion. This work shows that extended structures can be designed with
hydrogen bonding in organoplatinum compounds and that there is a fine balance between
formation of dimers or polymers through OH‚‚‚O, NH‚‚‚O, or NH‚‚‚Cl bonding forms and
formation of simpler structures arising from hydrogen bonding to solvent molecules or
counterions.
In tr od u ction
complexes of platinum.3-5 The present paper reports the
synthesis of organoplatinum(IV) complexes containing
substituents that are capable of taking part in hydrogen
bonding.3,5 The aim was to synthesize complexes which
exhibit extended polymerization in their solid-state
structures, as a result of hydrogen bonding between
molecules, and so to advance the broader field of
supramolecular organometallic chemistry.1-3 The ap-
proach was to use oxidative addition of alkyl halides,
in which the alkyl group contains hydrogen bonding
functional groups, to a dimethylplatinum(II) complex.
Such reactions are known to be tolerant to the presence
of a wide variety of functional groups and have previ-
ously been used to prepare covalently bonded oligomers,
polymers, and dendrimers.6 However, the application
to synthesis of hydrogen-bonded polymers has not been
reported. Indeed, there are few methods known for
synthesis of alkyl complexes of transition metals that
have functional groups capable of taking part in hydro-
gen bonding.
Hydrogen bonding can control the organization of
molecules or ions in the solid state and so has been
widely used in crystal engineering1 and supramolecular
synthesis.2 In inorganic complexes, the hydrogen-bond-
ing patterns may be similar to those in organic solids,
but there is also the potential for different types, such
as M-Cl‚‚‚H-N bonding.3 Hydrogen bonding in coor-
dination complexes of platinum has been established in
complexes having carboxylic acid substituents, for ex-
ample in a platinum(II) complex containing the ligand
3-(diphenylphosphino)propanoic acid, but there has been
little work on hydrogen bonding in organometallic
(1) (a) Braga, D.; Grepioni, F. Coord. Chem. Rev. 1999, 183, 19. (b)
Braga, D.; Grepioni, F.; Desiraju, G. R. Chem. Rev. 1998, 98, 1375. (c)
Mareque Rivas, J . C.; Brammer, L. Coord. Chem. Rev. 1999, 183, 43.
(d) Haiduc, I.; Edelmann, F. T. Supramolecular Organometallic
Chemistry; Wiley-VCH: Weinheim, Germany, 1999.
(2) (a) Lehn, J . M. Angew. Chem., Int. Ed. Engl. 1990, 29, 1304. (b)
Lehn, J . M. Supramolecular Chemistry: Concepts and Perspectives,
VCH: Weinheim, Germany, 1995. (c) Atwood, J . L., Davies, J . E. D.,
McNicol, D. D., Voegtle, F., Eds. Comprehensive Supramolecular
Chemistry; Pergamon: Oxford, U.K., 1996; Vol. 11. (d) Sharma, C. V.
K.; Desiraju, G. R. Perspectives in Supramolecular Chemistry: The
Crystal as a Supramolecular Entity; Wiley: Chichester, U.K., 1996.
(3) (a) Aullon, G.; Bellamy, D.; Brammer, L.; Burton, E. A.; Orpen,
A. G. Chem. Commun. 1998, 653. (b) Braga, D.; Grepioni, F.; Desiraju,
G. R. J . Organomet. Chem. 1997, 548, 33. (c) Burrows, A. D.; Chan,
C.-W.; Chowdhry, M. M.; McGrady, J . E.; Mingos, D. M. P. Chem. Soc.
Rev. 1995, 24, 329. (d) Rivas, J . C. M.; Brammer, L. Inorg. Chem. 1998,
37, 4756. (e) Rivas, J . C. M.; Brammer, L. New J . Chem. 1998, 1315.
(f) Aakeroy, C. B.; Beatty, A. M.; Leinen, D. S. Angew. Chem., Int. Ed.
Engl. 1999, 38, 1815. (g) Aakeroy, C. B.; Beatty, A. M.; Leinen, D. S.
J . Am. Chem. Soc. 1998, 120, 7383. (h) Lewis, G. R.; Orpen, A. G. J .
Chem. Soc., Chem. Commun. 1998, 1873.
Resu lts a n d Discu ssion
Several new organoplatinum(IV) complexes were
prepared by trans-oxidative addition of the correspond-
ing functionalized alkyl bromide to [PtMe2(bu2bipy)],
bu2bipy ) 4,4′-di-tert-butyl-2,2′-bipyridine,7,8 as shown
(4) Tse, C.; Cheung, K.; Chan, M. C.; Che, C.-M. Chem. Commun.
1998, 2295.
(5) Achar, S.; Puddephatt, R. J . Organometallics 1995, 14, 1681.
(6) Rendina, L. M.; Puddephatt, R. J . Chem. Rev. 1997, 97, 1735.
(7) Scott, J . D.; Puddephatt, R. J . Organometallics 1983, 2, 1643.
10.1021/om990942g CCC: $19.00 © 2000 American Chemical Society
Publication on Web 03/28/2000

1636 Organometallics, Vol. 19, No. 9, 2000
Fraser et al.
Sch em e 1
in Scheme 1. The bu2bipy ligand is used, instead of the
parent 2,2′-bipyridine, to enhance the solubility of the
products.9 The alkyl halides used contained functional
groups that could take part in intermolecular hydrogen
bonding to give dimeric to polymeric supramolecular
architectures in the solid state.
F igu r e 1. View of the structure of complex 2, showing a
hydrogen-bonded dimer. The OH protons were located in
the structure determination but not refined. Selected
distances (Å): Pt(1)-C(3) ) 2.071(6), Pt(1)-C(4) ) 2.084(6),
Pt(1)-C(1) ) 2.090(6), Pt(1)-N(1) ) 2.162(4), Pt(1)-N(2)
) 2.169(4), Pt(1)-Br(1) ) 2.5394(6), O(1)-C(2) ) 1.240(7),
O(2)-C(2) ) 1.297(8), O(1A)‚‚‚O(2B) ) 2.65(1), H(2B)‚‚‚
O(1A) ) 1.80.
Der iva tives w ith a Sin gle Ca r boxylic Acid Su b-
stitu en t. The carboxylic acid derived complexes [PtBr-
Me2(bu2bipy)(CH2CO2H)](2),[PtBrMe2(bu2bipy)(CH2C6H4-
CO2H)] (3), and [PtBrMe2(bu2bipy)(CH2C6H4CH2CO2H)]
(4) were prepared by reaction of complex 1 with bro-
moacetic acid, R-bromo-4-toluic acid, and 4-(bromo-
methyl)phenylacetic acid, respectively. In each case,
trans oxidative addition of the C-Br bond occurs rather
than the alternative cleavage of a Pt-Me bond by the
carboxylic acid. The complexes were readily character-
ized in terms of molecular structure by their 1H NMR
spectra by comparison with similar compounds.5 Each
complex gave a single methylplatinum resonance, in-
dicating trans oxidative addition, and the coupling
constant 2J (PtMe) decreased from 89 Hz in the plati-
num(II) complex 1 to 65-70 Hz in the platinum(IV)
products 2-4. The couplings 2J (PtCH2) were in the
range 90-95 Hz in the products. The infrared spectra
as Nujol mulls for 2-4 contain peaks due to ν(O-H) in
the range 2522-2700 cm-1 and ν(CdO) ) 1674-1680
cm-1, strongly suggesting that they exist as hydrogen-
bonded dimers.3,10,11
X-ray-quality crystals for 3 and 4, but the IR data are
similar to those for 2; therefore, it is very likely that
they adopt a similar solid-state structure.
Der iva tive w ith a Ur a cil Su bstitu en t. Since uracil
contains two hydrogen bond donors and acceptors,
complexes containing such groups have the potential to
form polymers rather than dimers. Oxidative addition
of 6-(chloromethyl)uracil to 1 gave the platinum(IV)
complex [PtClMe2(bu2bipy)(CH2C4H3N2O2)] (5) (Scheme
1). The IR spectrum for 5 contained peaks due to ν(N-
H) at 3410 and 3320 cm-1 and four peaks due to ν(Cd
O) in the region 1710-1620 cm-1, suggesting that there
are carbonyl groups involved in hydrogen bonding and
some not involved. The structure of 5 was determined
crystallographically and is shown in Figure 2.
The presence of a hydrogen-bonded dimer in the solid
state for 2 was confirmed by an X-ray structure deter-
mination. A view of the structure is given in Figure 1.
The O(1A)‚‚‚O(2B) distance was 2.65 Å, in the normal
range of 2.5-2.9 Å for similar hydrogen-bonded dimers.12
The CdO bond length (1.240(7) Å) was longer and the
C-O bond length(1.297(8) Å) shorter than in structures
with no hydrogen bonding,8 as expected for a hydrogen-
bonded structure.13 The conformation of the CH2CO2H
group is such that the carboxylic acid group is located
beneath the flat bu2bipy ring, presumably to minimize
steric hindrance. It has not been possible to obtain
The structure confirms that 5 is formed by trans
oxidative addition and shows that intermolecular hy-
drogen bonding does occur, but only to give dimers.
Thus, only one pair of NHCO groups of each uracil
substituent takes part in hydrogen bonding. The dis-
tance O(8A)‚‚‚N(9B) ) 2.82 Å is in the normal range of
2.81-3.04 Å for NH‚‚‚O hydrogen bonds.12 In the dimers
formed by hydrogen bonding, the uracil groups align
roughly under the bu2bipy groups. A similar form of
hydrogen bonding has recently been observed in the
2-thiouracil complex [W(CO)5(SC4N2H3O)]-, while uracil
gives a sheet structure in the solid state with all NH,
CdO, and even CH groups involved in hydrogen bond-
ing.14 It is likely that the limited hydrogen bonding in
complex 5 occurs as a result of steric hindrance to more
extensive association. The closest contact of the NHCO
groups that are not involved in self-association is to an
acetone solvate, with N(7)‚‚‚O(30) ) 3.27 Å and N(7)H‚
‚‚O(30) ) 2.45 Å, indicating a very weak interaction.12
Com p lexes w ith Meth yl Ca r ba m a te Su bstitu -
en ts. The complex [PtClMe2(bu2bipy)(CH2C6H4NHCO2-
(8) Achar, S.; Scott, J . D.; Vittal, J . J .; Puddephatt, R. J . Organo-
metallics 1993, 12, 4592.
(9) (a) Monaghan, P. K.; Puddephatt, R. J . J . Chem. Soc., Dalton
Trans. 1988, 595. (b) Crespo, M.; Puddephatt, R. J . Organometallics
1987, 6, 2548. (c) Monaghan, P. K.; Puddephatt, R. J . Organometallics
1985, 4, 1405. (d) Scott, J . D.; Puddephatt, R. J . Organometallics 1986,
5, 1538. (e) Scott, J . D.; Crespo, M.; Anderson, C. M.; Puddephatt, R.
J . Organometallics 1987, 6, 1772.
(10) Lambert, J . B.; Shurvell, H. F.; Lightner, D.; Cooks, R. G.
Structural Spectroscopy; Prentice-Hall: Englewood Cliffs, NJ , 1998.
(11) Marechal, Y. J . Chem. Phys. 1987, 11, 6344.
(12) (a) Desiraju, G. R.; Steiner, T. The Weak Hydrogen Bond; Oxford
Science:, Oxford, U.K., 1999. (b) J effrey, G. A. An Introduction to
Hydrogen Bonding; Oxford University Press: Oxford, U.K., 1997.
(13) Achar, S.; Vittal, J . J .; Puddephatt, R. J . Organometallics 1996,
15, 43.
(14) (a) Darensbourg, D. J .; Frost, B. J .; Derecskei-Kovacs, A.;
Reibenspies, J . H. Inorg. Chem. 1999, 38, 4715. (b) Sutor, D. J . Nature
1962, 195, 68.

Organoplatinum(IV) Complexes with Hydrogen Bonds
Organometallics, Vol. 19, No. 9, 2000 1637
F igu r e 3. View of the structure of 6‚THF, with NH‚‚‚
O(THF) hydrogen bonding. The hydrogen atoms are omit-
ted for clarity. There is a similar, independent molecule of
6‚THF in the lattice, but it is not shown. Selected distances
(Å; the equivalent data for the two independent molecules
are given, using the atom labeling for molecule 1 only): Pt-
C(33) ) 2.044(6), 2.063(8), Pt-C(34) ) 2.051(7), 2.052(9),
Pt-C(21) ) 2.068(6), 2.068(8), Pt-N(1) ) 2.157(5), 2.155(6),
Pt-N(12) ) 2.158(5), 2.143(6), Pt-Cl ) 2.473(2), 2.466(2),
C(29)-O(30) ) 1.18(1), 1.20(1), C(29)-O(31) ) 1.37(1),
1.35(1), C(32)-O(31) ) 1.45(1), 1.48(1), N(28)‚‚‚O(90) )
2.90(1), 2.99(1).
F igu r e 2. View of the structure of 5, showing hydrogen
bonding of the type CdO‚‚‚H-N. The hydrogen atoms are
omitted for clarity. Selected distances (Å): Pt-C(1) )
2.040(5), Pt-C(2) ) 2.063(5), Pt-C(3) ) 2.085(5), Pt-N(21)
) 2.135(4), Pt-N(10) ) 2.158(4), Pt-Cl ) 2.431(1), C(6)-
O(6) ) 1.229(6), C(8)-O(8) ) 1.230(6), O(8)‚‚‚N(B) )
2.82(1), O(8)‚‚‚H(9A) ) 1.95.
Sch em e 2
distances were 2.90 and 2.99 Å, in the normal range of
2.81-3.04 Å for NH‚‚‚O hydrogen-bonded compounds.12
To overcome this problem of hydrogen bonding to
solvent, a second structure determination was carried
out using a crystal of 6 grown from CH2Cl2/pentane. The
structure is shown in Figure 4. In this case, the
structure exhibits an extended one-dimensional poly-
meric structure with a zigzag shape, formed through
intermolecular NH‚‚‚ClPt hydrogen bonding. A recent
report has suggested that N-H‚‚‚Cl-M hydrogen bond-
ing may be generally favorable, but it is not clear why
it is preferred over the NH‚‚‚O hydrogen bonding that
is commonly observed in amides.3,12 For the two inde-
pendent molecules of 6, the intermolecular distances N‚
‚‚Cl were 3.22 and 3.27 Å, indicating the presence of
the hydrogen bond N-H‚‚‚Cl.3 One previously reported
example of intermolecular hydrogen bonding to an
organoplatinum(II) chloride occurs between ethynyl and
chloroplatinum groups, CtCH‚‚‚ClPt, giving a linear
chain association similar to that in Figure 4.15
Me)] (6) was prepared by oxidative addition of 4-(chlo-
romethyl)phenylisocyanate to1 togive [PtClMe2(bu2bipy)-
(CH2C6H4NCO)], followed by addition of methanol to
convert the isocyanate group to the corresponding
methyl carbamate (Scheme 2). The isocyanate derivative
was characterized by a strong peak in the IR spectrum
at 2300 cm-1, corresponding to ν(NdCdO),10 which
decays on addition of methanol as the carbamate is
The reaction of 1 with 1-(chloromethyl)-2,4-diisocy-
anatobenzene, followed by reaction of the product
[PtClMe2(bu2bipy){CH2C6H3(NCO)2}] with methanol,
gave the bis(carbamate) derivative [PtClMe2(bu2bipy)-
{CH2C6H3(NHCO2Me)2}] (7). The molecular structure
1
of 7 was defined by its H NMR spectrum, but it was
formed with ν(CdO) ) 1705 cm-1
.
not possible to grow single crystals for structure deter-
mination. However, the IR spectrum as a Nujol mull
gave ν(CdO) ) 1725 cm-1, which is at a higher wave-
number than expected for a hydrogen-bonded structure.
In principle, this complex could form a two- or three-
dimensional hydrogen-bonded supramolecular struc-
ture, but it is unlikely that such a structure is actually
present.
Complex 6 was characterized by two structure deter-
minations. The first crystal was grown from THF/
pentane solution and crystallized as the THF solvate.
There are two independent but similar molecules in the
unit cell, and the structure of one of them is shown in
Figure 3. Although the molecular structure is as ex-
pected, there is only hydrogen bonding between the NH
group and a THF solvent molecule (Figure 3), and so
there is no supramolecular association of molecules of
6. In the two independent molecules the N‚‚‚O(THF)
(15) J ames, S. L.; Verspui, G.; Spek, A. L.; van Koten, G. Chem.
Commun. 1996, 1309.

1638 Organometallics, Vol. 19, No. 9, 2000
Fraser et al.
F igu r e 4. View of the structure of 6‚2CH2Cl2, showing
part of the polymeric chain formed by NH‚‚‚Cl hydrogen
bonding. The molecules containing Pt(1) and Pt(2) are
independent. Solvent molecules are not shown, and only
the tertiary carbon atoms of the tert-butyl groups are shown
for clarity. Selected distances (Å; the equivalent data for
the two independent molecules are given, using the atom
labeling for molecule 1 only): Pt(1)-C(33) ) 2.03(1),
2.04(1), Pt(1)-C(34) ) 2.03(1), 2.04(1), Pt(1)-C(1) ) 2.09(1),
2.09(1), Pt(1)-N(24) ) 2.14(1), 2.13(1), Pt(1)-N(13) )
2.15(1), 2.14(1), Pt(1)-Cl(3) ) 2.467(2), 2.478(3), C(9)-
O(10) ) 1.18(2), 1.23(2), C(9)-O(11) ) 1.37(2), 1.31(2),
C(12)-O(11) ) 1.41(2), 1.54(2), Cl(3)‚‚‚N(48) ) 3.27(1),
3.22(1), Cl(3)-H(48) ) 2.40, 2.40.
F igu r e 5. View of the structure of 8[BF4]‚2(acetone),
showing hydrogen bonding to the acetone solvent molecule
(OH‚‚‚O, H‚‚‚O ) 1.81 Å) and to the BF4- counterion (OH‚
‚‚F, H‚‚‚F ) 1.85 Å). The second acetone is not shown.
Selected distances (Å): Pt-C(40) ) 2.056(4), Pt-C(41) )
2.069(4), Pt-C(30) ) 2.084(4), Pt-N(12) ) 2.143(3), Pt-
N(1) ) 2.159(3), Pt-N(21) ) 2.190(4), C(27)-O(28) )
1.189(7), C(27)-O(29) ) 1.310(7), C(37)-O(38) ) 1.210(6),
C(37)-O(39) ) 1.298(7), O(29)‚‚‚F(54) ) 2.64(1), F(54)‚‚‚
H(29) ) 1.85, O(39)‚‚‚O(63) ) 2.61(1), O(63)‚‚‚H(39) ) 1.81.
Sch em e 4
Sch em e 3
Secon d a r y Der iva tiza tion . Complexes that are
capable of forming extended hydrogen-bonded struc-
tures were formed by further derivatization of some of
the above complexes. Thus, abstraction of the bromide
ligand from complex 3 by use of AgBF4 in the presence
of isonicotinic acid gave the ionic complex [PtMe2(bu2-
bipy)(CH2C6H4CO2H)(NC5H4CO2H)][BF4] (8) according
to Scheme 3. In this way an organoplatinum(IV) com-
plex containing two carboxylic acid substituents is
readily formed.
2.61 Å and O(29)‚‚‚F(54) ) 2.64 Å support the presence
of strong hydrogen bonding in each case, since the
accepted ranges for such bonds are 2.48-2.90 and 2.65-
2.72 Å, respectively.12 Clearly these secondary bonding
effects compete well with the expected self-association
through hydrogen bond formation between carboxylic
acid groups that had been anticipated. Attempts to grow
crystals from several other organic solvents were unsuc-
cessful.
An alternative synthesis of complexes containing two
hydrogen-bonding donors is to couple 2 equiv of the
complex 3 or 4 by abstraction of bromide using AgBF4
in the presence of the bridging ligand 4,4′-bipyridyl )
bipy, as shown in Scheme 4. In this way, the complexes
[{PtMe2(bu2bipy)(CH2C6H4CO2H)}2(µ-bipy)][BF4]2 (9a )
and [{PtMe2(bu2bipy)(CH2C6H4CH2CO2H)}2(µ-bipy)]-
The structure of 8 was determined as the acetone
solvate, and the structure is illustrated in Figure 5. The
molecular structure of the cation is confirmed by the
structure determination, but no interesting supramo-
lecular structure is present. Thus, the toluic acid
substituent takes part in hydrogen bonding to an
acetone solvent molecule (OH‚‚‚OdCMe2), while the
isonicotinic acid substituent takes part in hydrogen
-
bonding to a BF4 counterion (OH‚‚‚FB), as shown in
Figure 5. The corresponding distances O(39)‚‚‚O(63) )

Organoplatinum(IV) Complexes with Hydrogen Bonds
Organometallics, Vol. 19, No. 9, 2000 1639
F igu r e 7. View of the structure of complex 10[BF4]2,
showing the weak hydrogen bonding OH‚‚‚F to the tet-
rafluoroborate anions. The hydrogen atoms are omitted for
clarity. Selected distances (Å): Pt-C(33) ) 2.05(1), Pt-
C(32) ) 2.07(1), Pt-C(21) ) 2.07(1), Pt-N(1) ) 2.150(7),
Pt-N(12) ) 2.155(6), Pt-N(41) ) 2.210(8), C(29)-O(30)
) 1.27(2), C(29)-O(31) ) 1.27(2), O(31A)‚‚‚F(54A) ) 2.86(1).
demonstrated in the structure of complex 8, this did not
occur in this case and the desired polymeric structure
was obtained. The intermolecular separation O(31A)‚‚
‚O(31D) ) 2.65 Å is in the range expected for a
hydrogen-bonded association.12
The structure of complex 10a is shown in Figure 7.
The molecular structure is similar to that of 9a , but any
hydrogen bonding was between the carboxylic acid
-
groups and the BF4 counterion (OH‚‚‚FB; O(31A)‚‚‚
F(54A) ) 2.86 Å, suggesting very weak association12);
therefore, no polymeric supramolecular structure was
observed in this case. It is remarkable that the minor
structural difference between 9a and 10a should lead
to this switch in preferred hydrogen bonding of the
carboxylic acid substituents.
F igu r e 6. View of part of the polymeric chain formed by
hydrogen bonding between carboxylic acid substituents in
the cation present in complex 9[BF4]2‚Et2O. There is a
center of symmetry at the midpoint of the central C-C
bond of the bridging bipyridine ligand. Selected distances
(Å): Pt-C(22) ) 2.054(6), Pt-C(21) ) 2.064(6), Pt-C(23)
) 2.094(6), Pt-N(1) ) 2.139(4), Pt-N(12) ) 2.146(4), Pt-
N(33) ) 2.173(5), C(30)-O(31) ) 1.23(1), C(30)-O(32) )
1.29(1), C(51)-O(52) ) 1.30(1), O(52)-C(53) ) 1.36(2),
C(61)-O(62) ) 1.50(2), O(62)-C(63) ) 1.33(1), O(31A)‚‚‚
O(32D) ) 2.65(1), O(31)‚‚‚H(32B) ) 1.81.
The derivatives [{PtMe2(bu2bipy)(CH2C6H4CO2H)}2-
(µ-bipy)][BPh4]2 (9b) and [{PtMe2(bu2bipy)(CH2C6H4-
CH2CO2H)}2(µ-bipy)][BPh4]2 (10b) were prepared by
anion exchange from 9a and 10a , respectively. Since the
counterion BPh4 is less likely than BF4 to take part
in hydrogen bonding, it was hoped that these salts
might form polymeric supramolecular structures. The
IR spectra for 9b and 10b contained peaks due to ν(Cd
O) stretching and ν(O-H) in the region expected for
hydrogen-bonded structures, but it has not been possible
to grow crystals for structure determinations to confirm
the expected polymeric structures.
-
-
[BF4]2 (10a ) were prepared. The IR spectra for 9a and
10a contained peaks due to ν(CdO) and ν(O-H) in the
range expected for hydrogen-bonded complexes.
The structure of complex 9a is shown in Figure 6.
There is a crystallographic center of symmetry at the
midpoint of the C(36)-C(36A) bond of 9a . Complex 9a
adopts a polymeric structure through intermolecular
hydrogen bonding between carboxylic acid groups, giv-
ing the zigzag chain structure shown in Figure 6.
Although the BF4 counterion has the ability to be
involved in hydrogen bonding to the carboxylic group
substituents in organoplatinum(IV) complexes, as was
Con clu sion s
The oxidative addition reaction gives a very simple,
high-yield synthesis of organoplatinum(IV) complexes
containing a wide range of functional groups that are
capable of taking part in hydrogen bonding. When the
product complex contains only one hydrogen bond donor/
acceptor pair, as in the carboxylic acid derivatives 2-4,
only dimerization can occur by association between
-

1640 Organometallics, Vol. 19, No. 9, 2000
Fraser et al.
crystallization from some solvents; in each case the presence
of H2O was confirmed by a resonance in the 1H NMR in the
range δ 2.8-3 or solvent from its characteristic 1H NMR
spectrum.
them, and this pattern is illustrated by the structure of
complex 2, shown in Figure 1. Two other possible
patterns are illustrated by the carbamate ester complex
6, which can form a hydrogen bond to solvent when
crystallized from THF, and so exist as a monomer, or
can form a polymer by intermolecular N-H‚‚‚Cl-Pt
hydrogen bonding, when crystallized from dichlo-
romethane. Association of 6 by intermolecular NH‚‚‚O
hydrogen bonding between carbamate groups was not
observed.
When the product complex contains two hydrogen
bond donor/acceptor pairs, polymer formation might
occur. However, in complex 5, only one such pair within
the uracil group takes part in intermolecular hydrogen
bonding; therefore, only a dimer is formed. This lack of
polymer formation is probably due to steric hindrance
to formation of the maximum number of hydrogen bonds
in 5; as seen in Figure 2, the remaining free NH and
CO groups in 5 are protected by the tert-butyl groups
of the supporting ligands. To overcome such effects, two
routes were developed to place hydrogen-bonding groups
on opposite ends of the complexes. Displacement of
bromide from 3 or 4 by nicotinic acid gave bis(carboxylic
acid) derivatives, but the structure of 8 displayed
hydrogen bonding to acetone and tetrafluoroborate
anion only, and thus, no supramolecular structure was
observed. Displacement of bromide from 3 or 4 by 4,4′-
bipyridine gave the binuclear dicationic complexes 9a
and 10a , which each contain two carboxylic acid groups.
While 10a gave very weak hydrogen bonding only to the
tetrafluoroborate anions, complex 9a gave the desired
form of intermolecular hydrogen bonding, leading to
formation of a polymer in the solid state.
In conclusion, the synthetic strategies developed here
allow synthesis of both neutral and cationic organo-
platinum(IV) complexes having hydrogen-bonding sub-
stituents, and self-association can lead to structures
from dimers to polymers. The greatest difficulty is in
predicting in advance which form of hydrogen bonding
will be preferred. There is a fine balance between the
predicted form of self-assembly and structures arising
from hydrogen bonding to Pt-Cl groups, to solvent
molecules, or, in the ionic complexes, to the counterions.
It is likely that, in at least some cases, the presence of
the bulky, hydrophobic tert-butyl substituents disfavor
tighter hydrogen-bonded structure formation. These
groups are useful for modifying the complex solubility,
thus allowing crystals to be grown for characterization
purposes, but they are not ideal for maximizing the
intermolecular hydrogen-bonding interactions. While
the prediction of preferred hydrogen-bonding patterns
for crystal engineering has proved to be difficult, the
complexes described here provide rare examples of self-
assembly through hydrogen bonding in alkyl derivatives
of transition metals1 and indicate that it is a fruitful
area for further study.
[P tBr Me2(bu 2bip y)(CH2CO2H)] (2). A mixture of complex
1 (100 mg) and bromoacetic acid (28 mg) in acetone (10 mL)
was stirred for 5 h at room temperature. The solvent was
removed under vacuum, and the product was recrystallized
using acetone/pentane to give a yellow product. Yield: 74%.
Anal. Calcd for C22H33BrN2O2Pt: C, 41.78; H, 5.25; N, 4.43.
Found: C, 42.31; H, 5.36; N, 4.18. NMR in acetone-d6 (δ(1H)):
1.42 (s, 18H, bu); 1.46 (s, 6H, 2J (PtH) ) 70 Hz, PtMe); 3.00 (s,
2
3
2H, J (PtH) ) 96 Hz, PtCH2); 7.82 (dd, 2H, J (H5H6) ) 6 Hz,
4J (H3H5) ) 2 Hz, bipy H5); 8.62 (d, 2H, J (H3H5) ) 2 Hz, bipy
4
H3); 9.18 (d, 2H, 3J (H5H6) ) 6 Hz, 3J (PtH6) ) 18 Hz, bipy H6).
IR (Nujol mull): ν(CO) 1674 cm-1; ν(OH) ) 2700, 2545 cm-1
.
[P tBr Me2(bu 2bip y)(CH2C6H4CO2H)] (3). This was pre-
pared similarly from complex 1 and R-bromo-4-toluic acid.
Yield: 87%. Anal. Calcd for C28H37BrN2O2Pt: C, 47.46; H, 5.26;
N, 3.95. Found: C, 47.04; H, 5.40; N, 3.73. NMR in acetone-d6
(δ(1H)): 1.41 (s, 18H, bu); 1.43 (s, 6H, 2J (PtH) ) 70 Hz, PtMe);
2
3
2.80 (s, 2H, J (PtH) ) 96 Hz, PtCH2); 6.34 (d, 2H, J (H2H3) )
6 Hz, 4J (PtH) ) 19 Hz, H2); 7.22 (d, 2H, 3J (H2H3) ) 6 Hz, H3);
7.22 (dd, 2H, 3J (H5H6) ) 6 Hz, 4J (H3H5) ) 2 Hz, bipy H5); 8.42
(d, 2H, J (H3H5) ) 2 Hz, bipy H3); 8.60 (d, 2H, J (H5H6) ) 6
4
3
Hz, 3J (PtH6) ) 18 Hz, bipy H6). IR (Nujol mull): ν(CO) ) 1674
cm-1; ν(OH) ) 2630, 2522 cm-1
.
[P tBr Me2(bu 2bip y)(CH2C6H4CH2CO2H)] (4). This was
prepared similarly from complex 1 and (4-(bromomethyl)-
phenyl)acetic acid. Yield: 85%. Anal. Calcd for C29H39N2O2-
BrPt‚H2O: C, 47.00; H, 5.58; N, 3.78. Found: C, 47.50; H, 5.43;
N, 3.81. NMR in acetone-d6: δ(1H) ) 1.40 (s, 6H, 2J (PtH) )
2
70 Hz, PtMe); 1.42 (s, 18H, bu); 2.70 (s, 2H, J (PtH) ) 93 Hz,
PtCH2); 3.25 (s, 2H, CH2); 6.16 (d, 2H, 3J (H2H3) ) 6 Hz, 4J (PtH)
3
) 19 Hz, H2); 6.44 (d, 2H, J (H2H3) ) 6 Hz, H3), 7.66 (dd, 2H,
3J (H5H6) ) 6 Hz, 4J (H3H5) ) 2 Hz, bipy H5), 8.32 (d, 2H,
4J (H3H5) ) 2 Hz, bipy H3); 8.60 (d, 2H, 3J (H5H6) ) 6 Hz,
3J (PtH6) ) 18 Hz, bipy H6). IR (Nujol mull): ν(CO) ) 1680
cm-1; ν(OH) ) 2668, 2545 cm-1
.
[P tClMe2(bu 2bip y)(CH2C4N2O2H3)] (5). This was pre-
pared similarly from complex 1 (100 mg) and 6-(chloromethyl)-
uracil (33 mg) in dry THF (30 mL). Yield: 86%. Anal. Calcd
for C25H35N4O2ClPt: C, 45.90; H, 5.39; N, 8.56. Found: C,
46.17; H, 5.50; N, 7.81. NMR in acetone-d6 (δ(1H)): 1.35 (s,
6H, 2J (PtH) ) 68 Hz, MePt); 1.44 (s, 18H, bu); 2.33 (s, 2H,
4
2J (PtH) ) 98 Hz, PtCH2); 4.38 (s, 1H, J (PtH) ) 15 Hz, uracil
H2); 7.78 (dd, 2H, 3J (H5H6) ) 6 Hz, 4J (H3H5) ) 2 Hz, bipy H5);
4
3
8.59 (d, 2H, J (H3H5) ) 2 Hz, bipy H3); 8.72 (d, 2H, J (H5H6)
) 6 Hz, J (PtH6) ) 18 Hz, bipy H6). IR (Nujol mull): ν(CO) )
3
1711, 1682, 1662, 1623 cm-1; ν(NH) ) 3410, 3320 cm-1
.
[P tClMe2(bu 2bip y){CH2C6H4NHCO2Me}] (6). A mixture
of complex 1 (100 mg) and 4-(chloromethyl)phenyl isocyanate
(34 mg) in dry THF (50 mL) was stirred under N2 overnight.
The solvent was removed under vacuum, and methanol (30
mL) was added. The solution was stirred for 5 h under N2.
The solvent was evaporated under vacuum, and the product
was recrystallized from acetone/pentane. Yield: 82%. Anal.
Calcd for C29H40ClN3O2Pt‚H2O: C, 48.97; H, 5.95; N, 5.91.
Found: C, 49.07; H, 5.83; N, 6.00. NMR in acetone-d6 (δ(1H)):
1.30 (s, 6H, 2J (PtH) ) 70 Hz, MePt); 1.40 (s, 18H, bu); 2.62 (s,
2H, 2J (PtH) ) 92 Hz, PtCH2); 3.60 (s, 3H, -OMe); 6.13 (s, 2H,
4
3
3J (H2H3) ) 8 Hz, J (PtH2) ) 14 Hz, H2); 6.72 (s, 2H, J (H2H3)
) 8 Hz, H3); 7.63 (dd, 2H, J (H5H6) ) 6 Hz, J (H3H5) ) 2 Hz,
3
4
bipy H5); 8.35 (d, 2H, J (H3H5) ) 2 Hz, bipy H3); 8.58 (d, 2H,
4
Exp er im en ta l Section
3
3J (H5H6) ) 6 Hz, J (PtH6) ) 19 Hz, bipy H6). IR (Nujol mull):
ν(CO) ) 1705 cm-1; ν(NH) ) 3400 cm-1
.
All reactions were performed under a nitrogen atmosphere
using standard Schlenk techniques. NMR and IR spectra were
recorded by using a Varian Gemini 300 NMR and a Perkin-
Elmer FT-IR 2000 spectrometer, respectively. Compound 1
was prepared using the literature method.7 Several of the
hydrogen-bonded complexes formed as hydrates or solvates on
[P tClMe2(bu 2bip y){CH2C6H3(NHCO2Me)2}] (7). This was
prepared similarly from complex 1 and 1-(chloromethyl)-2,4-
diisocyanatobenzene. Yield: 81%. Anal. Calcd for C31H43
-
ClN4O4Pt: C, 48.59; H, 5.66; N, 7.31. Found: C, 48.83; H, 5.67;
N, 7.54. NMR in acetone-d6 (δ(1H)): 1.36 (s, 6H, 2J (PtH) ) 68

Organoplatinum(IV) Complexes with Hydrogen Bonds
Organometallics, Vol. 19, No. 9, 2000 1641
Ta ble 1. Cr ysta llogr a p h ic Da ta for 2, 5, 6, 8, 9a , a n d 10a
2
5
6‚THF
6‚2CH2Cl2
8[BF4]‚2Me2CO
9[BF4]2‚Et2O
10[BF4]2
formula
C22H33Br-
N2O2Pt
632.50
293(2)
P21/n
6.787(1)
11.384(1)
31.124(1)
90.470(1)
2404.7(4)
4
C31H47Cl-
N4O4Pt
770.27
100(2)
C33H48Cl-
N3O3Pt
765.25
293(2)
P21/n
22.1988(3)
14.4142(2)
24.3526(4)
116.757(1)
6957.9(2)
8
C31H44Cl5-
N3O2Pt
863.03
200(2)
P21/c
13.9808(2)
23.6523(5)
24.3279(4)
103.257(1)
7830.3(2)
8
C40H54BF4-
N3O6Pt
954.76
292(2)
P21/n
17.0747(2)
14.7560(2)
17.3898(2)
103.678(1)
4257.18(9)
4
C37H51BF4-
N3O3Pt
867.71
200(2)
P21/n
14.5655(7)
15.1038(7)
19.4029(8)
93.965(3)
4258.3(3)
4
C68H86B2F8-
N6O4Pt2
1615.23
296(2)
fw
temp (K)
space group
a (Å)
b (Å)
c (Å)
P21/c
P21/n
12.647(3)
20.008(4)
13.675(3)
104.72(3)
3347(1)
4
12.4406(4)
22.708(1)
13.4517(5)
90.304(2)
3800.1(3)
2
â (deg)
V (Å3)
Z
d
calcd (Mg/m3) 1.747
1.529
1.453
1.464
1.490
1.353
1.412
abs coeff
(mm-1
F(000)
R1, wR2
7.515
4.311
4.144
3.954
3.360
3.347
3.742
)
1232
1552
3056
3440
1928
1748
1612
0.0381, 0.0834 0.0618, 0.0874 0.0742, 0.1381 0.1303, 0.2475 0.0466, 0.1075
0.1039, 0.1616 0.1047, 0.1840
Hz, MePt); 1.42 (s, 18H, bu); 2.54 (s, 2H, 2J (PtH) ) 90 Hz,
PtCH2); 3.63 (s, 3H, -OMe), 3.69 (s, 3H, -OMe); 5.85 (d, 1H,
3J (H2H3) ) 6 Hz, 4J (PtH2) ) 18 Hz, H2); 6.60 (dd, 1H, 3J (H2H3)
during which time AgBr precipitated, the solution was filtered
through Celite into a solution of 4,4′-bipyridyl (16 mg) in
acetone (5 mL). After 5 h, the solvent was evaporated under
vacuum and the product was recrystallized from CH2Cl2/
pentane to give a pale yellow solid. Yield: 84%. Anal. Calcd
for C67H84B2F8N6O4Pt2‚CH2Cl2: C, 48.75; H, 5.22; N, 4.94.
Found: C, 48.61; H, 5.52; N, 5.00. NMR in acetone-d6 (δ(1H)):
4
4
) 6 Hz, J (H3H5) ) 2 Hz, H3); 7.30 (d, 1H, J (H3H5) ) 2 Hz,
H5); 7.66 (dd, 2H, 3J (H5H6) ) 6 Hz, 4J (H3H5) ) 2 Hz, bipy H5);
4
3
8.27 (d, 2H, J (H3H5) ) 2 Hz, bipy H3); 8.67 (d, 2H, J (H5H6)
) 6 Hz, J (PtH6) ) 20 Hz, bipy H6). IR (Nujol mull): ν(CO) )
3
1725 cm-1; ν(NH) ) 3380 cm-1
.
1.35 (s, 12H, J (PtH) ) 67 Hz, PtMe); 1.38 (s, 36H, bu); 2.93
2
[P tMe2(bu 2bipy)(CH2C6H4CO2H)(NC5H4CO2H)][BF4] (8).
A solution of complex 3 was prepared by reaction of complex
1 (100 mg) with R-bromo-4-toluic acid (44 mg) in acetone (10
mL) as above. To this solution was added dropwise a solution
of AgBF4 (40 mg) in acetone (5 mL) to precipitate AgBr. After
30 min, the mixture was filtered through Celite into a solution
of isonicotinic acid (25 mg) in acetone (10 mL). The solvent
was evaporated under vacuum, and the product was recrystal-
lized from CH2Cl2/pentane to give a white solid. Yield: 84%.
Anal. Calcd for C34H42BF4N3O4Pt‚H2O: C, 47.67; H, 5.17; N,
4.90. Found: C, 47.94; H, 5.08; N, 5.01. NMR in acetone-d6
(δ(1H)): 1.39 (s, 18H, bu); 1.44 (s, 6H, 2J (PtH) ) 67 Hz, PtMe);
(s, 4H, 2J (PtH) ) 89 Hz, PtCH2); 3.28 (s, 4H, CH2); 6.23 (d,
4H, 3J (H2H3) ) 6 Hz, 4J (PtH) ) 17 Hz, H2); 6.47 (d, 4H,
3J (H2H3) ) 6 Hz, H3); 7.78 (dd, 4H, 3J (H5H6) ) 6 Hz, 4J (H3H5)
3
3
) 2 Hz, bipy H5); 7.85 (d, 4H, J (H2H3) ) 8 Hz, J (PtH) ) 18
Hz, µ-bipy H3); 8.37 (d, 4H, 4J (H3H5) ) 2 Hz, bipy H3); 8.48 (d,
4H, 3J (H2H3) ) 8 Hz, 4J (PtH) ) 17 Hz, µ-bipy H2); 8.92 (d,
4H, 3J (H5H6) ) 6 Hz, 3J (PtH6) ) 19 Hz, bipy H6). IR (Nujol
mull): ν(CO) ) 1686 cm-1; ν(OH) ) 2647, 2548 cm-1
.
[{P tMe2(bu 2bipy)(CH2C6H4CO2H)}2(µ-bipy)][BP h 4]2 (9b).
A mixture of complex 9a (100 mg) and NaBPh4 (44 mg) in
acetone (10 mL) was stirred for 5 h. The solvent was evapo-
rated under vacuum, and the product was recrystallized using
CH2Cl2/pentane to give a pale yellow solid. Yield: 80%. Anal.
Calcd for C114H122B2N6O4Pt2‚CH2Cl2: C, 64.64; H, 5.85; N, 3.93.
Found: C, 64.83; H, 5.68; N, 4.00. NMR in acetone-d6 (δ(1H)):
as for 9a + peaks due to anions. IR (Nujol mull): ν(CO) )
2
3
3.06 (s, 2H, J (PtH) ) 93 Hz, PtCH2); 6.48 (d, 2H, J (H2H3) )
8 Hz, J (PtH) ) 16 Hz, toluic H2); 7.28 (d, 2H, J (H2H3) ) 8
4
3
Hz, toluic H3); 7.86 (d, 2H, J (H2H3) ) 8 Hz, isonicotinic H3);
3
7.88 (dd, 2H, 3J (H5H6) ) 6 Hz, 4J (H3H5) ) 2 Hz, bipy H5); 8.50
(d, 2H, J (H3H5) ) 2 Hz, bipy H3); 8.64 (d, 2H, J (H2H3) ) 7
1694 cm-1; ν(OH) ) 2668, 2555 cm-1
.
4
3
Hz, J (PtH2) ) 20 Hz, isonicotinic H2); 8.95 (d, 2H, J (H5H6)
[{P t Me 2(b u 2b ip y)(CH 2C6H 4CH 2CO2H )}2(µ-b ip y)][B-
P h 4]2 (10b). This was prepared similarly from complex 10a
(100 mg) and NaBPh4 (42 mg) in acetone (10 mL). Yield: 79%.
Anal. Calcd for C116H126B2N6O4Pt2‚CH2Cl2: C, 64.91; H, 5.96;
N, 3.88. Found: C, 64.60; H, 5.90; N, 4.13. NMR in acetone-d6
(δ(1H)): as for 10a + peaks due to anions. IR (Nujol mull):
3
3
) 6 Hz, J (PtH6) ) 18 Hz, bipy H6). IR (Nujol mull): ν(CO) )
3
1694 cm-1; ν(OH) ) 3380 cm-1
.
[{P tMe2(bu 2bip y)(CH2C6H4CO2H)}2(µ-bip y)][BF 4]2 (9a ).
A solution of complex 3 was prepared from complex 1 (100 mg)
and R-bromo-4-toluic acid (44 mg) in acetone (10 mL) as above.
A solution of AgBF4 (40 mg) in acetone (5 mL) was added
dropwise. After 30 min, during which time AgBr precipitated,
this solution was filtered through Celite into a solution of 4,4′-
bipyridyl (16 mg) in acetone (5 mL). After 5 h, the solvent was
evaporated and the product was recrystallized from CH2Cl2/
pentane to give a pale yellow solid. Yield: 86%. Anal. Calcd
ν(CO) ) 1686 cm-1; ν(OH) ) 2647, 2548 cm-1
.
X-r a y Str u ctu r e Deter m in a tion s. A crystal suitable for
X-ray analysis was mounted on a glass fiber. Data were
collected using a Nonius Kappa-CCD diffractometer using
COLLECT (Nonius, 1998) software. The unit cell parameters
were calculated and refined from the full data set. Crystal cell
refinement and data reduction were carried out using the
Nonius DENZO package. The data were scaled using SCALE-
PACK (Nonius, 1998), and no other absorption corrections
were applied. The SHELXTL (G. M. Sheldrick, Madison, WI)
program package was used to solve and refine the structure.
All non-hydrogen atoms were refined with anisotropic thermal
parameters. A summary of the X-ray determinations is given
in Table 1, and individual descriptions are given below. The
accuracy of bond distances was low in some cases as a result
of disorder, but the structures are all well-defined.
for
C66H82B2F8N6O4Pt2‚H2O: C, 49.38; H, 5.27; N, 5.23.
Found: C, 49.42; H, 5.22; N, 5.08. NMR in acetone-d6 (δ(1H)):
2
1.39 (s, 36H, bu); 1.44 (s, 12H, J (PtH) ) 67 Hz, PtMe); 3.06
(s, 4H, 2J (PtH) ) 96 Hz, PtCH2); 6.46 (d, 4H, 3J (H2H3) ) 6
Hz, J (PtH) ) 17 Hz, H2); 7.27 (d, 4H, J (H2H3) ) 6 Hz, H3),
7.86 (dd, 4H, 3J (H5H6) ) 6 Hz, 4J (H3H5) ) 2 Hz, bipy H5); 7.88
(d, 4H, 3J (H2H3) ) 8 Hz, 3J (PtH) ) 18 Hz, m-bipy H3); 8.50 (d,
4
3
4H, J (H3H5) ) 2 Hz, bipy H3); 8.63 (d, 4H, J (H2H3) ) 8 Hz,
4J (PtH) ) 17 Hz, m-bipy H2); 8.95 (d, 4H, 3J (H5H6) ) 6 Hz,
3J (PtH6) ) 19 Hz, bipy H6). IR (Nujol mull): ν(CO) ) 1694
4
3
cm-1; ν(OH) ) 2668, 2555 cm-1
.
[P tBr Me2(bu 2bipy)(CH2CO2H)](2).Crystalsof[PtBrMe2(bu2-
bipy)(CH2CO2H)] were grown from methylene chloride. The
crystal size was 0.30 × 0.20 × 0.20 mm, and data were
collected over the range 1.9-25.0°. Systematic absences were
consistent with the monoclinic space group P21/n, and this was
borne out by successful refinement of the structure. One of
[{P tMe2(bu 2bip y)(CH 2C6H4CH2CO2H)}2(µ-bip y)][BF 4]2
(10a ). A solution of complex 4 was prepared by reaction of
complex 1 (100 mg) and (4-(bromomethyl)phenyl)acetic acid
(44 mg) in acetone (10 mL) as above. A solution of AgBF4 (40
mg) in acetone (5 mL) was added dropwise. After 30 min,

1642 Organometallics, Vol. 19, No. 9, 2000
Fraser et al.
the tert-butyl groups was disordered over two positions, and
each carbon atom was modeled with 50% occupancy. The
largest residual peak was found to be associated with the Pt
atom (1.044 e/Å3).
27.1°. The reflection data and systematic absences were
consistent with a monoclinic space group, P21/n. The largest
residual electron density peak (1.591 e/Å3) was associated with
an acetone of solvation.
[P tClMe2(bu 2bip y)(CH2C4N2O2H3)] (5). Crystals of PtCl-
Me2(bu2bipy)(CH2C4N2O2H3)‚2(acetone) were grown by slow
diffusion of pentane into an acetone solution. The crystal size
was 0.20 × 0.15 × 0.14 mm, and data were collected over the
range 4.1-26.4°. The reflection data and systematic absences
were consistent with a monoclinic system, P21/c. The two
acetone molecules were well-behaved. The largest residual
electron density peak (1.236 e/Å3) was associated with an
acetone of solvation.
[P tClMe2(bu 2bip y){CH2C6H4NHCO2Me}] (6). Crystals of
PtClMe2(bu2bipy)[CH2C6H4NHCO2Me]‚THF were grown by
slow diffusion of pentane into a THF solution. The crystal size
was 0.47 × 0.31 × 0.17 mm, and data were collected over the
range 1.7-26.4°. The reflection data and systematic absences
were consistent with a monoclinic system, P21/n. The THF
molecules of solvation were well-behaved. The largest residual
electron density peak (0.946 e/Å3) was associated with the atom
C(23A).
Crystals of [PtClMe2(bu2bipy){CH2C6H4NHCO2Me}]‚2CH2-
Cl2 were grown from methylene chloride solution by diffusion
of pentane. The crystal size was 0.64 × 0.59 × 0.25 mm, and
data were collected over the range 2.6-30.1°. The reflection
data and systematic absences were consistent with a mono-
clinic system, P21/c. The four solvent molecules in the asym-
metric unit were poorly behaved. Each one was refined as two
independent molecules with occupancies of 50%. Three could
be refined well anisotropically, but the fourth could not and
was kept isotropic. The largest residual electron density peak
(2.178 e/Å3) was associated with one of the platinum atoms.
[P tMe2(bu 2bipy)(CH2C6H4CO2H)(NC5H4CO2H)][BF4] (8).
Crystals of 8[BF4]‚2(acetone) were grown by slow diffusion of
pentane into an acetone solution. The crystal size was 0.36 ×
0.23 × 0.11 mm, and data were collected over the range 3.6-
[{P tMe2(bu 2bip y)(CH2C6H4CO2H)}2(µ-bip y)][BF 4]2 (9a ).
Crystals of 9a ‚(ether) were grown from slow diffusion of diethyl
ether into an acetonitrile solution. The crystal size was 0.38
× 0.23 × 0.07 mm, and data were collected over the range
2.7-30.5°. The reflection data and systematic absences were
consistent with a monoclinic space group, P21/n. There was
disorder in the methyl substituents of the tert-butyl groups;
they were modeled at half-occupancy, and the carbons were
kept isotropic. The diethyl ether of solvation was disordered
over two positions at half-occupancy, the O and C atoms were
also kept isotropic, and the bond lengths were fixed at standard
values. The largest residual electron density peak (1.529 e/Å3)
was associated with the platinum atom.
[{P tMe2(bu 2bip y)(CH 2C6H4CH2CO2H)}2(µ-bip y)][BF 4]2
(10a ). Crystals of 10[BF4]2 were grown by slow diffusion of
pentane into a methylene chloride solution. The crystal size
was 0.32 × 0.26 × 0.08 mm, and data were collected over the
range 2.2-26.1°. The reflection data and systematic absences
were consistent with a monoclinic system, P21/n. Both of the
tert-butyl groups were disordered, with methyl groups in two
positions (occupancy ratios of 50/50 and 60/40 for the two tert-
butyl groups). The 12 Me-C distances were constrained to be
the same. The largest residual electron density peak was 1.777
e/Å3 and was not close to another atom.
Ack n ow led gm en t. We thank the NSERC of Canada
for financial support.
Su p p or tin g In for m a tion Ava ila ble: Tables of X-ray data
for 2, 5, 6, 8, 9a , and 10a . This material is available free of
charge via the Internet at http://pubs.acs.org.
OM990942G