Metallation of unactivated methyl groups - Platinum (II) derivatives with 6-alkyl-2,2′-bipyridines

Article abstract of DOI:10.1002/1099-0682(200212)2002:12<3336::AID-EJIC3336>3.0.CO;2-Z

The reaction of K₂[PtCl₄] with three 6-alkyl-2,2′-bipyridines HL, (N₂C₁₀H₇R; R = CH₂Me, HL^et; CHMe₂, HL^ip; CH₂CMe₃, HL^np) affords five- and six-membered cyclometallated complexes [Pt(L)Cl] where L is a terdentate N,N,C anionic ligand which originates from HL through direct activation of a C(sp³)-H bond. In the case of HL^ip, metallation generates a stereogenic carbon atom β to the metal. Complex 5, [Pt(L^np)Cl], having an uncommon six-membered ring containing a Pt-C(sp³) bond, was studied in depth in solution, by means of 1- and 2- dimensional NMR spectroscopy, and in the solid state by X-ray diffraction. Differences are observed in the behaviour of these ligands: thus with HL^et an adduct, [Pt(HL^et)Cl₂], was also isolated and its structure was determined by X-ray diffraction. In the metallated species, the fourth ligand, Cl, can easily be substituted by neutral or anionic ligands (CO, PPh₃, CN^-). The metallated species react with potentially bidentate ligands L′-L″ [Ph₂PCH₂PPh₂ (dppm), Ph₂P(CH₂)₂PPh₂ (dppe), Ph₂P(CH₂)₂AsPh₂ (dppae)] to give, with different Pt:L ratios, mononuclear [Pt(L)(L′-L″)]⁺ or dinuclear [(L)Pt(μ-L′-L″)Pt(L)]⁺⁺ cationic species. In the second case an uncommon unsupported L′-L″ bridge is present. The cyclometallated species are stable in air and moisture, and the N,N,C system is rather robust. Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002.

Full text of DOI:10.1002/1099-0682(200212)2002:12<3336::AID-EJIC3336>3.0.CO;2-Z

FULL PAPER
Metallation of Unactivated Methyl Groups ؊ Platinum(II) Derivatives
with 6-Alkyl-2,2Ј-bipyridines
Antonio Zucca,*[a] Sergio Stoccoro,[a] Maria Agostina Cinellu,[a] Giovanni Minghetti,[a]
Mario Manassero,[b] and Mirella Sansoni[b]
Keywords: Platinum / N ligands / Cyclometallation
The reaction of K2[PtCl4] with three 6-alkyl-2,2Ј-bipyridines
HL, (N2C10H7R; R = CH2Me, HLet; CHMe2, HLip; CH2CMe3,
HLnp) affords five- and six-membered cyclometallated com-
plexes [Pt(L)Cl] where L is a terdentate N,N,C anionic ligand
which originates from HL through direct activation of a
ned by X-ray diffraction. In the metallated species, the fourth
ligand, Cl, can easily be substituted by neutral or anionic
ligands (CO, PPh3, CN−). The metallated species react with
potentially bidentate ligands LЈ−LЈЈ [Ph2PCH2PPh2 (dppm),
Ph2P(CH2)2PPh2 (dppe), Ph2P(CH2)2AsPh2 (dppae)] to give,
C(sp3)−H bond. In the case of HLip, metallation generates a with different Pt:L ratios, mononuclear [Pt(L)(LЈ−LЈЈ)]+ or di-
stereogenic carbon atom
β
to the metal. Complex 5,
nuclear [(L)Pt(µ−LЈ−LЈЈ)Pt(L)]++ cationic species. In the se-
cond case an uncommon unsupported LЈ−LЈЈ bridge is pre-
sent. The cyclometallated species are stable in air and moi-
sture, and the N,N,C system is rather robust.
[Pt(Lnp)Cl], having an uncommon six-membered ring contai-
ning a Pt−C(sp3) bond, was studied in depth in solution, by
means of 1- and 2- dimensional NMR spectroscopy, and in
the solid state by X-ray diffraction. Differences are observed
in the behaviour of these ligands: thus with HLet an adduct,
[Pt(HLet)Cl2], was also isolated and its structure was determi-
( Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany,
2002)
Introduction
mechanism is electrophilic, in the case of PtII both elec-
trophilic and nucleophilic behaviour has been ascer-
tained.[10] The reaction, besides the obvious electronic and
steric factors, seems to be affected by a number of factors:
we have shown in previous papers that even subtle differ-
ences in the substituents of the ligands can drive the cyclo-
metallation reactions towards unpredictable results.[7a]
Cyclometallated compounds, in particular those derived
from nitrogen ligands, have attracted considerable interest
as a consequence of the wide range of their potential ap-
plications in many areas including organic synthesis,[1]
homogeneous catalysis[2] (even asymmetric), photochem-
istry[3], and the design of new metallomesogens[4], sensors[5]
and antitumour drugs.[6]
In recent years, in addition to the classical bidentate N,C
systems, attention has also been devoted towards poten-
tially terdentate-bound anionic ligands able to coordinate
through different sets of donor atoms (e.g. N,N,C,[7]
N,C,N,[8] C,N,C[9]). The sequence of coordinating atoms, the
size of the metallacycles and the type of metallated carbon
atom can be tuned to obtain complexes with different prop-
erties.
In general, nitrogen donor ligands show a strong tend-
ency to form five-membered rings, although a few six-mem-
bered rings are known. The great majority of papers in this
field concern C(sp2)ϪH bond activation, in spite of the pre-
sent interest in activation of alkyl groups. Only few cyclo-
metallated species containing nitrogen ligands and
C(sp3)ϪPt bonds are known and, to the best of our know-
ledge, only two six-membered cyclometallated species with
a PtϪC(sp3) bond have been described,[11] but none of them
derives from a true CϪH activation.
Although cyclometallation reactions, especially those
concerning metals of the platinum group, have been extens-
ively studied, the factors that control the process are not
completely understood. Whereas for PdII the most common
Here we describe a series of platinum() complexes con-
taining terdentate bound anionic ligands with an
N,N,C(sp3) sequence of donor atoms obtained by the direct
activation of a methyl group of 6-alkyl-2,2Ј-bipyridines. The
substituents on the bipyridines have been chosen in order
to compare five and six-membered rings. In addition, one
of the ligands (HLip, N2C10H7CHMe2Ϫ6), is potentially
able to give a stereogenic carbon atom directly by
[a]
`
Dipartimento di Chimica, Universita di Sassari,
Via Vienna 2, 07100 Sassari, Italy
Fax: (internat.) ϩ39Ϫ079/229559
E-mail: zucca@uniss.it
[b]
Centro CNR,
Dipartimento di Chimica Strutturale
e
Stereochimica metallation.
`
Inorganica, Universita di Milano
Depending on the ligand and the reaction conditions
both adducts [Pt(HL)Cl2] and five- or six-membered cyclo-
Via Venezian 21, 20133 Milano, Italy
E-mail: m.manassero@csmtbo.mi.cnr.it
3336  2002 WILEY-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim 1434Ϫ1948/02/1212Ϫ3336 $ 20.00ϩ.50/0 Eur. J. Inorg. Chem. 2002, 3336Ϫ3346

Metallation of Unactivated Methyl Groups
FULL PAPER
metallated species, [Pt(L)Cl], can be obtained from view of molecule A is shown in Figure 1. The platinum
K2[PtCl4]. The chloride ligand in the metallated species has atom displays a square-planar coordination with a slight
been found to be rather substitution labile, so that its re- square-pyramidal distortion. The displacement of the metal
placement by anionic or neutral ligands as CNϪ, CO or atom from the best plane of atoms Cl(1), Cl(2), N(1), and
˚
˚
PPh3 has been studied. We also report on the reaction with N(2) is 0.090(1) A in molecule A and 0.111(1) A in molecule
the potentially chelating ligands LЈϪLЈЈ [Ph2PCH2PPh2 B. Corresponding bond lengths and angles in the two mole-
(dppm), Ph2P(CH2)2PPh2 (dppe), Ph2P(CH2)2AsPh2 cules are all very similar (see Table 4). The PtϪCl(1) and
˚
(dppae)] with 1:1 and 2:1 Pt/LЈϪLЈЈ molar ratios.
PtϪCl(2) distances, (average 2.298 and 2.284 A, respect-
The behaviour of [PtCl4]2Ϫ is compared with that of ively) are both in good agreement with the PtϪCl bond
et
[PdCl4]2Ϫ, which is previously described.[7a]
length, 2.299(2) A, found in [PtCl(Me)(HL )], compound
˚
19.[13] The PtϪN(2) distance, average 2.050 A, is longer
˚
˚
than the PtϪN(1) one, average 1.996 A, and the
Results and Discussion
Cl(1)ϪPtϪN(2) angle, average 100.5°, is much larger than
the Cl(2)ϪPtϪN(1) angle, average 92.7°. Both effects are
probably due to the steric hindrance of the ethyl substituent
on atom C(10). An even larger ClϪPtϪN(2) angle,
103.1(1)°, had been found in 19. It must be observed that
in compound 19 a clear intramolecular hydrogen bond was
found between a CH2 hydrogen atom and the Cl ligand
The ligands 6-ethyl-2,2Ј-bipyridine (HLet), 6-isopropyl-
2,2Ј-bipyridine (HLip) and 6-neopentyl-2,2Ј-bipyridine
(HLnp) were obtained as previously described.[12]
(Cl···H 2.28 A, C(11)ϪH···Cl angle 160.4°, see ref.[13]).
˚
There is no such hydrogen bond in either of the two present
independent molecules, which exhibit different conforma-
tions of the ethyl substituent, with a shortest Cl(1)···H dis-
˚
tance of 2.52 A and a C(11)ϪH···Cl(1) angle of 126.6° in
molecule B.
The activation of one C(sp3)ϪH bond was achieved with
HLip and HLnp, in high yields (ca. 90%), by reacting the
ligand with K2[PtCl4] in aqueous HCl under refluxing con-
ditions. In the case of HLet the metallation, possibly owing
to the presence of only one methyl group, is more difficult
and a mixture of the metallated complex [Pt(Let)Cl] (2) and
the adduct [Pt(HLet)Cl2] (1), is obtained. We recently re-
ported[7a] that the analogous reactions of these ligands with
Na2[PdCl4] give only the adducts [Pd(HL)Cl2]: CϪH activa-
tion however can be easily obtained from [Pd(OAc)2]. A
peculiar behaviour is observed with a forth ligand HLtb
(R ϭ C(CH3)3]: activation of a methyl group by reaction
with [PdCl4]2Ϫ occurs even at room temperature, whereas
Metallated Compounds
From K2[PtCl4] the metallated compounds [Pt(Lip)Cl] (3)
and [Pt(Lnp)Cl] (5) have been obtained in pure form,
whereas isolation of complex 2 requires separation from ad-
duct 1 by column chromatography. The synthesis of com-
plex 4 has been previously reported.[7b]
refluxing conditions are needed with [PtCl4]2Ϫ
.
The adduct [Pt(HLet)Cl2], 1, can also be synthesised from
cis-[Pt(DMSO)2Cl2] (see the Exp. Sect.) in fairly good
1
yields. The H NMR spectrum (see Table 1) shows all the
expected resonances: in particular the 6Ј-H and the CH2
protons are strongly deshielded with respect to the free li-
gand (∆δ ϭ 0.95 and 0.83 ppm, respectively) as is often ob-
served when a chlorine atom is coordinated in their proxim-
Metallation entails a C(sp3)ϪH activation to give a five-
ity. In addition the 6Ј-H is strongly coupled to platinum membered cycle in the case of compounds 2, 3 and 4, and
(3JPt-H ϭ 40 Hz), providing evidence for the coordination a less common six-membered ring in the case of complex 5.
of the nitrogen atom of the unsubstituted pyridine ring. To the best of our knowledge this is the first six-membered
Complex 1 was characterised in the solid state by X-ray dif- cyclometallated species of platinum() with nitrogen donors
fraction.
originating directly from an unactivated C(sp3)ϪH bond:
The structure consists of the packing of [Pt(HLet)Cl2] two precedent reports involved a benzylic CϪH bond[11a]
molecules with no unusual van der Waals contacts. There and an acidic CϪH group in the presence of alkali.[11b]
are two crystallographically independent molecules, A and
The metallated species were fully characterised by analyt-
B, in the asymmetric unit. Selected bond lengths and angles ical and spectroscopic methods. In particular NMR spec-
for the two molecules are reported in Table 4. An ORTEP troscopy (1H and 13C{1H}) gives evidence for a methylenic
Eur. J. Inorg. Chem. 2002, 3336Ϫ3346
3337

A. Zucca, S. Stoccoro, M. A. Cinellu, G. Minghetti, M. Manassero, M. Sansoni
FULL PAPER
Table 1. Proton NMR spectroscopic data[a]
CH3
CH2ϪPt
CH2ϪC, CH2ϪP/As CH
3.73 (q, 2 H) (7.5)
3.92 (t, 2 H) (6.4) [31]
3.45
H(6Ј)
other aromatics
Pt(HLet)Cl2
Pt(Let)Cl
1
2
3
1.43 (t, 3 H)
(7.5)
9.65
(dd, 1 H) [40]
9.23
(ddd, 1 H) [10]
9.21
7.4Ϫ8.2 (m, 6 H)
7.4Ϫ8.35 (m, 6 H)
7.25Ϫ8.25 (m, 6 H)
2.96 (t, 2 H)
(6.4)[85]
1.46 (d, 3 H) 2.66 (dd 1 H)
Pt(Lip)Cl
(7.2)
(12.0, 5.6) [89]
3.07 (dd 1 H)
(12.0, 7.5) [79]
(m, 1 H) (ddd, 1 H) [12]
Pt(Lnp)Cl
5
6
1.09 (s, 6 H) 2.43 (s, 2 H) [87]
2.82 (s, 2 H)
9.56
(ddd, 1 H) 10]
9.08
7.28Ϫ8.10 (m, 6 H)
7.40Ϫ8.18 (m, 6 H)
[Pt(Lip)(CN)
1.42 (d, 3 H) 2.57 (dd, 1 H)
3.54
(7.1)
(12.9, 5.5) [78]
3.01 (dd, 1 H)
(12.9, 7.2) [64]
(m, 1 H) (dd, 1 H) [15]
[Pt(Lip)(CO)][BF4]
7
1.54 (d, 3 H) 2.83 (dd,1 H)
3.88
8.85
7.68Ϫ8.55 (m, 6 H)
(7.0)
(12.2, 5.6) [66]
3.25 (dd, 1 H)
(12.2, 6.6) [52]
(m, 1 H) (ddd, 1 H) [15]
[Pt(Lnp)(CO)][BF4]
[Pt(Let)(PPh3)][BF4]
[Pt(Lip)(PPh3)][BF4]
8
9
1.17 (s, 6 H) 2.50 (s, 2 H) [52]
3.14 (s, 2 H)
8.76
7.58Ϫ8.82 (m, 6 H)
7.14Ϫ8.71 (m, 7 H)
7.14Ϫ8.69 (m, 22 H)
(dd, 1 H) [n.r]
[c]
2.21 (td, 2 H)
(6.2) [71]{2.7}
10 1.43 (d, 3 H) 2.08 (ddd, 1 H)
3.97 (t, 2 H) (6.2) [35]
[c]
3.52
(7.1)
(12.4, 6.8){3.4}[n.r.]
2.24 (ddd, 1 H)
(m, 1 H)
(12.4, 5.6){2.2}[n.r.]
[c]
[c]
[Pt(Lnp)(PPh3)][BF4]
11 0.86 (s, 6 H) 1.60 (d, 2 H)
2.91 (s, 2 H)
6.94Ϫ8.72 (m, 22 H)
6.97Ϫ8.35 (m, 34 H)
{7.1} [67]
[Pt2(Lnp)2(µ-dppm)][BF4]2 12 0.93 (s, 12 H) 1.52 (d, 4 H)
2.65 (s, 4 H) (bipy)
3.71 (t, 2 H)
{6.5} [60]
{12.2} (dppm)
2.81 (m, 4 H)
[c]
[Pt2(Lip)2(µ-dppe)][BF4]2 13 1.33 (d, 6 H) 2.12 (m, 2 H)
3.53
(m, 2 H)
7.24Ϫ8.42 (m, 34 H)
6.94Ϫ8.42 (m, 34 H)
6.96Ϫ8.42 (m, 34 H)
(7.2)
2.28 (m, 2 H)
[c]
[Pt2(Lnp)2(µ-dppe)][BF4]2 14 0.81 (s, 12 H) 1.61 (d, H)
2.94 (s, 4 H) (bipy)
2.72 (m, 4 H) (dppe)
2.97 (s, 2 H) (bipy)
2.99 (s, 2 H) (bipy)
2.73 (m, 4 H) (dppae)
[60] {ca 5.0}
[c]
[Pt2(Lnp)2(µ-dppae)][BF4]2 15[b] 0.87 (s, 6 H) 1.73 (d, 2 H)
0.88 (s, 6 H) {6.9} [ca 65]
1.84 (s, 2 H)
[ca 65][d]
1.69 (d, 2 H)
{7.3} [65]
[c]
[Pt(Lnp)(dppm)][BF4]
16 0.85 s, 6H
2.84 (s, 2 H) (bipy)
3.43 d {10.5} [49]
2H (dppm)
6.97Ϫ8.56 (m, 27 H)
[Pt(Lnp)(dppe)][BF4]
[Pt(Lnp)(dppae)][BF4]
17 0.31 (s, 3 H) 1.18Ϫ2.84
0.76 (s, 3 H) (m, 8 H)[d]
18 0.91 (s 6 H) 1.79 (d, 2 H)
{6.8} [62]
[c]
6.43Ϫ8.19 (m, 27 H)
6.92Ϫ8.64 (m, 27 H)
[c]
2.96 (s, 2 H) (bipy)
2.25 (m, 2 H) (dppae)
2.42 (m, 2 H) (dppae)
[a]
Room temperature, solvent CDCl3, chemical shifts in ppm from internal SiMe4, coupling constants in, JPt,H in square brackets, JP,H
[b]
[c]
[d]
in braces; n.r. ϭ not resolved. Solvent: CD2Cl2. In all the phosphane complexes the 6Ј-H is strongly shielded. Complex pattern
from δ ϭ 1.18 to 2.84 ppm, due CH2ϪPt, CH2 (dppe), CH2(bipy), 8 H.
group strongly coupled to the metal (2JPt,H ϭ 80Ϫ90,
1JPt,C ϭ 668Ϫ743 Hz, see Table 1 and 2).
Coordinated halides exert a strong deshielding effect. At
variance, the chemical shifts are not remarkably affected by
In complexes 2؊5 the signals of the 6Ј-H protons are the nature of the carbon atom, C(sp3) or C(sp2), bonded to
strongly deshielded and coupled to the metal (3JPt,H ϭ ca. the metal.
10 Hz). In the series of palladium() and platinum() N,N,C
For platinum() compounds, in the case of 5,5 fused
cyclometallated compounds derived from 6-substituted rings, values of ca. δ ϭ 9.20 ppm are typical, whereas for
2,2Ј-bipyridines[7aϪ7g] (see Scheme 1) the chemical shifts of 5,6 fused rings more deshielded resonances (ca. 9.60 ppm)
6Ј-H appear to be strongly dependent on the nature of the are usually observed. In the analogous palladium species
metal and of the fourth ligand as well as on the size of the the same trend is observed, but all the signals are less deshi-
metallated cycle.
elded (ca. 0.4 ppm) than in the corresponding platinum
3338
Eur. J. Inorg. Chem. 2002, 3336Ϫ3346

Metallation of Unactivated Methyl Groups
FULL PAPER
Table 2. 13C NMR spectroscopic data (room temperature, CDCl3, chemical shifts in ppm from TMS, coupling constants in Hz, JPt,C in
square brackets
[Pt(Let)Cl], 2
- 1.2 [743]
44.0
[Pt(Lip)Cl], 3
[Pt(Lnp)Cl], 5
[Pt(Lip)(CO)][BF4], 7
CH2ϪPt
CH3
CH2
10.1 [736]
21.8 [44]
18.2 [668]
29.6 [28]
55.5 [68]
16.2 [567]
22.4 [39]
CH
49.3 [10]
49.4 [5]
C
32.2 [28]
C3, C3Ј
C5, C5Ј
C4, C4Ј
127.7, 124.1 [51]
123.4 [11], 119.8 [35]
138.5, 135.6
127.3, 124.2 [59]
121.8 [12], 119.7 [36]
138.1, 135.4
120.2 [33], 121.3
128.7 [45], 126.8
136.6 (C4)
137.8 (C4Ј)
157.6, 154.6
164.2
129.8 [15], 125.3 [14]
125.1 [47], 122.1 [25]
143.5, 142.3
C2, C2Ј
C6
156.2, 152.6
172.5
C6Ј
147.9 [19]
147.8 [19]
148.0 [25]
152.3 [30]
Figure 1. ORTEP view of molecule A in compound 1; thermal
ellipsoids are drawn at the 30% probability level
complexes. Similar trends have also been recently observed
for analogous gold() cationic species [Au(N,N,C)Cl]ϩ [7g]
for which, however, less experimental data are available.
The 13C{1H} spectra of 2؊5 deserve comments: the
chemical shifts of the CH2ϪPt resonances depend mainly
Scheme 1
on the degree of substitution on the carbon β to the metal, constants JPt,C in the inner pyridine ring are much larger
irrespective of the cycle [e.g. PtϪCH2ϪC(CH3)2Ϫ, ca. than those of the outer one [e.g.: 3J(PtϪC(3) ϭ 33 Hz,
18Ϫ19 ppm (4 and 5), PtϪCH2ϪCH(CH3)Ϫ, ca. δ ϭ 3J(PtϪC(3Ј)] not observed, 4J(PtϪC(4)
ϭ
45 Hz,
10 ppm (3), and PtϪCH2ϪCH2-, Ϫ1.2 ppm (2)] reflecting 4J(PtϪC(4Ј) not observed] indicating that the pyridine in-
1
only electronic effects. At variance, the JPt,C values are volved in the cyclometallation is more tightly bonded than
higher for the five-membered rings (ca 740 Hz, 2؊4) than the other one, in agreement with the X-ray data.
for the six-membered one (668 Hz in 5).
The crystal structure of 5·CHCl3 consists of the packing
In the analogous palladium compounds the CH2ϪPd res- of [Pt(Lnp)Cl] and CHCl3 molecules in a 1:1 molar ratio
onances are shifted downfield (e.g. Pd(Ltb)Cl,
δ
ϭ
with no unusual van der Waals contacts. Selected bond
parameters are listed in Table 5. An ORTEP view of 5 is
32.8 ppm; Pd(Lnp)Cl, δ ϭ 34.9 ppm).[7a]
In the case of compound 5, taking into account the rarity shown in Figure 2. The Pt atom is in a square-planar coor-
of six-membered cyclometallated rings containing dination with a very slight square-pyramidal distortion. It
1
C(sp3)ϪPt bonds, complete assignment of H and 13C sig- is displaced by only 0.026(1) A from the best plane of atoms
˚
nals was accomplished by 2D NMR studies (COSY and Cl(1), N(1), N(2), and C(13). A comparison can be made
HETCOR experiments, see experimental). The coupling between compound 5 and the corresponding Pd derivative,
Eur. J. Inorg. Chem. 2002, 3336Ϫ3346
3339

A. Zucca, S. Stoccoro, M. A. Cinellu, G. Minghetti, M. Manassero, M. Sansoni
Table 3. 31P NMR spectroscopic data (room temperature, solvent CDCl3, chemical shifts in ppm downfield from external 85% H3PO4)
FULL PAPER
solvent
δ
1JPt,P /Hz
JP,P /Hz
3JPt,P /Hz
[Pt(Let)(PPh3)][BF4]
9
10
11
12
13
14
15
16
20.27
20.36
22.59
8.86
14.49
15.28
15.14
7.69
4038
4066
4453
4581
4020
4412
4414
4421
[Pt(Lip)(PPh3)][BF4]
[Pt(Lnp)(PPh3)][BF4]
[Pt2(Lnp)2(µ-dppm)][BF4]2
[Pt2(Lip)2(µ-dppe)][BF4]2
[Pt2(Lnp)2(µ-dppe)][BF4]2
[Pt2(Lnp)2(µ-dppae)][BF4]2
[Pt(Lnp)(dppm)][BF4]
CD2Cl2
CD2Cl2
CD2Cl2
CD2Cl2
32
94
52
52
83
Ϫ25.09
44.84
32.37
15.22
[Pt(Lnp)(dppe)][BF4]
[Pt(Lnp)(dppae)][BF4]
17
18
1912
4138
4382
˚
Table 4. Selected bond lengths (A) and angles (°) with e.s.d.s in
parentheses for compound 1
molecule A
molecule B
PtϪCl(1)
PtϪCl(2)
PtϪN(1)
PtϪN(2)
Cl(1)ϪPtϪCl(2)
Cl(1)ϪPtϪN(1)
Cl(1)ϪPtϪN(2)
Cl(2)ϪPtϪN(1)
Cl(2)ϪPtϪN(2)
N(1)ϪPtϪN(2)
2.295(2)
2.286(2)
1.998(6)
2.045(5)
84.9(1)
170.8(2)
101.3(2)
93.0(2)
2.300(2)
2.282(2)
1.994(5)
2.054(5)
87.1(2)
170.9(2)
99.7(2)
92.4(2)
172.5(2)
80.3(2)
173.6(2)
80.6(2)
˚
Table 5. Selected bond lengths (A) and angles (°) with e.s.d.s in
parentheses for compound 5
Figure 2. ORTEP view of compound 5. Thermal ellipsoids as in
Figure 1.
PtϪCl(1)
PtϪN(2)
Cl(1)ϪPtϪN(1)
Cl(1)ϪPtϪC(13)
N(1)ϪPtϪC(13)
2.309(1)
2.020(3)
95.5(1)
PtϪN(1)
PtϪC(13)
Cl(1)ϪPtϪN(2)
N(1)ϪPtϪN(2)
N(2)ϪPtϪC(13)
2.116(3)
2.040(4)
175.0(1)
In the case of compound 3, the activation of the methyl
group directly generates a stereogenic carbon atom β to the
metal atom, a result still rare,[7a] even if not unprecedented.
88.1(1)
176.1(1)
79.8(1)
96.7(1)
1
In agreement, the H NMR spectrum shows two diastereo-
topic hydrogens α to the metal atom (δΑ ϭ 2.66, dd; δB
3.07, dd).
ϭ
[PdLnpCl], compound 20.[7a] The PtϪCl, PtϪN(1), and
PtϪN(2) distances, 2.309(1), 2.116(3), and 2.020(3) A, re-
˚
spectively, are slightly shorter than the corresponding ones
˚
involving palladium, 2.314(1), 2.138(2), and 2.046(2) A, re-
Reactivity of the Metallated Species
spectively. This is in keeping with the recent observation
that platinum is slightly smaller than palladium.[7a,14] On
In contrast with the behaviour of the analogous cyclo-
the contrary, the PtϪC(13) bond, 2.040(4) A, is slightly metallated species containing PtϪC(sp2) bonds,[7d] displace-
˚
˚
longer than the PdϪC(13) one, 2.022(3) A. As pointed out ment of the chloride ligand in complexes 2Ϫ5 is easily ac-
in ref.[7a], this can be due to the different packing forces in complished in mild conditions by both neutral (e.g. CO,
the two nonisomorphous crystals. The conformation of the PPh3) and anionic ligands (e.g. CNϪ)
PdϪN(2)ϪC(10)ϪC(11)ϪC(12)ϪC(13) six-membered ring
Derivatives 7؊12 were obtained in good yields in the
is irregular, as previously found in 20, ref.[7a]. Atoms Pt, presence of [BF4]Ϫ and characterised by analytical and
N(2), C(10), and C(13) are approximately planar (maximum spectroscopic methods. In particular the carbonyl derivat-
˚
distances from their best plane are ϩ0.033(3) A for N(2) ives [Pt(L)CO][BF4], 7 and 8, show strong IR absorptions
and Ϫ0.023(4) A for C(10)], with atoms C(11) and C(12) in the region around 2100 cmϪ1 [ν˜max (cmϪ1) ϭ 2107, 7;
˚
˚
lying at Ϫ0.336(4) and ϩ0.471(4) A from this best plane.
2100, 8)].
3340
Eur. J. Inorg. Chem. 2002, 3336Ϫ3346

Metallation of Unactivated Methyl Groups
FULL PAPER
2
3
In the 1H and 13C{1H} NMR spectra of 7, the 2JPt-H and mer case no JP-P has been resolved, but a JPt-P (32 Hz) is
1JPt-C values relevant to the metallated methylene group are observed, whereas in the latter case a JP-P ϭ 52 Hz is pre-
3
4
small (JPt,H ϭ 66 and 52 Hz; JPt-C ϭ 567 Hz) in comparison sent but the JPt,P is negligible. The reaction with dppe has
with those of the chloride species 5 ( J ϭ 89, 79 and 736 Hz, also been carried out on complex 3, [Pt(Lip)Cl]: in this case,
respectively), as previously observed when a strong π ac- due to the presence of a couple of stereogenic centres two
ceptor ligand is cis to the metalϪcarbon bond.[7b]
diastereomers are expected, and this is reflected by the com-
Compounds 9؊11, [Pt(L)(PPh3)][BF4], can be obtained plex pattern of the H NMR spectrum,. It is also worth
1
1
both with a Pt/P 1:1 or 1:2 molar ratio, showing that the noting that in these dinuclear complexes the JPt,P is very
terdentate N,N,C system is rather robust. The 31P NMR different in the six- and five-membered species (1JPt,P
ϭ
1
spectra (see Table 3) are in agreement with a phosphorus 4020 Hz, 13, and JPt,P ϭ 4412 Hz, 14). Compound 15,
trans to a nitrogen atom: the JPt,P values in the five-mem- [(Lnp)Pt(µ-dppae)Pt(Lnp)][BF4]2, at variance with com-
1
bered compounds 9 and 10, as well as in [Pt(Ltb)- pounds 12؊14, is no longer symmetric so that resonances
(PPh3)][BF4],[7b] are in the range 4000Ϫ4100 Hz, whereas in relevant to two different bipy units are present in the H
1
the six-membered species 11 a greater value, 4453 Hz is NMR spectrum (Table 1).
found. Similar values (4400Ϫ4471 Hz) have been observed
in the case of the N,N,C(sp2) six-membered compounds de-
rived from substituted benzylbipyridines[7d] (see Scheme 1,
compounds of type IV, M ϭ Pt).
When the reaction is carried out with a Pt/LЈϪLЈЈ 1:1
molar ratio at least three different species should be consid-
ered: a pentacoordinated, (A), and two square-planar com-
pounds (B and C).
The reactivity of compound 5 with the potentially bident-
ate ligands LЈϪLЈЈ (Ph2P(CH2)PPh2, dppm, Ph2P(CH2)2-
PPh2, dppe, and Ph2P(CH2)2AsPh2, dppae) was studied
with the aim of establishing whether square-planar (mono-
or dinuclear) or five-coordinated complexes were formed.
The reaction was investigated both with a 1:1 and a 2:1
Pt/LЈϪLЈЈ molar ratio: in the first case mononuclear cat-
ionic species of the general formula [Pt(L)(LЈϪLЈЈ)]ϩ were
formed, whereas dinuclear species containing a not so com-
mon unsupported LЈϪLЈЈ bridging unit were isolated in the
second case.
The dinuclear species [(L)Pt(µ-LЈϪLЈЈ)Pt(L)]2ϩ, 12؊15,
1
were characterised mainly on the basis of H and 31P{1H}
NMR spectroscopy. In particular the 31P{1H} NMR spec-
tra of 12؊15 deserve comments: the chemical shifts rule out
a chelating behaviour of the ligands LЈϪLЈЈ and support a
bridging coordination.[15] In the analysis of the 31P NMR
spectra, due to the presence of 31P (100% natural abund-
ance) and 195Pt (33.8% natural abundance) nuclei, four iso-
topomers have to be considered.
In symmetric species, such as 12 and 14, the 31P NMR
spectra should consist of a singlet due to isotopomer I loc-
ated in the centre of a satellite system. If the complex pat-
tern due to IV is ignored owing to its low natural abund-
ance, the satellite system is governed by species IIϪIII,
which in symmetric species, are equivalent. Isotopomers II
and III give rise to an ABX spin system (X ϭ 195Pt) and
the 31P spectrum can be described as being formed by two
AB subspectra.[16] Two different situations are shown by the
dppm and dppe bridging systems, respectively: in the for-
Eur. J. Inorg. Chem. 2002, 3336Ϫ3346
3341

A. Zucca, S. Stoccoro, M. A. Cinellu, G. Minghetti, M. Manassero, M. Sansoni
FULL PAPER
In the case of dppm a type C species, 16, is formed as
indicated, inter alia, by the 31P{1H} NMR spectrum which
shows two different signals, corresponding to a coordinated
1
2
(δ ϭ 7.69 ppm, doublet, JPt,P ϭ 4421, JP,P ϭ 83 Hz), and
to an uncoordinated phosphorus atom (δ ϭ Ϫ25.9 ppm
3
2
1
doublet, JPt,P ϭ 94, JP,P ϭ 83 Hz). The H NMR spec-
trum, as expected, is almost coincident with that of
[Pt(Lnp)(PPh3)]ϩ (e.g. CH2ϪPt, δ ϭ 1.60 ppm, 11; 1.69, 16).
At variance, with dppe a type-B complex is obtained, 17: in
the 31P{1H} NMR spectrum two sets of signals, centred at
δ ϭ 44.84 ppm (1JPt-P ϭ 1912 Hz) and 32.37 ppm, (1JPt-P ϭ
4138 Hz), are consistent with phosphorus atoms trans to a
1
carbon and a nitrogen nucleus, respectively. The H NMR
spectrum is complex, which is likely due to the crowded
environment, all the protons of the four CH2 groups are
not equivalent anymore.
The nature of complex 17 has been confirmed by the res-
olution of the structure.
The crystal consists of the packing of [Pt(Lnp)(dppe)]ϩ
cations, [BF4]Ϫ anions and CH2Cl2 molecules in the molar
ratio 1:1:1 with no unusual van der Waals contacts. Prin-
cipal bond parameters are listed in Table 6. An ORTEP
view of the cation is shown in Figure 3. The Pt atom dis-
plays a square-planar coordination with a slight tetrahedral
distortion, with maximum distances from the best plane of
Figure 3. ORTEP view of compound 17; thermal ellipsoids as in
Figure 1
˚
Ϫ0.084(2) and ϩ0.1035(3) A for atoms C(13) and N(2), re-
˚
spectively. The PtϪP(1) distance, 2.314(1) A, is markedly
˚
the pyridine rings as well as those of the CH2ϪPt groups
are almost superimposable to those of compounds 11 and
16, providing further evidence for the terdentate behaviour
of the N,N,C ligand. In crowded species such as 16؊18, it
is reasonable to deem that either the different size or the
coordinating ability of the As atom with respect to P can
direct the reaction towards a different outcome.
longer than the PtϪP(2) one, 2.209(1) A, because of the
strong trans influence of the C(13) alkyl atom. Also the
˚
˚
PtϪC(13), 2.115(3) A, and PtϪN(2), 2.127(2) A, bond
lengths are elongated by the trans influence of atoms P(1)
and P(2), respectively. The PtϪN(2)ϪC(10)ϪC(11)Ϫ
C(12)ϪC(13) ring is in a boat conformation, with atoms
N(2), C(11), C(12), and C(13) approximately planar [max-
˚
imum distances from their best plane are Ϫ0.068(2) A for
˚
N(2) and ϩ0.074(3) A for C(10)] and atoms Pt and C(11)
˚
Conclusions
lying at Ϫ1.289(1) and Ϫ0.615(3) A from the best plane,
respectively. The P(1)ϪPtϪN(2) angle, 100.9(1)°, is larger
than the P(2)ϪPtϪC(13) one, 92.4(1)°, probably as a result
In this paper we have shown that organoplatinum()
of the steric hindrance of the noncoordinated pyridine ring. compounds containing an N,N,C(sp3) terdentate ligand are
The two pyridine rings are planar and form a dihedral angle readily formed from K2[PtCl4] through a direct C(sp3)ϪH
of 29.2(2)°.
bond activation of an unactivated aliphatic chain. Among
the species obtained, [Pt(Lnp)Cl], having a rare six-mem-
bered cyclometallated N,C(sp3) cycle, and [Pt(Lip)Cl], where
a stereogenic centre has been directly formed through
metallation, are of particular interest. The ligands studied
have different reactivities: with HLet the metallation can be
achieved with difficulty and an adduct species, which can
be regarded as an intermediate in the cyclometallation, has
been isolated in the solid state and studied by X-ray diffrac-
tion. Also the structure of [Pt(Lnp)Cl] has been solved, al-
˚
Table 6. Selected bond lengths (A) and angles (°) with e.s.d.s in
parentheses for cation 17
PtϪP(1)
PtϪN(2)
P(1)ϪPtϪP(2)
P(1)ϪPtϪC(13)
P(2)ϪPtϪC(13)
2.314(1)
2.127(2)
85.5(1)
173.5(1)
92.4(1)
PtϪP(2)
PtϪC(13)
P(1)ϪPtϪN(2)
P(2)ϪPtϪN(2)
N(2)ϪPtϪC(13)
2.209(1)
2.115(3)
100.9(1)
173.0(1)
81.6(1)
The spectroscopic evidences for 18, [Pt(Lnp)(dppae)]- lowing comparisons to be made with the analogous PdII
[BF4], indicate a monodentate P coordination of dppae, as six-membered N,C(sp3) metallacyle. NMR spectroscopic
for dppm, so that the N,N,C coordination environment is data seem to indicate that in the six-membered
retained. The 31P{1H} NMR resonance at δ ϭ 15.22 ppm, [Pt(N,N,C)L]nϩ species (L ϭ neutral, n ϭ 1; or anionic li-
is indicative of a nonchelating behaviour of dppae and the gand, n ϭ 0) the PtϪC bond is weaker and the PtϪL (L ϭ
1JPt,P ϭ 4382 Hz is typical for a P nucleus trans to a pyrid- PR3) bond is stronger than in the five-membered ones, as
1
1
inic nitrogen atom. In the 1H NMR spectrum the signals of indicated by JPt,C in 2؊5 and by JPt,P in 9؊18.
3342
Eur. J. Inorg. Chem. 2002, 3336Ϫ3346

Metallation of Unactivated Methyl Groups
FULL PAPER
tography on silica gel, using a mixture of CH2Cl2/acetone 20:1 as
eluent. Complex 2 was obtained with a 30% yield. M.p. 258Ϫ260
°C (dec). C12H11ClN2Pt (413.8): calcd. C 34.83, H 2.68, N 6.77;
found C 35.44, H 2.80, N 6.50%. IR (Nujol): ν˜ ϭ 1597 s 1556 w,
328 s cmϪ1. FABϩ: m/z ϭ 413 [Mϩ], 378 [M Ϫ Cl], 791 [M2ϪCl].
In the course of the study on the reactivity of these spe-
cies the chloride ligand has been shown to be rather labile
whereas the N,N,C system is rather robust. The chloride
ligand can easily be removed by anionic and neutral li-
gands: in the case of neutral bidentate ligands both mono-
and binuclear species can be obtained. Only in one case
[Pt(L)Cl] (L ؍ Lip, 3; L ؍ Lnp, 5): HL (1.00 mmol) and 2  HCl
(with dppe) has the external nitrogen atom of the terdentate (3.0 mL) were added to an aqueous solution (30 mL) containing
K2PtCl4 (1.00 mmol). The mixture was heated in a water bath until
a colourless solution was obtained and an orange precipitate
formed. The suspension was filtered off, washed with water, ethanol
and diethyl ether and recrystallised from CH2Cl2/Et2O
N,N,C ligand been displaced from the metal to give a
crowded [Pt(N,C)(P,P)]ϩ compound whose structure has
been resolved in the solid state.
All the new species are remarkably stable towards air and
moisture, even in solution, and so all the reactions can be
performed in air.
3: Yield 91% (389 mg), m.p. 245 °C. C13H13ClN2Pt (427.8): calcd.
C 36.50, H 3.06, N 6.55; found C 36.50, H 3.05, N 6.25%. IR
(Nujol): ν˜ ϭ 1596 s, 1552 w, 332 s cmϪ1. FABϩ: m/z ϭ 427 [Mϩ],
392 [M Ϫ Cl], 819[M2ϪCl].
Experimental Section
5: Yield 90% (410 mg), m.p.: 233 °C (dec). C15H17ClN2Pt (455.8)
calcd. C 39.52, H 3.76, N 6.15; found C 39.27, H 3.84, N 6.04%.
IR (Nujol): ν˜ ϭ 1600 s, 1564 w, 328 s cmϪ1. FABϩ: m/z ϭ 455 [Mϩ].
The ligands HL were prepared according to literature methods.[12]
K2[PtCl4] (43.035% Pt) was obtained from Engelhard S.r.l. and
[(DMSO)2PtCl2] was synthesised as described in ref[17]. All the solv-
ents were purified before use according to standard methods.[18]
Elemental analyses were performed with a PerkinϪElmer Ele-
mental Analyser 240B by Mr. A. Canu (Dipartimento di Chimica,
[Pt(Lip)(CN)] (6): Complex 3 (175 mg, 0.41 mmol) was added to a
methanolic solution (25 mL) of KCN (27 mg, 0.41 mmol) whilst
stirring. The mixture was stirred for 1 day, then evaporated to dry-
ness and the solid residue recrystallised from CH2Cl2/Et2O to give
the analytical sample as a yellow solid. Yield 56% (96 mg), m.p.
115 °C. C14H13N3Pt (418.3) calcd. C 40.19, H 3.13, N 10.04; found
C 39.67, H 3.06, N 9.62%. IR (Nujol): ν˜ ϭ 2105 m, 1595 s, 1557
`
Universita di Sassari). Conductivities were measured with a Philips
PW 9505 conductimeter. Infrared Spectra were recorded with a
PerkinϪElmer 983 using Nujol mulls. 1H, 13C{1H} and 31P{1H}
NMR spectra were recorded with a Varian VXR 300 spectrometer
operating at 299.9, 75.4 and 121.4 MHz respectively, and are col-
lected in Table 1Ϫ3.
w cmϪ1
.
[Pt(L)(CO)] [BF4] (L ؍ Lip, 7; L ؍ Lnp, 8): NaBF4 (121 mg,
1.00 mmol) was added to a solution of the relevant [Pt(L)Cl]
(0.25 mmol) in acetone (20 mL) whilst stirring and carbon monox-
ide, at atmospheric pressure, was bubbled through the solution.
After 6 h the solvent was evaporated to dryness and the solid res-
idue was crystallised from CH2Cl2/Et2O.
Chemical shifts are given in ppm relative to internal TMS (1H, 13C)
and external 85% H3PO4 (31P). The 2D experiments were per-
formed by means of standard pulse sequences.
The mass spectrometric measurements were performed on a VG
7070EQ instrument, equipped with a PDP 11Ϫ250 J data system
and operating under positive ion fast atom bombardment (FAB)
conditions with 3-nitrobenzyl alcohol as supporting matrix.
7 Yield 70% (89 mg), m.p.: 235 °C. ΛM (5·10Ϫ4 , acetone) ϭ 138
ohmϪ1 cm2 molϪ1. C14H13BF4N2OPt (507.2): calcd. C 33.16, H
2.58, N 5.52; found C 33.28, H 2.60, N 5.30%. IR (Nujol): ν˜ ϭ
2107 s 1598 s 1563 s 1050 b. FABϩ: m/z ϭ 420 [Mϩ], 392 [M Ϫ CO].
Preparations
[Pt(HLet)Cl2] (1): a) cis-[(DMSO)2PtCl2] (215 mg, 0.51 mmol) was
added to a solution of HLet (92 mg, 0.50 mmol) in CHCl3 (50 mL).
The yellow solution was stirred for 36 h, then evaporated to dry-
ness. The resulting solid was crystallised from CH2Cl2/Et2O to give
the analytical sample as a yellow solid. Yield 85% (191 mg). The
reaction can also be carried out in other solvents (e.g. EtOH).
8: Yield: 76% (102 mg), m.p.182Ϫ184 °C. ΛM (5.10Ϫ4 , acetone) ϭ
157 ohmϪ1 cm2 molϪ1. C16H17BF4N2OPt (535.2): calcd. C 35.91,
H 3.20, N 5.23; found C 35.40, H 3.06, N 5.11%. IR (Nujol): ν˜ ϭ
2100 s, 1600 s, 1560 w, 1050 s cmϪ1
.
[Pt(L)(PPh3)][BF4] (L ؍ Let, 9; L ؍ Lip, 10; L ؍ Lnp, 11): PPh3
(0.22 mmol) and NaBF4 (100 mg, 0.900 mmol) were added to a
solution of the relevant [Pt(L)Cl] (0.20 mmol) in acetone (30 mL)
whilst stirring. The mixture was stirred at room temperature, then
evaporated to dryness and crystallised from CH2Cl2/Et2O.
b) K2[PtCl4] (43.035% Pt, 1.297 g, 2.86 mmol) was dissolved in
H2O (30 mL) and filtered. HLet (523.7 mg, 2.85 mmol) and of 2 
HCl (5 mL) were added to the solution. The mixture was stirred at
room temperature until the solution became colourless. The precip-
itate that formed was filtered, washed with H2O, EtOH and Et2O
and recrystallised from CH2Cl2/Et2O to give the analytical sample.
Yield 30% (384 mg). M.p. 220 °C. C12H12Cl2N2Pt (450.2): calcd. C
32.01; H 2.69; N 6.22 ; found C 31.97; H 2.65; N 6.11%. IR (Nujol):
9: Yield 90% (131 mg), m.p. 253 °C. ΛM (5·10Ϫ4  acetone) ϭ 150
ohmϪ1 cm2 molϪ1. C30H26BF4N2PPt (727.4): calcd. C 49.54, H
3.60, N 3.85; found C 48.93, H 3.55, N 3.71%. FABϩ: m/z ϭ 640
[Mϩ], 378 [M Ϫ PPh3].
ν˜ ϭ 1600 s 1558 w, 1375 s, 335 w cmϪ1
.
10: Yield 76% (113 mg), m.p. 275 °C. ΛM (5·10Ϫ4 , acetone) ϭ
130 ohmϪ1 cm2 molϪ1. C31H28BF4 N2PPt (741.4): calcd. C 50.22,
H 3.81, N 3.78; found C 50.34, H 3.91, N 3.63%. IR (Nujol): ν˜ ϭ
1598 s, 1564 w, 1102 s, 1050br, s. FABϩ: m/z ϭ 654 [Mϩ] 392 [M
Ϫ PPh3].
[Pt(Let)Cl] (2): HLet (184 mg, 1.00 mmol) and 2  HCl (3.5 mL)
were added to an aqueous solution (30 mL) containing K2[PtCl4]
(1.00 mmol) in water. The mixture was heated in a water bath for
1 d: the precipitate that formed was filtered, washed with water,
EtOH and Et2O and recrystallised from CH2Cl2/Et2O. The crude
obtained (362 mg) was a mixture ca. 1:1 of compounds 1 and 2
(NMR criterion). The products were separated by column chroma-
11: Yield: 77% (118 mg), m.p. 263 °C. ΛM (5·10Ϫ4 , acetone) ϭ
150 ohmϪ1 cm2 molϪ1. C33H32BF4N2PPt (769.5): calcd. C 51.51,
Eur. J. Inorg. Chem. 2002, 3336Ϫ3346
3343

A. Zucca, S. Stoccoro, M. A. Cinellu, G. Minghetti, M. Manassero, M. Sansoni
FULL PAPER
H 4.19, N 3.64%; found C 51.26, H 4.09, N 3.65%. IR (Nujol):
(1497.7): calcd. C 45.71, H 4.04, N 3.74 ; found C 46.26, H 4.18,
N 3.71%. IR (Nujol): ν˜ ϭ 1602 s, 1569 w, 1050 br s cmϪ1
ν˜ ϭ 1602 s, 1568 w, 1050 s, 540 w. FABϩ: m/z ϭ 682 [Mϩ].
.
[Pt2(Lnp)2(µ-dppm)] [BF4]2 (12): A mixture containing 5 (42 mg,
0.092 mmol), dppm (17.4 mg, 0.046 mmol) and NaBF4 (43 mg) in
acetone (30 mL) was stirred at room temperature for 4 days, then
evaporated to dryness and recrystallised from CH2Cl2/Et2O, to give
the analytical sample as a yellow solid. Yield: 59% (34 mg), m.p
[Pt2(Lnp)2(µ-dppae)] [BF4]2 (15): A mixture containing 5 (39 mg,
0.085 mmol), dppae (18.8 mg, 0.0425 mmol) and NaBF4 (50 mg) in
acetone (30 mL) was stirred at room temperature for 1 day, then
evaporated to dryness and crystallised from CH2Cl2/Et2O, to give
the analytical sample as a yellow solid. Yield 80% (51 mg), m.p.
250Ϫ255 °C. C56H58AsB2F8N4Pt2P·0.5CH2Cl2 (1499.2): calcd. C
45.26, H 3.97, N 3.74; found C 45.02, H 3.98, N 3.68%.
168 °C (dec.). ΛM (5 10Ϫ4 , acetone) ϭ 260 ohmϪ1 cm2 molϪ1
.
C55H56B2F8N4P2Pt2·0.5CH2Cl2 (1441.2): calcd. C 46.25, H 3.99, N
3.89 ; found C 46.37, H 4.03, N 3.96%. IR (Nujol): ν˜ ϭ 2100 s,
1600 s, 1560 w, 1050 br s cmϪ1. FABϩ: m/z ϭ 1224 [Mϩ], 1311
[Mϩ ϩ BF4].
[Pt(Lnp)(LЈ؊LЈЈ)][BF4] (LЈ؊LЈЈ ؍ dppm, 16, LЈ؊LЈЈ ؍ dppe, 17,
LЈ؊LЈЈ ؍ dppae, 18): NaBF4 (120 mg) was added to an acetone
solution (30 mL) of
5 (103 mg, 0.25 mmol) and LЈϪLЈЈ
[Pt2(L)2(µ-dppe)] [BF4]2 (L ؍ Lip, 13; L ؍ Lnp, 14): dppe
(0.20 mmol) and NaBF4 (150 mg) were added to a suspension of
the relevant [Pt(L)Cl] (0.40 mmol) in acetone (25 mL) whilst stir-
ring. The mixture was stirred for a few hours, then evaporated to
dryness and crystallised by CH2Cl2/Et2O to give the analytical
sample.
(0.25 mmol) whilst stirring. The mixture was stirred for 4 h, then
evaporated to dryness. The solid obtained was crystallised from
CH2Cl2/Et2O to give the analytical sample as a yellow solid.
LЈϪLЈЈ ϭ dppm, 16, pale-yellow. Yield: 90% (201 mg); m.p.
238Ϫ240 °C. C40H39BF4N2P2Pt (891.6): calcd. C 53.88, H 4.41, N
3.14; found C 53.40, H 4.53, N 3.07%.
13: Yield 75% (203 mg); m.p. 280 °C. ΛM (5.10Ϫ4 , acetone) ϭ
202 ohmϪ1 cm2 molϪ1. C52H50B2F8N4PPt2 (1356.7): calcd. C 46.04,
H 3.71, N 4.13; found C 45.74, H 3.74, N 4.01%. (IR (Nujol): ν˜ ϭ
LЈϪLЈЈ ϭ dppe, 17, yellow. Yield: 88% (199 mg). M.p. 182Ϫ5 °C
(dec). ΛM (5 10Ϫ4 , acetone)
ϭ .
133 ohmϪ1 cm2 molϪ1
1598 s 1564 w, 1050 broad cmϪ1
.
C41H41BF4N2P2Pt (905.6): calcd. C 54.38, H 4.56, N 3.09; found
14: (yellow) Yield 93% (279 mg); m.p. 184 °C (dec). ΛM (5 10Ϫ4
, acetone) ϭ 248 ohmϪ1 cm2 molϪ1. C56H58B2F8N4P2Pt2·CH2Cl2
C 54.42, H 4.56, N 3.11%. IR (Nujol): ν˜ ϭ 1600, 1580 w, 1050 s,
540 s cmϪ1
.
Table 7. Crystallographic experimental details
Compound
1
5·CHCl3
17[BF4]·CH2Cl2
Formula
M
Colour
C12H12Cl2N2Pt
450.24
yellow
monoclinic
P21/c (no. 14)
14.909(2)
9.503(1)
17.732(2)
90
99.87(2)
90
2511.2(6)
8
C16H18Cl4N2Pt
575.24
C42H43BCl2F4N2P2Pt
990.57
yellow-orange
triclinic
pale yellow
triclinic
Crystal system
Space group
¯
¯
P1 (no. 2)
P1 (no. 2)
˚
a/A
9.209(1)
10.813(1)
10.980(1)
78.77(1)
65.60(1)
82.07(1)
974.6(2)
2
11.969(1)
13.307(1)
13.659(1)
75.97(1)
83.35(1)
89.67(1)
2095.8(3)
2
˚
b/A
˚
c/A
α/°
β/°
γ/°
3
˚
V/A
Z
F(000)
1680
296
2.38
548
296
1.96
984
296
1.57
T/K
Dc/g cmϪ3
Crystal dimensions (mm)
µ (Mo-Kα)/cmϪ1
Min. and max.transmiss. factors
Scan mode
0.33 ϫ 0.45 ϫ 0.50
117.0
0.81Ϫ1.00
ω
0.16 ϫ 0.27 ϫ 0.44
78.3
0.88Ϫ1.00
ω
0.13 ϫ 0.30 ϫ 0.44
36.3
0.59Ϫ1.00
ω
ω-scan width/°
1.20 ϩ 0.35 tan θ
Frame width/°
0.30
20
2450
0.30
20
2450
Time per frame/s
No. of frames
Detector/sample distance/cm
θ-range/°
Reciprocal space explored
Measured reflections (total, independent)
Rint
5.00
3Ϫ26
full sphere
12214, 4798
0.029
5.00
3Ϫ26
full sphere
32505, 12183
0.026
3Ϫ27
quadrant
5444, 5444
Unique observed reflections with IϾ3σ(I)
Final R and RЈ[a]
No. of variables
Goodness of fit[b]
4239
0.030, 0.037
308
3965
0.023, 0.028
209
10764
0.024, 0.033
496
1.40
0.94
1.19
[a]
2 1/2 [b]
2
R ϭ [Σ(|Fo Ϫ k|Fc||)/ΣFo], RЈ ϭ [Σw(Fo Ϫ k|Fc|)2/ΣwFo ]
.
[Σw(Fo Ϫ k|Fc|)2/(No Ϫ Nv)]1/2, where w ϭ 1/[σ(Fo)]2, σ(Fo) ϭ [σ2(Fo ) ϩ
(0.04Fo2)2]1/2/2Fo, No is the number of observations, Nv the number of variables.
3344
Eur. J. Inorg. Chem. 2002, 3336Ϫ3346

Metallation of Unactivated Methyl Groups
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.
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1 was carried out on an
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362 reflections (for 5·CHCl3 and 17[BF4]·CH2Cl2, respectively)
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[7o]
´ ` ´
A. Fernandez, P. Urıaa, J. J. Fernandez, M.
601, 22Ϫ33.
´
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´
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` ´
M. Crespo, M. Font-Bardıa, S. Perez, X. Solans, J. Or-
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www.ccdc.cam.ac.uk/conts/retrieving.html [or from the Cambridge
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Eur. J. Inorg. Chem. 2002, 3336Ϫ3346