Cationic phenyl and chloro-platinum(II) complexes with cyanamides and cyanoguanidine. X-ray structure of trans-[Pt(Ph)(NCNMe2)(PPh 3)2][BPh4]

Article abstract of DOI:10.1016/S0020-1693(02)00746-6

The phenyl-platinum(II) organocyanamide trans-[Pt(Ph)(NCNR ₂)(PPh₃)₂][BPh₄] (R=Me 1a, Et 1b) or cyanoguanidine cis-[Pt(Ph){NCNC(NH₂)₂}(PPh ₃)₂][BPh₄] (2) complexes have been prepared by treatment of cis-[PtCl₂(PPh₃)₂] in THF with NCNR₂ or NCNC(NH₂)₂, respectively, in the presence of Na[BPh₄], whereas the cyanoguanidine chloro-complex cis-[PtCl{NCNC(NH₂)₂}(PPh₃)₂] [BF₄] (3) has been obtained by using Tl[BF₄] instead of Na[BPh₄]. Complex 3 reacts further with cyanoguanidine, in the presence of Na[BPh₄], to produce the di(cyanoguanidine) cis-[Pt{NCNC(NH₂)₂nf>)₂][BPh ₄]₂ complex 5, whereas the amine complex cis-[PtCl(NH ₂R′)(PPh₃)₂][BF₄] (R′=CH₂C₆H₄Me-4, 4) is formed on reaction of the former with NH₂R′ in CH₂Cl ₂. The X-ray structure of 1a is also reported.

Full text of DOI:10.1016/S0020-1693(02)00746-6

Inorganica Chimica Acta 334 (2002) 395ꢃ402
/
www.elsevier.com/locate/ica
Cationic phenyl and chloro-platinum(II) complexes with cyanamides
and cyanoguanidine. X-ray structure of trans-
[Pt(Ph)(NCNMe2)(PPh3)2][BPh4]
Cristina M.P. Ferreira a, M. Fa´tima C. Guedes da Silva a, Teresa Duarte a,
Joao J.R. Frau´sto da Silva a, Armando J.L. Pombeiro a,*, Rino A. Michelin b,
˜
Vadim Yu. Kukushkin c
a Centro de Qu´ımica Estrutural, Complexo I, Instituto Superior Te´cnico, Av. Rovisco Pais, 1049-001 Lisbon, Portugal
b Dipartimento di Processi Chimici dell’ Ingegneria, Universita` di Padova, Via F. Marzolo 9, 35131 Padua, Italy
c Department of Chemistry, St. Petersburg State University, 198904 Stary Petergof, Russia
Received 4 December 2001; accepted 24 December 2001
Dedicated to Professor Andrew Wojcicki on the occasion of his retirement from the Ohio State University
Abstract
The phenyl-platinum(II) organocyanamide trans-[Pt(Ph)(NCNR2)(PPh3)2][BPh4] (RꢀMe 1a, Et 1b) or cyanoguanidine cis-
/
[Pt(Ph){NCNC(NH2)2}(PPh3)2][BPh4] (2) complexes have been prepared by treatment of cis-[PtCl2(PPh3)2] in THF with NCNR2 or
NCNC(NH2)2, respectively, in the presence of Na[BPh4], whereas the cyanoguanidine chloro-complex cis-
[PtCl{NCNC(NH2)2}(PPh3)2][BF4] (3) has been obtained by using Tl[BF4] instead of Na[BPh4]. Complex 3 reacts further with
cyanoguanidine, in the presence of Na[BPh4], to produce the di(cyanoguanidine) cis-[Pt{NCNC(NH2)2}2(PPh3)2][BPh4]2 complex 5,
whereas the amine complex cis-[PtCl(NH2R?)(PPh3)2][BF4] (R?ꢀCH2C6H4Me-4, 4) is formed on reaction of the former with
/
NH2R? in CH2Cl2. The X-ray structure of 1a is also reported. # 2002 Elsevier Science B.V. All rights reserved.
Keywords: Cyanoguanidine; Cyanamide; Phenylation; Platinum complexes
1. Introduction
[3] or to other substrates (e.g. mono- and di-enes [4],
allyls [5] and acyls [6]) or even as a BPh3 transfer reagent
CSiMe3 (or a
The possible active role of the tetraphenylborate
anion in coordination chemistry has been well recog-
nized and is a matter of current interest from both the
structural and synthetic points of view, with potential
significance in catalysis.
to cyanide [7] or to the cyanosilane NÅ
/
derivative) [8] to produce the isocyanotriphenylborate
ꢁ
CNBPh3 ligand. The metal phenylation in some cases
involves replacement of an halide ligand which normally
requires solvent refluxing conditions, as in the reactions
of Na[BPh4] with cis-[PtCl2(PEt3)2] [9], [RuCl(h5-
The detection (by nuclear Overhauser effects) of
ꢁ
interionic contacts in solution between BPh4 and
C5H5)(CO)2] [10] or [NiX(L)][BPh4] [Xꢀ
/
Cl, Br; Lꢀ
/
some organometallic complexes has been reported [1].
The anion can ligate a metal center in a variety of modes
[2] and can act as a phenylation agent either to the metal
N(C2H4AsPh)3] [11] to give trans-[Pt(Ph)2(PEt3)2],
[Ru(Ph)(h5-C5H5)(CO)2] or [Ni(Ph)L][BPh4], respec-
tively.
In the current study, on attempting the preparation of
di(alkylcyanamide) or di(cyanoguanidine)platinum(II)
complexes on reaction of a THF suspension of cis-
[PtCl2(PPh3)2] with the appropriate cyano-reagent in the
presence of Na[BPh4], we observed the occurrence of
metal phenylation, smoothly and at room temperature,
* Corresponding author. Tel.: ꢂ351-218-419 237; fax: ꢂ351-218-
464 455.
E-mail addresses: pombeiro@ist.utl.pt (A.J.L. Pombeiro),
rino.michelin@unipd.it (R.A. Michelin), kukushkin@vk2100.spb.edu
(V.Y. Kukushkin).
0020-1693/02/$ - see front matter # 2002 Elsevier Science B.V. All rights reserved.
PII: S 0 0 2 0 - 1 6 9 3 ( 0 2 ) 0 0 7 4 6 - 6

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C.M.P. Ferreira et al. / Inorganica Chimica Acta 334 (2002) 395ꢃ402
/
to give the corresponding phenylated mono(cyano-
reagent) complexes. Their syntheses and properties, as
well as of a related chloro-cyanoguanidine complex and
further reactions are now described.
This work also provides a contribution to the devel-
opment of the chemistry of platinum complexes with
group of a cyanoguanidine ligand at the intermediate
cis-[Pt{NCNC(NH2]2}2(PPh3)2]2ꢂ, combined with de-
protonation and chelation of the guanidine unit.
It is noteworthy to mention that in reactions (1) and
(2) the metal phenylation proceeds smoothly at room
temperature (for ca. 5 days) in preference to the
replacement of both chloride ligands by two dialkylcya-
namides, with formation of the phenylated complexes 1
and 2 instead of the expected di(alkylcyanamide)
products. The use of a lower excess of Na[BPh4] and
of the cyanamide, and shorter reaction times, results in
the formation of the known [12] mono(alkylcyanamide)
complexes cis-[PtCl(NCNR2)(PPh3)2][BPh4].
cyanamides and cyanoguanidine ligands [12ꢃ14], which
/
is still underdeveloped in spite of the interest of these
unsaturated nitrogen-compounds in synthesis [15,16]
and their significance in biology [17,18]. It also falls
within our interest on the extension to platinum of the
investigation of the coordination chemistry of cyana-
mides at different transition metal centers namely of Mo
[19,20], Re [21ꢃ
on the activation of small molecules of synthetic and
biological importance [25ꢃ52].
/
23] and Fe [24], and, in a broader sense,
A cis-to-trans isomerization also occurs in reactions
(1), as observed in the formation of trans-
/
[Pt(Ph)L(PR3)2]ꢂ (Lꢀ
/
MeOH, H2O; RꢀMe, Et, Ph)
/
[54] from the reaction of [BPh4]ꢁ with cis-
[PtL2(PR3)2]2ꢂ. However, the cis geometry is mainly
preserved in the case of the cyanoguanidine reaction (3),
although a small amount of the trans isomer was
detected by 31P {1H} NMR (see below).
2. Results and discussion
2.1. Syntheses
In cis-[PtCl{NCNC(NH2)2}(PPh3)2][BF4] (3), the cy-
anoguanidine ligand is displaced by 4-methylbenzyla-
Treatment of a THF solution of cis-[PtCl2(PPh3)2]
with an excess of the organocyanamide NCNR2 (Rꢀ
/
mine NH2R? (R?ꢀCH2C6H4Me-4), in CH2Cl2, at room
/
Me or Et) (sixfold molar ratio) or of the cyanoguanidine
NCNC(NH2)2 (fourfold molar ratio), in the presence of
Na[BPh4] (added in the same molar amount as that of
the cyano-reagent), resulted, at room temperature, in the
formation of the corresponding complexes trans-
temperature, to yield (reaction 4, Scheme 1) the corre-
sponding amine complex cis-[PtCl(NH2R?)(PPh3)2][BF4]
(4), although no reaction was detected with p-toluidine
under similar experimental conditions. Moreover, no
nucleophilic addition by the amine or by the alcohol to
the organo cyanamide or cyanoguanidine ligands was
observed for any of the mono-cationic complexes 1, 2, or
3, in contrast with the ready methanol addition quoted
[13] for the ligated cyanoguanidine at the dicationic
complex cis-[Pt{NCNC(NH2)2}2(PPh3)2][BPh4]2 with a
stronger activation towards such a type of reaction.
The remaining chloride ligand in complex 3 undergoes
further replacement by cyanoguanidine upon prolonged
(5 days) stirring of a THF suspension with the latter
reagent (in a twofold molar ratio), in the presence of
Na[BPh4], to give, although in low yield, cis-
[Pt{NCNC(NH2)2}(PPh3)2][BPh4]2 (5) (reaction 5,
Scheme 1). However, the latter complex can be obtained
[Pt(Ph)(NCNR2)(PPh3)2][BPh4] (RꢀMe 1a, Et 1b) or
/
cis-[Pt(Ph){NCNC(NH2)2}(PPh3)2][BPh4] (2) (Scheme
1, reactions 1 or 2, respectively).
In these reactions, not only the expected chloride
replacement by the cyano-species has occurred, but also
its unusual substitution for a phenyl group originated
from tetraphenylborate with the conceivable concomi-
tant formation of the THF×
/
BPh3 Lewis acidꢃbase
/
adduct. Even diphenylation was detected, in the case
of the reaction with NCNMe2, affording, besides 1a, the
known [53] diphenylated product trans-[Pt(Ph)2(PPh3)2].
When Tl[BF4] was used as the chloride abstractor
instead of Na[BPh4], simple halide replacement was
observed and cis-[PtCl{NCNC(NH2)2}(PPh3)2][BF4] (3)
was the product from the reaction of cis-[PtCl2(PPh3)2]
with cyanoguanidine (reaction 3, Scheme 1). A com-
pound, initially formulated [12] in an analogous way
but with the [BPh4]ꢁ counter-ion, i.e. cis-
[PtCl{NCNC(NH2)2}(PPh3)2][BPh4], was isolated upon
addition of MeOH to an acetone solution of the product
from the prolonged reaction of cis-[PtCl2(PPh3)2] with
cyanoguanidine in THF, in the presence of Na[BPh4].
However, it should be reformulated (on the basis of
identical IR and NMR spectroscopic data and elemental
in
a better yield and more directly from cis-
[PtCl2(PPh3)2], on its reaction with cyanoguanidine in
the presence of Na[BPh4] following a reported [13]
procedure. Nevertheless, as shown in this study, metal
phenylation then also occurs to produce 2 (reaction 2,
Scheme 1).
2.2. Characterization
The complexes obtained in this study have been
characterized by IR and multinuclear NMR spectro-
scopies, FAB MS, elemental analysis and, in the case of
1a, also by X-ray diffraction. The data for complex 5
analysis)
as
Pt-{NHC(OMe)Ä
upon nucleophilic addition of the alcohol to the cyano
the
NC(NH2)Ä
azametallacycle
cis-[(PPh3)2-
ꢀ
ꢁ
/ /
/
/
NH}][BPh4] [13] formed

C.M.P. Ferreira et al. / Inorganica Chimica Acta 334 (2002) 395ꢃ
/
402
397
Scheme 1.
have already been reported [13] and are not discussed
again.
2.2.1. Molecular structure
The molecular structure of trans-[Pt(Ph)(NCNMe2)-
(PPh3)2][BPh4] (1a) has been obtained by X-ray diffrac-
tion and is depicted in Fig. 1 and selected bond lengths
and angles are given in Table 1. In the complex cation,
the Pt atom has a square-planar environment with the
phenyl ligand trans to the organocyanamide and the two
phosphines trans to each other. The PtÃ
/
N(1) distance,
˚
˚
2.100(5) A, is longer than the average value, 1.980(2) A,
quoted [55] for the PtÃN(nitrile) bond lengths in square-
planar Pt(II) complexes, in particular that observed,
/
˚
2.048(6) A [12], for trans-[Pt(CF3)(NCNEt2)(PPh3)2]-
N bond agrees with the
strong trans influence of the phenyl ligand as discussed
[BF4]. Such an elongated PtÃ
/
below.
Within the linear dimethyl cyanamide ligand, the
amine N atom displays a distorted trigonal-planar
geometry instead of the pyramidal one that is observed
Fig. 1. Molecular structure of the complex cation trans-
[Pt(Ph)(NCNMe2)(PPh3)2]ꢂ (1a).
[56] in the uncoordinated organocyanamide. The N(2)Ã
/
˚
C(7) distance, 1.260(12) A, is shorter than the corre-
mide behaves as an effective s and p electron-donor to
the cationic Pt(II) center.
˚
sponding one in the free dimethylcyanamide, 1.351 A
[56], indicating a double bond character and a signifi-
cant contribution of the resonance form (a), as observed
e.g. for trans-[Pt(CF3)(NCNEt2)(PPh3)2][BF4] [12] and
[Cr(NCNEt2)(CO)5] [57]. Hence, the dimethyl-cyana-

398
C.M.P. Ferreira et al. / Inorganica Chimica Acta 334 (2002) 395ꢃ402
/
Table 1
influence (see also above) of the ligated phenyl com-
pared with the nitrogen ligands. Complex 2, in CDCl3
solution, appears to be slightly contaminated (ca. 6%)
with the trans isomer, as shown by the detection of the
˚
Selected bond lengths (A) and angles (8) for trans-
[Pt(Ph)(NCNMe2)(PPh3)2][BPh4]×Et2O (1a) with e.s.d. in parentheses
Bond lengths
Pt(1)ÃN(1)
Pt(1)ÃC(1)
Pt(1)ÃP(1)
Pt(1)ÃP(2)
N(1)ÃC(7)
N(2)ÃC(7)
N(2)ÃC(8)
N(2)ÃC(9)
2.100(5)
2.016(5)
2.3105(13)
2.3080(13)
1.107(9)
1.260(12)
1.241(19)
1.54(2)
corresponding singlet at a chemical shift [d ꢁ121.56 rel.
P(OMe)3] and with JPPt (3098.0 Hz) that are comparable
with those exhibited by the trans phenylated complexes
/
C(1)ÃC(2)
C(2)ÃC(3)
C(3)ÃC(4)
C(4)ÃC(5)
C(5)ÃC(6)
C(1)ÃC(6)
1.387(6)
1.401(7)
1.371(9)
1.370(9)
1.381(7)
1.395(7)
1a or 1b [d ꢁ
/
121.44 or ꢁ123.04, JPPt 3061.4 or 3067.8
/
Hz, respectively].
The presence of the phenyl ligand in complexes 1 and
1
2 is clearly recognized by the detection, in the H NMR
Bond angles
spectrum (Table 3), at a higher field (d ca. 6.3ꢃ6.9) than
/
P(1)ÃPt(1)ÃP(2)
P(1)ÃPt(1)ÃN(1)
P(1)ÃPt(1)ÃC(1)
N(1)ÃPt(1)ÃC(1)
P(2)ÃPt(1)ÃN(1)
P(2)ÃPt(1)ÃC(1)
Pt(1)ÃN(1)ÃC(7)
173.26(4)
89.09(13)
90.36(14)
178.20(18)
88.54(13)
92.19(13)
173.9(6)
Pt(1)ÃC(1)ÃC(2)
Pt(1)ÃC(1)ÃC(6)
N(1)ÃC(7)ÃN(2)
C(7)ÃN(2)ÃC(9)
C(8)ÃN(2)ÃC(9)
C(7)ÃN(2)ÃC(8)
120.3(3)
121.5(3)
176.2(12)
112.9(13)
106.9(14)
137.0(12)
the bulky of the phenyl resonance of the PPh3 ligand
and the [BPh4]ꢁ counter-ion, of a set of two triplets and
one doublet (3JHH
platinum satellites (3JHPt
ꢀ
/
6ꢃ
/
8 Hz), the latter with the
ꢀ
/
53ꢃ59 Hz), with the ex-
/
pected integration, assigned to the meta, para and ortho
protons, respectively, of the ligated Ph. The 13C {1H}
NMR spectra (Table 3) confirm the existence of this
ligand, by disclosing, for the trans complexes 1a and 1b,
the expected triplet (2JCP ca. 8 Hz, d ca. 130) assigned to
the ipso-C.
The N(1)Ã
/
C(7) bond length of the cyano group,
˚
˚
1.107(9) A, is shorter than that known, 1.180 A [56],
C)
coordination shift to a higher wavenumber (see below).
for free NCNMe2, being consistent with the IR n(NÅ
/
The other carbon resonances of this ligand are
detected as singlets at higher fields (d 130ꢃ123), which
/
split into the expected doublets (JCH ca. 160 Hz) in the
proton-undecoupled 13C NMR spectra. The cyano-
carbons of the dialkylcyanamides resonate as singlets
at d ca. 123.
The resonances of the various types of aromatic
carbons of the PPh3 ligands have also been assigned,
by comparison with those [12] of the related complexes
2.2.2. Spectroscopic data
Complexes 1ꢃ
pellets) in the range 2260ꢃ
approximately 75ꢃ
25 cmꢁ1 than those observed for
/
3 exhibit strong n(NÅ
/
C) bands (KBr
/
2210 cmꢁ1, higher by
/
the free cyano-compounds. They are comparable with
those shown [12] by the related complexes trans-
[Pt(CF3)(L)(PPh3)2][BF4] [Lꢀ
or NCNEt2] and trans-[PtCl(NCNR2)(PPh3)2][BPh4]
(RꢀMe or Et).
/
NCNC(NH2)2, NCNMe2
trans-[Pt(CF3)(L)(PPh3)2][BF4] [Lꢀ
Et), NCNC(NH2)2], at chemical shifts which increase in
the order ipso (d ca. 129ꢃ130), para (d ca. 132ꢃ134)
and meta (d ca. 134.6ꢃ136.6), with a substantial higher
field complexation shift for the ipso carbons as observed
[12] e.g. for trans-[Pt (CF3)(L)(PPh3)2][BF4] [Lꢀ
/
NCNR2 (Rꢀ/Me,
/
/
/
For the cyanoguanidine complexes 2 and 3, other
broad and medium or weak intensity bands in the
/
approximately 3500ꢃ
n(NH) whereas additional strong bands at 1640ꢃ
cmꢁ1 are assigned to d(NH) and/or n(CÄ
N).
The cis geometry for complexes 2ꢃ4 is suggested by
strong band at approxi-
/
3000 cmꢁ1 range, are due to
/
/1550
NCNC(NH2)2, NCNH2, NCNMe2 or NCNEt2].
For the complex 3, they appear as doublets (1JCP
/
ꢀ
/
/
2
56.8 or 64.7 Hz, JCP
4
11.6 Hz, JCP
ꢀ
/
ꢀ
/
2.5 Hz and
the detection of a mediumꢃ
/
3JCP
1b with a trans geometry, they consist (with the
ꢀ/10.4 or 11 Hz, respectively), whereas for 1a and
mately 540 cmꢁ1 which is known [58] to be diagnostic of
the cis arrangement of the two phosphine ligands. This
geometry is confirmed by their 31P {1H} NMR spectra
(Table 2) which exhibit two distinct resonances i.e. two
exception of the para carbons resonance which is a
singlet) of triplets due to virtual coupling to the two
1
trans 31P nuclei [1/2j JCPꢂ3
/
JCPjꢀ
/
28.5 Hz, 1/
3
doublets [2JPP
[2JPP
16ꢃ19 Hz] and an higher field unresolved
ꢀ18.2 Hz for 4] or a lower field doublet
/
2j JCPꢂ4
/
JCPjꢀ
/
5.1 or 5.9 Hz, and 1/2j JCPꢂ5
/
JCPjꢀ
/
2
ꢀ
/
/
resonance (for 2 and 3), with the expected 195Pt
satellites.
6.2 Hz, for the ipso-, ortho- and meta- carbons,
respectively].In the 13Cꢃ1
H coupled spectra, those
resonances split into the expected (or not fully resolved)
/
1
For the non-phenylated cis complexes 3 and 4, JPPt
patterns.
falls in the 3747ꢃ3234 Hz range, but, for the phenylated
/
In the FAB MS spectra of all the complexes, the
molecular ions Mꢂ are clearly detected, as well as the
corresponding fragments derived from the loss of the
cis complex 2, that corresponding to the P-nucleus trans
to the phenyl ligand is much lower, 1564 Hz (whereas
that for the other phosphorus is 4459 Hz) similarly to
what has been quoted [54] for cis-[Pt(Ph)L(PMe3)2]ꢂ
nitrogen-ligand, [M-L]ꢂ [Lꢀ
/
NCNR2 (Rꢀ
/
Me 1a, Et
1b), NCNC(NH2)2 (2 or 3) or NH2CH2C6H4Me-4 (4)].
(LꢀMeOH or H2O), indicating a much stronger trans
/

C.M.P. Ferreira et al. / Inorganica Chimica Acta 334 (2002) 395ꢃ
/
402
399
Table 2
1H and 31P {1H} NMR data for trans-[Pt(Ph)(NCNR2)(PPh3)2][BPh4] (RꢀMe 1a or Et 1b), cis-[Pt(Ph){NCNC(NH2)2}(PPh3)2][BPh4] (2), cis-
[PtCl{NCNC(NH2)2}(PPh3)2][BF4] (3) and cis-[PtCl(NH2CH2C6H4Me-4)(PPh3)2][BF4] (4)
Complex
1H
31P {1H}
a
b
a
b
b
d
Integ.
J
Assign.
d
2JPP
1JPPt
c
1a
7.39ꢃ
7.03 t
6.88 t
/
7.13 m
38H
8H
4H
2H
1H
2H
6H
38H
8H
4H
2H
1H
2H
4H
6H
50H
2H
2H
1H
1H
1H
2H
30H
2H
2H
30H
2H
2H
2H
3H
1H
PPh3ꢂHo (BPh4ꢁ
)
ꢁ121.44 s
3061.4
3JHHꢀ7.4
3JHHꢀ7.4
3JHHꢀ8.0
3JHHꢀ6.3
3JHHꢀ7.2
Hm (BPh4ꢁ
)
Hp (BPh4ꢁ
Ho (Ph)
Hp (Ph)
Hm (Ph)
N(CH3)2
)
6.57 d
6.47 t
6.30 t
1.51 s
d
1b
7.49ꢃ
/
7.27 m
PPh3ꢂHo (BPh4ꢁ
)
ꢁ123.04 s
3067.8
7.01 t
6.86 t
3JHHꢀ7.2
Hm (BPh4ꢁ
)
3JHHꢀ7.1
Hp (BPh4ꢁ
Ho (Ph)
Hp (Ph)
Hm (Ph)
)
6.59 d
6.45 t
6.27 t
2.12 q
0.48 t
3JHHꢀ7.2 (3JHPtꢀ52.8)
3JHHꢀ7.4
3JHHꢀ7.5
3JHHꢀ7.4
N(CH2CH3)2
N(CH2CH3)2
PPh3 ꢂ (BPh4ꢁ
Ho (Ph)
3JHHꢀ7.4
2
7.79ꢃ
/
6.96 m, br
)
ꢁ124.82 d
ꢁ129.17 s, br
16.0
1563.84
4458.58
6.87 d
6.54 t
3JHHꢀ7.2 (3JHPtꢀ59.0)
3JHHꢀ7.3
Hm (Ph)
Hp (Ph)
6.45 t
5.37 s
3JHHꢀ7.3
NCNC(NH2)2
NCNC(NH2)2
NCNC(NH2)2
PPh3
3.78 s, br
3.57 s, br
e
3
7.63ꢃ
/
7.24 m, br
ꢁ131.33 d
ꢁ136.64 s, br
19.3
3583.1
3731.6
7.09 s, l
6.58 s, l
C(NH2)2
C(NH2)2
4
7.52ꢃ
/
7.20 m
PPh3
ꢁ127.95 d
ꢁ136.06 d
18.2
18.2
3747
3234
7.12 d
6.81 d
7.5
7.5
NH2CH2C6H4CH3
NH2CH2C6H4CH3
NH2CH2C6H4CH3
NH2CH2C6H4CH3
NH2CH2C6H4CH3
3.94 s, br
2.32 s, br
1.71 s,br
a
In CD2Cl2 unless otherwise stated; d values in ppm relative to SiMe4 (1H) and P(OMe)3 31P).
(
In Hz.
b
c
In CDCl3.
In CDCl3.
d
e
1H spectrum in DMSO-d6; oꢀorto; mꢀmeta; pꢀpara; sꢀsinglet; dꢀdoublet; tꢀtriplet; qꢀquartet; mꢀmultiplet; brꢀbroad.
3. Experimental
3.1. Preparation of complexes trans-[Pt(Ph)(NCNR2)-
(PPh3)2][[BPh4] (RꢀMe 1a, Et 1b)
/
All reactions were carried out under dinitrogen, by
using standard vacuum and inert gas flow techniques.
The solvents were dried by standard procedures and
freshly distilled before use. IR spectra were recorded on
a Bio Rad FTS 3000 MX instrument and NMR spectra
on a Varian Unity 300 spectrometer. Positive-ion FAB
mass spectra were obtained on a Trio 2000 instrument
by bombarding 3-nitrobenzyl alcohol (NBA) matrixes of
A suspension of cis-[PtCl2(PPh3)2] (0.15 g, 0.19 mmol)
in THF (30 ml) was treated with NCNR2 (91.5 ml, 1a;
132.4 ml, 1b; 1.14 mmol) and Na[BPh4] (0.390 g, 1.14
mmol), and left stirred at room temperature (r.t.) for
approximately 5 days. It was then filtered and the
solvent removed in vacuo. Addition of CH2Cl2 (10 ml)
to the residue followed by filtration (removal of sodium
salts), concentration in vacuo and addition of Et2O
resulted in the precipitation of complex 1a or 1b as a
white microcrystalline solid which was filtered off,
washed with Et2O and dried in vacuo (ca. 0.135 g,
the samples with 8 keV (ca. 1.28ꢄ
105 J) Xe atoms.
/
Mass calibration for data system acquisition was
achieved using CsI. Elemental analyses were carried
out at the Laborato´rio de Ana´lises of the Instituto
Superior Te´cnico. The complex cis-[PtCl2(PPh3)2] was
prepared by a published method [59], whereas the other
reagents were purchased from Aldrich.
60% yield). IR (KBr pellet, cmꢁ1): n(NÅ
/C) 2245 (s), 1a,
2250 (s), 1b. Anal. Calc. for 1a, C69H61N2P2BPt: C 69.9;
H 5.1; N 2.4. Found: C 69.8; H 5.1, N 2.6%. For 1b,

400
C.M.P. Ferreira et al. / Inorganica Chimica Acta 334 (2002) 395ꢃ402
/
Table 3
13C {1H} and 13C NMR data 1H and 31P {1H} NMR data for trans-[Pt(Ph)(NCNR2)(PPh3)2][BPh4] [R2ꢀMe2 (1a) ou Et2 (1b) and cis-
[PtCl{NCNC(NH2)2}(PPh3)2][BF4] (3)
Complex
d
13C {1H}
13C
1JCH (Hz)
Assign.
a
ꢁ
1a
164.83
136.89
134.64
132.78
132.01
129.37
128.95
128.84
128.57
126.14
123.66
123.13
122.22
39.06
q
(1JCBꢀ49.4 Hz)
q,br
dm
dm
n.o
dm
dm
dm
dm
n.o
dm
s,br
dm,br
dt
Ci BPh4
ꢁ
s
157.8
157.5
Cm BPh4
Cm PPh3
Ci Ph
t [1/2(3JCPꢂ5JCP)ꢀ6.2 Hz]
t (2JCPꢀ8.5 Hz)
s
161.2
163.0
159.3
159.3
Cp PPh3
Co PPh3
Ph
t [1/2(2JCPꢂ4JCP)ꢀ5.1 Hz]
s
s
Ph
Ci PPh3
t [1/2(1JCPꢂ3JCP)ꢀ28.6 Hz]
ꢁ
s
s
s
s
155.0
Co BPh4
NCN(CH3)2
159.9
156.3 (2JCPꢀ7.9 Hz)
142.4
Ph
Cp BPh4
ꢁ
s
q
NCN(CH3)2
ꢁ
a
1b
164.95
136.99
134.70
132.07
129.72
129.40
128.99
128.84
128.75
126.07
123.11
122.36
122.18
45.82
q
s
(1JCBꢀ49.5 Hz)
q,br
dm
dm
dm
n.o
dm
dm
dm
t,br
dm
dm
s,br
dt
Ci BPh4
Cm BPh4
ꢁ
158.7
169.1
162.9
t [1/2(3JCPꢂ5JCP)ꢀ6.2 Hz]
Cm PPh3
Cp PPh3
Ci Ph
s
t (2JCPꢀ8.1 Hz)
t [1/2(2JCPꢂ4JCP)ꢀ5.9 Hz]
163.3
159.9
159.9
Co PPh3
Ph
Ph
s
s
t [1/2(1JCPꢂ3JCP)ꢀ28.5 Hz]
Ci PPh3
Co BPh4
a
ꢁ
q
s
s
s
s
s
s
(2JCBꢀ2.7 Hz)
152.6
159.9
Ph
NCN(CH2CH3)2
156.3 (2JCHꢀ7.3 Hz)
142.5
127.8
Cp BPh4
ꢁ
dt
dq
NCN(CH2CH3)2
NCN(CH2CH3)2
NCNC(NH2)2
Cm (PPh3)
13.27
b
3
164.72
136.58
135.96
133.89
133.49
131.19
130.66
130.16
129.37
129.22
s
d [3JCPꢀ10.4 Hz]
d [3JCPꢀ11.0 Hz]
d [4JCPꢀ2.5 Hz]
d [4JCPꢀ2.5 Hz]
s. f
d [2JCPꢀ11.6 Hz]
d [2JCPꢀ11.6 Hz]
d [1JCPꢀ56.8 Hz]
d [1JCPꢀ64.7 Hz]
dm
dm
dm,br
dm,br
n.o
dm
dm
n.o
n.o
159.3
162.3
160.5
162.9
Cm? (PPh3)
Cp (PPh3)
Cp? (PPh3)
NCNC(NH2)2
Co (PPh3)
Co? (PPh3)
163.9
162.1
Ci (PPh3)
Ci? (PPh3)
Spectra recorded in CDCl3 unless otherwise stated; d values in ppm relative to SiMe4; iꢀipso; oꢀorto; mꢀmeta; pꢀpara; sꢀsinglet;
dꢀdoublet; tꢀtriplet; qꢀquartet; dmꢀdoublet of multiplets; dtꢀdoublet of triplets; dqꢀdoublet of quartets; brꢀbroad; n.o.ꢀnot observed.
Quartet with relative intensities 1:1:1:1.
a
b
In CD2Cl2.
C71H65N2BP2Pt: C 69.9; H 5.3; N 2.3. Found: C 69.0; H
5.3; N 2.3%.
as a white solid which was filtered off, washed with Et2O
and dried in vacuo (68 mg, ca. 30% yield). IR (KBr
pellet, cmꢁ1): n(NH) 3460 (m,br), 3350 (m,br); n(NÅ
/
C)
C) 1620 (m,br) 1550 (s,br).
Anal. Calc. for C92H79N4B2P2Pt: C 64.5; H 4.8; N 4.4.
Found: C 63.8; H 4.9; N 4.6%.
2210 (s); d(NH) and/or n(NÄ
/
3.2. Preparation of cis-
[Pt(Ph){NCNC(NH2)2}(PPh3)2][BPh4] (2)
A suspension of cis-[PtCl2(PPh3)2] (0.15 g, 0.19 mmol)
with NCNC(NH2)2 (0.063 g, 0.76 mmol) and Na[BPh4]
(0.26 g, 0.76 mmol) in THF (40 ml) was stirred at r.t. for
5 days and thereafter filtered and the solvent removed in
vacuo. CH2Cl2 (10 ml) was added to the residue, the
solution filtered (removal of the sodium salts), concen-
trated in vacuo and Et2O added. Complex 2 precipitated
3.3. Preparation of cis-
[PtCl{NCNC(NH2)2}(PPh3)2][BF4] (3)
A suspension of cis-[PtCl2(PPh3)2] (0.20 g, 0.25 mmol)
in THF (30 ml) at r.t. with a slight excess of
NCNC(NH2)2 (1:1.1) and of Tl[BF4] (1:1.1) was stirred

C.M.P. Ferreira et al. / Inorganica Chimica Acta 334 (2002) 395ꢃ
/
402
401
for 5 h. The solution was then filtered and the filtrate
was taken to dryness. CH2Cl2 (ca. 10 ml) was added to
the residue, the solution filtered (removal of the thallium
salts) and concentrated in vacuo. Dropwise addition of
Et2O led to the formation of an oily residue which was
isolated by decantation of the supernatant solution.
were obtained from 10 043 reflections measured, 9362
0.0172). Final wR(F2)ꢀ
independent (Rint 0.0959,
R1ꢀ0.0374. Intensity data were collected using a
Enraf-Nonius CAD4 diffractometer in the range 3.05ꢃ
59.978 with index ranges ꢁ165h 516, 05k 518,
305l 51. Structure was solved by direct methods
using SHELXS-97 [60] program and refined with SHELXL-
ꢀ
/
/
/
/
/
/
/
/
/
ꢁ
/
/
/
Addition of Et2O followed by application of the freezeꢃ
/
thaw technique and vigorous stirring resulted in the
formation of a white powder of compound 3 which was
filtered off and dried in vacuo (150 mg, ca. 50% yield).
IR (KBr pellet, cmꢁ1): n(NH) 3460 (m,br), 3360 (m,br);
97 [61] with the WinGX graphical user interface [62].
The maximum and minimum peaks in the final differ-
ꢁ3
˚
1.13 e A
ence electron density map were of 1.03 and ꢁ
/
located in the immediate vicinity of the platinum atom.
n(NÅ
/
C) 2260 (s,br), 2200 (s,br); d(NH) 1640 (m,br)
1550 (s,br). Anal. Calc. for C38H34N4B2F4P2Pt: C 49.3;
H 3.7; N 6.1. Found: C 49.7; H 3.8; N 5.7%.
4. Supplementary material
3.4. Preparation of cis-[PtCl(NH2R?)(PPh3)2][BF4]
Crystallographic data (excluding structure factors) for
the structure reported in this paper have been deposited
with the Cambridge Crystallographic Data Centre as
supplementary publication no. CCDC-176397. Copies
of the data can be obtained free of charge on application
to CCDC, 12 Union Road, Cambridge CB2 1EZ, UK
(R?ꢀCH2C6H4Me-4 4)
/
4-MeC6H4CH2NH2 (25.8 ml, 0.22 mmol) was added
to a solution of cis-[PtCl{NCNC(NH2)}(PPh3)2] (3)
(0.10 g, 0.11 mmol) in CH2Cl2 (20 ml) which was then
stirred overnight at r.t., whereafter it was filtered and
concentrated in vacuo. Addition of Et2O resulted in the
precipitation of complex 5 as a white solid which was
filtered off and dried in vacuo (48 mg, 45% yield). IR
(KBr pellet, cmꢁ1): n(NH) 3280 (w,br), 3220 (w,br);
d(NH) 1570 (w). Anal. Calc. for C44H41NBP2ClF4Pt: C
54.8; H 4.3; N 1.5. Found: C 54.4; H 4.9; N 1.3%.
(fax:
ac.uk).
ꢂ44-1223-336-033; e-mail: deposit@ccdc.cam.
/
Acknowledgements
We thank Mr. Indale´cio Marques for the FAB-MS
spectra and the Laborato´rio de Ana´lises of the I.S.T.
(Dr. Maria Caˆndida N. Vaz) for the elemental analyses.
The work has been partially supported by the Founda-
tion for Science and Technology (Portugal) and the
ICCTI (Portugal)/CNR (Italy) cooperation programme.
3.5. Preparation of cis-
[Pt{NCNC(NH2)2}2(PPh3)2][BPh4]2 (5)
A THF (20 ml) solution of cis-[PtCl{NCNC(NH2)2}-
(PPh3)2][BF4] (3) (0.050 g, 0.054 mmol) was treated with
NCNC(NH2)2 (0.009 g, 0.10 mmol) and Na[BPh4]
(0.037 g, 0.10 mmol) and the mixture stirred for
approximately 5 days whereupon the solution was
filtered and the solvent removed in vacuo. Extraction
with CH2Cl2 (7 ml) followed by filtration and addition
of Et2O led to the separation of complex 5 as a white
solid which was filtered off, washed with Et2O and dried
in vacuo (ca. 20% yield). The complex can be prepared,
in a more direct way and with a better yield (40%), by
starting from cis-[PtCl2(PPh3)2] instead of 3, following a
previously reported [13] procedure. IR (KBr pellet,
cmꢁ1): n(NH) 3460(m,br), 3380 (m,br), 3060 (m,br),
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