Synthesis and Reactivity of (Pentafluorophenyl)platinate(II) Complexes with Bridging 1,8-Naphthyridine (napy) and X Ligands (X = C6F5 , OH, Cl, Br, I, SPh). Crystal Structure of [NBu4][Pt2(μ-napy)(μ-OH)(C6F 5)4]·CHCl3

Article abstract of DOI:10.1021/ic960092m

By reaction of [NBu₄]₂[Pt₂(μC₆F ₅)₂(C₆F₅)₄] with 1,8-naphthyridine (napy), [NBu₄][Pt(C₆F₅)₃(napy)] (1) is obtained. This compound reacts with cis-[Pt(C₆F₅)₂(THF)₂] to give the dinuclear derivative [NBu₄][Pt₂(μ-napy)(μ-C₆F ₂)-(C₆F₅)₄] (2). The reaction of several HX species with 2 results in the substitution of the bridging C₆F₅ by other ligands (X) such as OH (3), Cl (4), Br (5), I (6), and SPh (7), maintaining in all cases the naphthyridine bridging ligand. The structure of 3 was determined by single-crystal X-ray diffraction. The compound crystallizes in the monoclinic system, space group P2₁ /n, with a = 12.022(2) A?, b = 16.677(3) A?, c = 27.154(5) A?, β= 98.58(3)°, V = 5383.2(16) A?³, and Z = 4. The structure was refined to residuals of R = 0.0488 and R_w = 0.0547. The complex consists of two square-planar platinum(II) fragments sharing a naphthyridine and OH bridging ligands, which are in cis positions. The short Pt-Pt distance [3.008(1) A?] seems to be a consequence of the bridging ligands.

Full text of DOI:10.1021/ic960092m

Inorg. Chem. 1996, 35, 7345-7349
7345
Synthesis and Reactivity of (Pentafluorophenyl)platinate(II) Complexes with Bridging
1,8-Naphthyridine (napy) and X Ligands (X ) C6F5, OH, Cl, Br, I, SPh). Crystal Structure
of [NBu4][Pt2(µ-napy)(µ-OH)(C6F5)4]‚CHCl3
Irene Ara, Jose´ M. Casas, Juan Fornie´s,* and Angel J. Rueda
Departamento de Qu´ımica Inorga´nica, Instituto de Ciencia de Materiales de Arago´n, Universidad de
Zaragoza-CSIC, E-50009 Zaragoza, Spain
ReceiVed January 26, 1996X
By reaction of [NBu4]2[Pt2(µ-C6F5)2(C6F5)4] with 1,8-naphthyridine (napy), [NBu4][Pt(C6F5)3(napy)] (1) is obtained.
This compound reacts with cis-[Pt(C6F5)2(THF)2] to give the dinuclear derivative [NBu4][Pt2(µ-napy)(µ-C6F5)-
(C6F5)4] (2). The reaction of several HX species with 2 results in the substitution of the bridging C6F5 by other
ligands (X) such as OH (3), Cl (4), Br (5), I (6), and SPh (7), maintaining in all cases the naphthyridine bridging
ligand. The structure of 3 was determined by single-crystal X-ray diffraction. The compound crystallizes in the
monoclinic system, space group P21/n, with a ) 12.022(2) Å, b ) 16.677(3) Å, c ) 27.154(5) Å, â ) 98.58(3)°,
V ) 5383.2(16) Å3, and Z ) 4. The structure was refined to residuals of R ) 0.0488 and Rw ) 0.0547. The
complex consists of two square-planar platinum(II) fragments sharing a naphthyridine and OH bridging ligands,
which are in cis positions. The short Pt-Pt distance [3.008(1) Å] seems to be a consequence of the bridging
ligands.
Introduction
Cl] with AgClO4 (1:1 molar ratio) in CH2Cl2 (a procedure for
synthesizing only the platinum complex);3 (ii) a more general
process consisting of reacting [NBu4]2[M(C6F5)4] and cis-[M′-
(C6F5)2(THF)2] (1:1 molar ratio) in CHCl3.4 Attempts to prepare
other palladium or platinum complexes containing at least one
C6F5 bridging group have been unsuccesful: for instance, the
reactions between [NBu4]2[PtX(C6F5)3] (X ) Cl, Br, I) and cis-
[M(C6F5)2(THF)2] (M ) Pd, Pt) in CH2Cl2 (1:1 molar ratio)
render mixtures of [NBu4]2[Pt2(µ-C6F5)2(C6F5)4] and [NBu4]2-
[M2(µ-X)2(C6F5)4] instead of the expected [NBu4]2[MM′(µ-
C6F5)2X(C6F5)3] or [NBu4]2[MM′(µ-C6F5)(µ-X)(C6F5)4].4
In this paper we study the reaction of [NBu4][Pt(C6F5)3L] [L
) didentate N-donor ligand napy (1,8-naphthyridine), bpy (2,2′-
bipiridine)] with cis-[M(C6F5)2(THF)2] (M ) Pt, Pd) with the
aim of preparing dinuclear [NBu4][PtM(µ-L)(µ-C6F5)(C6F5)4]
complexes containing both C6F5 and L acting as bridging
ligands. The reaction takes place sucessfully when L ) napy,
but when L ) bpy, a rearrangement reaction takes place.
Aryl groups are typical terminal ligands1 that, in some cases,
can act as bridging ligands forming M(µ-C)M′ electron-deficient
(3c-2e) bonds which are highly reactive.2 However, the
pentafluorophenyl group has proved to be very reluctant to act
as a bridging ligand, probably because of the presence of
electron-withdrawing substituents, which reduce the capability
of the ipso-C atom to participate in this type of bond. In fact,
as far as we know, the only complexes with bridging C6F5
groups are the anionic homo- or heterometallic palladium or
platinum complexes [NBu4]2[MM′(µ-C6F5)2(C6F5)4] (M ) Pd,
Pt; M′ ) Pd, Pt)3,4 and their preparation has been carried out
using two synthetic methods: (i) reaction of [NBu4]2[Pt(C6F5)3-
X Abstract published in AdVance ACS Abstracts, November 1, 1996.
(1) (a) Schrock, R. R.; Parshall, G. W. Chem. ReV. 1976, 76, 243.
(2) (a) Malone, J. F.; McDonald, W. S. J. Chem. Soc., Dalton Trans. 1972,
2646. (b) Malone, J. F.; McDonald, W. S. J. Chem. Soc., Dalton Trans.
1972, 2649. (c) ten Hoedt, R. W. M.; Noltes, J. G.; Speck, A. L. J.
Chem. Soc., Dalton Trans. 1978, 1800. (d) Gambarotta, S.; Floriani,
C.; Chiesi-Villa, A.; Guastini, G. J. Chem. Soc., Chem. Commun. 1983,
1156. (e) Edwards, P. G.; Gellert, R. W.; Marks, M. W.; Bau, R. J.
Am. Chem. Soc. 1982, 104, 2072. (f) van Koten, G.; Noltes, J. G. J.
Am. Chem. Soc. 1979, 101, 6593. (g) Chiang, M. Y.; Bo¨hlen, E.; Bau,
R. J. Am. Chem. Soc. 1985, 107, 1679. (h) Khan, S. I.; Edwards, P.
G.; Yuan, H. S. H.; Bau, R. J. Am. Chem. Soc. 1985, 107, 1682. (i)
Wakefield, B. J. Organolithium Compounds; Pergamon, Oxford, U.K.,
1974; p 10. (j) Walczack, M.; Walczack, K.; Mink, R.; Rausch, M.
D. J. Am. Chem. Soc. 1978, 100, 6382. (k) Hofstee, H. K.; Boersma,
J.; van der Kerk, G. J. M. J. Organomet. Chem. 1978, 168, 241. (l)
Nesmeyanov, A. N.; Perelova, E. G.; Grandberg, K. I.; Lemenovskii,
D. A.; Baukova, T. V.; Afanassova, O. B. J. Organomet. Chem. 1974,
65, 131. (m) Gambarotta, S.; Floriani, C.; Chiesi-Villa, A.; Guastini,
G. J. Chem. Soc., Chem. Commun. 1983, 1304. (n) Uso´n, R.; Laguna,
A.; Brun, P. J. Organomet. Chem. 1980, 197, 369. (o) Evans, D. G.;
Hughes, G. R.; Mingos, D. M. P.; Basset, J. M.; Welch, A. J. J. Chem.
Soc., Chem. Commun. 1980, 1255. (p) Bradford, C. W.; Nyholm, R.
S.; Gainsford, G. J.; Guss, J. M.; Ireland, R. R.; Mason, R. J. Chem.
Soc., Chem. Commun. 1972, 87. (q) Machelett, B. Z. Chem. 1976,
16, 116. (r) Mu¨ller, H., Seidel, W.; Go¨rls, H. J. Organomet. Chem.
1993, 445, 133. (s) Klose, A.; Solari, E.; Floriani, C.; Chiesi-Villa,
A.; Rizzoli, C.; Re, N. J. Am. Chem. Soc. 1994, 116, 9123.
Experimental Section
General Methods. C, H, and N analyses were carried out with a
Perkin-Elmer 240B microanalyzer. IR spectra were recorded over the
4000-200 cm-1 range on a Perkin-Elmer 883 spectrophotometer using
Nujol mulls between polyethylene sheets. 1H and 19F NMR spectra
were recorded on a Varian XL-200 or a Unity-300 in CDCl3 or HDA
solutions. Negative ion FAB mass spectra were recorded on a VG-
Autospec spectrometer operating at ca. 30 kV, using the standard cesium
ion FAB gun and 3-nitrobenzyl alcohol as matrix. [NBu4]2[Pt(C6F5)3-
Cl],5 [NBu4]2[Pt2(µ-C6F5)2(C6F5)4],3,4 cis-[M(C6F5)2(THF)2] (M ) Pd,
Pt),6 and 1,8-naphthyridine7 were prepared as described elsewhere. Fb
denotes a fluorine substituent of the bridging C6F5 group.
[NBu4][Pt(C6F5)3(napy)] (1). (a) To a yellow solution of [NBu4]2-
[Pt2(µ-C6F5)2(C6F5)4] (0.150 g, 0.080 mmol) in CH2Cl2 (30 mL) was
added napy (0.021 g, 0.160 mmol) (molar ratio 1:2). After 4 h of
stirring at room temperature, the resulting pale yellow solution was
(5) Uso´n, R.; Fornie´s, J.; Toma´s, M ; Fandos, R. J. Organomet. Chem.
1984, 263, 253.
(6) Uso´n, R.; Fornie´s, J.; Toma´s, M.; Menjo´n, B. Organometallics 1985,
4, 1912.
(3) Uso´n, R.; Fornie´s, J.; Toma´s, M.; Casas, J. M.; Cotton, F. A.; Falvello,
L. R.; Llusar, R. Organometallics 1988, 7 , 2279.
(4) Uso´n, R.; Fornie´s, J.; Toma´s, M.; Casas, J. M.; Navarro, R. J. Chem.
Soc., Dalton Trans. 1989, 169.
(7) Pandler, W. W.; Kress, T. J. J. Org. Chem. 1967, 32, 832.
S0020-1669(96)00092-4 CCC: $12.00 © 1996 American Chemical Society

7346 Inorganic Chemistry, Vol. 35, No. 25, 1996
Ara et al.
evaporated to dryness. The oily residue was treated with diethyl ether
(5 mL) and evaporated to dryness. Upon addition of PrOH (20 mL)
FAB- MS: m/z 1224 [Pt2(C6F5)4(napy)Cl]-. IR (cm-1): C6F5 X-
sensitive mode,8 811 m, 800 m; others, 1633 w, 1500 vs, 1062 s, 960
vs; napy, 835 m, 579 w; ν(Pt-Cl), 286 m. 1H NMR (acetone-d6): δ
9.4 (dd, 2H, o-H), 8.9 (dd, 2H, m-H), 7.7 (dd, 2H, p-H). 19F NMR
(acetone-d6): δ -114.8 [mc, 3J(195Pt,F) ) 510.1 Hz, 4F, o-F], -116.7
[mc, 3J(195Pt,F) ) 422.2 Hz, 4F, o-F], -165.2 (t, 2F, p-F), -166.2 (mc,
4F, m-F), -167.0 (t, 2F, p-F), -168.2 (mc, 4F, m-F).
i
and after 30 min of stirring, a pale-yellow solid was obtained (1) and
i
was filtered off and washed with PrOH and n-hexane. Yield: 53%.
Anal. Found (calcd for C42H42F15N3Pt): C, 47.34 (47.19); H, 4.12
(3.96); N, 3.77 (3.93). FAB- MS: m/z 827 [Pt(C6F5)3(napy)]-. IR
(cm-1): C6F5 X-sensitive mode,8 802 s, 787 m, 770 m; others, 1626
w, 1493 vs, 1054 s, 953 vs; napy, 832 m. 1H NMR (CDCl3): δ 9.6
[NBu4][Pt2(µ-napy)(µ-Br)(C6F5)4] (5). As described for complex
4, 2 (0.30 g, 0.19 mmol) was reacted with an aqueous solution of 0.354
M HBr (0.53 mL, 0.19 mmol). Yield: 78%. Anal. Found (calcd for
C48H42BrF20N3Pt2): C, 38.16 (38.16); H, 2.56 (2.80); N, 2.71 (2.78).
FAB- MS: m/z 1267 [Pt2(C6F5)4(napy)Br]-. IR (cm-1): C6F5 X-
sensitive mode,8 809 m, 798 m; others, 1632 w, 1504 vs, 1495 vs,
1062 s, 957 vs; napy, 835 m, 580 w. 1H NMR (CDCl3): δ 8.9 (m,
2H, o-H), 8.6 (m, 2H, m-H), 7.7 (m, 2H, p-H). 19F NMR (CDCl3): δ
3
[d, J(195Pt,H) ) 34.4 Hz, 1H, o-H], 9.0 [d, 1H, o′-H], 8.2 (d, 1H,
m-H),8.1 (d, 1H, m′-H), 7.4 (m, 1H, p-H), 7.3 (m, 1H, p′-H). 19F
NMR(CDCl3): δ -116.9 [mc, 3J(195Pt,F) ) 588.0 Hz, 2F, o-F], -118.3
3
[mc, J(195Pt,F) ) 380.8 Hz, 4F, o-F], -166.9 (mc, 6F, m-F), -168.4
(t, 3F, p-F).
(b) To a solution of [NBu4]2[Pt(C6F5)3Cl] (1.000 g, 0.822 mmol) in
THF (30 mL) was added AgClO4 (0.170 g, 0.822 mmol), and the
mixture was stirred at room temperature for 30 min. The AgCl formed
was filtered off, and the resulting solution was evaporated to dryness.
The oily residue was dissolved in CH2Cl2 (30 mL) and reacted with
napy (0.107 g, 0.822 mmol) at room temperature for 10 h. The resulting
mixture was evaporated to dryness and the residue was treated with
iPrOH (50 mL) for 1 h. The pale yellow solid, 1, was filtered off and
3
-119.2 [mc, 4F, o-F], -122.0 [mc, J(195Pt,F) ) 477.6 Hz, 4F, o-F],
-162.0 (t, 2F, p-F), -165.0 (mc, 8F, m-F), -166.7 (t, 2F, p-F).
[NBu4][Pt2(µ-napy)(µ-I)(C6F5)4] (6). Following the same procedure
as above, 2 (0.150 g, 0.094 mmol) in CH2Cl2 (20 mL) was reacted
with 0.28 mL (0.094 mmol) of 0.350 M HI. Yield: 85%. Anal. Found
(calcd for C48H42F20IN3Pt2) : C, 37.25 (37.00); H, 2.61 (2.71); N, 2.60
(2.69). FAB- mass spectrum: m/z 1554 [NBu4][Pt2(C6F5)4(napy)I]-.
IR (cm-1): C6F5 X-sensitive mode,8 805 m, 794 m; others, 1635 w,
1504 vs, 1500 vs, 1064 s, 958 vs; napy, 835 m, 580 w. 1H NMR
(CDCl3): δ 9.2 (dd, 2H, o-H), 8.5 (dd, 2H, m-H), 7.3 (dd, 2H, p-H).
19F NMR (CDCl3): δ -118.5 (mc, 4F, o-F), -120.2 (mc, 4F, o-F),
-165.2 (t, 2F, p-F), -165.4 (t, 2F, p-F), -166.4 (mc, 4F, m-F), -166.8
(mc, 4F, m-F).
i
washed with PrOH and n-hexane. Yield: 80%.
[PPN][Pt(C6F5)3(napy)] (1a) and [PPh3Et][Pt(C6F5)3(napy)] (1b).
To a solution of 1 (0.500 g, 0.470 mmol) in MeOH was added (PPN)-
Cl (Ph3PNPPh3Cl) (0.540 g, 0.940 mmol) (molar ratio 1:2) was added,
and 1a precipitated (84% yield). Complex 1b (1, 0.500 g, 0.470 mmol;
PPh3EtBr, 0.348 g, 0.470 mmol) was prepared in a similar way (83%
yield).
[NBu4][Pt2(µ-napy)(µ-C6F5)(C6F5)4] (2). To a solution of 1 (0.100
g, 0.094 mmol) in CH2Cl2 (40 mL), was added cis-[Pt(C6F5)2(THF)2]
(0.063 g, 0.094 mmol) (molar ratio 1:1) was added. The resulting
yellow solution was immediately evaporated to dryness, and the residue
was treated with CHCl3 (5 mL) and evaporated to dryness. The final
residue was stirred with n-hexane (20 mL) for 30 min, rendering a
yellow solid which was filtered off. Yield: 72%. Anal. Found (calcd
for C54H42F25N3Pt2): C, 40.68 (40.58); H, 2.81 (2.65); N, 2.41 (2.63).
IR (cm-1): C6F5 X-sensitive mode,8 815 m, 800 m, 795 m, 753 sh;
others, 1634 w, 1608 w, 1497 vs, 1063 s, 959 vs; napy, 834 m, 579 w.
1H NMR (CDCl3): δ 8.9 (d, 2H, o-H), 8.6 (d, 2H, m-H), 7.7 (m, 2H,
[NBu4][Pt2(µ-napy)(µ-SPh)(C6F5)4] (7). A 0.175 g (0.110 mmol)
sample of 2 was reacted with 12 µL (0.110 mmol) of HSPh in 20 mL
of CHCl3. After 15 min of stirring, the solution was evaporated to
dryness and the residue was treated with n-hexane for 2 h, to render a
orange solid (7) that was filtered off. Yield: 81%. Anal. Found (calcd
for C54H47F20N3Pt2S) : C, 42.44 (42.11); H, 3.28 (3.14); N, 2.54 (2.73);
S, 2.58(2.08). FAB- MS m/z 1297 [Pt2(C6F5)4(napy)(SPh)]-. IR
(cm-1): C6F5 X-sensitive mode,8 808 m, 789 m; others, 1632 w, 1499
vs, 1058 s, 956 vs; napy, 835 m, 578 w; SPh, 697 w, 488 w. 1H NMR
(CDCl3): δ 9.5 [dd, 2H, o-H], 8.4 (d, 2H, m-H), 7.6 (m, 2H, p-H). 19
F
3
NMR (CDCl3): δ -115.7 (mc, 4F, o-F), -118.1 [mc, J(195Pt,F) )
451.6 Hz, 4F, o-F], -166.0 (t, 2F, p-F), -166.8 (t, 2F, p-F), -167.2
(mc, 8F, m-F).
3
p-H). 19F NMR (CDCl3): δ -97.5 [mc, J(195Pt,F) ) 188.2 Hz, 2F,
o-Fb],-117.2 [mc, 3J(195Pt,F) ) 463.2 Hz, 4F, o-F], -122.9 [mc, 3J(195
-
Pt,F) ) 473.5 Hz, 4F, o-F], -153.0 (t, 1F, p-Fb), -164.9 (mc, 4F, m-F),
-166.9 (mc, 4F, m-F), -168.4 (mc, 2F, m-Fb), -162.1 (t, 2F, p-F),
-165.4 (t, 2F, p-F).
[PPN][Pt2(µ-napy)(µ-C6F5)(C6F5)4] (2a) and [PPh3Et][Pt2(µ-
napy)(µ-C6F5)(C6F5)4] (2b). Complexes 2a and 2b were synthesized
from 1a or 1b following a similar procedure to that described for 2
(78% and 74% yield respectively).
[NBu4][PtPd(µ-napy)(µ-OH)(C6F5)4] (8). To a solution of
[NBu4][Pt(C6F5)3(napy)] (0.20 g, 0.187 mmol) in CH2Cl2 (40 mL) cis-
[Pd(C6F5)2(THF)2] (0.11 g, 0.187 mmol) was added (molar ratio 1:1).
The yellow solution was immediately evaporated to dryness and the
residue was dissolved in CHCl3 (5 mL) and evaporated again. The
final residue was stirred with n-hexane (20 mL) for 30 min rendering
a solid which was filtered off. Yield: 85%. Anal. Found (calcd for
C48H43F20N3OPdPt) : C, 42.21 (42.41); H, 2.95 (3.19); N, 2.83 (3.09).
IR (cm-1): C6F5 X-sensitive mode,8 799 m, 769 m; others, 1632 w,
1499 vs, 1058 s, 957 vs; napy, 836 m, 579 w. 1H NMR (CDCl3): δ
9.2 [dd, 1H, o-H], 9.0 [dd, 1H, o-H], 8.4 (td, 2H, m-H), 7.5 (m, 1H,
p-H), 7.4 (m, 1H, p-H). 19F NMR (CDCl3): δ -113.9 (mc, 2F, o-F),
-115.1 (mc, 2F, o-F), -118.9 (mc, 2F, o-F), -119.0 (mc, 2F, o-F),
-163.1 (t, 1F, p-F), -163.3 (t, 1F, p-F), -165.1 (mc, 2F, m-F), -165.4
(t, 1F, p-F), -165.6 (t, 1F, p-F), -165.7 (mc, 2F, m-F), -166.5 (mc,
2F, m-F), -166.9 (mc, 2F, m-F).
Reaction of [NBu4][Pt(C6F5)3(bpy)] with cis-[Pt(C6F5)2(THF)2].
To a solution of [NBu4][Pt(C6F5)3(bpy)] (0.100 g, 0.091 mmol) in CHCl3
(30 mL) was added cis-[Pt(C6F5)2(THF)2] (0.062 g, 0.091 mmol) (molar
ratio 1:1). The solution quickly turned orange and then a precipitate
appeared. After 30 min of stirring at room temperature, the solvent
was evaporated to dryness and CHCl3 (10 mL) was added. The pale
yellow precipitate (identified by IR spectroscopy as [Pt(C6F5)2(bpy)])
was filtered off (65% yield). The resulting solution was evaporated to
dryness, and the final residue was stirred with n-hexane (20 mL) finally
rendering a solid, which was filtered off and identified as [NBu4]2[Pt2-
(µ-C6F5)2(C6F5)4] (56% yield).
[NBu4][Pt2(µ-napy)(µ-OH)(C6F5)4] (3). [NBu4][Pt2(µ-napy)(µ-
C6F5)(C6F5)4] (2) (0.165 g, 0.103 mmol) was dissolved in MeOH (30
mL), and then 2 mL of H2O was added. After 24 h of stirring, the
solution was evaporated to ca. 5 mL, and an orange solid began to
precipitate. The solid was filtered off and 20 mL of H2O were added
to the resulting solution. Partial evaporation rendered an additional
amount of 3. Total yield: 90%. Anal. Found (calcd for C48H43F20N3-
OPt2): C, 39.96 (39.80); H, 2.80 (2.99); N, 3.04 (2.90). FAB- mass
spectrum: m/z 1205 [Pt2(C6F5)4(napy)(OH)]-. IR (cm-1): C6F5 X-
sensitive mode,8 812 m, 800 m; others, 1636 w, 1498 vs, 1062 s, 958
vs; napy, 836 m, 579 w. 1H NMR (acetone-d6): δ 9.3 (dd, 2H, o-H),
8.9 (dd, 2H, m-H), 7.6 (dd, 2H, p-H). 19F NMR (acetone-d6): δ -117.3
[mc, 3J(195Pt,F) ) 475.2 Hz, 4F, o-F], -118.6 [mc, 3J(195Pt,F) ) 492.4
Hz, 4F, o-F], -166.6 (m, 4F, p-F), -166.9 (mc, 4F, m-F), -167.4 (mc,
4F, m-F).
[NBu4][Pt2(µ-napy)(µ-Cl)(C6F5)4] (4). To a yellow solution of 2
(0.250 g, 0.156 mmol) in CH2Cl2 (30 mL) was added 0.34 mL (0.156
mmol) of 0.464 M HCl. The color of the solution immediately turned
dark orange. The solution was evaporated to dryness and the residue
was stirred with n-hexane (20 mL) for 5 min rendering an orange solid,
4, which was filtered off. Yield: 87%. Anal. Found (calcd for
C48H42ClF20N3Pt2): C, 39.55 (39.31); H, 3.07 (2.89); N, 2.90 (2.86).
Reaction of 2 with CH3COOH. To a solution of 2 (0.135 g, 0.084
mmol) in 20 mL of CH2Cl2 was added 0.24 mL of 0.35 M CH3COOH.
After 30 min of stirring at room temperature, the solution was evaported
to dryness and the residue treated with n-hexane, yielding a solid
(8) Uso´n, R.; Fornie´s, J. AdV. Organomet. Chem. 1988, 28, 188.

(Pentafluorophenyl)platinate(II) Complexes
Inorganic Chemistry, Vol. 35, No. 25, 1996 7347
Table 1. Crystal Data for [NBu4][Pt2(µ-OH)(µ-napy)(C6F5)4]‚CHCl3
(1)a
observed in other 1,8-naphthyridine platinum complexes cis-
[PtCl(PR3)(napy)] (PR3 ) PEt3, PPh3, PMe2Ph) studied by
Dixon10 in which, at room temperature, the two N atoms are
alternatively coordinated to the platinum center through a five-
coordinate transition state and only at low temperature (-70
°C) is the fluxional process slow enough to distinguish two
different pyridine rings.
chemical formula
fw
Pt2Cl3F20O1N3C49H43
1567.4
space group
a, Å
b, Å
P21/n (No. 14)
12.022(2)
16.677(3)
c, Å
27.154(5)
Complex 1 is stable not only in the solid state but also in
dichloromethane or acetone solutions at room temperature. This
stability in solution is in sharp contrast to the behavior of the
analogous [NBu4][Pt(C6F5)3(phen)] complex which rearranges
very quickly to [Pt(C6F5)2(phen)] and [NBu4]2[Pt(C6F5)4] in
dichloromethane and more slowly in acetone solutions.11 The
greater tendency of 1,10-phenanthroline to act as a chelating
ligand may be the reason for this rearrangement, which was
not observed for 1.
Synthesis of [NBu4][Pt2(µ-C6F5)(µ-napy)(C6F5)4]. As we
have stated before, and according to our previous experience, a
reasonable synthetic strategy for the preparation of a dinuclear
platinum compound with only one pentafluorophenyl bridging
ligand is to react an anionic complex such as [Pt(C6F5)3(L)]n-
(L being a potentially bridging ligand) with cis-[Pt(C6F5)2-
(THF)2]. If such a reaction were to take place according to eq
1, the desired compound could be formed.
â, °
98.58(3)
5383.2(16)
4
1.787
5.45
V, Å3
Z
d
calc, g/cm3
µ(Mo KR), cm-1
λ, Å
temp, °C
R
0.710 73 (graphite monochromator)
-73
0.0488
0.0547
Rw
a R ) ∑|Fo - Fc|/∑|Fo|. Rw ) (∑w|Fo - Fc| /∑w|Fo| )1/2
.
2
2
identified as a mixture of the starting material and 3. Longer reaction
time (up to 14 h) rendered 3 only. Yield: 95%.
X-ray Structure Analysis. A batch of pale yellow crystals of 3.-
CHCl3 was grown by slow diffusion of n-hexane into a solution of 3
in chloroform at low temperature (-30 °C). A representative crystal
of dimensions 0.30 × 0.15 × 0.23 mm was selected and mounted on
a Siemens/STOE AED2 four circle diffractometer. The basic crystal-
lographic parameters for this complex are listed in Table 1. Data were
collected at 200 K by the ω-θ scan technique. The cell constants are
based on 24 reflections with 20 < 2θ < 28°, including Friedel pairs.
Three standard reflections were measured after every 240 min of beam
exposure during data collection, showing no systematic variation in
decay. Data reduction included an empirical correction (Ψ-scan
method, 10 reflections, transmission factors ) 1.000 and 0.410). The
structure was solved by the Patterson heavy-atom method, which
revealed the positions of the platinum atoms of the anion. The
remaining non-H atoms were located in successive Fourier syntheses
and refined with anisotropic temperature factors. H atoms, except those
of the methyl groups, were constrained to ride on their C atoms and
located at fixed positions with a C-H distance of 0.96 Å and a common
isotropic thermal parameter of 0.053(8) Å2. During the course of the
refinement, regions of electron density that were at nonbonding
distances to either the anion or the cation were refined as one molecule
of lattice chloroform. One of the Cl atoms was disordered over two
sitessCl(3) and Cl(4)sat half-occupancy. Positional restraints were
applied to the C-Cl and Cl‚‚‚Cl distances. A difference map following
convergence had six peaks between 1.32 and 1 e/Å3, located in the
area of the central heavy atoms. This effect is common in crystals
containing strongly scattering and strongly absorbing elements. A total
of 4953 data with F > 4σFo were used to refine 713 parameters. Final
residuals were R ) 0.0488 and Rw ) 0.0547, with a quality of fit
indicator of 1.06.
[NBu4][Pt(C6F5)3(L)] + cis-[Pt(C6F5)2(THF)2] f
[NBu4][Pt2(µ-C6F5)(µ-L)(C6F5)4] + 2THF (1)
However, [NBu4]2[Pt(C6F5)3X] (X ) Cl, Br, I) reacts with
cis-[Pt(C6F5)2(THF)2] in CH2Cl2, rendering mixtures of [NBu4]2-
[Pt2(µ-C6F5)2(C6F5)4] and [NBu4]2[Pt2(µ-X)2(C6F5)4], as a result
of a rearrangement process, instead of the desired [NBu4][Pt2-
(µ-C6F5)(µ-X)(C6F5)4].4 Bearing this in mind, and with the aim
of preparing dinuclear complexes with one bridging C6F5 ligand
by a method similar to that schematized in eq 1, we chose
[NBu4][Pt(C6F5)3(napy)] (1) as the starting material since (a)
napy is a potential dinucleating agent which in 1 acts as a
monodentate ligand,12 and (b) the rigidity of this ligand increases
the possibilities of bringing the metal centers together, favoring
the formation of the C6F5 bridge or a metal-metal interaction.13
Thus, the reaction of [NBu4][Pt(C6F5)3(napy)] with cis-[Pt-
(C6F5)2(THF)2] (molar ratio 1:1) in CH2Cl2 results, after
evaporation to dryness, in the formation of the dinuclear [NBu4]-
[Pt2(µ-C6F5)(µ-napy)(C6F5)4] (2). We have not been able to
isolate suitable crystals of 2 for an X-ray study and attempts to
grow crystals of [PPN][Pt2(µ-C6F5)(µ-napy)(C6F5)4] (2a) and
[PPh3Et][Pt2(µ-C6F5)(µ-napy)(C6F5)4] (2b) have also been un-
succesful. However, the 1H and 19F NMR spectra of 2 indicate
that in this complex the two metal centers are bridged by both
the napy ligand and the C6F5 ligand (eq 1, L ) napy).
All calculations were performed on a Micro Vax 3100 workstation
with the SHELXTL PLUS software package.9
Results and Discussion
1
The H NMR spectrum of 2 shows three signals for the six
The mononuclear complex [NBu4][Pt(C6F5)3(napy)] (1),
which is used as the starting material, was obtained by a
cleavage reaction of the C6F5-bridged derivative [NBu4]2[Pt2-
(µ-C6F5)2(C6F5)4] with 1,8-naphthyridine in 1:2 molar ratio. This
reaction takes place under mild conditions and takes ap-
proximately 4 h to complete. Another alternative procedure
which renders a better yield consists of reacting [NBu4]2[PtCl-
(C6F5)3] with AgClO4 and 1,8-naphthyridine (1:1:1 molar ratio).
The 1H NMR spectrum of 1 (see Experimental Section) indicates
that 1,8-naphthyridine is acting as a monodentate ligand, so that
only one N-donor atom is involved in the coordination to the
platinum center. This result differs from the fluxional behavior
aromatic protons, indicating a highly symmetric arrangement
(10) Dixon, K. R. Inorg. Chem. 1977, 16, 2618.
(11) Uso´n, R.; Fornie´s, J.; Toma´s, M.; Casas, J. M.; Fortun˜o, C. Inorg.
Chim. Acta 1995, 235, 51.
(12) (a) Sacconi, L.; Mealli, C.; Gatteschi, D. Inorg. Chem. 1974, 13, 1985.
(b) Mealli, C.; Zanobini, F. J. Chem. Soc., Chem. Commun. 1982, 97.
(c) Tikkanen, W. R.; Binamira-Soriaga, E.; Kaska, W. C.; Ford, P. C.
Inorg. Chem. 1984, 23, 141. (d) Tiripicchio, A.; Tiripicchio-Camellini,
M.; Uso´n, R.; Oro, L. A.; Ciriano, M. A.; Viguri, F. J. Chem. Soc.,
Dalton Trans. 1984, 125. (e) Cabeza, J. A.; Oro, L. A.; Tiripicchio,
A.; Tiripicchio-Camellini, M. J. Chem. Soc., Dalton Trans. 1988, 1437.
(f) Munakata, M.; Maekawa, M.; Kitagawa, S.; Adachi, M.; Masuda,
H. Inorg. Chim. Acta 1990, 167, 181.
(13) (a) Krumm, M.; Lippert, B.; Randaccio, L.; Zangrando, E. J. Am.
Chem. Soc. 1991, 113, 5129. (b) Krumm, M.; Zangrando, E.;
Randaccio, L.; Menzer, S.; Lippert, B. Inorg. Chem. 1993, 32, 700.
(c) So´va´go´, I.; Kiss, A.; Lippert, B. J. Chem. Soc., Dalton Trans. 1995,
489.
(9) SHELXTL-PLUS Software Package for the Determination of Crystal
Structures, Release 4.0. Siemens Analytical X-Ray Instruments, Inc.,
Madison, WI, 1990.

7348 Inorganic Chemistry, Vol. 35, No. 25, 1996
Ara et al.
Chart 1
Scheme 1
of the napy ligand in which both pyridine rings are equivalent
and coordinated to the platinum atoms. The 19F NMR spectrum
unambigously reflects the structural role of the C6F5 ligands.
The signals at -117.2 [3J(195Pt,F) ) 463.2 Hz, 4F, o-F], -122.9
[3J(195Pt,F) ) 473.5 Hz, 4F, o-F], -164.9 (4F, m-F), -166.9
(4F, m-F), -162.1 (2F, p-F), and -165.4 (2F, p-F) ppm are
assigned to the two types of terminal C6F5 ligands. The signals
at -97.5 [3J(195Pt,F) ) 188.2 Hz, 2F, o-F], -153.0 (1F, p-F),
and -168.4 (2F, m-F) ppm are due to another type of
pentafluorophenyl group. As can be seen the o- and p-fluorine
atoms of this group appear at lower fields than the typical o-
and p-fluorine resonances of terminal C6F5 groups suggesting
the bridging role of this pentafluorophenyl ring. In addition,
the o-fluorine signal shows platinum satellites the intensity of
which (satellites/central signal ratio: 46.07/53.93) unambigously
establishes that this pentafluorophenyl group is bridging two
platinum centers according to the theoretical isotopomers ratio
[(a) Pt(µ-C6F5)Pt (43.82%), (b) 195Pt(µ-C6F5)Pt (44.74%) while
no platinum satellites due to the less abundant isotopomer (c)
195Pt(µ-C6F5)195Pt (11.42%) are observed in the spectrum]
(satellites/central signal ratio: 44.74/43.82 + 5.71).
The formation of 2 indicates that complex 1 acts as a didentate
metalloligand toward cis-[Pt(C6F5)2(THF)2], producing the
displacement of both THF ligands and that the coordination
sphere of the platinum center is completed by the formation of
an electron-deficient bridging system (µ-C6F5) (Chart 1a). It
is interesting to note the preference of 2 for a structure such as
that represented in Chart 1a instead of that shown in Chart 1b,
with a donor-acceptor PtfPt bond which one could expect
taking into account the well-documented basicity of these
platinum substrates.14
in this solution is the result of the reaction of the hydrolized
intermediate, of the hydrolisis of 2, or both.
Finally, it must be pointed out that the reaction conditions of
1 and cis-[Pt(C6F5)2(THF)2] in the NMR tube are completely
different from those used in the preparation of 2 (see Experi-
mental Section) since, in the latter, the reactants are mixed at
room temperature (approximately 20 °C) and the reaction
mixture is immediately evaporated to dryness (Scheme 1.d).
Both facts favor the displacement and the elimination of THF
from the reaction mixture and the formation of complex 2. It is
probably due to this fact that we have not detected any hydrolisis
product during the preparation of complex 2.
We have also studied a similar reaction between [NBu4][Pt-
(C6F5)3(bpy)]15 and cis-[Pt(C6F5)2(THF)2] (molar ratio 1:1)
which results in the formation of cis-[Pt(C6F5)2(bpy)] and [NBu4]-
[Pt2(µ-C6F5)2(C6F5)4] (eq 2) (identified by elemental analyses
and IR spectra) instead of the formation of the dinuclear
derivative. This process seems to be a consequence of the
greater tendency of the bpy to act as a chelating ligand rather
than as a bridging one.15
[NBu4][Pt(C6F5)3(bpy)] + cis-[Pt(C6F5)2(THF)2] f
cis-[Pt(C6F5)2(bpy)] + [NBu4][Pt2(µ-C6F5)2(C6F5)4] +
2 THF (2)
The electron-deficient Pt(µ-C6F5)Pt bond in 2 is unstable
toward hydrolysis, and when H2O is added to a methanol
solution of 2 and stirred for 24 h, [NBu4][Pt2(µ-OH)(µ-napy)-
(C6F5)4] (3) is formed in a high yield.16 Other reactants such
us HX (X ) Cl, Br, I, SPh) behave in a similar way, yielding
the corresponding [NBu4][Pt2(µ-X)(µ-napy)(C6F5)4] complexes
(eq 3), and the reaction takes place faster than with water.
However, treatment of 2 with an aqueous solution of acetic acid
renders 3 instead of the acetato complex.
The reaction between 1 and cis-[Pt(C6F5)2(THF)2] has been
followed by 19F NMR spectroscopy. Equimolar amounts of the
reagents were mixed at -78 °C, and no reaction was observed
until -30 °C. At this temperature some changes in the signals
are observed, indicating the begining of the reaction. However,
the resonance due to the o-fluorine atoms of the bridging C6F5
group could not be detected until 10 °C. When the temperature
was increased, all of the signals due to 2 were observed in the
NMR spectrum of the mixture. All these facts suggest that an
intermediate complex [probably a dinuclear compound resulting
from the displacement of only one THF group (see Scheme 1.a)]
is formed prior to the formation of 2 (Scheme 1.b). In addition
a concomitant although minor process also takes place given
that at -20 °C o-fluorine and p-fluorine signals due to C6F5H
begin to be detected. The formation of C6F5H must be the result
of hydrolisis of some species present in the solution. Since
neither 1 nor cis-[Pt(C6F5)2(THF)2] hydrolize under these
conditions and 2 is not yet present at this temperature, C6F5H
must be the result of the hydrolisis of the suggested intermediate
complex (Scheme 1.c). At the end of the experiment (40 °C)
signals due to [NBu4][Pt2(µ-OH)(µ-napy)(C6F5)4] (3) are also
observed. However, we cannot determine if the presence of 3
[NBu4][Pt2(µ-C6F5)(µ-napy)(C6F5)4] + HX f
[NBu4][Pt2(µ-X)(µ-napy)(C6F5)4] + HC6F5 (3)
X ) OH (3), Cl (4), Br (5), I (6), SPh (7)
1
The H NMR spectra of complexes 3-7 are similar to that
described for 2, showing that the two pyridine rings of the napy
ligand are equivalent. The signal of the ortho hydrogen atoms
shows a shoulder due to coupling with 195Pt. The 19F NMR
spectra of these complexes show two types of terminal pen-
(15) Uso´n, R.; Fornie´s, J.; Toma´s, M.; Mart´ınez, F.; Casas, J. M.; Fortun˜o,
C. Inorg. Chim. Acta 1995, 235, 51.
(14) (a) Uso´n, R.; Fornie´s, J. Inorg. Chim. Acta 1992, 198-200, 219. (b)
Cotton, F. A.; Falvello, L. R.; Uso´n, R.; Fornie´s, J.; Toma´s, M.; Casas,
J. M.; Ara, I. Inorg. Chem. 1987, 26, 1366. (c) Uso´n, R.; Fornie´s, J.;
Toma´s, M.; Ara, I.; Casas, J. M.; Mart´ın, A. J. Chem. Soc., Dalton
Trans. 1991, 2253.
(16) We have carried out a 19F NMR study of this hydrolisis process in
CD2Cl2 (donor solvents cannot be used for this purpose, since complex
2 reacts with them producing the cleavage of the Pt(µ-C6F5)Pt bridging
system), and it has been observed that the reaction is first order with
respect to the platinum binuclear complex.

(Pentafluorophenyl)platinate(II) Complexes
Inorganic Chemistry, Vol. 35, No. 25, 1996 7349
Table 2. Selected Bond Distances (Å) and Angles (deg) for the
Complex [NBu4][Pt2(µ-OH)(µ-napy)(C6F5)4]
Pt(1)-O(1)
Pt(1)-N(1)
Pt(1)-C(1)
Pt(1)-C(7)
Pt(1)...Pt(2)
2.092(8)
2.129(12)
2.007(14)
2.005(14)
3.008(1)
Pt(2)-O(1)
Pt(2)-N(2)
Pt(2)-C(13)
Pt(2)-C(19)
2.121(8)
2.116(12)
2.018(15)
1.985(13)
C(1)-Pt(1)-O(1)
C(7)-Pt(1)-O(1)
C(7)-Pt(1)-N(1)
C(13)-Pt(2)-C(19)
C(19)-Pt(2)-O(1)
C(19)-Pt(2)-N(2)
Pt(1)-O(1)-Pt(2)
175.0(4)
92.2(5)
176.3(5)
87.4(6)
92.0(5)
177.1(5)
91.1(3)
C(1)-Pt(1)-C(7)
C(1)-Pt(1)-N(1)
O(1)-Pt(1)-N(1)
92.3(5)
90.5(5)
85.1(4)
C(13)-Pt(2)-O(1) 177.7(5)
C(13)-Pt(2)-N(2)
O(1)-Pt(2)-N(2)
Pt(2)-N(2)-C(32) 131.2(10)
94.1(5)
86.4(4)
C(31)-N(2)-C(32) 114.2(12) Pt(1)-N(1)-C(32) 126.3(9)
N(2)-C(32)-N(1) 119.2(12)
tafluorophenyl groups (trans to the N-atoms of the napy ligand
and trans to the X-bridging ligand) (see Experimental Section).
Finally, we have also attempted the synthesis of the heterodi-
nuclear [NBu4][PtPd(µ-C6F5)(µ-napy)(C6F5)4] by reacting [NBu4]-
[Pt(C6F5)3(napy)] with cis-[Pd(C6F5)2(THF)2]. However, in no
case have we been able to isolate the product with bridging
C6F5 and we only obtain the hydroxo compound [NBu4][PtPd-
(µ-OH)(µ-napy)(C6F5)4], which could be the result of the hydro-
lysis of the former due to a greater lability of the Pd-C bonds.
Crystal structure of [NBu4][Pt2(µ-OH)(µ-napy)(C6F5)4]‚-
CHCl3. Crystallographic data and selected bond distances and
angles for complex 2 are given in Tables 1 and 2 respectively.
The structure of the complex anion is shown in Figure 1. The
core of the anion comprises two platinum atoms 3.008(1) Å
apart, bridged by an OH and a napy ligands. Each platinum
center has also two terminal cis C6F5 groups which form a
square planar environment for both metals. The terminal Pt-C
bond distances are equal within experimental error [1.985(13)-
2.018(15) Å] as are the two pairs of Pt-O and Pt-N distances
[Pt(1)-O(1) ) 2.092(8), Pt(2)-O(1) ) 2.121(8), Pt(1)-N(1)
) 2.129(12) and Pt(2)-N(2) ) 2.116(12) Å]. The bond angles
around each platinum center range from 85.1(4) to 94.1(5)° for
cis ligands, the smallest angle corresponding to O-Pt-N, and
from 175.0(4) to 177.7(5)° for trans ligands. The distance
between the two platinum atoms lies at the upper end of the
range for Pt-Pt bonding distances [3.008(1) Å] although Pt-
Pt interactions have been invoked for systems with longer
internuclear separations (e.g., the 3.39 Å stacking separation in
[PtCl2(en)]417 ). We think, however, that in this case the short
Figure 1. Perspective drawing of the [Pt2(µ-napy)(µ-OH)(C6F5)4]-
anion showing 40% probability ellipsoids. Hydrogen atoms are omitted.
Pt‚‚‚Pt distance is merely a consequence of the steric constraints
imposed by the bridging ligands which also cause the coordina-
tion planes of the platinum atoms to form an angle of 87.01-
(24)°. This fact prevents a suitable overlapping of the orbitals
for the formation of the metal-metal bond.
The rigidity of the napy ligand seems in fact to play a key
role in the structure of the anion of 3 since in the related anion
[Pt2(µ-dppm)(µ-I)(C6F5)4]- the Pt‚‚‚Pt distance is 4.45 Å and
the dihedral angle formed by the coordination planes of the two
platinum centers is 44.9(1)°.15 It is also remarkable that, as a
consequence of this type of coordination, the napy ligand results
clearly distorted with the C(32)-N(1)-Pt(1) and C(32)-N(2)-
Pt(2) angles [131.2(10) and 126.3(9)°, respectively] rather
different from the expected 120°.
1
On the basis of the H and 19F NMR spectra we consider
that the structures of complexes 2, 4, 5, 6, and 7 are similar to
that of complex 3.
Acknowledgment. We thank the Comisio´n Interministerial
de Ciencia y Tecnolog´ıa (Spain) for financial support (Project
PB92-0364) and for a grant (to A.J.R.).
Supporting Information Available: Tables of crystallographic data
and refinement parameters, atomic coordinates, complete bond distances
and angles, anisotropic displacement parameters and H-atom coordinates
(12 pages). Ordering information is given on any current masthead
page.
(17) Martin, D. S., Jr.; Hunter, L. D.; Kroening, R.; Coley, R. F. J. Am.
Chem. Soc. 1971, 93, 1276.
IC960092M