Diimine supported group 10 hydroxo, oxo, amido, and imido complexes

Article abstract of DOI:10.1039/b715663d

A series of L₂ = diimine (Bian = bis(3,5-diisopropylphenylimino) acenapthene, Bu^t₂bpy = 4,4′-di-tert-butyl-2, 2′-bipyridine) supported aqua, hydroxo, oxo, amido, imido, and mixed complexes have been prepared. Deprotonation of [L₂Pt(μ-OH)] ₂²⁺ with 1,8-bis(dimethylamino)naphthalene, NaH, or KOH yields [(L₂Pt)₂(μ-OH)(μ-O)]⁺ as purple (Bian) or red (Bu^t₂bpy) solids. Excess KOH gives dark blue [(Bian)Pt(μ-O)]₂. MeOTf addition to [(Bu^t ₂bpy)₂Pt₂(μ-OH)(μ-O)]⁺ gives [(Bu^t₂bpy)₂Pt₂(μ-OH)(μ-OMe)] ²⁺ while [(Bian)Pt(μ-O)]₂ yields [(Bian) ₂Pt₂(μ-OMe)(μ-O)]⁺. Treatment of [(Bian)Pt(μ-O)]₂ with "(Ph₃P)Au⁺" gives deep purple [(Bian)₂Pt₂(μ-O)(μ-OAuPPh ₃)]⁺ while (COD)Pt(OTf)₂ gives a low yield of [(Bian)Pt₃(μ-OH)₃(COD)₂](OTf)₃. Ni(Bu^t₂bpy)Cl₂ and [(Ph₃PAu) ₃(μ-O)]⁺ in a 3: 2 ratio yield red [Ni ₃(Bu^t₂bpy)₃(μ-O) ₂]²⁺. M(Bu^t₂bpy)Cl₂ (M = Pd, Pt) and [(Ph₃PAu)₃(μ-O)]⁺ give [M(Bu^t₂bpy)(μ-OAuPPh₃)]₂ ²⁺ and [Pd₄(Bu^t₂bpy) ₄(μ-OAuPPh₃)]³⁺. Addition of ArNH ₂ to [M(Bu^t₂bpy)(μ-OH)]₂ ²⁺ (M = Pd, Pt) gives [Pt₂(Bu^t ₂bpy)₂(μ-NHAr)(μ-OH)]²⁺ (Ar = Ph, 4-tol, 4-C₆H₄NO₂) and [M(Bu^t ₂bpy)(μ-NHAr)]₂²⁺ (Ar = Ph, tol). Deprotonation of [Pt₂(Bu^t₂bpy) ₂(μ-NH-tol)(μ-OH)]²⁺ with 1,8-bis(dimethylamino) naphthalene or NaH gives [Pt₂(Bu^t₂bpy) ₂(μ-NH-tol)(μ-O)]⁺. Deprotonation of [Pt(Bu ^t₂bpy)(μ-NH-tol)]₂²⁺ with KOBu^t gives deep green [Pt(Bu^t₂bpy)(μ-N-tol) ]₂. The triflate complexes M(Bu^t₂bpy)(OTf) ₂ (M = Pd, Pt) are obtained from M(Bu^t₂bpy) Cl₂ and AgOTf. Treatment of Pt(Bu^t₂bpy)(OTf) ₂ with water gives the aqua complex [Pt(Bu^t ₂bpy)(H₂O)₂](OTf)₂. This journal is The Royal Society of Chemistry.

Full text of DOI:10.1039/b715663d

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www.rsc.org/dalton | Dalton Transactions
Diimine supported group 10 hydroxo, oxo, amido, and imido complexes†
Anupam Singh,a U. Anandhi,a Maria Agostina Cinellub and Paul R. Sharp*a
Received 11th October 2007, Accepted 29th January 2008
First published as an Advance Article on the web 4th March 2008
DOI: 10.1039/b715663d
A series of L2 = diimine (Bian = bis(3,5-diisopropylphenylimino)acenapthene, But2bpy =
4,4ꢀ-di-tert-butyl-2,2ꢀ-bipyridine) supported aqua, hydroxo, oxo, amido, imido, and mixed complexes
2+
have been prepared. Deprotonation of [L2Pt(l-OH)]2 with 1,8-bis(dimethylamino)naphthalene, NaH,
or KOH yields [(L2Pt)2(l-OH)(l-O)]+ as purple (Bian) or red (But2bpy) solids. Excess KOH gives dark
blue [(Bian)Pt(l-O)]2. MeOTf addition to [(But2bpy)2Pt2(l-OH)(l-O)]+ gives
[(But2bpy)2Pt2(l-OH)(l-OMe)]2+ while [(Bian)Pt(l-O)]2 yields [(Bian)2Pt2(l-OMe)(l-O)]+. Treatment of
[(Bian)Pt(l-O)]2 with “(Ph3P)Au+” gives deep purple [(Bian)2Pt2(l-O)(l-OAuPPh3)]+ while
(COD)Pt(OTf)2 gives a low yield of [(Bian)Pt3(l-OH)3(COD)2](OTf)3. Ni(But2bpy)Cl2 and
[(Ph3PAu)3(l-O)]+ in a 3 : 2 ratio yield red [Ni3(But2bpy)3(l-O)2]2+. M(But2bpy)Cl2 (M = Pd, Pt) and
[(Ph3PAu)3(l-O)]+ give [M(But2bpy)(l-OAuPPh3)]2 and [Pd4(But2bpy)4(l-OAuPPh3)]3+. Addition of
2+
2+
ArNH2 to [M(But2bpy)(l-OH)]2 (M = Pd, Pt) gives [Pt2(But2bpy)2(l-NHAr)(l-OH)]2+ (Ar = Ph,
4-tol, 4-C6H4NO2) and [M(But2bpy)(l-NHAr)]2 (Ar = Ph, tol). Deprotonation of
2+
[Pt2(But2bpy)2(l-NH-tol)(l-OH)]2+ with 1,8-bis(dimethylamino)naphthalene or NaH gives
[Pt2(But2bpy)2(l-NH-tol)(l-O)]+. Deprotonation of [Pt(But2bpy)(l-NH-tol)]2 with KOBut gives deep
2+
green [Pt(But2bpy)(l-N-tol)]2. The triflate complexes M(But2bpy)(OTf)2 (M = Pd, Pt) are obtained
from M(But2bpy)Cl2 and AgOTf. Treatment of Pt(But2bpy)(OTf)2 with water gives the aqua complex
[Pt(But2bpy)(H2O)2](OTf)2.
by deprotonation of hydroxo and amido complexes and by oxo–
chloro exchange using the gold oxo complex [(Ph3PAu)3(l-O)]+.
Introduction
Complexes with late transition metals bonded to hydroxo,
amido, oxo and imido ligands1–5 have attracted wide atten-
tion for their conflicting soft acid–hard base interactions and
Results and discussion
their relevance in several areas including chemotherapy drugs,6,7
enzyme modeling,8–15 and various catalytic and stoichiometric
processes.1,16–27 Our efforts have been primarily focused on the
synthesis of oxo and imido complexes of the heavier late transition
metals Rh, Ir, Pd, Pt, and Au.5 Our simplest approach to these
oxo and imido complexes is deprotonation of the conjugate-acid
hydroxo and amido complexes. This has required the simultaneous
development of the hydroxo and amido chemistry. The majority of
these hydroxo and amido complexes bear supporting phosphine
ligands and our initial attempts to expand to N-donor ligand
systems such as pyridine and bipyridine met with limited success
due to the poor solubility of the complexes. Solubility problems
were overcome with substituted cyclic and acyclic diimine ligands
and we reported the synthesis and characterization of hydroxo
and amido complexes of Pt(II) and Pd(II) bearing various diimine
ligands.28 However, efforts to deprotonate the hydroxo and amido
complexes to give oxo and imido complexes were mostly unsuc-
cessful. We now report the synthesis of Ni(II), Pd(II), and Pt(II)
diimine supported complexes with oxo or imido ligands both
Oxo complexes by deprotonation
The dihydroxo complexes [(Bian)Pt(l-OH)]2(BF4)2 (Bian =
bis(3,5-diisopropylphenylimino)acenapthene) and [(But2bpy)-
Pt(l-OH)]2(BF4)2 (But2bpy = 4,4ꢀ-di-tert-butyl-2,2ꢀ-bipyridine)
undergo facile single deprotonation with stoichiometric or excess
1,8-bis(dimethylamino)naphthalene (Scheme 1). The resulting
hydroxo-oxo complexes are isolated as purple (1) or red (2)
salts. (Complex 2 was previously incorrectly reported as a dioxo
complex.29) The same products are obtained when NaH (2)
or KOH (1) are used as the base and these are preferred for
clean isolation of the complexes. Treatment of [(But2bpy)Pd(l-
OH)]2(BF4)2 with NaH gives a yellow complex that is believed to
be [(But2bpy)2Pd2(l-OH)(l-O)]BF4, the Pd analog of 2. However,
characterization is limited to 1H NMR spectroscopy and elemental
analysis and this assignment must be considered tentative espe-
cially considering the rarity of Pd oxo complexes.30–34
It should be noted that previous attempts to deprotonate
[(Bian)Pt(l-OH)]2(BF4)2 with LiN(SiMe3)2 and KOBut gave com-
plex mixtures28 and that deprotonation of phosphine analogs,
2+
[L2Pt(l-OH)]2 (L = a phosphine or L2 = a diphosphine)
a125 Chemistry, University of Missouri, Columbia, Missouri, 65211, USA.
E-mail: sharpp@missouri.edu
require much stronger bases. While pKa1 in DMSO for these
phosphine complexes is only known to be less than 18, a value
bDipartimento di Chimica, Universita` di Sassari, Via Vienna 2, I-07100,
Sassari, Italy
of 11.9
0.1 for related [(L2Pt)2(l-OH)(l-NMePh)]2+ (L2
=
dppe) has been measured.35 The pKa for singly protonated 1,8-
† CCDC reference numbers 663517–663527. For crystallographic data in
CIF or other electronic format see DOI: 10.1039/b715663d
bis(dimethylamino)naphthalene in DMSO is reported as 7.5.36,37
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H-6 proton at 8.68 ppm. This strong shift to higher frequency
for one of the But2bpy H-6 protons is attributed to weak hydrogen
interactions with the oxo ligand (Fig. 1). A similar shift is observed
in the analogous amido oxo complex 14 (see below).
Fig. 1 Drawing of the cationic portion of 2 showing proposed hydrogen
interactions.
Confirmation of the hydroxo-oxo formulation for 2 is obtained
from the reaction of 2 with MeOTf which yields yellow hydroxo-
methoxo complex [(But2bpy)2Pt2(l-OH)(l-OCH3)](BF4)(OTf) (3,
eqn (1)). 1H NMR spectra for 3 show the OMe peak at 3.12 ppm
and the OH peak at 4.21 ppm. The two But2bpy H-6 proton signals
appear at similar positions (8.72 and 8.68 ppm) consistent with loss
of the hydrogen interaction on methylation of the oxo ligand.
Scheme 1
(1)
Assuming that there is no large change in the relative ba-
sicities in CH2Cl2 then pKa1 for [(Bian)Pt(l-OH)]2(BF4)2 and
[(But2bpy)Pt(l-OH)]2(BF4)2 must be less than 7.5 in DMSO,
many units lower than the analogous phosphine complexes. This is
consistent with the weaker donor properties of the diimine ligands
as compared to the phosphine ligands. We also note that the
UV-Vis absorption spectrum of [(But2bpy)2Pt2(l-OH)(l-O)]BF4
(2) is essentially identical to that of the complex formulated as
[(bpy)2Pt2(l-OH)3]+, produced by increasing the pH of an aqueous
solution of [(bpy)2Pt2(l-OH)2]2+ to above 8.38 We therefore propose
that [(bpy)2Pt2(l-OH)3]+ be reformulated as [(bpy)2Pt2(l-OH)(l-
O)]+, the water soluble bpy analog of 2.
Deprotonation of the remaining OH group in 1 is possible.
If the reaction mixture containing 1 and excess KOH is stirred
for prolonged periods (ca. 2 h) the mixture becomes deep blue
and dark blue dioxo complex [(Bian)Pt(l-O)]2 (4) is isolated
1
(Scheme 1). H NMR spectra for 4 show a single peak for each
type of Bian ligand proton indicative of a planar mmm-symmetric
structure. Again, peaks are often broadened from protic impurities
but sharpen when solid KOH is added to the solution. Attempts
to further characterize 4 by X-ray diffraction were thwarted by an
inability to isolate suitable crystals. The preparation of derivatives
of 4 was therefore undertaken.
1H NMR spectra of isolated 1 often show broad peaks,
which sharpen on addition of 1,8-bis(dimethylamino)naphthalene
suggesting that the broadening is associated with proton exchange
with trace acidic impurities. The spectra show the expected
asymmetry in the Bian ligand with peaks observed for half the Bian
ligand on the hydroxo side and peaks for the other half on the oxo
side of the complex. Only two peaks are observed for the isopropyl
methyl groups indicating that the structure is either planar with
the OH group in the plane or if non-planar inverting rapidly on the
NMR time scale. An X-ray crystal structure determination on a
crystal of 1 grown from CD2Cl2–Et2O was conducted. The crystals
contain two crystallographically independent cations each located
on an inversion center requiring disorder of the oxo and hydroxo
ligands and averaging of the Pt–O bond distances. This and poor
quality eliminate much of the significance of the structure other
than to confirm the connectivit◦y.
“Ph3PAuBF4” (prepared from Ph3PAuCl and AgBF4) addition
to a stirred blue solution of 4 results in a dark purple solution
of [(Bian)2Pt2(l-O)(l-OAuPPh3)](BF4) (5) (Scheme 2). A crystal
of 5 was subjected to a single crystal X-ray structure analysis.
Crystal data and data parameters are listed in Table 1. Selected
distances and angles are listed in Table 2. A drawing of the
solid-state structure of the cationic portion is given in Fig. 2.
The Ph3PAu+ fragment is bonded to one of the oxo ligands
approximately perpendicular to the Pt2O2 diamond core reducing
the mmm symmetry of 4 to m symmetry for 5. Relatively short Au–
Pt distances suggest closed-shell interactions between the metal
centers.39,40
The 31P NMR spectrum for 5 shows the expected singlet
1
(23 ppm) but the H NMR spectrum displays only one peak (as
opposed to the two predicted from the X-ray structure) for each
type of proton in the acenaphthylene portion of the Bian ligand.
Similarly, while the X-ray structure predicts 8 signals for the Bian
isopropyl methyl groups and 4 signals for the isopropyl CHs only
half this number is observed. These data indicate effective mm
symmetry. This could come about if, in solution, the Ph3PAu+
fragment is either bridging between the two oxo ligands or rapidly
exchanging (on the NMR time scale) between the two oxo sites.
1
The H NMR spectra at 25 C for 2 are broad and show only
one signal for each type of But2bpy protons suggesting rapid
proton exchange between the hydroxo and oxo ligands. At −70 ◦C
(M = Pt) the spectrum is also broad but is resolved into a pattern
expected for non-exchanging 2 with two signals for each type of
But2bpy proton. The resonance for one of the But2bpy H-6 protons
at 10.00 ppm is at significantly higher frequency than for the other
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Table 2 Selected distances and angles for [(Bian)2Pt2(l-O)(l-
OAuPPh3)]BF4 (5)
Au1–O1
Au1–P1
Pt1–O1
Pt1–O2
Pt1–N1
Pt1–N2
2.054(5)
2.218(2)
2.021(5)
1.961(5)
2.018(6)
1.993(7)
Au1–Pt1
Au1–Pt2
Pt2–O1
Pt2–O2
Pt2–N3
Pt2–N4
3.0494(5)
3.1949(5)
2.023(5)
1.972(5)
2.009(6)
2.007(6)
O1–Au1–P1
O2–Pt1–N2
O2–Pt1–N1
N1–Pt1–N2
O2–Pt1–O1
N1–Pt1–O1
N2–Pt1–O1
Pt1–O1–Au1
Pt2–O1–Au1
176.24(15)
97.8(3)
174.4(2)
79.3(3)
Pt1–Au1–Pt2
O2–Pt2–N4
O2–Pt2–N3
N4–Pt2–N3
O2–Pt2–O1
N3–Pt2–O1
N4–Pt2–O1
Pt1–O1–Pt2
Pt1–O2–Pt2
56.626(10)
101.4(2)
175.1(2)
80.1(3)
80.1(2)
99.1(2)
172.3(2)
94.3(2)
97.8(2)
80.4(2)
103.3(2)
170.6(2)
96.9(2)
103.2(2)
Fig. 2 Drawing (50% probability ellipsoids) of the cationic portion of the
solid-state structure of [(Bian)2Pt2(l-O)(l-OAuPPh3)]BF4 (5).
Scheme 2
Interestingly, when the probe temperature is raised to 25 ◦C
the 31P NMR peak broadens, as do the 1H NMR signals for
1
the Bian isopropyl groups. The H NMR signals for the Bian
acenaphthylene unit remain sharp. This broadening is apparently
due to exchange of the Ph3PAu+ fragment with trace amounts of
Ph3PAuCl that is visible in the low temperature 31P NMR spectra
(33 ppm) but not in the room temperature spectrum. Given the
crowded structure of 5 (see below) the exchange is attributed to
Ph3PAu+ dissociation from 5.
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Addition to the oxo ligand of 4 is also observed when MeOTf
is added to solutions of 4 and dark purple [(Bian)2Pt2(l-O)(l-
OMe)]OTf (6) is isolated. A crystal structure determination on a
crystal of 6 confirms the connectivity but the structure is of poor
quality with badly disordered solvent molecules and triflate anion.
As in 5, 1H NMR data for 6 are inconsistent with the m symme-
try of the solid-state structure. Two signals (overlapping) for each
type of proton in the acenaphthylene portion of the Bian ligand are
observed but only 4 signals for the Bian isopropyl methyl groups
and 2 signals for the isopropyl CHs are present. We attribute
this higher apparent symmetry to rapid inversion at the methoxo
ligand oxygen atom effectively producing mirror symmetry around
the Pt2O2 plane. The methoxo methyl group signal is observed at
2.48 ppm. The reaction of 4 with excess MeOTf was investigated
and gave a red product that is likely (Bian)Pt(OTf)2. However, this
product was not completely characterized (see Experimental).
Treatment of a blue solution of 4 with Pt(COD)(OTf)2 first
gives a purple solution but this changes to yellow-brown. A
Fig. 3 Drawing (50% probability ellipsoids) of the cationic portion of the
solid-state structure of [(Bian)Pt3(l-OH)3(COD)2] (OTf)3 (7).
Table 4 Selected distances and angles for [(But2bpy)3Ni3(l-O)2](BF4)2
(8)a
1
brown solid is isolated that by H NMR spectroscopy shows a
symmetric environment for the Bian ligand and a Pt-bonded COD
ligand in about a 1 : 1 ratio. Recrystallization yielded a small
amount of orange-red crystals, which were identified by an X-ray
diffraction analysis as the hydroxo bridged complex [(Bian)Pt3(l-
OH)3(COD)2] (OTf)3 (7) (Fig. 3, eqn (2)). Crystal data and data
parameters are listed in Table 1. Selected distances and angles are
given in Table 3. The H+ source is unknown but is presumably
from trace water in the reaction system. Related complexes with a
Pt3(l-OH)3 core have been reported.41–45
Ni1–O1
Ni2–O1
Ni1–Ni2
1.852(4)
1.845(3)
2.4816(12)
Ni1–N1
Ni2–N2
Ni2–Ni2*
1.880(5)
1.874(4)
2.5488(15)
N1–Ni1–N1*
O1–Ni1–O1*
O1–Ni1–N1
O1–Ni2–N2
Ni2–O1–Ni2*
84.8(3)
76.7(3)
99.2(2)
99.27(15)
87.37(18)
N2–Ni2–N2
O1–Ni2–O1*
O1–Ni1–N1*
O1–Ni2–N2*
Ni2–O1–Ni1
84.3(2)
77.1(2)
176.0(2)
175.51(17)
84.33(15)
a Atoms with an asterisk are related to unmarked atoms by inversion.
(2)
A drawing of the cationic portion of the solid-state structure of 8
is given in Fig. 4. Crystal data and data parameters are listed in
Table 1. Selected distances and angles are listed in Table 4. The
core structure consists of a triangle of Ni atoms bicapped by the
oxo ligands. H NMR data are in agreement with the solid-state
structure showing a single set of signals for a symmetric But2bpy
ligand.
Oxo complexes by chloro–oxo exchange
1
We have previously reported the use of the Au oxo complex
[(Ph3PAu)3(l-O)]BF4 as an oxide ion source in exchange re-
actions with [M(diene)(l-Cl)]2 (M = Rh, Ir),46 (COD)PtCl2,47
(DBCOT)PtCl2 (DBCOT = dibenzo[a,e]cyclooctatetraene)48 and
(But2bpy)PdCl2 and find it effective here for Ni(II) and
30
(3)
Pt(II) chloro complexes. Thus, mixing Ni(But2bpy)Cl2 with
[(Ph3PAu)3(l-O)]BF4 in a 3 : 2 ratio in CH2Cl2 yields the red oxo
complex [Ni3(But2bpy)3(l-O)2](BF4)2 (8) and Ph3PAuCl (eqn (3)).
Treatment of Ni(But2bpy)Cl2 with 1 equiv of [(Ph3PAu)3(l-
O)]BF4 gives a product different from 8 by 31P NMR spectroscopy.
Attempts to isolate this product yielded only 8. In analogy to the
Pd and Pt chemistry that follows this product is believed to be
[Ni(But2bpy)(l-OAuPPh3)]2(BF4)2. Its instability relative to 8 and
the analogous Pt and Pd complexes is attributed to the greater
oxophilicity expected for the more electropositive Ni center.
In contrast to Ni, Pt(But2bpy)Cl2 and [(Ph3PAu)3(l-O)]BF4
gives only the mixed Pt–Au oxo complexes [M(But2bpy)(l-
OAuPPh3)]2(BF4)2 (9, M = Pt, Scheme 3). We previously reported
the analogous reaction with Pd(But2bpy)Cl2 that gives the Pd
analog 9 (M = Pd).30 Both the Pd and Pt derivatives have now
been structurally characterized by X-ray diffraction. The crystals
are isomorphous and the complexes are isostructural. Crystal data
and data parameters are listed in Table 1. Selected distances and
angles for the Pt structure are listed in Table 5 and a drawing of
Table 3 Selected distances and angles for [(Bian)(COD)2Pt3(l-OH)3)]
(OTf)3 (7)
Pt1–O1
Pt1–O2
Pt2–O2
Pt2–O3
Pt2–C41
Pt2–C42
Pt2–C38
Pt2–C37
2.001(6)
2.003(6)
2.047(6)
2.064(6)
2.123(9)
2.130(9)
2.156(9)
2.161(9)
Pt1–N1
Pt1–N2
Pt3–O1
Pt3–O3
Pt3–C50
Pt3–C46
Pt3–C49
Pt3–C45
2.004(7)
2.019(7)
2.040(6)
2.080(6)
2.136(10)
2.136(10)
2.141(9)
2.152(9)
O1–Pt1–O2
O1–Pt1–N1
O2–Pt1–N1
O2–Pt2–O3
Pt1–O1–Pt3
Pt1–O2–Pt2
88.3(2)
94.8(3)
176.8(3)
92.4(2)
126.9(3)
123.1(3)
O1–Pt1–N2
O2–Pt1–N2
N1–Pt1–N2
O1–Pt3–O3
Pt2–O3–Pt3
175.3(3)
95.7(3)
81.2(3)
90.0(2)
131.1(3)
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Table 5 Selected Distances and Angles for [(But2bpy)Pt(l-OAuPPh3)]2-
(BF4)2 (9b)a
Pt1–O1
Pt1–O1*
Pt1–N1
Pt1–N2
Pt1–Pt1*
2.034(3)
2.017(3)
1.996(4)
1.994(4)
3.0642(4)
Au1–O1
Au1–P1
Au1–Pt1
Au1–Pt1*
2.057(3)
2.2170(15)
2.9937(3)
3.2600(3)
Pt1–Au1–Pt1*
N1–Pt1–N2
N1–Pt1–O1*
N1–Pt1–O1
Pt1–O1–Au1
Pt1–O1–Au1*
58.493(8)
80.63(18)
177.60(15)
99.50(16)
94.06(14)
106.31(16)
O1–Au1–P1
N2–Pt1–O1*
N2–Pt1–O1
O1–Pt1–O1*
Pt1–O1–Pt1*
171.91(10)
98.06(16)
177.42(16)
81.71(15)
98.29(15)
a Atoms with an asterisk are related to unmarked atoms by inversion.
Fig. 5 Drawing (50% probability ellipsoids) of the inversion-centered
cationic portion of the solid-state structure of [Pt(But2bpy)(l-OAuPPh3)]2-
(BF4)2 (9, M = Pt).
Altering the 1 : 1 reactant ratio in the reaction of M(But2bpy)Cl2
with [(Ph3PAu)3(l-O)]BF4 does not change the identity of the
reaction products when M = Pt. However, as previously re-
ported, with M = Pd the new oxo complex [Pd4(But2bpy)4(l-
OAuPPh3)](BF4)3(l-O)2 (10) is obtained (Scheme 3). Addition of
Pd(But2bpy)Cl2 to 9 also yields 10. The lack of formation of a
similar complex for Pt is presumably kinetic.
Fig. 4 Drawing (50% probability ellipsoids) of the cationic portion of
the solid-state structure of [Ni3(But2bpy)3(l-O)2](BF4)2 (8). Mirrors in the
Ni1, O1, N1 and the Ni atom plane relate labeled and unlabeled atoms.
Amido and imido complexes
A well-established method for the synthesis of late transition
metal amido complexes is by the reaction of amines, particularly
aryl amines, with hydroxo complexes (for recent examples, see
references 35,49–51). This is an effective method with the But2bpy
complexes but the final product depends on the metal and the
reaction conditions (Scheme 4). (Similar behavior is observed for
analogous phosphine complexes.52) Treatment of the Pt dihydroxo
complex [Pt(But2bpy)(l-OH)]2(BF4)2 with 4 equivalents of ArNH2
yields the amido hydroxo complexes [Pt2(But2bpy)2(l-NHAr)(l-
OH)](BF4)2 (11, Ar = Ph, 4-tol, 4-C6H4NO2). Under the same
conditions the Pd dihydroxo complex [Pd(But2bpy)(l-OH)]2(BF4)2
yields the diamido complexes [Pd(But2bpy)(l-NHAr)]2(BF4)2 (12,
Ar = Ph, 4-tol, 4-C6H4NO2). The analogous Pt diamido complex
[Pt(But2bpy)(l-NH(4-tol))]2(BF4)2 (13) is obtained by further
treatment of 11 (Ar = 4-tol) with 4-toluidine. Complexes 11 and
12 are also formed from the dihydroxo complexes and LiNHAr.
The difference between the Pt and Pd chemistry is attributed to
the greater kinetic reactivity of a second row transition metal
as compared to a third row transition metal, a well-known
phenomenon.53
Scheme 3
the cationic portion is given in Fig. 5. Data for the Pd complex
have been previously reported.30
The cationic portion consists of an inversion symmetric dimer
containing a planar M2O2 diamond core with a Ph3PAu group
bonded to each oxo ligand. The Ph3PAu groups are oriented
approximately perpendicular to the diamond plane in anti-
positions with respect to one another. NMR spectra for 9 suggest
the same structure in solution. A singlet for the AuPPh3 group
is observed at 25.5 (M = Pt) and 26.6 (M = Pd) ppm in the 31P
NMR spectra. 1H NMR spectra show a symmetric pattern for the
But2bpy ligand with a single But resonance.
Solid-state X-ray crystal structure determinations (Tables 1 and
6) on 12 (Ar = Ph, 4-tol) reveal retention of the diamond core with
slight deviations from planarity. A drawing of the structure of 12
(Ar = Ph) is given in Fig. 6. The aryl rings are found to be in an
2318 | Dalton Trans., 2008, 2314–2327
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Table 6 Selected distances and angles for [(But2bpy)Pd(l-NHAr)]2(BF4)2
(12, Ar = Ph, 4-tol)a
Ar = Ph and 5.20 and 2.55 ppm for Ar = p-tol. The higher shift
resonance in each set is assigned to the NH group. Complexes
12 and 13 show only one resonance for each type of proton on
the But2bpy ligand consistent with high symmetry of the dication.
The NH signals are observed at 2.83 (Ar = 4-tol), 2.89 (Ar = Ph),
and 3.54 (Ar = 4-NO2C6H4) ppm for 12. A larger N–H shift of
4.97 ppm is observed for 13 and is similar to the N–H shifts in
11. Larger N–H and O–H shifts for Pt over the Pd complexes are
probably related to a greater acidity for the Pt complexes.
Ar = Ph
Ar = 4-tol
Pd1–N1
Pd1–N2
Pd1–N3
Pd1–N3*
Pd1–Pd1*
N3–C(ipso)
2.024(2)
2.045(2)
2.047(2)
2.053(2)
3.1099(4)
1.428(4)
2.034(3)
2.039(3)
2.055(2)
2.053(3)
3.1015(8)
1.434(4)
N1–Pd1–N2
N1–Pd1–N3
79.77(9)
176.29(11)
98.81(10)
100.45(10)
174.58(11)
81.31(11)
113.49(19)
113.3(2)
79.89(10)
175.83(10)
98.64(10)
99.85(10)
175.11(10)
81.96(10)
113.38(18)
111.70(18)
98.04(10)
Amido-oxo and diimido complexes
N1–Pd1–N3*
N2–Pd1–N3
N2–Pd1–N3*
N3–Pd1–N3*
C(ipso)–N3–Pd1
C(ipso)–N3–Pd1*
Pd1–N3–Pd1*
Deprotonation of amido hydroxo 11 (Ar = 4-tol) is accomplished
with either NaH or 1,8-bis(dimethylamino)naphthalene yielding
the orange amido oxo complex [Pt2(But2bpy)2(l-NH-tol-4)(l-
O)]BF4 (14, Scheme 5). As with the dihydroxo complexes (see
above) deprotonation with 1,8-bis(dimethylamino)naphthalene
indicates a DMSO pKa for 14 that is under 7.5, the pKa of 1,8-
bis(dimethylamino)naphthalene in DMSO.36,37 This is consider-
ably less than the pKa (11.9) for the diphosphine analog [(L2Pt)2(l-
OH)(l-NMePh)]2+ (L2 = dppe).35 Complex 14 is also obtained
when [Pt(But2bpy)(l-OH)]2(BF4)2 is refluxed in THF with 4
equivalents of toluidine contrasting sharply to the formation of
amido-hydroxo 11 in CH2Cl2 (see above). The 1H NMR spectrum
for 14 is very similar to that of 11 (Ar = 4-tol) with two exceptions.
A signal for an OH group is absent and the resonance for one of the
But2bpy H-6 protons is strongly shifted from 8.78 to 10.28 ppm.
The shift to higher frequency is attributed to interactions between
the But2bpy H-6 protons and the new oxo ligand (see Scheme 5)
similar to what is observed for the analogous hydroxo-oxo complex
2 (see above). Unfortunately, crystals for an X-ray analysis, which
could possibly confirm the interaction, could not be obtained.
98.69(11)
a Atoms with an asterisk are related to unmarked atoms by inversion.
Scheme 4
Scheme 5
Treatment of diamido 13 with KOBut in CH2Cl2 gives a deep
green complex, which we have assigned as the neutral diimido
complex [Pt(But2bpy)(l-N-4-tol)]2 15 (eqn (4)). No 1H NMR
signal for an N–H group could be detected and the signals for
the N–Ar ligand and the But2bpy ligands indicate a symmetric
structure. While there is a slight shift of the But2bpy H-6 protons
to higher frequency on deprotonation (from 8.47 ppm in 13 to
9.06 ppm in 15) there is not the dramatic shift indicative of the
hydrogen atom interactions observed for oxo complexes 2 and 14.
This is likely due to a blocking effect of the 4-tol group on the
imido nitrogen atom.
Fig. 6 Drawing (50% probability ellipsoids) of the solid-state structure
of [Pd(But2bpy)(l-NHPh)]2(BF4)2 (12, Ar = Ph). Labeled and unlabeled
atoms are related by an inversion center.
anti-orientation across the diamond core in both structures with
the BF4 anions hydrogen bonded to the amido hydrogen atoms.
1
Solution H NMR data for 11, 12, and 13 are consistent with
the assigned structures. Two sets of resonances for each type of
proton on the But2bpy ligand are observed for 11 and resonances
for the OH and NH groups are observed at 5.17 and 2.25 ppm for
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Table 7 Selected distances and angles for (But2bpy)Pd(OTf)2 (16)
Pd1–N2
Pd1–N1
1.9715(17)
1.9815(16)
Pd1–O1
Pd1–O4
2.0503(15)
2.0589(14)
N2–Pd1–N1
N2–Pd1–O1
N1–Pd1–O1
81.31(7)
174.27(6)
92.99(6)
N2–Pd1–O4
N1–Pd1–O4
O1–Pd1–O4
95.00(6)
173.92(7)
90.72(6)
Table 8 Selected distances and dngles for [(But2bpy)Pt(H2O)2](OTf)2
(17), and [(But2bpy)Pt(H2O)2](OTf)2·Et2O (17·Et2O)
17
17·Et2O
Pt1–N2
Pt1–N1
Pt1–O2
Pt1–O1
1.966(5)
1.974(5)
2.049(5)
2.052(5)
1.974(3)
1.982(2)
2.038(2)
2.043(2)
Fig. 7 Drawing (50% probability ellipsoids) of the solid-state structure
of Pd(But2bpy)(OTf)2 (16, M = Pd). Rotational disorder observed in the
But groups is illustrated.
N2–Pt1–N1
N2–Pt1–O2
N1–Pt1–O2
N2–Pt1–O1
N1–Pt1–O1
O2–Pt1–O1
81.1(2)
94.5(2)
175.1(2)
173.8(2)
94.9(2)
81.52(10)
93.37(10)
174.78(10)
175.87(9)
94.51(10)
90.61(10)
89.67(19)
(4)
Triflate and aqua54 complexes
During the course of this investigation the triflate complexes
(But2bpy)M(OTf)2 (16, M = Pd, Pt) were prepared (Scheme 6).
The Pt complex has been previously prepared in an identical
manner,55 as have closely related triflate complexes.56,57 An X-ray
crystal structure determination of the Pd derivative (Tables 1 and
7) confirmed the identity of the complex and shows bonding of
the triflate anions to the Pt center. A drawing of the molecule is
provided in Fig. 7. The triflate anions are readily displaced from
the Pt center of 16 (M = Pt) by water yielding the dicationic
aqua complex [Pt(But2bpy)(H2O)2](OTf)2 (17) (for other diimine
Pt aqua complexes see: references 58,59). Unsolvated and ether
solvated crystals were isolated and both were subjected to X-ray
crystal structure determinations (Tables 1 and 8). A drawing of the
unsolvated structure is shown in Fig. 8. The ether solvate is similar
except that one of the triflate anions is only hydrogen bonded to
one of the water ligands allowing hydrogen bonding of the ether
molecule to the other water ligand (see supporting information).
Fig. 8 Drawing (50% probability ellipsoids) of the solid-state structure
of the unsolvated form of [Pt(But2bpy)(H2O)2](OTf)2 (17).
planar, as found for the complexes here, or “bent” by folding along
the X–X axis.60,61 Planarity is promoted by high electronegativity
X groups and weak donor ligands on the metal center consistent
with the planarity of the structure reported here.
As a result of the similar sizes of Pt and Pd and O and
N the M2X2 diamond core angles for our complexes are all
comparable with M–X–M angles close to 100◦ and the X–M–X
angles at about 80◦. These angles fall within the range reported for
the many analogous Pt and Pd complexes with this core structure.62
Three of the complexes reported here are exceptional. Complexes
1, 5, and 6 are the first structurally characterized Pt complexes
containing truly l2-oxo ligands bridging between two Pt centers.
Other reported Pt and Pd bridged oxo complexes are l3,21,29,47,52,63–67
or l4,33,68 or if l2 are found to be associated with Li salts through
coordination of the oxo ligand to an alkali metal ion effectively
giving l3-oxo complexes.29,52,69,70 While the disorder between the
oxo and hydroxo ligands in 1 and the poor structure quality of 6
do not allow an examination of the structural details of a l2-oxo
ligand, complex 5 allows an internal comparative analysis of a
l3-oxo and a l2-oxo ligand and this structure will be examined in
more detail.
Scheme 6
Structures
˚
The Au–O distance of 2.054(5) A in 5 is in the range observed
All of the Pt and Pd structures, except that of triplatinum complex
7 and the mononuclear complexes 16 and 17, are based on an M2X2
diamond core (M = Pd, Pt; X = N, O). This core for d8 metals with
a variety of X groups has attracted attention for its tendency to be
in other Au(I) l3-oxo complexes47,48,71 including 9 (M = Pt). In
˚
addition, the Pt–Au distances (3.195 and 3.049 A) are consistent
with d8–d10 closed-shell interactions between the Au and Pt centers.
˚
A difference of 0.056 A between the Pt–O distances for the
2320 | Dalton Trans., 2008, 2314–2327
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˚
to oxo and imido complexes. The diimine ligand supported
complexes described here show similar features but the facile
deprotonation of the hydroxo complexes and the amido complexes
indicate that the diimine ligands impart greater acidity to the
hydroxo and amido ligands. This apparent greater acidity may
be attributed to the reduced metal center electron donation of
diimine ligands as compared to phosphine ligands. The reduced
metal center electron density allows for a greater M–O interaction
and more electron density transfer from the hydroxo or amido
ligand to the metal center.
l3-oxo ligand (average = 2.022 A) and the l2-oxo ligand (average =
˚
1.967(8) A) suggests a lengthening of this distance on coordination
of the Ph3PAu+ fragment to the oxo ligand. This is consistent
with the well-known phenomenon of increasing bond lengths with
increasing atom coordination number.72 As discussed next, steric
interactions may also play a role in the lengthening of the Pt–O
distances.
The coordination environment of the Pt centers of 5 is strongly
distorted from planarity. This is primarily due to a displacement
of the Au bonded oxygen atom O1 out of the Pt coordination
˚
planes defined by Pt1, N1, N2, O2 (deviation < 0.06 A) and Pt2,
˚
˚
N3, N4, O2 (deviation < 0.05 A). The O1 displacement is 0.42 A
Experimental
˚
for the Pt1 plane and 0.93 A for the Pt2 plane. This displacement
appears to arise from steric interactions of the phenyl rings of the
Ph3PAu+ fragment with the Pri2C6H3 groups of the Bian ligand and
probably accounts for the facile exchange of the Ph3PAu+ fragment
with Ph3PAuCl in solution (see above).
Complex 9 (M = Pt) is related to 5 by replacement of the
Bian ligand with a But2bpy ligand and by coordination of another
Ph3PAu+ fragment to the second oxo group. As might be expected,
Experiments were performed under a dinitrogen atmosphere in
a Vacuum Atmospheres Corporation dry box. Solvents were
dried by standard techniques and stored under dinitrogen over
˚
4 A molecular sieves or sodium metal unless otherwise indi-
cated. NMR spectra were recorded at ambient temperatures
unless otherwise indicated on a Bruker AMX-250, -300, or -500
spectrometer using external CFCl3 (19F), K2PtCl4(aq) (195Pt), and
H3PO4 (31P) as standards and are reported in ppm with negative
˚
˚
the Pt–O (2.026(12) A) and Au–O (2.057(3) A) distances are
very similar to those of the l3-oxo group in 5. Again, the steric
interactions causing the distortions in 5 are absent in 9 due now
to the replacement of the Bian ligand with the less sterically
demanding But2bpy ligand and the coordination environment of
the Pt centers is now essentially planar.
1
shifts to lower frequency of the standard. For H NMR spectra
solvent impurities were used to reference back to SiMe4. Labeling
of the Bian and But2bpy ligands for the NMR assignments is
given in Scheme 1. Mass spectra were obtained on a Finnigan
TSQ7000 mass spectrometer. Desert Analytics performed the
microanalyses (inert atmosphere). The presence of solvent of
crystallization in the analyzed samples was confirmed by NMR
Nickel complex 8 can also be considered to be based on a
diamond core where anyone of the three Ni(II) centers may be
taken to bridge across the two oxygen atoms of an Ni2O2 diamond
core. With the smaller sized Ni center the core angles in 8 are
reduced to average values of 85.8◦ (Ni–O–Ni) and 76.9◦ (O–
Ni–O). A more accurate description of the core structure of 8
is that of a trigonal bipyramid or a dioxo bicapped triangle.
While this structural motif has been observed before for Ni(II)
complexes with an Ni3O2 core these have been, with one exception,
RO ligand complexes and not oxo ligand complexes.73–77 The
exception is a Ni6 structure with a single l6-oxo ligand bridging
two Ni3OH units.78 The Ni–O bonds in these complexes range from
spectroscopy. Pd(But2bpy)Cl2,88 Pt(But2bpy)Cl2,29 [(But2bpy)Pt(l-
OH)]2(BF4)2,29 [(Ph3PAu)3(l3-O)]BF4,89 (COD)Pt(OTf)2
and
90,91
92
(Bian)PtCl2 were prepared by literature procedures. Nickel(II)
chloride was dried overnight at 100 ◦C. Other reagents were
purchased from commercial sources (Aldrich or Acros) and used
as received.
(But2bpy)NiCl2
A solution of NiCl2 (200 mg, 1.54 mmol) in absolute ethanol
(30.0 mL) was added to a stirred suspension of But2bpy (413 mg,
1.54 mmol) in absolute ethanol (30.0 mL). The reaction mixture
was refluxed with stirring. Over 5 h the yellow solution slowly
became green and a green solid deposited. The green solid product
was collected by filtration, washed with hot ethanol and then
diethyl ether and then dried at 160 ◦C for 3 h. Yield: 565.0 mg
(92%). The product was recrystallized for analysis from CH2Cl2–
ether. Anal. calcd (found) for C18H24N2NiCl2: C, 54.27 (54.15); H,
6.03 (6.13); N, 7.03 (6.87%). 1H NMR (CD2Cl2): The paramagnetic
product shows only a broad peak at 1.69 ppm.
˚
1.906(8) to 2.516(5) A, generally longer than the average value of
˚
1.849 A in 8. Oxo ligands are encountered in diatomic Ni(III)
complexes with Ni2O2 cores. Those that have been structurally
characterized show Ni–O bond distances similar to those in
8 (1.841(7), 1.870(8);15 1.888(6), 1.854(7);79 1.843(5), 1.857(4),
1.76(3), 1.81(2) A ). A single Ni–O–Ni bridge exists in the Ni(III)
complex [Ni(salen)]2O. Here the Ni–O distances are shorter than
in 8 at 1.790(2) A.81 Mixed-metal Ni oxo complexes have also been
reported. In the Ni(II) complex [Ni(acac)2(PhHgOHgPh)]2 the
structure consists of a Ni2O2 diamond core with two PhHg units
coordinated to each oxo group. The Ni–O distance is 2.096(4) A.
80
˚
˚
82
˚
[CrFeNiO(OCCH)(py)] metals are disordered.83 Finally, the Pd
and Pt sulfido analogs of 884 and sulfido complexes with Ni3S2
trigonal bipyramidal cores with phosphine,85 allyl,86 and sulfur87
ligands have been reported and structurally characterized.
[Pt(l-OH)(Bian)]2(BF4)2
This complex was prepared by the following modified literature
procedure.28 (Bian)PtCl2 (50 mg, 0.065 mmol) was suspended in
2 mL of THF. AgBF4 (30 mg, 0.015 mmol), a small amount of
polyvinyl pyridine, and a drop of water were added. The mixture
was refluxed overnight. The volatiles were then removed in vacuo
and the residue dissolved in 15 mL of CH2Cl2. The solution was
passed through a pad of diatomaceous earth, reduced in volume
Concluding remarks
Previous work in our group has focused on phosphine ligand
supported hydroxo and amido complexes and their deprotonation
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to ca. 3 mL, layered with diethyl ether, and cooled to 0◦C to obtain
dark red needle shaped crystals of the product. Yield: 36 mg (70%).
0.800 mmol). The mixture became yellow within 20 min. The
mixture was further stirred for 20 h and then filtered. The
filtrate was concentrated in vacuo to ca. 10 mL. Ether (20 mL)
was added and the mixture was stored at −30 ◦C for 3 h.
The resulting fine microcrystalline yellow product was isolated
by filtration. Yield: 113 mg (72%). Anal. calcd (found) for
C36H49BF4N4O2Pd2·0.5CH2Cl2: C, 48.02 (47.60); H. 5.48 (5.61);
N, 6.14 (6.01%). The product was recrystallized from CH2Cl2–
[(But2bpy)Pd(l-OH)]2(BF4)2
Solid AgBF4 (390 mg, 2.00 mmol) and 3–4 drops of water were
added to a solution of (But2bpy)PdCl2 (445 mg, 1.00 mmol)
in CH2Cl2 (60 mL). The reaction mixture was stirred for 6 h
and then filtered. The filtrate was concentrate in vacuo to ca.
10 mL. Ether (30 mL) was added and the mixture was cooled at
−30 ◦C for 3 h. The resulting fine microcrystalline pale yellow
product was isolated by filtration. Yield: 365 mg (76%). The
product was recrystallized from CH2Cl2–ether. Anal. calcd (found)
for C36H50N4B2F8O2Pd2: C, 45.17 (44.98); H. 5.26 (5.36); N, 5.85
1
ether. H NMR (250 MHz, CD2Cl2): 8.66 (d, JHH = 5.9 Hz, 4H,
6,6ꢀ-H-bpy), 7.95 (d, JHH = 1.8 Hz, 4H, 3,3ꢀ-H-bpy), 7.73 (dd,
JHH = 5.9 and 1.8 Hz, 4H, 5,5ꢀ-H-bpy), 1.42 (s, 36H, But).
M = Pt (2)
Method A.
A
solution of [{(But2bpy)Pt(l-OH)]2(BF4)2
1
(5.75%). H NMR (300 MHz, CD2Cl2): 8.31 (d, JHH = 6.0 Hz,
4H, 6,6ꢀ-H-bpy), 7.89 (d, JHH = 1.6 Hz, 4H, 3,3ꢀ-H-bpy), 7.65 (dd,
JHH = 6.0 & 1.6 Hz, 4H, 5,5ꢀ-H-bpy), 1.43 (s, 36H, But), 0.28 (s,
2H, OH).
(227 mg, 0.200 mmol) in CH2Cl2 (20 mL) was vigorously stirred
with solid NaH (19.2 mg, 0.800 mmol). The mixture changed
from yellow to orange to red over a 30 min period. Stirring was
continued for 6 h and then the mixture was filtered. The filtrate
was concentrated in vacuo to ca. 10 mL. Ether (20 mL) was added
and the mixture was stored at −30 ◦C for 24 h. The resulting brick
red microcrystalline solid was isolated by filtration and dried in
vacuo. Yield: 187 mg (89%).
[Pt2(l-OH)(l-O)(Bian)2](BF4) (1)
Method A. To a red solution of [Pt(l-OH)(Bian)]2(BF4)2
(50 mg, 0.031 mmol) dissolved in 3 mL of reagent grade
CH2Cl2 was added ∼10 equivalents of 1,8-bis(dimethylamino)-
naphthalene. The reaction mixture was stirred for 15 min during
which time it turned from red to purple. The mixture was stirred
for an additional 15 min, passed through a pad of diatomaceous
earth, and the volatiles removed in vacuo to give a purple solid. The
solid was dissolved in a minimum volume of CH2Cl2 and ether was
added to give a purple precipitate of the product contaminated
with protonated 1,8-bis(dimethylamino)naphthalene salt which
could not be eliminated.
Method B. A THF solution (2 mL) of 1,8-bis(dimethyl-
amino)naphthalene (42.8 mg, 0.200 mmol) was added to a
suspension of [(But2bpy)Pt(l-OH)]2(BF4)2 (113 mg, 0.100 mmol)
in THF (10 mL). The solution changed from yellow to orange
within 10 min then after 30 min it became red. The reaction
mixture was stirred for 16 h and then filtered. The resulting product
was collected by filtration. Yield: 90.0 mg (86%). The product
was recrystallized from CH2Cl2–ether. Anal. calcd (found) for
C36H49N4BF4O2Pt2·0.7CH2Cl2: C, 39.85 (38.82); H. 4.59 (4.61);
1
Method B. To a red solution of [Pt(l-OH)(Bian)]2(BF4)2
(25 mg, 0.016 mmol) in 3 mL of reagent grade CH2Cl2 was added
4 mg of a crushed KOH pellet. The reaction mixture slowly turns
purple after stirring for 15 min. At this point the stirring was
stopped and the volatiles removed in vacuo to obtain a purple
solid. The purple solid was dissolved in CH2Cl2, the solution
passed through a pad of diatomaceous earth and the solvent
N, 5.06 (4.96%). H NMR (250 MHz, CD2Cl2): 9.33 (br s, 4H,
6,6ꢀ-H-bpy), 7.64 (d, JHH = 2 Hz, 4H, 3,3ꢀ-H-bpy), 7.49 (dd, 6 and
2 Hz, 4H, 5,5ꢀ-H-bpy), 1.27 (s, 36H, But). The OH signal was not
observed. UV-Vis (kmax/nm, CH2Cl2): 380, 320, 305, 270, 250.
[(But2bpy)2Pt2(l-OH)(l-OCH3)](BF4)(OTf) (3)
A solution of MeOTf (33.0 mg. 0.200 mmol) was added drop-wise
to a stirred solution of [(But2bpy)2Pt2(l-OH)(l-O)](BF4) (20 mg,
0.019 mmol) in CH2Cl2 (10 mL). The mixture changed from red
to yellow within 10 min. Stirring was continued for 2 h then the
mixture was filtered. The filtrate was concentrate in vacuo to ca.
4 mL. Ether (12 mL) was added and mixture cooled at −30 ◦C for
24 h. The resulting yellow solid was isolated by filtration. Yield:
19.7 mg (90%). The product was recrystallized from CH2Cl2–ether.
Anal. calcd (found) for C38H52BF7N4O5Pt2S·0.5(CH2Cl2): C, 36.89
evaporated to dryness to give the purple product in quantitative
1
yield. H NMR (CD2Cl2): 8.31 and 8.23 (overlapping d’s, JHH
=
ꢀ
7.8 Hz, 2H and 2H, H5 and H5 ), 7.50 (br t, JHH ∼ 8 Hz, 4H,
ꢀ
ꢀ
ꢀ
ꢀ
H4 and H4 ), 7.22–7.35 (m, 12H, H10,11,12,10 11 12 ), 6.93 (br d, JHH
ꢀ
∼ 7 Hz, 2H, H3 or H3 ), 6.75 (br d, JHH ∼ 7 Hz, 2H, H3 or
ꢀ
H3 ), 3.30 (br sept, JHH ∼ 7 Hz, 4H, CH(CH3)2), 3.17 (br sept,
JHH ∼ 7 Hz, 4H, CH(CH3)2), 1.33 (br d, JHH ∼ 7 Hz, 12H,
CH(CH3)2), 1.12 (br d, JHH ∼ 7 Hz, 12H, CH(CH3)2), 0.96
(br d, JHH ∼ 7 Hz, 12H, CH(CH3)2), 0.90 (br d, JHH ∼ 7 Hz,
12H, CH(CH3)2), −1.84 (br s, 1H, OH). The 1H NMR spectrum
is often broadened due to trace protic impurities but sharpens
on addition of 1,8-bis(dimethylamino)naphthalene. Crystals were
grown at room temperature by layering a CD2Cl2 solution with
1
(37.09); H, 4.26 (3.99); N, 4.47 (4.28%). H NMR (250 MHz,
CD2Cl2): 8.72 (d, JHH = 6.1 Hz, 2H, 6-H-bpy), 8.68 (d, JHH
=
5.6 Hz, 2H, 6ꢀ-H-bpy), 7.93 (d, JHH = 1.8 Hz, 2H, 3-H-bpy), 7.85
(d, JHH = 1.8 Hz, 2H, 3ꢀ-H-bpy), 7.69 (dd, JHH = 6.1 and 1.8 Hz,
2H, 5-H-bpy), 7.62 (dd, JHH = 6.1 and 1.8 Hz, 2H, 5ꢀ-H-bpy), 4.21
(s, 1H, OH), 3.12 (s, 3H, Me), 1.44 (s, 18H, But), 1.42 (s, 18H, But).
˚
˚
Et2O. Crystal data: a = 18.4678(18) A, b = 15.3307(15) A, c =
◦
˚
24.099(2) A, b = 99.058(2) , monoclinic, P21/c.
[(But2bpy)2M2(l-OH)(l-O)]BF4. M = Pd
[Pt(l-O)(Bian)]2 (4)
A solution of [{(But2bpy)Pd(l-OH)]2(BF4)2 (191 mg, 0.200 mmol)
To a red solution of [Pt(l-OH)(Bian)]2(BF4)2 (50 mg, 0.031 mmol)
dissolved in 3 mL of CH2Cl2 was added a 10 mg portion of a
in CH2Cl2 (20 mL) was vigorously stirred with solid NaH (19.2 mg,
2322 | Dalton Trans., 2008, 2314–2327
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crushed KOH pellet and one drop of water. The reaction mixture
turned purple after stirring for 15 min, and then finally became
the dark blue of the product after two hours of stirring. The
reaction mixture was then evaporated to dryness, the residue
dissolved in a minimum amount of CH2Cl2, passed through a
pad of diatomaceous earth, and the volatiles removed in vacuo.
The resulting blue solid product was washed with petroleum ether
and dried in vacuo. Yield (35 mg, 80%). 1H NMR (CD2Cl2): 8.10
(d, JHH = 8.2 Hz, 4H, H5), 7.39 (t, JHH = 7.7 Hz, 4H, H11), 7.24 (d,
˚
˚
with toluene. Crystal data: a = 16.346(3) A, b = 28.541(6) A, c =
◦
˚
15.987(3) A, b = 99.362(4) , monoclinic, P21/c.
Reaction of [Pt(l-O)(Bian)]2 (4) with excess MeOTf
To a solution of 4 (10 mg, 0.0070 mmol) dissolved in 4 mL of
CH2Cl2 was added methyl triflate (6.0 mg, 0.036 mmol) in 2 mL of
CH2Cl2. As the mixture was stirred over an hour the color changed
from blue to purple and later to dark-red. The dark-red solution
was evaporated to dryness, washed with pentane and dried in vacuo
to give an incompletely characterized red compound that ma◦y be
[(Bian)Pt(OTf)2]. Yield (8.0 mg, 85%). 1H NMR (CD2Cl2, 25 C):
8.29 (d, JHH = 7.5 Hz, 4H, H5), 7.33 (d, JHH = 7.5 Hz, 8H, H10),
7.60–7.51 (overlapping t, JHH = 7.5 Hz, 8H, H4 and H11) 6.78 (d,
JHH = 7.5 Hz, 4H, H3), 3.41 (septet, JHH = 7.5 Hz, 8H, CH(CH3)2),
1.21 (d, JHH = 7.5 Hz, 24H, CH(CH3)2), 0.82 (d, JHH = 7.5 Hz,
24H, CH(CH3)2. 19F NMR (CD2Cl2, 25 ◦C): −79.04.
JHH = 7.7 Hz, H10,12), 7.12 (t, JHH = 7.7 Hz, 4H, H4), 6.55 (d, JHH
=
7.1 Hz, 4H, H3), 3.38 (sept, JHH = 6.9 Hz, 8H, CH(CH3)2), 1.22
(d, JHH = 6.9 Hz, 24H, CH(CH3)2), 0.82 (d, JHH = 6.9 Hz, 24H,
CH(CH3)2). Anal. calcd (Found) for C72H80N4O2Pt2·0.5 CH2Cl2:
C, 59.44 (59.40); H, 5.58 (5.57); N, 3.73 (3.83%).
[(Bian)2Pt2(l2-O)(l3-OAuPPh3)](BF4) (5)
To a solution of 4 (15 mg, 0.011 mmol) dissolved in 2 mL of
CH2Cl2 was added 10 mg of freshly prepared “Ph3PAuBF4” (from
Ph3PAuCl and AgBF4 in THF)93 in CH2Cl2. The reaction mixture
changed from blue to dark purple. The reaction mixture was stirred
for 20 min and then the volatiles were removed in vacuo. The
residue was washed with petroleum ether and dried in vacuo to
give the bluish-purple solid product. Yield (25 mg, 91%). Crystals
suitable for X-ray diffraction and analysis were grown at room
temperature by layering a CH2Cl2 solution with toluene. Anal.
calcd (Found) for C90H95AuBF4N4O2PPt2: C, 54.88 (55.14); H,
4.86 (4.73); N, 2.85 (2.76%). 1H NMR (CD2Cl2, −20 ◦C): 8.24 (d,
JHH = 8.2 Hz, 4H, H5), 7.50–7.18 (m, 31H, PPh3 and H4,10,11,12),
6.76 (d, JHH = 7.2 Hz, 4H, H3), 3.55 (br sept, JHH = 6.5 Hz, 4H,
CH(CH3)2), 3.10 (br sept, JHH = 6.6 Hz, 4H, CH(CH3)2), 1.07
(d, JHH = 6.6 Hz, 12H, CH(CH3)2), 0.98 (d, JHH = 6.6 Hz, 12H,
CH(CH3)2), 0.72 and 0.70 (overlapping d’s, JHH = 6.6 Hz, 12H and
12H, CH(CH3)2). 31P NMR (CH2Cl2, 101 MHz, −20 ◦C): 22.9 (s).
Spectra (the 2,6-Pri2C6H3 signals only) are broadened at 25 ◦C due
to exchange with traces of Ph3PAuCl, which is visible at 32 ppm
in the 31P NMR spectrum. Identical NMR spectra are observed
with mixtures of 4 and Ph3PAuCl.
Reaction of [Pt(l-O)(Bian)]2 (4) with [Pt(COD)(OTf)2]:
[(Bian)(COD)2Pt3(l-OH)3](OTf)3 (7)
[Pt(COD)(OTf)2] (9.0 mg, 0.015 mmol) in 1 mL of CH2Cl2 was
added drop-wise to a blue solution of 4 (10 mg, 0.0070 mmol)
dissolved in 4 mL of CH2Cl2. The reaction slowly changed from
blue to purple and finally to yellow brown. The dark-yellow brown
solutionwas concentrated, layered withether, andstored at −30◦C
to give a brown solid. 1H NMR of the brown solid (CD2Cl2): 8.33
(d, JHH = 7.5 Hz, H5), 7.60–7.51 (overlapping t, JHH = 7.5 Hz, H4
and H11), 7.33 (d, JHH = 7.5 Hz, H10), 6.79 (d, JHH = 7.5 Hz, H3),
5.67 (br s with satellites, JPt–H = 68 Hz, COD), 3.25 (sept, JHH
=
6.7 Hz, CH(CH3)2), 2.76 (br m, COD), 2.23 (br d, JPt–H = 8 Hz,
COD), 1.37 (d, JHH = 6.7 Hz, CH(CH3)2), 0.83 (d, JHH = 6.7 Hz,
24H, CH(CH3)2). The Bian to COD ratio was ∼1 : 1 by integration.
A few orange-red crystals deposited from a CH2Cl2 solution of
the brown solid over a 4-day period at room temperature. The
orange-red crystals were characterized by X-ray diffraction as the
trihydroxo complex [(Bian)(COD)2Pt3(l-OH)3](OTf)3 (7).
[(But2bpy)3Ni3(l3-O)2](BF4)2 (8)
A solution of Ni(Butbpy)Cl2 (30 mg, 0.075 mmol) in CH2Cl2
(3 mL) was added to a stirred solution of [(LAu)3(l3-O)]BF4
(74 mg, 0.050 mmol) in CH2Cl2 (3 mL). The mixture changed
from yellow to red within 5 min. The reaction was further stirred
for 25 min and then concentrated in vacuo to ca. 3 mL. THF
(6 mL) was added and the mixture was cooled at −30 ◦C for 24 h.
The resulting fine microcrystalline red product was isolated by
filtration. Yield: 66 mg (74%). Crystals for the X-ray analysis were
obtained by slow recrystallization from CH2Cl2–THF. Anal. calcd
(found) for C54H72N6Ni3O2B2F8: C, 54.65 (53.00); H. 6.11 (5.43);
[(Bian)2Pt2(l-O)(l-OMe)]OTf (6)
To a stirred solution of 4 (15 mg, 0.011 mmol) dissolved in 4 mL
of toluene was added methyl triflate (3 mg, 0.02 mmol) in 1 mL
of toluene. A purple solid precipitated from the mixture. The dark
purple solid was isolated by filtration, washed with pentane and
dried in vacuo. Yield (11 mg, 75%). Crystals for the X-ray analysis
were obtained by layering a CH2Cl2 solution with toluene. Anal.
calcd. (Found) for C74H83F3N4O5Pt2S: C, 55.97 (55.64); H, 5.27
(5.54); N, 3.53 (3.93%). 1H NMR (CD2Cl2, 25 ◦C): 8.29 and 8.26
ꢀ
(overlapping d’s, JHH = 8 Hz, 2H and 2H, H5,5 ), 7.52 (t, JHH
=
1
N, 7.08 (6.37%). H NMR (250 MHz, CD2Cl2): 8.11 (d, JHH
=
ꢀ
ꢀ
ꢀ
ꢀ
7.5 Hz, 4H, H4,4 ) 7.40–7.28 (m, 8H, H11,11 and H10,10 or H12,12 ),
5.9 Hz, 6H, 6,6ꢀ-H-bpy), 7.84 (d, JHH = 1.8 Hz, 6H, 3,3ꢀ-H-bpy),
7.66 (dd, JHH = 5.9 and 1.8 Hz, 6H, 5,5ꢀ-H-bpy), 1.40 (s, 54H,
But).
ꢀ
ꢀ
7.22 (d, JHH = 7.5 Hz, 4H, H10,10 or H12,12 ), 6.70 (d, JHH = 7.2 Hz,
ꢀ
ꢀ
4H, H3 or H3 ) 6.59 (d, JHH = 7.2 Hz, 4H, H3 or H3 ), 3.38 (sept,
JHH = 6.8 Hz, 4H, CH(CH3)2), 3.12 (septet, JHH = 6.8 Hz, 4H,
CH(CH3)2), 2.48 (s with broad base, 3H, OMe), 1.40 (d, JHH
=
[(But2bpy)Pt(l3-O)(AuPPh3)]2(BF4)2 (9, M = Pt)
A solution of Pt(But2bpy)Cl2 (106 mg, 0.200 mmol) in CH2Cl2
(3 mL) was added to a stirred solution of [(LAu)3(l3-O)]BF4
(296 mg. 0.200 mmol) in CH2Cl2 (3 mL). The mixture changed
6.8 Hz, 12H, CH(CH3)2), 1.13 (d, JHH = 6.8 Hz, 12H, CH(CH3)2),
0.92 (d, JHH = 6.8 Hz, 12H, CH(CH3)2), 0.85 (d, JHH = 6.8 Hz,
12H, CH(CH3)2). 19F NMR (CD2Cl2, 25 ◦C): −79.0. Crystals
were grown at room temperature by layering a CD2Cl2 solution
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from yellow to golden-yellow within 15 min. The reaction was
further stirred for 25 min and then concentrated in vacuo to ca.
3 mL. Toluene (6 mL) was added and the mixture was stored at
−30 ◦C for 24 h. The resulting fine microcrystalline yellow-orange
product was isolated by filtration. Yield: 150 mg (73%). Crystals
for X-ray analysis were obtained by recrystallization from CD2Cl2–
ether. Anal. calcd (found) for C72H78N4Au2B2F8O2P2Pt2: C, 42.14
7.8 Hz, 2H, 2,2ꢀ-H-aniline), 7.88 (d, JHH = 1.5 Hz, 2H, 3-H-bpy),
7.82 (d, JHH = 1.8 Hz, 2H, 3ꢀ-H-bpy), 7.78 (dd, JHH = 6.0 and
1.5 Hz, 2H, 5-H-bpy), 7.57 (dd, JHH = 6.3 and 2.1 Hz, 2H, 5ꢀ-H-
bpy), 7.39 (t, JHH = 7.6 Hz, 1H, 3-H-aniline), 7.15 (t, JHH = 6.6,
1H, 3ꢀ-H-aniline), 5.20 (s, 1H, NH), 2.55 (br s, 1H, OH), 1.44 (s,
18H, But), 1.38 (s, 18H, But).
1
(42.13); H. 3.80 (3.87); N, 2.73 (2.80%). H NMR (300 MHz,
Ar = 4-C6H4NO2
CD2Cl2): 9.00 (d, 4H, JHH = 6.0 Hz, 6,6ꢀ-H-bpy), 8.09 (d, 4H,
JHH = 1.8 Hz, 3,3ꢀ-H-bpy), 7.58 (dd, 4H, JHH = 6.1 Hz, JHH
=
A solution of 4-nitroaniline (97.0 mg, 0.704 mmol) was added
to a stirred solution of [(But2bpy)Pt(l-OH)]2(BF4)2 (200 mg,
0.176 mmol) in CH2Cl2 (50 mL). The solution turned from yellow
to orange within 20 min. The reaction was further stirred for
24 h and then filtered. The resulting filtrate was concentrated in
vacuo to ca. 15 mL. To this solution ether (30 mL) was added
and the product was isolated by filtration. Yield: 326 mg (74%).
Crystals for an X-ray analysis were obtained by recrystallization
from CD2Cl2–ether at −30 ◦C but these gave very poor results
and contained badly disordered solvent molecules. 1H NMR
(300 MHz, CD2Cl2): 8.75 (d, 2H, JHH = 5.8 Hz, 6-H-bpy), 8.46 (d,
2H, JHH = 8.9 Hz, 2,2ꢀ-H-p-nitroaniline), 8.41 (d, 2H, JHH = 6.2 Hz,
6ꢀ-H-bpy), 8.23 (d, 2H, JHH = 8.9 Hz, 3,3ꢀ-H-p-nitroaniline), 7.87
(d, 2H, 3-H-bpy), 7.83 (d, 2H, JHH = 1.4 Hz, 3ꢀ-H-bpy), 7.79 (d,
2H, JHH = 6.0, 5-H-bpy), 7.60 (d, 2H, JHH = 4.3, 5ꢀ-H-bpy), 5.66
(s, 1H, NH), 2.83 (s, 1H, OH), 1.45 (s, 18H, But), 1.39 (s, 18H,
But).
1.9 Hz, 5,5ꢀ-H-bpy), 7.44–7.24 (m, 30 H, Ph), 1.45 (s, 36H, But).
1
31P{ H} NMR (101 MHz, CD2Cl2): 23.1 (s). 195Pt NMR (64 MHz,
CD2Cl2): −1255 (s).
[(But2bpy)2Pt2(l-OH)(l-NHAr)](BF4)2 (11). Ar = 4-tol
A CH2Cl2 solution (5 mL) of p-toluidine (75.3 mg, 0.704 mmol)
was added to a stirred solution of [(But2bpy)Pt(l-OH)]2(BF4)2
(200 mg, 0.176 mmol) in CH2Cl2 (50 mL). The mixture changed
from yellow to orange within 20 min. The reaction was further
stirred for 2 h and then filtered. The filtrate was concentrated in
vacuo (15 mL). To this solution ether (30 mL) was added and the
apricot colored product was isolated by filtration. Yield: 200 mg
(93%). The product was recrystallized from CH2Cl2–ether. Anal.
calcd (found) for C43H57N5B2F8OPt2: C, 42.19 (42.27); H. 4.66
(4.79); N, 5.72 (5.58%).
MS (ESI/APC-direct infusion, CH2Cl2, m/z): 1136.4 (10%,
[{(C18H24N2)2Pt2(l-OH)(l-NHC6H4CH3-4)}]+), 1048.4 (13%,
[{(C18H24N2)2Pt2(l-OH)(l-NHC6H4CH3-4)}]2+), 525.1 (23%, [(C18-
H24N2)Pt(C7H8N)(OH)/2]), 516.0 (100%, [(C18H24N2)Pt(C7-
[(But2bpy)Pd(l-NHAr)]2(BF4)2 (12). Ar = Ph
Method A. A solution of aniline (93.0 mg, 1.00 mmol) in
CH2Cl2 (5 mL) was added to [(But2bpy)Pd(l-OH)]2(BF4)2 (239 mg,
0.250 mmol) in CH2Cl2 (50 mL). The mixture changed from yellow
to red within 30 min. The reaction was stirred for 4 h and then
filtered. The filtrate was concentrate in vacuo to ca. 15 mL. To
this solution ether (30 mL) was added and the resulting fine
microcrystalline yellow product was isolated by filtration. Yield:
221 mg (80%).
H8N)/2]). 1H NMR (300 MHz, CD2Cl2): 8.78 (d, 2H, JHH
=
5.6 Hz, 6-H-bpy), 8.40 (d, 2H, JHH = 5.9 Hz, 6ꢀ-H-bpy), 8.14 (d,
2H, JHH = 8.3 Hz, 2,2ꢀ-H-p-tol), 7.86 (s, 2H, 3-H-bpy), 7.81 (s,
2H, 3ꢀ-H-bpy), 7.78 (d, 2H, JHH = 4.6 Hz, 5-H-bpy), 7.57 (d, 2H,
JHH = 5.3 Hz, 5ꢀ-H-bpy), 7.19 (d, 2H, JHH = 8.2 Hz, 3,3ꢀ-H-p-tol),
5.17 (s, 1H, NH), 2.55 (s, 1H, OH), 2.25 (s, 3H, Me-p-tol), 1.44 (s,
18H, But), 1.39 (s, 18H, But).
Method B. A CH2Cl2 solution (5 mL) of LiPhNH (99.0 mg,
1.00 mmol) was added to a stirred solution of [(But2bpy)Pd(l-
OH)]2(BF4)2 (239 mg, 0.250 mmol) in CH2Cl2 (50 mL). Within
30 min the color of reaction changed from yellow to red. The
reaction was further stirred for 4 h and then filtered. The filtrate
was concentrate in vacuo to ca. 15 mL. Ether (30 mL) was
added and the resulting fine microcrystalline yellow product was
isolated by filtration. Yield: 219 mg (79%). Crystals for the X-
ray analysis were obtained by recrystallization from THF–ether at
−30 ◦C. Anal. calcd (found) for C48H60B2F8N6Pd2·0.5(CH2Cl2): C,
50.66 (50.43); H. 5.35 (5.26); N, 7.31 (6.93%). 1H NMR (250 MHz,
CD2Cl2): 8.59 (d, JHH = 7.5 Hz, 4H, NC6H5), 8.17 (d, JHH = 6.2 Hz,
4H, 6,6ꢀ-H-bpy), 7.79 (d, JHH = 1.8 Hz, 4H, 3,3ꢀ-H-bpy), 7.55 (dd,
JHH = 6.2 and 1.8 Hz, 4H, 5,5ꢀ-H-bpy), 7.31 (t, JHH = 8.8 Hz, 4H,
NC6H5), 7.03 (t, JHH = 7.5 Hz, 2H, NC6H5), 2.89 (s, 2H, NH),
1.35 (s, 36H, But).
Ar = Ph
Method A.
A
solution of [(But2bpy)Pt(l-OH)]2(BF4)2
(283.5 mg, 0.250 mmol) in CH2Cl2 (25 mL) was added to a stirred
solution of aniline (93.0 mg, 1.00 mmol) in CH2Cl2 (5 mL). The
mixture changed from yellow to red within 20 min. The reaction
was further stirred for 4 h and then filtered. The filtrate was
concentrate in vacuo to ca. 10 mL. Ether (20 mL) was added
and the resulting fine microcrystalline yellow-orange product was
isolated by filtration. Yield: 245 mg (81%).
Method B. A solution of LiPhNH (99.0 mg, 1.00 mmol) in
CH2Cl2 (5 mL) was added to a stirred solution of [(But2bpy)Pt(l-
OH)]2(BF4)2 (283.5 mg, 0.250 mmol) in CH2Cl2 (20 mL). Within
30 min the color of the mixture changed from yellow to red. The
mixture was further stirred for 4 h and then filtered. The filtrate
was concentrate in vacuo to ca. 10 mL. Ether (20 mL) was added
and the resulting fine microcrystalline yellow-orange product was
isolated by filtration. Yield: 240 mg (79%). Anal. calcd (found) for
C42H55N5B2F8OPt2·1.5CH2Cl2: C, 39.08 (39.11); H. 4.37 (4.48); N,
5.24 (5.04%). 1H NMR (300 MHz, CD2Cl2): 8.78 (d, JHH = 6.0 Hz,
Ar = 4-tol
A solution of [(But2bpy)Pd(l-OH)]2(BF4)2 (239 mg, 0.250 mmol)
in CH2Cl2 (50 mL) was reflux with p-toluidine (107 mg, 1.00 mmol)
with stirring for 20 h and then filtered. The filtrate was concentrate
2H, 6-H-bpy), 8.41 (d, JHH = 6.3 Hz, 2H, 6ꢀ-H-bpy), 8.26 (d, JHH
2324 | Dalton Trans., 2008, 2314–2327
=
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in vacuo to ca. 15 mL. Ether (30 mL) was added and the resulting
fine microcrystalline yellow product was isolated by filtration.
Yield: 230 mg (81%). Crystals for the X-ray analysis were obtained
by recrystallization from CD2Cl2–ether at −30 ◦C. Anal. calcd
(found) for C50H64N6B2F8Pd2: C, 52.86 (52.05); H. 5.63 (5.65);
N, 7.40 (7.20%). (The low carbon value probably results from
became deep yellow and an orange solid deposited. The orange
solid was collected by filtration. Yield: 113.0 mg (45%).
Method C. A THF solution (2 mL) of proton sponge
(68.5 mg, 0.320 mmol) was added to a stirred solution/suspension
of [(But2bpy)2Pt2(l-OH)(l-NHC6H4Me-4)](BF4)2 (195 mg,
0.160 mmol) in THF (30 mL). The reaction mixture was
refluxed with stirring for 6 h. The resulting solid product was
collected by filtration. Yield: 137.0 mg (75%). The product
was recrystallized from CH2Cl2–ether. Anal. calcd (found) for
C43H56N5BF4OPt2·0.5NaBF4 (method A): C, 43.37 (42.97); H. 4.74
(4.75); N, 5.88 (5.89%). MS (ESI/APC-direct infusion, CH2Cl2,
m/z): 1084.4 (90%, [(C18H24N2)2Pt2(l-O)(l-NHC6H4CH3-4)]+),
568.0 (100%, [(C18H24N2)Pt(l-NC6H4CH3-4)]), 268.9 (24%,
occluded CH2Cl2.) 1H NMR (300 MHz, CD2Cl2): 8.52 (d, JHH
=
8.2 Hz, 4H, H-p-tol), 8.26 (d, JHH = 6.0 Hz, 4H, 6,6ꢀ-H-bpy), 7.68
(d, JHH = 1.8 Hz, 4H, 3,3ꢀ-H-bpy), 7.55 (dd, JHH = 6.0 & 1.8 Hz,
4H, 5,5ꢀ-H-bpy), 7.09 (d, JHH = 8.2 Hz, 4H, H-p-tol), 2.83 (s, 2H,
NH), 2.17 (s, 6H, Me-p-tol), 1.34 (s, 36H, But).
Ar = 4-C6H4NO2
1
[C18H24N2]). H NMR (300 MHz, CD2Cl2): 10.28 (d, 2H, 6-H-
A solution of [(But2bpy)Pd(l-OH)]2(BF4)2 (150 mg, 0.157 mmol)
in CH2Cl2 (50 mL) was refluxed with 4-nitroaniline (87.0 mg,
0.630 mmol). The bright yellow solution was further refluxed with
stirring for 5 h and then filtered. The filtrate was concentrate in
vacuo to ca. 15 mL. Ether (30 mL) was added and the resulting fine
microcrystalline yellow product was isolated by filtration. Yield:
172 mg (91%). The product was recrystallized from CH2Cl2–ether.
Anal. calcd (found) for C48H58N8O4B2F8Pd2: C, 48.16 (48.34); H.
bpy), 8.14 (d, 2H, JHH = 5.8 Hz, 2,2ꢀ-H-p-tol), 7.68 (d, 2H, JHH
=
4.4 Hz, 6ꢀ-H-bpy), 7.60 (d, 2H, 3-H-bpy), 7.55 (d, 2H, 5-H-bpy),
7.43 (d, 2H, 3ꢀ-H-bpy), 7.14 (d, 2H, 3,3ꢀ-H-p-tol), 5.46 (s, 1H,
NH), 2.32 (s, 3H, Me-p-tol), 1.31 (s, 18H, But), 1.04 (s, 18H, But).
[(But2bpy)Pt(l-N-4-tol)]2 (15)
A
solution of [(But2bpy)Pt(l-NH-4-tol)]2(BF4)2 (91.8 mg,
1
4.84 (4.31); N, 9.36 (9.10%). H NMR (300 MHz, CD2Cl2): 8.79
0.070 mmol) in CH2Cl2 (50 mL) was vigorously stirred with solid
ButOK (17.0 mg, 0.070 mmol). The solution color changed from
yellow to black green within 10 min. Stirring was continued for
15 h and then the mixture was filtered. The volume of the filtrate
was reduced in vacuo to ca. 15 mL. Ether (30 mL) was added and
the resulting dark green product was isolated by filtration. Yield:
68.0 mg (74%). Anal. calcd (found) for C50H62N6Pt2: C, 52.81
(d, JHH = 8.8 Hz, 4H, H-p-nitroaniline), 8.19 (d, JHH = 8.8 Hz, 4H,
H-p-nitroaniline), 8.14 (d, JHH = 6.0 Hz, 4H, 6,6ꢀ-H-bpy), 7.81 (d,
JHH = 1.9 Hz, 4H, 3,3ꢀ-H-bpy), 7.59 (dd, JHH = 6.0, 4H, 1.9 Hz,
5,5ꢀ-H-bpy), 3.54 (s, 2H, NH), 1.36 (s, 36H, But).
[(But2bpy)Pt(l-NH-4-tol)]2(BF4)2 (13)
1
(52.35); H. 5.50 (5.12); N, 7.39 (7.05%). H NMR (300 MHz,
A solution of p-toluidine (42.8 mg, 0.400 mmol) was added to a
suspension of [(But2bpy)2Pt2(l-OH)(l-NH-4-tol)](BF4)2 (245 mg,
0.200 mmol) in CH2Cl2 (50 mL). The solution was stirred for
20 h and then filtered. The filtrate was concentrate in vacuo to
ca. 15 mL. To this solution ether (30 mL) was added and the
amber product was isolated by filtration. Yield: 210 mg (80%).
The product was recrystallized from CD2Cl2–ether. Anal. calcd
CD2Cl2): 9.06 (d, 4H, JHH = 6.1 Hz, 6,6ꢀ-H-bpy), 8.71 (d, 4H,
JHH = 8.0 Hz, 2,2ꢀ-H-p-tol), 7.73 (d, 4H, JHH = 1.6 Hz, 3,3ꢀ-H-
bpy), 7.61 (dd, 4H, JHH = 6.0 AND Hz, 1.9-H-bpy), 7.07 (d, 4H,
JHH = 7.9 Hz, 3,3ꢀ-H-p-tol), 2.17 (s, 6H, Me-p-tol), 1.35 (s, 36H,
But).
(But2bpy)Pd(OTf)2 (16). M = Pd
(found) for C50H64N6B2F8Pt2: C, 45.73 (45.14); H. 4.87 (4.99); N,
1
A solution of Pd(But2bpy)Cl2 (44.5 mg, 0.100 mmol) in CH2Cl2
(3 mL) was stirred with solid AgSO3CF3 (51.4 mg, 0.200 mmol)
for 1 h in the absence of light. The reaction mixture changed
from yellow to golden-yellow within 15 min with a pale purple
precipitate of AgCl. The yellow solution was collected by filtration
and then dried in vacuo. The solid was recrystallized from CH2Cl2–
ether. Yield: 61.2 mg (91%). Crystals for X-ray analysis were
obtained by recrystallization from CD2Cl2–ether. Anal. calcd
(found) for C20H24N2PdS2O6F8: C, 35.71 (35.62); H. 3.57 (3.61);
6.40 (6.27%). H NMR (300 MHz, CD2Cl2): 8.47 (d, 4H, JHH
=
6.1 Hz, 6,6ꢀ-H-bpy), 8.31 (d, 4H, JHH = 8.2 Hz, 2,2ꢀ-H-p-tol), 7.81
(d, 4H, JHH = 1.9 Hz, 3,3ꢀ-H-bpy), 7.61 (dd, 4H, JHH = 6.2 and
2.0 Hz, 5,5ꢀ-H-bpy), 7.16 (d, 4H, JHH = 8.1 Hz, 3,3ꢀ-H-p-tol), 4.97
(s, 2H, NH), 2.25 (s, 6H, Me-p-tol), 1.40 (s, 36H, But).
[(But2bpy)2Pt2(l-NH-4-tol)(l-O)]BF4 (14)
Method A. A solution of [(But2bpy)2Pt2(l-OH)(l-NH-4-
tol)](BF4)2 (122 mg, 0.100 mmol) in THF (50 mL) was vigorously
stirred with solid NaH (4.80 mg, 0.200 mmol). The solution
became orange within 30 min. Stirring was continued for 3 h and
then the mixture was filtered. The filtrate was reduced in vacuo
to ca. 15 mL. To this solution ether (30 mL) was added and the
resulting orange solid product was isolated by filtration. Yield:
98.0 mg (87%).
N, 4.16 (3.97%). 1H NMR (250 MHz, CD2Cl2): 8.69 (d, 2H, JHH
=
6.3 Hz, 6,6ꢀ-H-bpy), 7.83 (d, 2H, JHH = 2.0 Hz, 3,3ꢀ-H-bpy), 7.64
(dd, 2H, JHH = 6.3 Hz, JHH = 2.1 Hz, 5,5ꢀ-H-bpy), 1.44 (s, 18H,
But).
M = Pt
This known complex55 was prepared similarly to the Pd ana-
log using Pt(But2bpy)Cl2 (53.4 mg, 0.100 mmol) in place of
Pd(But2bpy)Cl2. Yield: 55.0 mg (90%). Anal. calcd (found) for
C20H24N2PtS2O6F8: C, 31.53 (31.43); H. 3.15 (3.29); N, 3.67
(3.46%). 1H NMR (300 MHz, CD2Cl2): 8.64 (d, 2H, JHH = 6.3 Hz,
Method B. A THF solution (5 mL) of p-toluidine (94.1 mg,
0.880 mmol) was added to a suspension of [(But2bpy)Pt(l-
OH)]2(BF4)2 (249 mg, 0.220 mmol) in THF (50 mL). The reaction
mixture was brought to reflux with stirring. Over 6 h the solution
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6,6ꢀ-H-bpy), 7.90 (d, 2H, JHH = 1.9 Hz, 3,3ꢀ-H-bpy), 7.69 (dd, 2H,
JHH = 6.3 Hz, JHH = 2.1 Hz, 5,5ꢀ-H-bpy), 1.45 (s, 18H, But). 195Pt
NMR (64 MHz, CD2Cl2): −3084.4 (s).
22 K. Noro, Y. Ozawa, M. Taguchia and A. Yagasaki, Chem. Commun.,
2002, 1770.
23 E. Szuromi, S. Hui and P. R. Sharp, J. Am. Chem. Soc., 2003, 124,
10522.
24 E. Szuromi, J. Wu and P. R. Sharp, J. Am. Chem. Soc., 2006, 128, 12088.
25 M. A. Cinellu, G. Minghetti, F. Cocco, S. Stoccoro, A. Zucca and M.
Manassero, Angew. Chem., Int. Ed., 2005, 44, 6892.
26 M. A. Cinellu, G. Minghetti, F. Cocco, S. Stoccoro, A. Zucca, M.
Manassero and M. Arca, Dalton Trans., 2006, 5703.
27 J. A. Keith, R. J. Nielsen, J. Oxgaard and W. A. Goddard, J. Am. Chem.
Soc., 2007, 129, 12342.
28 S. Kannan, A. J. James and P. R. Sharp, Polyhedron, 2000, 19, 155.
29 J. J. Li, W. Li and P. R. Sharp, Inorg. Chem., 1996, 35, 604.
30 A. Singh and P. R. Sharp, Dalton Trans., 2005, 2080–2081.
31 T. M. Anderson, R. Cao, E. Slonkina, B. Hedman, K. O. Hodgson,
K. I. Hardcastle, W. A. Neiwert, S. Wu, M. L. Kirk, S. Knottenbelt,
E. C. Depperman, B. Keita, L. Nadjo, D. G. Musaev, K. Morokuma
and C. L. Hill, J. Am. Chem. Soc., 2005, 127, 11948.
32 T. Hosokawa, M. Takano and S. I. Murahashi, J. Am. Chem. Soc.,
1996, 118, 3990.
[(But2bpy)Pt(OH2)2](OTf)2 (17)
A solution of [(But2bpy)Pt(OTf)2] (20.0 mg, 0.025 mmol) in
CH2Cl2 (6 mL) was stirred with 2 equiv of water. The reaction
was further stirred for 2 h and then concentrated in vacuo to
ca. 3 mL. Ether (6 mL) was added and the mixture was cooled
at −30 ◦C for 24 h. The resulting fine microcrystalline yellow
solid was isolated by filtration. Yield: 19.7 mg (94%). Crystals for
◦
the X-ray analysis were obtained from CD2Cl2–ether at −30 C
(ether solvate) or by slow evaporation (in the drybox) of a CH2Cl2
solution (unsolvated). Anal. calcd (found) for C20H28N2PtS2O8F8:
C, 28.75 (28.19); H. 3.38 (3.21); N, 3.35 (3.10%). 1H NMR
(250 MHz, CD2Cl2): 8.56 (d, 2H, JHH = 6.2 Hz, 6,6ꢀ-H-bpy), 8.27
(s, 4H, H2O), 7.95 (d, 2H, JHH = 1.9 Hz, 3,3ꢀ-H-bpy), 7.72 (dd,
2H, JHH = 6.3 Hz, JHH = 2.1 Hz, 5,5ꢀ-H-bpy), 1.47 (s, 18H, But).
33 Y. Zhang, R. J. Puddephatt, L. Manojlovic-Muir and K. W. Muir,
Chem. Commun., 1996, 2599.
34 N. W. Aboelella, J. T. York, A. M. Reynolds, K. Fujita, C. R. Kinsinger,
C. J. Cramer, C. G. Riordan and W. B. Tolman, Chem. Commun., 2004,
1716.
35 U. Anandhi and P. R. Sharp, Inorg. Chem., 2004, 43, 6780.
36 I. Kaljurand, A. Kutt, L. Soovali, T. Rodima, V. Maemets, I. Leito and
I. A. Koppel, J. Org. Chem., 2005, 70, 1019.
Acknowledgements
37 A. L. Llamas-Saiz, C. Foces-Foces and J. Elguero, J. Mol. Struct., 1994,
328, 297.
38 S. Wimmer, P. Castan, F. L. Wimmer and N. P. Johnson, J. Chem. Soc.,
Dalton Trans., 1989, 403.
Support from the Chemical Sciences, Geosciences and Biosciences
Division, Office of Basic Energy Sciences, Office of Science,
U. S. Department of Energy (DE-FG02-88ER13880) is gratefully
acknowledged. A grant from the National Science Foundation
(9221835) provided a portion of the funds for the purchase of
the NMR equipment. We thank Chad Magee for initial synthetic
work on 1 and Dr Charles Barns for X-ray data collection and
processing.
39 O. Crespo, A. Laguna, E. J. Fernandez, J. M. Lopez-de-Luzuriaga, P. G.
Jones, M. Teichert, M. Monge, P. Pyykko, N. Runeberg, M. Schutz and
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