Synthesis and characterization of novel dinuclear and cationic cyclobutadiene platinum complexes

Article abstract of DOI:10.1016/S0022-328X(98)00873-0

Reactions of the cyclobutadiene platinum complexes [PtCl₂(C₄R₄)] (R=Me 1a, R=Et 1b) with diphosphines Ph₂PPPh₂ (=-CC- (dppa), -CH₂- (dppm), -(CH₂)₂- (dppe), -(CH₂)₃- (dppp), -(CH₂)₄- (dppb)) in a 2:1 molar ratio result in formation of novel binuclear cyclobutadiene platinum complexes [{PtCl₂(C₄R₄)}₂(μ-Ph ₂PPPh₂)] (R=Me 2, Et 3). In contrast, reactions in equimolar ratio lead to formation of cationic complexes with dppe, dppp and dppb [PtCl(C₄R₄){Ph₂P(CH₂) _nPPh₂}]Cl (n=2-4, R=Me 5, Et 6). Complexes 2, 3 and 5, 6 were fully characterized by microanalysis and by NMR and IR spectroscopies. Structural characterization of [{PtCl₂(C₄Me₄)}₂(μ-Ph ₂PCH₂PPh₂)] (2b) reveals a piano-stool coordination at each platinum center defined by the η⁴-C₄Me₄ ligand, two Cl atoms and one P atom. The P-C-P angle of 131.0(4)° is larger than that expected for tetrahedral geometry. The X-ray structure of [PtCl(C₄Me₄){Ph₂P(CH₂) ₃PPh₂}]Cl·CH₂Cl₂ (5b·CH₂Cl₂) reveals a Pt atom coordinated by the η⁴-C₄Me₄ ligand, chloride and the two phosphorus donors in a piano-stool conformation. In the solid state, these cations are arranged to form channels with a diameter of 13.8 A in which solvent molecules (CH₂Cl₂) are embedded.

Full text of DOI:10.1016/S0022-328X(98)00873-0

Journal of Organometallic Chemistry 570 (1998) 129–139
Synthesis and characterization of novel dinuclear and cationic
cyclobutadiene platinum complexes
Michael Gerisch a, Kristin Kirschbaum b, Clemens Bruhn a, Harry Schmidt a, Julian A. Davies b,
Dirk Steinborn a,*
a Institut fu¨r Anorganische Chemie, Martin-Luther-Uni6ersita¨t Halle-Wittenberg, Kurt-Mothes-Strasse 2, D-06120 Halle, Germany
b Department of Chemistry, Uni6ersity of Toledo, 2801 W. Bancroft Street, Toledo, OH 43606, USA
Received 18 June 1998
Abstract
‡
Reactions of the cyclobutadiene platinum complexes [PtCl2(C4R4)] (R=Me 1a, R=Et 1b) with diphosphines Ph2P PPh2
‡
(
= –CꢀC– (dppa), –CH2– (dppm), –(CH2)2– (dppe), –(CH2)3– (dppp), –(CH2)4– (dppb)) in a 2:1 molar ratio result in
‡
formation of novel binuclear cyclobutadiene platinum complexes [{PtCl2(C4R4)}2(v-Ph2P PPh2)] (R=Me 2, Et 3). In contrast,
reactions in equimolar ratio lead to formation of cationic complexes with dppe, dppp and dppb [PtCl(C4R4){Ph2P(CH2)nPPh2}]Cl
(n=2–4, R=Me 5, Et 6). Complexes 2, 3 and 5, 6 were fully characterized by microanalysis and by NMR and IR spectroscopies.
Structural characterization of [{PtCl2(C4Me4)}2(v-Ph2PCH2PPh2)] (2b) reveals a piano-stool coordination at each platinum center
defined by the p4-C4Me4 ligand, two Cl atoms and one P atom. The P–C–P angle of 131.0(4)° is larger than that expected for
tetrahedral geometry. The X-ray structure of [PtCl(C4Me4){Ph2P(CH2)3PPh2}]Cl·CH2Cl2 (5b·CH2Cl2) reveals a Pt atom
coordinated by the p4-C4Me4 ligand, chloride and the two phosphorus donors in a piano-stool conformation. In the solid state,
˚
these cations are arranged to form channels with a diameter of 13.8 A in which solvent molecules (CH2Cl2) are embedded. © 1998
Elsevier Science S.A. All rights reserved.
Keywords: Platinum; Cyclobutadiene complexes; Phosphine complexes; X-ray diffraction
1. Introduction
(R, R%=Me, Et, n-Pr) to yield cyclobutadiene platinum
complexes [PtCl2(C4R2R%)] [3,4]. The X-ray structures
2
Cyclobutadiene platinum complexes first were pre-
pared by reaction of [PtCl2(CO)2] with dipheny-
lacetylene by Canziani et al. [1]. During investigations
of the platinum-catalyzed addition of alcohols to alky-
nes [2] we discovered a convenient synthesis of cyclobu-
tadiene platinum complexes: Hexachloroplatinic(IV)
acid reacts in n-butanol to give Zeise’s acid with 1-
butene as a ligand, H[PtCl3(p2-C4H8)], and this complex
reacts with dialkylsubstituted alkynes RCꢀCR%
of [PtCl2(C4R4)] (R=Me 1a, Et 1b) revealed that these
complexes are monomeric in the solid state [3,4]a.
These 16-electron complexes react with donor ligands L
to give 18-electron complexes of the type
[PtCl2(C4R2R2%)L] (L=PPh3, AsPh3, SbPh3, py, p-tol
(para-toluidine)) [4]b, [5]. Furthermore, reaction of
[PtCl2(C4Me4)] (1a) with 2,2%-bipyridine (bpy) was
shown to form
a
cationic complex [PtCl-
(C4Me4)(bpy)]Cl [6].
We here report reactions of [PtCl2(C4R4)] (1) with
diphosphines, which result in binuclear and cationic
cyclobutadiene(diphosphine)platinum complexes.
* Corresponding author. Tel.: +49 345 5525620; fax: +49 345
5527028; e-mail: steinborn@chemie.uni-halle.de
0022-328X/98/$ - see front matter © 1998 Elsevier Science S.A. All rights reserved.
PII S0022-328X(98)00873-0

130
M. Gerisch et al. / Journal of Organometallic Chemistry 570 (1998) 129–139
Scheme 1. i) dppa (2:1); ii) dppm, dppe, dppp, dppb (2:1); iii) dppm (1:1); iv) dppe, dppp (1:1); v) dppb (1:1).
Scheme 2.
2. Results and discussion
[PtCl2(dppb)] was not observed. In all other reactions
the complexes 4 are the final products. With dppe and
dppp, the intermediate cationic complexes could be
isolated (5(6)b), or observed in solution (5(6)a) by
NMR spectroscopy. With dppm, the cationic com-
plexes could not be detected as intermediates at ambi-
ent temperatures. No identifiable products were
obtained by reaction with dppa in equimolar ratio.
The cationic complexes 5(6)b and 5(6)c were obtained
as well-shaped, yellow-orange crystals in 60–97%
yields. They crystallized as methylene chloride solvates
(5(6)b·CH2Cl2, 5(6)c·CH2Cl2). Apart from aging, they
were found to be air-stable over 2–3 weeks.
2.1. Syntheses
The complexes [PtCl2(C4R4)] (R=Me 1a, Et 1b)
react in methylene chloride at ambient temperature
‡
‡
with Ph2P PPh2 ( = –CꢀC– (dppa), –CH2– (dppm),
–(CH2)2– (dppe), –(CH2)3– (dppp) and –(CH2)4–
(dppb)) in a 2:1 molar ratio to give binuclear complexes
‡
‡
[{PtCl2(C4R4)}2(v-Ph2P PPh2)] (R=Me 2, Et 3;
=
–CꢀC– a, –CH2– b, –(CH2)2– c, –(CH2)3– d,
–(CH2)4– e) (Scheme 1(i, ii)). In reactions with dppm,
dppe
and
dppp,
the
corresponding
[PtCl2-
{Ph2P(CH2)nPPh2}] complexes (4) (n=1–3) are formed
as side products (ca. 5–20%). They were identified in
solution by comparison of 31P-NMR data with litera-
ture data [7]. The binuclear complexes 2 and 3 were
isolated in high yields (65–93%) as yellow to yellow-
orange crystals which are air-stable over several
weeks.
With an equimolar ratio of 1 and Ph2P(CH2)nPPh2
(n=1–4), the reactions yield cationic complexes
[PtCl(C4R4){Ph2P(CH2)nPPh2}]Cl (R=Me 5, Et 6)
and/or the corresponding complexes 4 by cleavage of
cyclobutadiene (Scheme 1(iii–v)). The proposed path-
way is shown in Scheme 2. In the case of dppb, cationic
complexes 5(6)c are the final products; formation of
2.2. NMR and IR spectra
Selected NMR data of the binuclear complexes 2 and
3 are given in Tables 1–3. In all complexes 2 and 3 the
resonances due to the alkyl protons of the cyclobutadi-
ene ligands are shifted upfield by 0.21–0.40 ppm with
respect to those in 1. In the tetramethyl-substituted
complexes with dppa 2a, dppp 2d and dppb 2e, the
methyl protons appear as a doublet due to 4J(P,H)
coupling (5.1–6.1 Hz) with platinum satellites
(3J(Pt,H)=14.3–16.4 Hz). The values of J(Pt,H) are
smaller than that found for 1a (18.1 Hz) [4]a but are
similar to those in [PtCl2(C4Me4)L] (7) (L=py, p-tol,
3

M. Gerisch et al. / Journal of Organometallic Chemistry 570 (1998) 129–139
131
Table 1
‡
Selected 1H- and 13C-NMR data (l in ppm, J in Hz) for [{PtCl2(C4Me4)}2(v-Ph2P PPh2)] (2)
Complex
1H-NMR
13C-NMR
m-L
l(CH3)
Dla
3J(Pt,H)
D3Jb
l(C4)
Dla
1J(Pt,C)
D1Jb
1a
2a
2b
2c
2d
2e
—
1.60
1.31
1.25
1.26
1.20
1.24
—
18.1
14.3
—
—
16.4
16.0
—
−3.8
—
—
−1.7
−2.1
103.8
99.1
97.7
97.3
96.7
96.7
—
143
123
127
124
—
dppa
dppm
dppe
dppp
dppb
−0.29
−0.35
−0.34
−0.40
−0.36
−4.7
−6.1
−6.5
−7.1
−7.1
−20
−16
−19
−20
123
c
Data for [PtCl2(C4Me4)] (1a) are given for comparison.
a Dl=l(2)–l(1a).
b DJ=J(2)–J(1a).
c 195Pt satellites could not be observed due to a poor signal-to-noise ratio.
Table 2
‡
Selected 1H- and 13C-NMR data (l in ppm, J in Hz) for [{PtCl2(C4Et4)}2(v-Ph2P PPh2)] (3)
Complex
1H-NMR
13C-NMR
a
m-L
l(CH2)
Dl
l(CH3)
Dla
l(C4)
Dla
1J(Pt,C)
D1Jb
1b
3a
3b
3c
3d
3e
—
2.01
1.77
1.72
1.63
1.67
1.69
—
1.28
0.99
1.07
1.01
1.02
1.00
—
106.5
102.2
100.5
101.2
100.2
100.1
—
−4.3
−6.0
−5.3
−6.3
−6.4
149
120
122
126
128
125
—
dppa
dppm
dppe
dppp
dppb
−0.24
−0.29
−0.38
−0.34
−0.32
−0.29
−0.21
−0.27
−0.26
−0.28
−29
−27
−23
−21
−24
Data for [PtCl2(C4Et4)] (1b) are given for comparison.
a Dl=l(3)–l(1b).
b DJ=J(3)–J(1b).
Table 3
‡
31P-NMR data (l in ppm, J in Hz) for [{PtCl2(C4R4)}2(v-Ph2P PPh2)] (2/3)
Complex
Complex
m-L
l(31P)
Dl(31P)a
1J(Pt,P)
L
l(31P)
−14.6
Dl(31P)a
1J(Pt,P)
2a
dppa
dppm
dppe
dppp
dppb
−11.1
13.2c
12.7e
13.4
18.9
34.8
24.5
30.1
28.3
4225
4237d
4309f
4331
4335
3a
dppa
15.4
32.9
23.6
28.3
26.8
4116
4132h
4241j
4312
3997
2bb
2cb
2d
3bb
3cb
3d
dppm
dppe
dppp
dppb
11.3g
11.8i
11.6
11.5
2e
13.0
3e
a
Dl=l(2/3)–l(free diphosphine).
b Coupling constants were obtained by simulation.
c 2J(P,P)=50.4 Hz.
d 3J(Pt,P)=109.4 Hz.
e 3J(P,P)=51.2 Hz.
f 4J(Pt,P)B1 Hz.
g 2J(P,P)=49.8 Hz.
h 3J(Pt,P)=105.6 Hz.
i 3J(P,P)=43.9 Hz.
j 4J(Pt,P)B1 Hz.
PPh3, AsPh3, SbPh3) (3J(Pt,H)=14.1–16.3 Hz) [4]b.
Due to the non-zero value of the 2/3J(P,P) coupling and
the superposition of the three subspectra of the plat-
inum isotopomers (195Pt: I=12, 33.8% abundance), the
coupling constants J(Pt,H) and J(P,H) could not be
calculated for the complexes 2b and 2c.
In 2 and 3, the 13C-NMR resonances of the cyclobu-
tadiene carbon atoms are shifted upfield by 4–7 ppm
compared with those in the 16-electron complexes 1a
and 1b, respectively. Similar upfield shifts (4–11 ppm)
were found in the mononuclear 18-electron complexes
[PtCl2(C4R4)L] (R=Me 7, Et 8; L=py, p-tol, PPh3,
3
4

132
M. Gerisch et al. / Journal of Organometallic Chemistry 570 (1998) 129–139
Table 4
Selected 1H- and 13C-NMR data (l in ppm, J in Hz) for [PtCl(C4Me4)(Ph2P(CH2)nPPh2)]Cl (5)
Complex
1H-NMR
13C-NMR
a
b
a
b
L
l(CH3)
Dl
3J(Pt,H)
D3J
l(C4)
Dl
1J(Pt,C)
D1J
1a
5a
5b
5c
—
1.60
1.74
1.54
1.32
—
0.14
−0.06
−0.28
18.1
12.1
12.1
12.5
—
103.8
—
143
—
c
dppe
dppp
dppb
−6.0
−6.0
−5.6
102.3
103.0
−1.5
−0.8
88
88
−55
−55
Data for [PtCl2(C4Me4)] (1a) are given for comparison.
a Dl=l(5)–l(1a).
b DJ=J(5)–J(1a).
c Due to the limited stability, a spectrum could not be obtained.
Table 5
Selected 1H- and 13C-NMR data (l in ppm, J in Hz) for [PtCl(C4Et4)(Ph2P(CH2)nPPh2)]Cl (6)
Complex
1H-NMR
13C-NMR
b
L
l(CH2)
Dla
l(CH3)
Dla
l(C4)
Dla
1J(Pt,C)
D1J
—
1b
6a
6b
6c
—
2.01
1.94
1.87
1.72
—
1.28
1.02
1.01
1.00
—
106.5
—
149
c
dppe
dppp
dppb
−0.07
−0.14
−0.29
−0.26
−0.27
−0.28
105.0
105.5
−1.5
−1.0
93
−56
d
Data for [PtCl2(C4Et4)] (1b) are given for comparison.
a Dl=l(6)–l(1b).
b DJ=J(6)–J(1b).
c Due to the limited stability, a spectrum could not be obtained.
d 195Pt satellites could not be observed due to a poor signal-to-noise ratio.
Table 6
31P-NMR parameters for [PtCl(C4R4)(Ph2P(CH2)nPPh2)]Cl (5/6)
Complex
Complex
a
R=Me
L
l(31P)
Dl
1J(Pt, P)
R=Et
L
l(31P)
Dla
1J(Pt,P)
5a
5b
5c
dppe
dppp
dppb
30.5
−6.9
0.9
42.3
9.8
16.2
3322
3262
3462
6a
6b
6c
dppe
dppp
dppb
29.1
−8.9
−1.3
40.9
7.8
14.0
3262
3224
3402
a Dl=l(5/6)–l(free diphosphine).
AsPh3, SbPh3) [4]b. The appearance of only one reso-
nance for the cyclobutadiene carbon atoms indicates
free rotation of the ligand. Coordination of the diphos-
phine to platinum causes a decrease in 1J(Pt,C) in 2 and
3 by 16–20 and 21–29 Hz, respectively. A similar
decrease (19 Hz, 22 Hz) was found in
[PtCl2(C4R4)(PPh3)] (R=Me 7c, Et 8c).
In agreement with the structures shown in Scheme 1
31P-NMR spectra show singlet resonances with plat-
inum satellites. Coordination of the diphosphine in 2
and 3 result in downfield shifts for the 31P resonances
(Dl(31P)=15–35ppm; Table 3). As no long-range
couplings are observed in the 31P-NMR spectra of the
v-dppa 2(3)a, v-dppp- 2(3)d and v-dppb complexes
2(3)e, these spectra result from A and AX spin systems.
However, 31P-NMR spectra of v-dppm 2(3)b and v-
dppe complexes 2(3)c are complex due to the non-zero,
long-range couplings 2/3J(P,P) and the presence of plat-
inum isotopomers. Thus, these spectra result from su-
perposition of A2 (43.8%), ABX (44.8%) and AA%XX%
subspectra (11.4%) (A, B=31P; X=195Pt). Spectra were
simulated using the program PERCH [8], Table 3. For
example, Fig. 1 shows that the observed spectrum of
[{PtCl2(C4Me4)}2(v-Ph2PCH2PPh2)] (2b) was simulated
adequately by superposition of the three calculated
ABX, AA%XX% and A2 subspectra (the A2 subspectrum
exhibits only one singlet and is not shown in Fig. 1).
1
Selected H- and 13C-NMR parameters of the com-
plexes 5 and 6 are given in Tables 4 and 5. The
resonances of the alkyl protons of the cyclobutadiene

M. Gerisch et al. / Journal of Organometallic Chemistry 570 (1998) 129–139
133
downfield shift (Dl=0.07 ppm) was observed in the
spectrum of [PtCl(C4Me4)(bpy)]Cl (l=1.67 ppm) [6].
In spectra of the tetramethyl-substituted complexes 5,
the methyl protons appear as 1:2:1 triplets (4J(P,H)=
5.8–6.0 Hz) with platinum satellites (3J(Pt,H)=12.1–
12.5 Hz). Similar to the case of the binuclear complexes
3
2 (DJ=5.6–6.0 Hz), the J(Pt,H) coupling constants in
5 are smaller than those in 1a (18.1 Hz), which lacks a
phosphine ligand.
The 13C-NMR spectra of cationic dppp (5(6)b) and
dppb (5(6)c) complexes reveal small upfield shifts of the
cyclobutadiene ring carbon atoms by 0.8–1.5 ppm with
respect to complexes 1 (cf. Dl=4–7 ppm in 2 and 3).
1
The values of J(Pt,C) are more than 50 Hz smaller
than those observed in 1 (cf. DJ: −20 to −30 Hz in
2 and 3) and this may be due to a decrease in the
s-electron density between platinum and the carbon
atoms of the cyclobutadiene ring caused by coordina-
tion of an additional strong donor ligand to platinum.
The 31P-NMR spectra of 5 and 6 show chemical and
magnetic equivalence of both P atoms (superposition of
A2 and A2X spin systems; A=31P, X=195Pt) and
1J(Pt,P) can be obtained directly (Table 6). The values
are about 600–1000 Hz smaller than those observed for
2 and 3. The magnitudes of the downfield shift of the
31P resonances in the five-, six- and seven-membered
1,3-diphospha-2-platina rings depend on the ring size
and are about 42 ppm (5(6)a), 9 ppm (5(6)b) and 15
ppm (5(6)c), respectively. Similar values were also
Fig. 1. Experimental (a) and simulated (b, c) 31P-NMR spectra of
[{PtCl2(C4Me4)}2(v-Ph2PCH2PPh2)] (2b). The spectra b (AA% part of
the AA%XX% subspectrum) and c (AB part of the ABX subspectrum;
A, B=31P; X=195Pt) were separately calculated and are shown in
the approximate ratio of their abundances (44.8% : 11.4%).
ligands in 5 and 6 are shifted upfield (0.06–0.29 ppm)
with respect to those of 1. Similar upfield shifts were
observed for the binuclear complexes 2 and 3. In con-
trast, a downfield shift of the methyl proton resonances
was found (Dl=0.14 ppm) for the complex
[PtCl(C4Me4){Ph2P(CH2)2PPh2}]Cl (5a).
A
similar
Fig. 2. ORTEP-III plot [16] of the molecular structure of [{PtCl2(C4Me4)}2(v-Ph2PCH2PPh2)] (2b), 40% displacement ellipsoids. Second position
of disordered cyclobutadiene ring on Pt(1) is displayed as dashed lines.

134
M. Gerisch et al. / Journal of Organometallic Chemistry 570 (1998) 129–139
Table 7
within 3| and are similar to PtꢁC4 distances in the
˚
Selected bond distances (A) and bond angles (°) for
[{PtCl2(C4Me4)}2(v-PPh2CH2PPh2)] (2b)
˚
related complexes 1a, 7e and 9 (1.869(1)−1.901(8) A)
[4]a, [5,10]. Remarkably, the two ClꢁPtꢁCl angles differ
significantly (96.76(7)° vs 92.91(8)°) for no obvious
reason. The first value is comparable with that in 7e
(95.33(4)°) [10] and the second value with those in 1a
(92.3(1)°) and in 9 (92.30(9)°). As expected from Gut-
mann’s bond length rules [11], the PtꢁCl bond lengths
Pt(1)–C(1)
Pt(1)–C(2)
Pt(1)–C(3)
Pt(1)–C(4)
Pt(1)–Cl(1)
Pt(1)–Cl(2)
Pt(1)–P(1)
C(1)–C(2)
C(2)–C(3)
C(3)–C(4)
C(1)–C(4)
P(1)–C(9)
2.06(2) [2.11(2)] Pt(2)–C(10)
2.19(2) [2.20(2)] Pt(2)–C(11)
2.21(2) [2.27(2)] Pt(2)–C(12)
2.10(1) [2.09(2)] Pt(2)–C(13)
2.141(7)
2.095(8)
2.160(7)
2.212(8)
2.457(2)
2.445(2)
2.336(2)
1.47(1)
1.46(1)
1.45(1)
1.46(1)
1.835(7)
2.448(2)
2.470(2)
2.331(2)
Pt(2)–Cl(3)
Pt(2)–Cl(4)
Pt(2)–P(2)
˚
(2.445(2)–2.470(2) A) are in the range of those found
1.42(3) [1.46(3)] C(10)–C(11)
1.35(3) [1.46(3)] C(11)–C(12)
1.56(2) [1.59(3)] C(12)–C(13)
1.40(3) [1.36(3)] C(10)–C(13)
for the other 18-electron complexes 7e and 9 (2.425(3)–
˚
2.458(1) A) and are larger than those in the 16-electron
˚
complexes 1a and 1b (2.323(2)–2.339(6) A) [3,4]a.
The cyclobutadiene ring on Pt(2) is square-planar;
there is no significant deviation of the four endocyclic
CꢁCꢁC angles (88.4(7)–91.6(7)°) from 90° and the four
1.824(7)
P(2)–C(9)
Cl(1)–Pt(1)–Cl(2) 96.76(7)
Cl(3)–Pt(2)–Cl(4)
Cl(3)–Pt(2)–P(2)
Cl(4)–Pt(2)–P(2)
92.91(8)
90.62(7)
92.26(7)
Cl(1)–Pt(1)–P(1)
Cl(2)–Pt(1)–P(1)
C(1)–C(2)–C(3)
C(2)–C(3)–Cl(4)
C(1)–C(4)–C(3)
C(2)–C(1)–C(4)
P(1)–C(9)–P(2)
89.83(6)
92.76(7)
˚
CꢁC bond lengths (1.45(1)–1.47(1) A) are essentially
equal. The disordered cyclobutadiene ring on Pt(1)
seems to differ from the idealized square-planar geome-
try (ÚCꢁCꢁC=86(1)–94(2)/82(1)–94(1)°; d(CꢁC)=
94(2) [94(2)]
88(2) [82(2)]
86(1) [93(2)]
92(2) [91(2)]
131.0(4)
C(10)–C(11)–C(12) 88.4(7)
C(11)–C(12)–Cl(13) 91.6(7)
C(10)–C(13)–C(12) 89.1(7)
C(11)–C(10)–C(13) 90.9(7)
˚
1.35(3)–1.56(2)/1.36(3)–1.59(3) A). The Pt atoms are
not symmetrically coordinated to the cyclobutadiene
ligands as revealed by the large range of PtꢁC bond
Values for the dashed cyclobutadiene moiety (Fig. 2) are given in
square brackets.
˚
lengths (at Pt(1): 2.06(2)–2.27(2) A, at Pt(2): 2.095(8)–
˚
2.212(8) A). This is in agreement with results found for
7e, where a wide range of PtꢁC bond lengths are also
found in other complexes with chelating R2P(CH2)nPR2
(n=2–4) ligands [9].
˚
observed (2.105(4)–2.195(5) A). The methyl sub-
stituents of the cyclobutadiene rings are displaced from
the plane, defined by the four carbon atoms of the
cyclobutadiene ring, away from platinum by 0.03(4)–
The IR spectra of complexes 2, 3, 5 and 6 show that
coordination of the diphosphine to platinum leads to a
significant decrease in wavenumber of the PtꢁCl vibra-
tion. Thus, for 2 and 3, 6(PtꢁCl) appeared at ca.
260/230 cm−1 compared with 315/299 cm−1 in
[PtCl2(C4Me4)] (1a) and 315/297 cm−1 in [PtCl2(C4Et4)]
(1b) [4]. No PtꢁCl vibrations were observed above 200
cm−1 in the mononuclear cationic complexes 5 and 6
with two coordinated p-donors.
˚
0.40(4)/0.08(4)–0.37(4) A at Pt(1) and 0.12(2)–0.30(2)
˚
A at Pt(2). These values are similar to those observed in
˚
7e (0.083(6)–0.401(6) A). It is noteworthy that coordi-
nation of dppm as a bridging ligand causes an increase
in the P(1)ꢁC(9)ꢁP(2) angle (131.0(4)°) with respect to
that typical of tetrahedral carbon.
2.3. Structure of [{PtCl2(C4Me4)}2(v-Ph2PCH2PPh2)]
(2b)
The molecular structure of 2b is shown in Fig. 2.
Selected bond lengths and angles are listed in Table 7.
The cyclobutadiene ligand on Pt(1) is disordered. The
structure of 2b reveals a piano-stool coordination at
each
platinum,
similar
to
that
found
in
[PtCl2(C4Me4)(SbPh3)] (7e) [10].
The PtꢁP distances are equal within 3| (d(PtꢁP)=
˚
2.331(2)/2.336(2) A) and are slightly shorter than that
˚
in [PtCl2(C4Me2Ph2)(PPh3)] (9) (d(PtꢁP)=2.353(2) A)
[5]. The distances between platinum atoms and the
planes of the cyclobutadiene rings (d[Pt(1)ꢁC4]=
1
˚
˚
1.88(1)/1.90(1) A; d[Pt(2)ꢁC4]=1.884(4) A) are equal
1
Here and following the first figure refers to one position (solid
Fig. 3. ORTEP-III plot of the molecular structure of the cation in
[PtCl(C4Me4){Ph2P(CH2)3PPh2}]Cl.CH2Cl2 (5b.CH2Cl2), 30% dis-
placement ellipsoids.
lines in Fig. 2) and the second to the other position (dashed lines) of
the disordered p4-C4Me4 ligand.

M. Gerisch et al. / Journal of Organometallic Chemistry 570 (1998) 129–139
135
Table 8
The square-planar cyclobutadiene ring (d(CꢁC)=
˚
Selected bond distances (A) and bond angles (°) for [PtCl(C4Me4)-
(Ph2P(CH2)3PPh2)]Cl·CH2Cl2 (5b·CH2Cl2)
˚
1.427(7)–1.469(8) A; ÚCꢁCꢁC=89.1(4)–91.2(5)°) is
not symmetrically bound to Pt: There are two shorter
˚
PtꢁC bonds (2.135(5)/2.140(5) A) and two longer PtꢁC
Pt–C(2)
Pt–C(6)
C(2)–C(3)
C(2)–C(6)
Pt–P(1)
2.135(5)
2.140(5)
1.450(8)
1.462(7)
2.330(1)
2.348(1)
Pt–C(3)
Pt–C(7)
C(6)–C(7)
C(3)–C(7)
Pt–Cl(1)
2.273(5)
2.221(5)
1.469(8)
1.427(7)
2.509(1)
˚
bonds (2.221(5)/2.273(5) A). The methyl groups are
displaced from the ring plane away from Pt by 0.22(1)–
˚
0.54(1) A. The bond angles at the methylene carbon
atoms C(9), C(10) and C(11) of the chelating diphos-
phine ligand are each slightly larger (113.9(4)–
115.6(4)°) than that typical of tetrahedral carbon.
The complex 5b·CH2Cl2 crystallizes in the trigonal
Pt–P(2)
P(1)–Pt–P(2)
91.85(5)
88.86(5)
90.73(5)
113.9(4)
115.6(4)
C(10)–C(11)–P(2)
C(2)–C(3)–C(7)
C(2)–C(6)–C(7)
C(3)–C(7)–C(6)
C(3)–C(2)–C(6)
114.1(3)
91.2(5)
89.1(4)
90.1(4)
89.5(4)
Cl(1)–Pt–P(1)
Cl(1)–Pt–P(2)
P(1)–C(9)–C(10)
C(9)–C(10)–C(11)
(
space group R3. The crystal structure (Fig. 4) reveals a
trigonal arrangement of cations [PtCl(C4Me4)-
{Ph2P(CH2)3PPh2}]+ such that channels are formed
˚
with a diameter of about 13.8 A, parallel to the c-axis.
The methylene chloride is embedded in these channels.
The choride anions are positioned on other lattice
sites such that short intermolecular Cl···HꢁC contacts
2.4. Structure of [PtCl(C4Me4)(Ph2P(CH2)3PPh2)]Cl ·
CH2Cl2 (5b ·CH2Cl2)
˚
(2.67 A) to a hydrogen atom of a methylene bridge
The molecular structure of the cation present in
5b·CH2Cl2 is shown in Fig. 3. Selected bond lengths
and angles are listed in Table 8. As found for 2b,
described previously, platinum exhibits a piano-stool
coordination defined by the p4-C4Me4 ligand, one chlo-
ride and two p-donors groups.
˚
(C(11)) are observed (Cl···C=3.53 A; Ú(ClꢁH–C)=
147.6°). However, it should be noted that all hydrogen
atoms are placed in calculated positions. Nevertheless,
these values are in the range of reported Cl···HꢁC
˚
hydrogen bonds distances (d(Cl···H)=2.6–2.9 A,
˚
d(Cl···C)=ca. 3.5 A, Ú(ClꢁHꢁC)\90°) [12]. Thus,
˚
The PtꢁCl bond length (2.509(1) A) is longer than
stabilization by hydrogen bonding in 5b·CH2Cl2 may
be present.
˚
those in 1a, 2b, 7e and 9 (2.323(2)–2.470(2) A). The
PtꢁP distances differ slightly from each other (2.330(1)
These results demonstrate the versatile reactivity of
the electronically unsaturated 16-electron complexes
[PtCl2(C4R4)] (1) towards diphosphines to give novel,
neutral binuclear and cationic mononuclear cyclobuta-
diene platinum complexes, depending on the nature of
the diphosphine used and the Pt:P molar ratio.
˚
vs 2.348(1) A), and are comparable to those observed in
˚
2b and 9 (2.331(2)–2.353(2) A). The PꢁPtꢁP angle is
91.85(5)°. The ClꢁPtꢁP angles are also close to 90°
(88.86(5)°, 90.73(5)°). The distance of Pt from the plane
˚
of the cyclobutadiene ligand is 1.930(2) A.
Fig. 4. View of the unit cell of [PtCl(C4Me4){Ph2P(CH2)3PPh2}]Cl.CH2Cl2 (5b.CH2Cl2) along the c-axis, only the major (70%) position of the
solvate molecule is displayed.

136
M. Gerisch et al. / Journal of Organometallic Chemistry 570 (1998) 129–139
3. Experimental section
C)=127.3 (‘d’, N=49 Hz), (m-CH)=128.1 (s),
(p-CH)=131.2 (s), (o-CH)=134.6 (s). 31P-NMR
(CD2Cl2, 81 MHz, 293 K): l(P)=13.2 (s+m,
All syntheses were carried out under argon using
standard Schlenk techniques. Solvents were dried and
distilled prior to use. [PtCl2(C4Me4)] (1a) and
[PtCl2(C4Et4)] (1b) were synthesized by literature meth-
ods [4]a. Other chemicals were commercial materials
used without further purification.
Microanalyses (C, H, Cl) were performed by the
University of Halle microanalytical laboratory using
CHNS-932 (LECO) and Vario EL (elementar Analy-
sensysteme) elemental analyzers. NMR spectra were
obtained on Varian Gemini 200 and VXR 400 spec-
trometers. Chemical shifts are relative to CHDCl2 (l
5.32 ppm), CD2Cl2 (l 53.8 ppm), CHCl3 (l 7.24 ppm)
and CDCl3 (l 77.0 ppm) as internal references; l(31P) is
relative to external H3PO4 (85%). IR spectra were
recorded on a Galaxy Mattson 5000 FT-IR spectrome-
ter using CsBr pellets.
3
2
1J(Pt,P)=4237 Hz, J(Pt,P)=109.4 Hz, J(P,P)=50.4
Hz).
‡
2c ( =ꢁ(CH2)2ꢁ, dppe): Yield: 106 mg (93%). Anal.
Found: C, 43.78; H, 4.03; Cl, 12.56. C42H48Cl4P2Pt2
(1146.75). Calc.: C, 43.99; H, 4.22; Cl, 12.37. IR:
1
w(PtꢁCl)=257 (w), 230 (m) cm−1. H-NMR (CD2Cl2,
400 MHz, 293 K): l(CH3)=1.26 (24H, m), (CH2)=
3.08 (4H, m), (m-, p-CH)=7.40 (12H, m), (o-CH)=
7.68 (8H, m). 13C-NMR (CDCl3, 100 MHz, 293 K):
l(CH3)=7.3 (s), (CH2)=24.6 (‘t’, N=30 Hz), (C4)=
1
2
97.3 (d+dd, J(Pt,C)=124 Hz, J(P,C)=1.4 Hz), (m-
CH)=128.6 (‘t’, N=10.4 Hz), (i-C)=130.3 (‘t’,
N=50 Hz), (p-CH)=130.7 (s), (o-CH)=133.7 (‘t’,
N=10.2 Hz). 31P-NMR (CDCl3, 81 MHz, 293 K):
l(P)=12.7 (s+m, 1J(Pt,P)=4309 Hz, 4J(Pt,P)B1
3
Hz, J(P,P)=51.2 Hz).
‡
2d ( =ꢁ(CH2)3ꢁ, dppp): Yield: 98 mg (84%). Anal.
‡
3.1. Synthesis of [{PtCl2(C4R4)}2(v-Ph2P PPh2)]
(2a–e, 3a–e)
Found: C, 44.48; H, 4.45; Cl, 12.39. C43H50Cl4P2Pt2
(1160.78). Calc.: C, 44.49; H, 4.34; Cl, 12.22. IR:
w(PtꢁCl)=260 (w), 255 (sh), 229 (sh), 225 (w) cm−1
.
In a typical synthesis, [PtCl2(C4Me4)] (1a) (75 mg,
0.20 mmol) or [PtCl2(C4Et4)] (1b) (86 mg, 0.20 mmol)
was placed into a Schlenk tube and dissolved in
methylene chloride (3 ml) at r.t. After adding the
corresponding diphosphine (0.10 mmol) the reaction
solution was stirred for 5–10 h and diethyl ether (5 ml)
was added. A precipitate formed which was filtered off,
washed with diethyl ether and dried briefly in vacuo.
1H-NMR (CD2Cl2, 200 MHz, 293 K): l(CH3)=1.20
(24H, d+dd, 3J(Pt,H)=16.4 Hz, 4J(P,H)=5.1 Hz),
(PCH2CH2)=1.75 (2H, m), (PCH2CH2)=2.88 (4H,
m), (m-, p-CH)=7.35 (12H, m), (o-CH)=7.67 (8H,
m). 13C-NMR (CDCl3, 100 MHz, 293 K): l(CH3)=7.3
(s), (PCH2CH2)=19.3 (s), (PCH2CH2)=30.0 (‘q’, N=
32 Hz), (C4)=96.7 (d+dd, 1J(Pt,C)=123 Hz,
2J(P,C)=3.0 Hz), (m-CH)=128.4 (d, 3J(P,C)=10.0
Hz), (i-C)=129.2 (d, 1J(P,C)=48 Hz), (p-CH)=130.7
‡
2a ( =ꢁCꢀCꢁ, dppa): Yield: 91 mg (80%). Anal.
2
Found: C, 43.83; H, 3.97; Cl, 12.96. C42H44Cl4P2Pt2
(1142.72). Calc.: C, 44.15; H, 3.88; Cl, 12.41. IR:
(s), (o-CH)=133.4 (d, J(P,C)=10.0 Hz). 31P-NMR
(CDCl3, 81 MHz, 293 K): l(P)=13.4 (s+d,
1
w(PtꢁCl)=262 (m), 233 (sh), 229 (m) cm−1. H-NMR
1J(Pt,P)=4331 Hz).
‡
(CD2Cl2, 200 MHz, 293 K): l(CH3)=1.31 (24H, d+
dd, 3J(Pt,H)=14.3 Hz, 4J(P,H)=6.0 Hz), (m-, p-
CH)=7.46 (12H, m), (o-CH)=7.82 (8H, m).
13C-NMR (CD2Cl2, 100 MHz, 293 K): l(CH3)=7.7
2e ( =ꢁ(CH2)4ꢁ, dppb): Yield: 98 mg (84%). Anal.
Found: C, 44.51; H, 4.26, Cl, 12.49. C44H52Cl4P2Pt2
(1174.80). Calc.: C, 44.99; H, 4.46; Cl, 12.07. IR: w(Pt–
.
Cl)=257 (m), 229 (sh), 225 (w) cm−1 1H-NMR
1
2
(s), (C4)=99.1 (d+dd, J(Pt,C)=123 Hz, J(P,C)=
4.1 Hz), (CꢀC)=101.6 (dd+dd, 1J(P,C)=76 Hz,
2J(P,C)=4.6 Hz, 2J(Pt,C)=26 Hz), (m-CH)=129.1
(d, 3J(P,C)=11.7 Hz), (i-C)=129.5 (d+dd,
(CD2Cl2, 200 MHz, 293 K): l(CH3)=1.24 (24H, d+
dd, Hz, Hz),
3J(Pt,H)=16.0 4J(P,H)=6.1
(PCH2CH2)=1.41 (4H, m), (PCH2CH2)=2.87 (4H,
m), (m-, p-CH)=7.41 (12H, m), (o-CH)=7.74 (8H,
m). 13C-NMR (CD2Cl2, 100 MHz, 293 K): l(CH3)=
7.4 (d, 3J(P,C)=2.2 Hz), (C4)=96.7 (s), (m-CH)=
128.6 (d, 3J(P,C)=10.2 Hz), (p-CH)=130.9 (s),
2
1J(P,C)=44 Hz, J(Pt,C)=27 Hz), (p-CH)=131.9 (d,
4J(P,C)=2.6 Hz), (o-CH)=134.1 (d, 2J(P,C)=12.9
Hz). 31P-NMR (CD2Cl2, 81 MHz, 293 K): l(P)= −
1
2
11.1 (s+d, J(Pt,P)=4225 Hz).
(o-CH)=133.4 (d, J(P,C)=10.0 Hz), resonances for
‡
2b ( =ꢁCH2ꢁ, dppm): Yield: 85 mg (75%). Anal.
PCH2CH2, PCH2CH2 and i-C could not be observed
due to a poor signal-to-noise ratio. 31P-NMR (CD2Cl2,
81 MHz, 293 K): l(P)=13.0 (s+d, 1J(Pt,P)=4335
Hz).
Found: C, 43.19; H, 4.01; Cl, 12.85. C41H46Cl4P2Pt2
(1132.72). Calc.: C, 43.48; H, 4.09; Cl, 12.52. IR: w(Pt–
Cl)=260 (m), 229 (sh), 224 (m) cm−1 1H-NMR
.
‡
(CD2Cl2, 200 MHz, 293 K): l(CH3)=1.25 (24H, m),
3a ( =ꢁCꢀCꢁ, dppa): Yield: 100 mg (80%). Anal.
2
(CH2)=5.04 (2H, t, J(P,H)=7.1 Hz), (m-, p-CH)=
Found: C, 47.52; H, 4.85; Cl, 11.22. C50H60Cl4P2Pt2
(1254.94). Calc.: C, 47.85; H, 4.82; Cl, 11.30. IR:
7.21 (12H, m), (o-CH)=7.61 (8H, m). 13C-NMR
(CD2Cl2, 100 MHz, 293 K): l(CH3)=7.7 (s), (CH2)=
24.3 (m), (C4)=97.7 (s+d, 1J(Pt,C)=127 Hz), (i-
1
w(PtꢁCl)=265 (m), 250 (m), 230 (m) cm−1. H-NMR
(CDCl3, 400 MHz, 293 K): l(CH3)=0.99 (24H, t),

M. Gerisch et al. / Journal of Organometallic Chemistry 570 (1998) 129–139
137
‡
(CH2)=1.77 (16H, m), (m-, p-CH)=7.43 (12H, m),
(o-CH)=8.05 (8H, m). 13C-NMR (CDCl3, 100 MHz,
3e ( =ꢁ(CH2)4ꢁ, dppb): Yield: 127 mg (97%). Anal.
Found: C, 48.04; H, 5.15; Cl, 10.65. C52H68Cl4P2Pt2
(1287.02). Calc.: C, 48.53; H, 5.33; Cl, 11.02. IR: w(Pt–
3
293 K): l(CH3)=11.7 (d, J(P,C)=2.9 Hz), (CH2)=
17.3 (s), (C4)=102.2 (d+dd, 1J(Pt,C)=120 Hz,
2J(P,C)=4.0 Hz), (m-CH)=129.0 (d, 3J(P,C)=11.5
Cl)=258 (w), 250 (w), 229 (w), 224 (w) cm−1 1H-
.
NMR (CDCl3, 200 MHz, 293 K): l(CH3)=1.00 (24H,
t), (PCH2CH2)=1.32 (4H, m), (CH2)=1.69 (16H, dq,
4J(P,H)=3.8 Hz), (PCH2CH2)=2.86 (4H, m), (m-,
p-CH)=7.41 (12H, m), (o-CH)=7.73 (8H, m). 13C-
NMR (CDCl3, 100 MHz, 293 K): l(CH3)=11.5 (s),
(CH2)=17.3 (s), (PCH2CH2)=25.2 (m), (PCH2-
4
Hz), (p-CH)=131.7 (d, J(P,C)=2.3 Hz), (o-CH)=
2
134.2 (d, J(P,C)=12.1 Hz), resonances for CꢀC and
i-C could not be observed due to a poor signal-to-noise
ratio. 31P-NMR (CDCl3, 81 MHz, 293 K): l(P)=
1
−14.6 (s+d, J(Pt,P)=4116 Hz).
‡
1
3b ( = –CH2–, dppm): Yield: 107 mg (86%). Anal.
CH2)=26.7 (d, J(P,C)=32 Hz), (C4)=100.1 (d+dd,
2
Found: C, 47.64; H, 4.87; Cl, 11.63. C49H62Cl4P2Pt2
1J(Pt,C)=125 Hz, J(P,C)=3.1 Hz), (i-C)=128.2 (d,
(1294.94). Calc.: C, 47.27; H, 5.02; Cl, 11.39. IR: w(Pt–
1J(P,C)=51 Hz), (m-CH)=128.5 (d, 3J(P,C)=10.6
Cl)=249 (w), 235 (w), 222 (w) cm−1
.
1H-NMR
Hz), (p-CH)=130.8 (s), (o-CH)=133.3 (d, J(P,C)=
2
(CDCl3, 200 MHz, 293 K): l(CH3)=1.07 (24H, t),
(CH2)=1.72 (16H, m), (PCH2)=5.03 (2H, m), (m-,
p-CH)=7.18 (12H, m), (o-CH)=7.63 (8H, m). 13C-
NMR (CDCl3, 100 MHz, 293 K): l(CH3)=11.6 (s),
(CH2)=17.3 (s), (PCH2)=22.9 (m), (C4)=100.5 (s+
9.9 Hz). 31P-NMR (CDCl3, 81 MHz, 293 K): l(P)=
1
11.5 (s+d, J(Pt,P)=3997 Hz).
3.2. Synthesis of [PtCl(C4R4){Ph2P(CH2)nPPh2}]Cl
(5a–c, 6a–c)
1
d, J(Pt,C)=122 Hz), (i-C)=127.1 (‘d’, N=41 Hz),
(m-CH)=127.5 (‘t’, N=10.5 Hz), (p-CH)=130.7 (s),
In a typical synthesis, [PtCl2(C4Me4)] (1a) (75 mg,
0.20 mmol) or [PtCl2(C4Et4)] (1b) (86 mg, 0.20 mmol)
was placed into a Schlenk tube and dissolved in
methylene chloride (3 ml) at room temperature. After
adding the corresponding diphosphine in an equimolar
ratio (0.20 mmol) the reaction solution was stirred for
2–3 h and diethyl ether (5 ml) was added to induce
precipitation. After standing over night the precipitate
was filtered off, washed with diethyl ether and dried
briefly in vacuo.
(o-CH)=134.3 (br s). 31P-NMR (CDCl3, 81 MHz, 293
1
3
K): l(P)=11.3 (s+m, J(Pt,P)=4132 Hz, J(Pt,P)=
2
105.6 Hz, J(P,P)=49.8 Hz).
3c ( =ꢁ(CH2)2ꢁ, dppe): Yield: 113 mg (90%). Anal.
Found: C, 47.68; H, 5.01; Cl, 11.53. C50H64Cl4P2Pt2
‡
(1258.97). Calc.: C, 47.70; H, 5.12; Cl, 11.26. IR: w(Pt–
Cl)=267 (w), 249 (w), 229 (w), 225 (w) cm−1 1H-
.
NMR (CDCl3, 200 MHz, 293 K): l(CH3)=1.01 (24H,
t), (CH2)=1.63 (16H, m), (PCH2)=3.02 (4H, m), (m-,
p-CH)=7.38 (12H, m), (o-CH)=7.71 (8H, m). 13C-
NMR (CDCl3, 100 MHz, 293 K): l(CH3)=11.7 (d,
3J(P,C)=2.9 Hz), (CH2)=17.5 (s), (PCH2)=24.4 (m),
(C4)=101.2 (‘t’+d, 1J(Pt,C)=126 Hz, N=3.5 Hz),
(m-CH)=128.4 (‘t’, N=10.6 Hz), (i-C)=129.9 (‘t’,
N=49 Hz), (p-CH)=130.6 (s), (o-CH)=133.7 (‘t’,
N=9.9 Hz). 31P-NMR (CDCl3, 81 MHz, 293 K):
l(P)=11.8 (s+m, 1J(Pt,P)=4241 Hz, 4J(Pt,P)B1
1
5a (n=2, dppe): characterized only in solution. H-
NMR (CD2Cl2, 200 MHz, 293 K): l(CH3)=1.74 (12H,
3
4
t+d, J(Pt,H)=12.1 Hz, J(P,H)=5.8 Hz), (PCH2)=
2.02–3.05 (4H, br m), (CH)=7.21–7.76 (20H, m).
31P-NMR (CD2Cl2, 81 MHz, 293 K): l(P)=30.5 (s+
1
d, J(Pt,P)=3322 Hz).
5b·CH2Cl2 (n=3, dppp): Yield: 126 mg (72%). Anal.
Found:
C,
49.88;
H,
4.96;
Cl,
15.77.
3
Hz, J(P,P)=43.9 Hz).
C35H38Cl2P2Pt·CH2Cl2 (871.55). Calc.: C, 49.61; H,
‡
1
3d ( = –(CH2)3–, dppp): Yield: 82 mg (65%). Anal.
4.63; Cl, 16.27. H-NMR (CD2Cl2, 200 MHz, 293 K):
Found: C, 47.84; H, 5.07; Cl, 11.34. C51H66Cl4P2Pt2
l(CH3)=1.54 (12H, t+dt, 3J(Pt,H)=12.1 Hz,
4J(P,H)=5.9 Hz), (PCH2CH2)=2.20–2.60 (2H, br m),
(PCH2CH2)=3.14–3.62 (4H, br m), (CH)=7.02–7.58
(20H, m). 13C-NMR (CD2Cl2, 100 MHz, 293 K):
l(CH3)=8.5 (s), (PCH2CH2)=19.1 (s), (PCH2CH2)=
25.0 (‘quin’, N=18 Hz), (C4)=102.3 (s+d,
1J(Pt,C)=88 Hz), (m-CH)=128.3 (s), (p-CH)=131.7
(s), (o-CH)=133.5 (s), a resonance for i-C could not
be observed due to a poor signal-to-noise ratio. 31P-
NMR (CD2Cl2, 81 MHz, 293 K): l(P)= −6.9 (s+d,
1J(Pt,P)=3262 Hz).
(1273.00). Calc.: C, 48.12; H, 5.23; Cl, 11.14. IR: w(Pt–
Cl)=258 (w), 250 (w), 232 (w), 216 (w) cm−1 1H-
.
NMR (CDCl3, 200 MHz, 293 K): l(CH3)=1.02 (24H,
t), (CH2)=1.67 (16H, dq, 4J(P,H)=4.0 Hz),
(PCH2CH2)=1.90 (2H, m), (PCH2CH2)=2.85 (4H,
m), (m-, p-CH)=7.38 (12H, m), (o-CH)=7.70 (8H,
m). 13C-NMR (CDCl3, 100 MHz, 293 K): l(CH3)=
11.5 (d, 3J(P,C)=2.3 Hz), (CH2)=17.2 (s),
(PCH2CH2)=18.1 (s), (PCH2CH2)=29.1 (‘q’, N=45
Hz), (C4)=100.2 (d+dd, 1J(Pt,C)=128 Hz,
2J(P,C)=3.8 Hz), (m-CH)=128.3 (d, 3J(P,C)=10.7
Hz), (i-C)=129.2 (d, 1J(P,C)=49 Hz), (p-CH)=130.6
5c·CH2Cl2 (n=4, dppb): Yield: 120 mg (68%). Anal.
Found:
C,
49.62;
H,
4.93;
Cl,
15.43.
2
(s), (o-CH)=133.4 (d, J(P,C)=10.0 Hz). 31P-NMR
C36H40Cl2P2Pt·CH2Cl2 (885.58). Calc.: C, 50.18; H,
1
(CDCl3, 81 MHz, 293 K): l(P)=11.6 (s+d,
4.78; Cl, 16.01. H-NMR (CDCl3, 200 MHz, 293 K):
1J(Pt,P)=4312 Hz).
l(CH3)=1.32 (12H, t+dt, 3J(Pt,H)=12.5 Hz,

138
M. Gerisch et al. / Journal of Organometallic Chemistry 570 (1998) 129–139
4J(P,H)=6.0 Hz), (PCH2CH2)=2.32–2.64 (4H, br m),
(PCH2CH2)=3.36–3.79 (4H, br m), (CH)=7.10–7.72
(20H, m). 13C-NMR (CD2Cl2, 100 MHz, 293 K):
l(CH3)=7.9 (s), (PCH2CH2)=22.0 (s), (PCH2CH2)=
l(CH3)=1.01 (12H, t), (CH2)=1.87 (8H, m),
(PCH2CH2)=2.70–3.08 (2H, br m), (PCH2CH2)=
3.45–3.78 (4H, m), (CH)=7.22–7.78 (20H, m). 13C-
NMR (CD2Cl2, 100 MHz, 293 K): l(CH3)=12.4 (t,
4J(P,C)=4.1 Hz), (CH2)=17.7 (s), (PCH2CH2)=18.8
(s), (PCH2CH2)=25.2 (‘quin’, N=17 Hz), (C4)=105.0
(s+d, 1J(Pt,C)=93 Hz), (phenyl-C)=128.7–134.7
(m). 31P-NMR (CD2Cl2, 81 MHz, 293 K): l(P)= −8.9
1
28.0 (‘t’, N=32 Hz), (C4)=103.0 (s+d, J(Pt,C)=88
Hz), (m-CH)=128.5 (m), (p-CH)=129.5 (s), (o-
CH)=132.6 (m), a resonance for i-C could not be
observed due to a poor signal-to-noise ratio. 31P-NMR
1
1
(CDCl3, 81 MHz, 293 K): l(P)=0.9 (s+d, J(Pt,P)=
(s+d, J(Pt,P)=3224 Hz).
3462 Hz).
6c·CH2Cl2 (n=4, dppb): Yield: 127 mg (97%). Anal.
1
6a (n=2, dppe): characterized only in solution. H-
Found:
C,
52.07;
H,
5.17;
Cl,
14.61.
NMR (CD2Cl2, 200 MHz, 293 K): l(CH3)=1.02 (12H,
t), (CH2)=1.94 (8H, m), (PCH2)=2.14–3.22 (4H, br
m), (CH)=7.08–7.74 (20H, br m). 31P-NMR (CD2Cl2,
81 MHz, 293 K): l(P)=29.1 (s+d, 1J(Pt,P)=3262
Hz).
C40H48Cl2P2Pt·CH2Cl2 (941.69). Calc.: C, 52.29; H,
5.35; Cl, 15.06. H-NMR (CDCl3, 200 MHz, 293 K):
1
l(CH3)=1.00 (12H, t), (CH2)=1.72 (8H, dq),
(PCH2CH2)=2.45–2.88 (4H, br m), (PCH2CH2)=
3.57–3.80 (4H, br m), (CH)=7.28–7.82 (20H, m).
13C-NMR (CDCl3, 100 MHz, 293 K): l(CH3)=11.8
(s), (CH2)=18.3 (s), (PCH2CH2)=26.7 (m),
(PCH2CH2)=28.4 (m), (C4)=105.5 (s), (phenyl-C)=
129.0–134.4 (m). 31P-NMR (CD2Cl2, 81 MHz, 293 K):
6b·CH2Cl2 (n=3, dppp): Yield: 115 mg (60%). Anal.
Found:
C,
52.14;
H,
5.34;
Cl,
14.96.
C39H46Cl2P2Pt·CH2Cl2 (927.66). Calc.: C, 51.79; H,
1
5.22; Cl, 15.29. H-NMR (CD2Cl2, 200 MHz, 293 K):
1
l(P)= −1.3 (s+d, J(Pt,P)=3402 Hz).
3.3. X-ray structure determinations
Table 9
Data collection for 2b was performed on
a
Crystal data collection and processing parametersa for 2b and
5b·CH2Cl2
SIEMENS Smart Platform diffractometer using three
different € settings and 0.3° increment scans, corre-
sponding to a nominal hemisphere of data 2qB59.76°.
Frame time was set to 10 s. Corrections for absorption
Complex
2b
5b·CH2Cl2
Formula
C41H46Cl4P2Pt2 C36H40Cl4P2Pt
and decay were applied using SADABS [13] (Tmin/Tmax
:
Molecular weight
Temperature (K)
Crystal size (mm3)
Crystal system
Space group (number)
Z
1132.70
293(1)
871.51
240(2)
0.42/0.80). X-ray measurement for 5b·CH2Cl2 was car-
ried out on a STOE IPDS image plate diffractometer.
133 frames were recorded oscillating the crystal 1.5°
around the €-axis. Absorption correction was applied
to the data numerically (Tmin/Tmax: 0.50/0.66).
0.45×0.40×0.30 0.20×0.20×0.20
Monoclinic
Trigonal
(
Cc/9
4
R3/148
18
Unit cell dimensions
Intensities were collected using graphite monochrom-
˚
a (A)
17.0855(4)
15.4437(4)
16.5379(5)
90
43.798(4)
43.798(4)
10.7773(9)
90
˚
atized Mo–Kh radiation (u0=0.71073 A). The struc-
˚
b (A)
˚
tures were solved by direct methods (SHELXS-86) [14]
and structure refinement was carried out by full-matrix
least-squares procedures on F2 (SHELXL-93 [15]).
Crystal data and details of the data collections and
refinements for 2b and 5b·CH2Cl2 are summarized in
Table 9.
One of the two tetramethylcyclobutadiene units in 2b
is disordered. The model refined contains two positions
with equal occupancies. All disordered carbon atoms
were refined with isotropic thermal parameters, all
other non-hydrogen atoms with anisotropic thermal
parameters. The solvate molecule in 5b·CH2Cl2 was
included in two positions with probabilities of 70 and
30%, respectively. The ClꢁC bond lengths were re-
strained to be equal with an effective S.D. of 0.03. The
position with the lower probability was refined using
isotropic displacement parameters. Hydrogen atoms
were in both structures included in the refinement as
riding atoms.
c (A)
h (°)
i (°)
k (°)
102.164(1)
90
90
120
3
˚
V (A )
4265.8(2)
1.764
17904(3)
1.455
Dcalc (g cm−3
)
v(Mo–Kh) (mm−1
F(000)
)
6.904
3.898
2184
7776
q Range for data collection (°) 2.34–29.88
Total data
Total unique data
Observed data (F\2|(F))
Rint.
wR2, all data
R1, observed data
Goodness of fit (S), all data 0.989
Parameters 434
1.86–25.00
19798
6932
14894
7896
7050
5480
0.0422
0.0694
0.0313
0.0538
0.0846
0.0330
0.969
400
1.387/−0.752
Largest residual peak hole (e 1.039/−1.329
−3
˚
A
)
1
a R1=S(ꢀFoꢀ−ꢀFcꢀ)/SꢀFoꢀ, wR2=[Sw(Fo2−Fc2)2/Sw(F2o)2]2, S (good-
1
ness of fit)=[Sw(F2o−Fc2)2/(Nobs−Nparam)]2.

M. Gerisch et al. / Journal of Organometallic Chemistry 570 (1998) 129–139
139
[2] D. Steinborn, R. Nu¨nthel, K. Krause, J. Organomet. Chem. 414
(1991) C54.
4. Supplementary material
[3] D. Steinborn, R. Nu¨nthel, J. Sieler, R. Kempe, Chem. Ber. 126
(1993) 2393.
Atomic coordinates, equivalent isotropic displace-
ment parameters, hydrogen atom positions and
isotropic thermal parameters, anisotropic thermal
parameters, all bond distances and bond angles have
been deposited at the Cambridge Crystallographic Data
Center (CCDC). Any request to the CCDC for this
material should quote the full literature citation and the
reference number HE1027. They can be obtained, upon
request, from the Director, Cambridge Crystallographic
Data Center, 12 Union Road, Cambridge, CB2, 1EZ,
UK, citing the deposition no. 102184 (2b) and no.
102185 (5b·CH2Cl2), the authors and the reference.
[4] (a) D. Steinborn, M. Gerisch, F.W. Heinemann, J. Scholz, K.
Schenzel, Z. Anorg. Allg. Chem. 621 (1995) 1421. (b) M.
Gerisch, D. Steinborn, Z. Anorg. Allg. Chem. 621 (1995) 1426.
[5] F. Canziani, C. Allevi, L. Garlaschelli, M.C. Malatesta, A.
Albinati, F. Ganazzoli, J. Chem. Soc. Dalton Trans. (1984)
2637.
[6] A. Ho¨rnig, PhD Thesis, RWTH, Aachen, Germany, 1993, p.
197.
[7] (a) D.A. Slack, M.C. Baird, Inorg. Chim. Acta. 24 (1977) 277.
(b) A.R. Sanger, J. Chem. Soc. Dalton Trans. (1977) 1971. (c)
T.G. Appleton, M.A. Bennett, I.B. Tomkins, J. Chem. Soc.
Dalton Trans. (1976) 439.
[8] PERCH, Version 2/95©, University of Kuopio, Finland.
[9] (a) S.O. Grim, W.L. Briggs, R.C. Barth, C.A. Tolman, J.P.
Jesson, Inorg. Chem. 13 (1974) 1095. (b) P.E. Garrou, Inorg.
Chem. 14 (1975) 1435. (c) P.E. Garrou, Chem. Rev. 81 (1981)
229.
Acknowledgements
[10] F.W. Heinemann, M. Gerisch, K. Schenzel, D. Steinborn, Z.
Kristallogr. 211 (1996) 388.
[11] V. Gutmann, G. Resch, W. Linert, Coord. Chem. Rev. 43
(1982) 133.
This work was supported by the Deutsche
Forschungsgemeinschaft and the Fonds der Chemisc-
hen Industrie. We thank the companies Merck and
Degussa for gifts of chemicals. The authors thank
Professor H.P. Abicht (Halle) for a gift of dppb. M.G.
thanks the DAAD for a grant.
[12] (a) R. Taylor, O. Tennard, J. Am. Chem. Soc. 104 (1982) 5063.
(b) C.B. Aakeroy, K.R. Seddon, Z. Naturforsch. 48b (1993)
1023.
[13] G.M. Sheldrick, University of Go¨ttingen, Germany, 1996.
[14] G.M. Sheldrick, Acta Crystallogr. A46 (1990) 467.
[15] G.M. Sheldrick, SHELXL 93, Program for the refinement of
crystal structures, University of Go¨ttingen, Germany, 1993.
[16] M.N. Burnett, C.K. Johnson, ORTEP-III: Oak Ridge Thermal
Ellipsoid Plot Program for Crystal Structure Illustrations, Oak
Ridge National Laboratory Report ORNL-6895, 1996.
References
[1] F. Canziani, A. Quarta, A. di Martino, J. Organomet. Chem. 26
(1971) 285.
.