Dichloro(norbornadiene)platinum(II): A comparison with dichloro(cyclooctadiene)platinum(II)

Article abstract of DOI:10.1107/S0108270104012491

The crystal structure of the title compound, (bicyclo[2.2.1]-hepta-2,5- diene)dichloroplatinum(II), [PtCl₂(C₇H₈)], has been determined from single-crystal X-ray analysis. The coordination sphere about the Pt atom is pseudo-square planar, with shorter Pt - C distances than in the corresponding dichloro(cyclooctadiene)platinum(II) complex.

Full text of DOI:10.1107/S0108270104012491

metal-organic compounds
Acta Crystallographica Section C
Crystal Structure
Communications
ISSN 0108-2701
Dichloro(norbornadiene)platinum(II):
a comparison with dichloro(cyclo-
octadiene)platinum(II)
Figure 1
The molecular structure of (I), showing 30% probability displacement
ellipsoids. H atoms have been omitted for clarity.
due to the different bite angles of the NBD and COD
supporting ligands.
The PtÐC bond lengths in (I) do not re¯ect the enhanced
lability of the NBD chelate. They are, in fact, signi®cantly
shorter than those found in (II); the average PtÐC bond
Jeffrey L. Butikofer, Eric W. Kalberer, William C. Schuster
and Dean M. Roddick*
Department 3838, Chemistry, 1000 East University Avenue, University of Wyoming,
Laramie, WY 82071, USA
Ê
Ê
length in (I) is 2.145 A, versus 2.170 A in (II). Therefore, the
II
increased lability often observed for NBD in Pt systems
Correspondence e-mail: dmr@uwyo.edu
cannot be attributed to a loosely bound NBD ligand, but
probably results from relief of binding strain associated with
the small bite angle. The PtÐCl bond lengths in (I), as well as
the C C alkene bond lengths, are very similar to those found
in (II), indicating that NBD and COD have similar donating
abilities.
Received 18 May 2004
Accepted 21 May 2004
Online 30 June 2004
The crystal structure of the title compound, (bicyclo[2.2.1]-
hepta-2,5-diene)dichloroplatinum(II), [PtCl (C H )], has
2
7
8
been determined from single-crystal X-ray analysis. The
coordination sphere about the Pt atom is pseudo-square
planar, with shorter PtÐC distances than in the corresponding
dichloro(cyclooctadiene)platinum(II) complex.
Experimental
We have recently reported an improved synthesis of (I) (Butikofer et
al., 2004). Single crystals of (I) were obtained by heating a benzene
2 2
solution of (NBD)Pt(CH Cl) at 373 K in a sealed NMR tube.
Formation of (I) most likely resulted from thermal decomposition
(via ethylene loss) of the chloromethyl species at these temperatures.
Comment
In platinum(II) chemistry, norbornadiene (NBD) is generally
considered to be a more labile ligand than 1,5-cyclooctadiene
Crystal data
� 3
[PtCl
M = 358.12
2
(C
7
H
8
)]
x
D = 2.946 Mg m
(
COD; Appleton et al., 1986, 1989). This lability is often
Mo Kꢁradiation
Cell parameters from 35
re¯ections
r
Monoclinic, C2=c
a = 12.8717 (17) A
b = 11.5173 (12) A
Ê
c = 12.6441 (13) A
attributed to the smaller bite angle of the chelating NBD
ligand versus COD. However, there are very few corre-
sponding structurally characterized COD (Klein et al., 1999)
and NBD (Kickelbick et al., 2002) platinum(II) complexes. We
now report the crystal structure of the title compound,
Ê
Ê
ꢀ
ꢂ= 4.8±12.5
� 1
ꢃ= 17.95 mm
T = 298 (2) K
ꢀ
ꢀ
= 120.507 (12)
Ê
3
V = 1615.0 (3) A
Z = 8
Rectangular prism, colorless
0.52 Â 0.12 Â 0.08 mm
(
(
NBD)PtCl , (I), and compare it with that of (COD)PtCl , (II)
2
2
Data collection
Syed et al., 1984).
Bruker P4 diffractometer
Rint = 0.055
ꢀ
!
scans
Absorption correction: scan
SHELXL97; Sheldrick, 1997)
min = 0.080, Tmax = 0.237
ꢂmax = 27.5
h = � 1 ! 16
(
T
k = � 1 ! 14
l = � 16 ! 14
2
1
1
291 measured re¯ections
843 independent re¯ections
559 re¯ections with I > 2ꢄ(I)
3 standard re¯ections
every 97 re¯ections
intensity decay: 1%
The two Cl atoms and the centroids of the alkene NBD
Table 1
Selected geometric parameters (A, ).
bonds form an essentially square-planar environment around
the Pt atom in (I). The bite angle, as de®ned by the angle
between the two alkene centroid positions and the Pt atom, is
Ê
ꢀ
Pt1ÐC2
Pt1ÐC5
Pt1ÐC1
Pt1ÐC4
2.140 (8)
2.144 (8)
2.146 (7)
2.148 (7)
Pt1ÐCl2
Pt1ÐCl1
C1ÐC2
C4ÐC5
2.3056 (19)
2.3058 (19)
1.391 (12)
1.386 (12)
ꢀ
7
0.3 . This is similar to what has been observed in other
II
NBD)Pt complexes, such as (NBD)Pt(Cl)Me (69.1 ; Kick-
ꢀ
(
elbick et al., 2002) and (NBD)Pt(2-ethoxynapth-1-yl) (70.4 ;
ꢀ
2
Debaerdemaeker et al., 1987), but is signi®cantly smaller than
ꢀ
C5ÐPt1ÐC1
C2ÐPt1ÐC4
C2ÐPt1ÐCl2
C1ÐPt1ÐCl2
66.2 (3)
65.8 (3)
98.8 (2)
97.8 (2)
C5ÐPt1ÐCl1
C4ÐPt1ÐCl1
Cl2ÐPt1ÐCl1
98.9 (2)
97.9 (2)
92.02 (8)
the bite angle of 87.3 found for (II), as expected. The ClÐ
ꢀ
PtÐCl bond angle in (I) [92.02 (8) ] is slightly larger than the
ꢀ
corresponding angle in (II) [89.78 (5) ], and this is most likely
Acta Cryst. (2004). C60, m353±m354
DOI: 10.1107/S0108270104012491
# 2004 International Union of Crystallography m353

metal-organic compounds
Re®nement
Supplementary data for this paper are available from the IUCr electronic
archives (Reference: NA1667). Services for accessing these data are
described at the back of the journal.
2
Re®nement on F
2
H-atom parameters constrained
2 2 2
2
R[F > 2ꢄ(F )] = 0.035
wR(F ) = 0.090
S = 1.06
w = 1 /[ꢄ(F
where P = (F
(Á/ꢄ)max < 0.001
o
) + (0.0552P) ]
2
2 2
+ 2F )/3
o c
Ê
� 3
1
9
843 re¯ections
1 parameters
Áꢅmax = 2.00 e A
Áꢅmin = � 2.24 e AÊ
References
� 3
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Ê
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1
.2Ueq(C).
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This work was supported by the National Science Founda-
tion (grant No. CHE-0093049).
ꢁ
m354 Jeffrey L. Butikofer et al.
[PtCl
2 7 8
(C H )]
Acta Cryst. (2004). C60, m353±m354