Investigating the effects of steric hindrance on the coordination of 2-aminothiazoyl based ligands

Article abstract of DOI:10.1016/j.ica.2004.06.045

The ligands 2-(diphenylphosphino)aminothiazole (dppat) 2- (diphenylphosphino)amino-4-methylthiazole (Medppat) and 2-(diphenylphosphino) amino-4-tert-butylthiazole (Budppat) have been prepared. Reaction of these ligands with MCl₂ (COD) gives [MCl(dppat-P,N)(dppat-P)][Cl], [MCl(Medppat-P,N)(Medppat-P)][Cl], and [PtCl₂ (^tBu-dppat- P₂], respectively. The increased bulk at the 4-position limits the formation of a P, N system in Budppat. The X-ray structure of [PtCl(Medppat-P,N)(Medppat-P)][Cl] reveals that the monodentate ligand has undergone a tautomerism upon coordination.

Full text of DOI:10.1016/j.ica.2004.06.045

Inorganica Chimica Acta 358 (2005) 1393–1400
www.elsevier.com/locate/ica
Investigating the effects of steric hindrance on the coordination of
2-aminothiazoyl based ligands
*
Heather L. Milton, Matthew V. Wheatley, Alexandra M.Z. Slawin, J. Derek Woollins
School of Chemistry, University of St. Andrews, St. Andrews, Fife KY16 9NB, UK
Received 21 May 2004; accepted 26 June 2004
Available online 6 August 2004
Dedicated to Prof. F.G.A. Stone in recognition of his outstanding contributions to inorganic chemistry
Abstract
The ligands 2-(diphenylphosphino)aminothiazole (dppat) 2-(diphenylphosphino)amino-4-methylthiazole (Medppat) and 2-(diph-
enylphosphino)amino-4-tert-butylthiazole (Budppat) have been prepared. Reaction of these ligands with MCl2 (COD) gives
[MCl(dppat-P,N)(dppat-P)][Cl], [MCl(Medppat-P,N)(Medppat-P)][Cl], and [PtCl2 (tBu-dppat-P2], respectively. The increased bulk
at the 4-position limits the formation of a P, N system in Budppat. The X-ray structure of [PtCl(Medppat-P,N)(Medppat-P)][Cl]
reveals that the monodentate ligand has undergone a tautomerism upon coordination.
Ó 2004 Elsevier B.V. All rights reserved.
Keywords: Phosphorus; Hemilabile; Coordination; X -ray structure
1. Introduction
is increased to a tert-butyl group bidentate coordination
is blocked.
The study of hemilabile ligand is of continuing
importance both because of the intrinsic academic inter-
est and their potential in catalysis [1–8]. We have an
ongoing interest in phosphines which are obtained by
P–N bond forming reactions [9–14]. Here, we report
on the synthesis and coordination of three new phos-
phines 2-(diphenylphosphino)aminothiazole (dppat)
2-(diphenylphosphino)amino-4-methylthiazole (Medp-
pat)and 2-(diphenylphosphino)amino-4-tert-butylthiaz-
ole (Budppat). Preliminary complexation reactions
indicate that whilst the parent compound and its methyl
substituted congener behave as monodentate, P, and
bidentate, PN, ligands when the substitutionally bulk
2. Results and discussion
The synthesis of dppat proceeds as we have seen for
the previous phosphorus–nitrogen bond forming reac-
tions, although the reaction was performed at ꢀ78 °C
since this gave a purer product.
N
N
Ph2PCl, Et3N
-78oC, thf
+ Et3N.HCl
NH
PPh2
NH2
S
S
1
ð1Þ
*
Corresponding
+44 133 446 3384.
author.
Tel.:
+44 133 446 3869;
fax:
Dppat is colourless air tolerant solid which is readily
soluble in chlorinated solvents, but less so in solvents
such as toluene, acetone and methanol, and not at all
E-mail addresses: jdw3@st-andrews.ac.uk, jdw3@st-and.ac.uk
(J.D. Woollins).
0020-1693/$ - see front matter Ó 2004 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2004.06.045

1394
H.L. Milton et al. / Inorganica Chimica Acta 358 (2005) 1393–1400
soluble in diethyl ether and hexane. The 31P NMR
S
Cl
(CDCl3) of dppat displays a singlet at d(P) 41.3 ppm
whilst the H spectrum clearly shows the presence of
S
1
N
N
HN
PPh2
an amine proton at d(H) 7.9 ppm as a broad peak,
indicative of extensive hydrogen-bonding and the thia-
zoyl ring protons appear at d(H) 6.7 and 6.5 ppm (dou-
blets JH–H = 4 Hz). The IR spectrum clearly shows the
v(N–H) band at 3076 cm ꢀ1, and the expected v(C–N)
Cl
Cl
N
HN
PPh2
Pt
PPh2
HN
Cl
Pt
S
PPh2
N
S
N
H
and v(C–S) stretches at 1541 and 1150 cmꢀ1
,
respectively.
Cl
Reaction of dppat with elemental sulfur in toluene
generated the expected sulfide of dppat; dppatS (2),
which was recrystallised from warm toluene to give the
desired product as a air stable colourless solid. The 31P
NMR shows a singlet at d(P) 50.2 ppm whilst in the
1H NMR of 2 the thiazoyl protons are clearly visible
at d(H) 6.4 and 6.2 ppm We reacted dppat with
[PtCl2(cod)] in dichloromethane to give [PtCl(dppat-
P,N)(dppat-P)][Cl] (3). The structure was assigned from
spectroscopic studies; in the 31P NMR a pair of doublets
is observed at d(P) 65 ppm (1JPt–P = 4058 Hz), 23 ppm
(1JPt–P = 3646 Hz), (2JP–P = 11.74 Hz). The 1H NMR
of 3 shows a significant change in the chemical shift of
the amine protons, at d(H) 11.0 and 10.4 ppm and
clearly displays the thiazoyl protons from both ligands
at d(H) 6.5, 6.0, 5.5 and 5.0 ppm. The IR spectrum of
3 has bands attributable to v(N–H) in the 3100–2900
cmꢀ1 region, whilst two peaks for v(C–N) are found at
1577 and 1551 cmꢀ1, and the v(C–S) bands from the thi-
azoyl ring are seen at 1159 and 1103 cmꢀ1. The 26 cmꢀ1
difference in the v(C–N) peaks is consistent for the che-
lated and non-chelated forms of the ligand. Dppat was
also reacted with [PdCl2(cod)] and [PdBr2(cod)] to give
the analogous compound [PdCl(dppat-P,N)(dppat-
P)][Cl] (4) and [PdBr2 (dppat-P,N)(dppat-P)][Br]
(5)which displayed similar spectroscopic properties to
(3) (see Fig. 1).
S
2Cl
N
S
H
N
N
HN
PPh2
Cl
PPh2
S
Pt
Pt
N
N
PPh2
PPh2
N
N
S
H
H
Fig. 1. The four possible isomers of [PtCl(dppat)(dppat-P)][Cl].
Reaction of dppat with [{RhCl(l-Cl)(g6–C5H5)}2]
in acetonitrile generated another chelated complex;
[RhCl(g6–C5H5)(dppat-P,N)][Cl] (7). The 31P NMR
shows a doublet at d(P) 94.2 ppm (1JRh–P = 141 Hz),
as was noted in the case of 6 this high shift is a first
indication of dppat binding in a bidentate fashion.
1
The H NMR is consistent with the patterns seen in
6 with the amine proton disappearing from the spectra
and the thiazoyl protons clearly visible at d(H) 7.0 and
6.8 ppm. The IR spectrum shows the v(C–N) at 1572
cmꢀ1, this is comparable with the data for 3, 4 and
5 and strongly suggests a metal bound nitrogen. We
also reacted dppat with [{RuCl(l-Cl)(g6-p-cymene)}2]
in acetonitrile to generate the [RuCl(g6-p-cymene)-
(dppat-P,N)][Cl] (8), which spectroscopically compares
well 7.
Reaction of dppat with [{Pd(l-Cl)(g3–C3H6)]}2] in
acetonitrile could generate a mono- or a bi-dentate
complex depending on the ligandÕs behaviour. The
reaction generated a yellow solid which displays a sin-
glet at d(P) 84.4 ppm in the 31P NMR, very close to the
value seen for the chelated ligand in 5 and this together
with the IR data suggests that the product of the reac-
tion is indeed chelated being [Pd(g3–C3H6)(dppat-
P,N)][Cl] (6).
In many previous literature examples complexes of
[RuCl2(g3:g3-C10H16)(L)] (where L is a phosphorus–ni-
trogen ligand) generates a monodentate bound phos-
phorus bound ligand, due to the steric concerns based
around the allyl ligand on the metal. The reaction of
[RuCl(l-Cl)(C10H16)] with dppat in acetonitrile gener-
ated [RuCl2 (C10H16)(dppat-P)] (9) as a brown solid in
good yield. The 31P NMR spectrum shows the expected
1
singlet at (P) 42.5 ppm. The H NMR clearly shows
the amine proton at d(H) 8.6 ppm as a doublet with
2JP–H = 15 Hz, which is similar to the values seen for
monodentate behaviour in dpppa and itÕs derivatives.
Cl
3
[{RuCl( -Cl)(
:
3-C10H16)}2]
N
N
S
Cl
Ru P
Cl
Pd
N
PPh2
N
NH
PPh2
Ph2
H
S
N
H
S
9
ð2Þ
6

H.L. Milton et al. / Inorganica Chimica Acta 358 (2005) 1393–1400
1395
The IR spectrum shows close similarities with the
monodentate complexes previously described. The
v(N–H) band is seen as a sharp peak once more at
3173 cmꢀ1, the allyl v(C–H) stretches are seen in the
dppat, generating [PtCl(Me-dppat-P,N)(Me-dppat-
P)][Cl] (12) with d(P) 62.1 ppm (1JPt–P = 4089 Hz) and
2
d(P) 20.9 ppm (1JPt–P = 3700, JP–P = 9 Hz,). The IR
data shows that there is no considerable difference in
one of the v(N–H) shift compared to the free ligand
(3093 cmꢀ1), however a second v(N–H) stretch located
at 2790 cmꢀ1 indicates either increased hydrogen-bond-
ing in the complex, or a more dramatic shift in the amine
proton, the phenomenon is more clearly understood on
examination of the crystal data. The trend of two dis-
tinct ligands is continued by the shifts seen for the
v(C–N) and v(C–S) stretches, this are seen at 1576,
1555, 1147 and 1105 cmꢀ1. The X-ray structure of 12 re-
veals (Fig. 3) that the amine proton on the monodentate
bound ligand has shifted from the N–H spacer group to
the nitrogen found in the thiazoyl ring. This effect does
explain the frequencies of the v(N–H) vibrations and the
range 2845–2956 cmꢀ1
stretches are clearly visible at 1519 and 1134 cmꢀ1
. The v(C–N) and v(C–S)
,
respectively. The X-ray structure of 9 (Fig. 2) confirms
the monodentate coordination of the ligand, the bond
lengths and angles are normal, though the P–N bond
length is relatively short for P–N phosphines. There is
an intramolecular hydrogen bond between the N–H
group and one of the chloride ligands [N(2)ꢁ ꢁ ꢁCl(1)
˚
3.02, H(2)ꢁ ꢁ ꢁCl(1) 2.20 A, Cl(1)ꢁ ꢁ ꢁH(2)–N(2) 139.9°].
The synthesis of the methyl derivative of dppat;
Medppat (10) proceeds in a similar fashion to that of
dppat itself. The major difference is that as a conse-
quence of the extra methyl group the solubility of Medp-
pat is greatly increased compared to dppat.
1
broadening seen in the H NMR of the complexes and
suggests fluxional behaviour.
Ph2P-Cl, Et3N
N
We can see from Fig. 3 that the platinum is square
planar. There are some significant differences between
the two ligands in the complex not least because the
monodentate bound ligand is deprotonated at N(7).
Thus the P(1)–N(2) bond is much shorter in the mon-
dentate ligand than for bidentate partner P(21)–N(22)
similarly the C(3)–N(2) bond length is also reduced in
the deprotonated ligand and there is a slight increase
in the C(23)–N(27) bond length compared with C(3)–
N(7).
N
ð3Þ
NH
PPh2
NH2
S
S
DMAP, thf, -78oC
Medppat has d(P) 40.2 ppm in the 31P NMR and the
1H nmr values which are as expected. MedppatS (11)
was synthesised in toluene by addition of elemental sul-
fur to Medppat and recrystallisation from toluene gen-
erates a pure sample as a colourless solid.
To compare the coordination chemistry of Me-dppat
to that of dppat, a series of complexes were synthesised.
The reaction of Medppat with [PtCl2(cod)] shows that
Medppat does coordinate in much the same way as
Fig. 3. Crystal Structure of [PtCl(Me-dppat-P,N)(Me-dppat-P)][Cl]
˚
(12). Selected bond lengths (A) and angles (°): Pt(1)–P(1) 2.256(3),
Pt(1)–P(21) 2.214(3), Pt(1)–Cl(1) 2.332(3), Pt(1)–N(27) 2.141(8), P(1)–
N(2), 1.616(9), P(21)–N(22), 1.674(10), N(2)–C(3), 1.292(12), N(22)–
C(23), 1.333(13), P(1)–Pt(1)–P(21) 93.57(9), P(1)–Pt(1)–Cl(1)
88.26(10), P(1)–Pt(1)–N(27) 175.8(3), P(21)–Pt(1)–N(27) 85.5(3),
N(27)–Pt(1)–Cl(1), 95.4(3) P(21)–Pt(1)–Cl(1) 171.50(12), Pt(1)–P(1)–
N(2) 116.8(3), Pt(1)–P(21)–N(22) 101.3(4).
Fig. 2. Crystal Structure of [RuCl2(g3:g3-C10H16)(dppat-P)] (9),
Selected bond lengths (A) and angles (°): Ru(1)–Cl(2) 2.4117(13),
Ru(1)–P(1) 2.4155(12), Ru(1)–Cl(1) 2.4450(14), P(1)–N(2) 1.684(4),
N(2)–C(3) 1.379(6), Cl(2)–Ru(1)–Cl(1) 172.23(4), P(1)–Ru(1)–Cl(1)
89.19(4).
˚

1396
H.L. Milton et al. / Inorganica Chimica Acta 358 (2005) 1393–1400
As with dppat, Medppat was also reacted with
complex with the ligand mondentate bound via the
phosphorus; d(P) 62.3 ppm, v(C–N) 1531 cmꢀ1
[PdCl2(cod)] to give [PdCl(Me-dppat-P,N)(Me-dppat-
P)][Cl] (13) as a yellow solidand with [{RuCl(l-Cl)(g6-
p-cymene)}2] to give [RuCl(g6-p-cymene)(Me-dppat-
P,N)][Cl] (14) which have the expected spectroscopic
properties.
.
The coordination chemistry of dppat and its deriva-
tives correlates quite well. It is clear that the addition
of a methyl group in the 4-position is not sufficient to
prevent the chelation of the thiazoyl nitrogen. The addi-
tion of a tBu group in the 4-position however does have
an effect. In square planar complexes it is apparent that
the butyl group blocks the bidentate P,N mode of
coordination.
To further investigate steric influence on the proper-
ties of these thiazoyl ligands we synthesised 2-diph-
enylphosphinoamino-5-tert-butylthiazoyl
(Budppat)
(15) by the same method as for dppat and Medppat.
The increased solubility of Budppat made it difficult to
obtain a pure sample, as recrystallisation was very diffi-
cult. Budppat gave the expected singlet d(P) 39.7 ppm
which correlates well with the values for dppat and
Medppat (41.3 and 40.2 ppm, respectively).
3. Experimental
All manipulations were carried out in an atmosphere
of nitrogen, unless stated otherwise. All solvents were
either freshly distilled from an appropriate drying agent
(thf, Et2O, dcm) or obtained as anhydrous grade from
1
Aldrich. H and 31P NMR spectra were recorded using
N
a Jeol Delta FT (270 MHz) spectrometer. IR spectra
were recorded as KBr discs (prepared in air) on a Per-
kin–Elmer 2000 FTIR/RAMAN spectrometer. All sig-
nificant peaks (>800 cmꢀ1) are quoted to serve as a
fingerprint. Silver salts, 2-aminothiazole, 2-amino-4-
methylthiazole, 2-amino-4-tert-butylthiazole (Aldrich
Chemical Co.) and BuLi (2.5M, Lancaster) were pur-
chased and used as received. Triethylamine and chlorod-
iphenylphosphine were distilled prior to use.
Dimethylaminopyridine (DMAP) was sublimed before
use. The various metal starting materials were made
by the appropriate literature methods; [MCl2(cod)]
(M = Pt or Pd; cod = cycloocta-1,5-diene) [15,16],
[{MCl(l-Cl)(Cp*)}2 ] (M = Rh or Ir) [17], [{Rh(l-
NH
S
PPh2
Budppat.
The amine peak is seen as a doublet (2JP–H = 7 Hz)
at d(H) 8.2 in the H NMR spectrum of 15, the thai-
zoyl proton is visible as a sharp singlet at d(H) 6.2
ppm, and the Bu protons are seen at d(H) 1.2 ppm
again as a sharp singlet. The IR data gave the ex-
pected resonances with bands at 3343 cmꢀ1 for v(N–
H), 1524 for v(C–N), 1098 for v(C–S) and 996 for
v(P–N).
Reaction of Budppat with [PtCl2(cod)] gave a very
soluble white solid (16) which could only be isolated
by cooling a saturated diethyl ether solution of 16 which
has d(P) 53.5 ppm [1JPt–P = 4040 Hz]. Based on the sim-
plicity of the 31P data 16 is formulated as [PtCl2(tBu-
dppat-P2]. In the 1H nmr the ligand amine proton is ob-
served as a broad singlet at d(H) 11.2 ppm, the one
remaining thiazoyl proton is also easily observed at
d(H) 5.9 as a sharp singlet which supports the proposed
structure. It appears that the extra bulk provided by the
tBu group is sufficient to prevent binding by the nitrogen
of the thiazoyl ring.
1
t
Cl)(cod)}2 ] [18], [{RuCl(l-Cl)(g6p-MeC6H4 Pr)}2] [19],
i
[{RuCl(l-Cl)(g3:g3-C10H16)}2] [20], [{PdCl(l-Cl)(g3-
C3H5)}2] [21].
3.1. 2-(diphenylphosphino)aminothiazole(dppat) (1)
Chlorodiphenylphosphine (4.23 cm3, 24 mmol) in 30
cm3 of thf was added dropwise to a mixture of 2-ami-
nothiazole (2.36 g, 24 mmol) and triethylamine (3.44
cm3, 25 mmol) in 100 cm3 of thf at ꢀ78 °C. After addi-
tion was complete the mixture was allowed to warm to
room temperature overnight. The resultant white pre-
cipitate was filtered and the filtrate reduced to dryness
in vacuo. The crude product was recrystallised by cool-
ing a concentrated chloroform solution at 4 °C over-
Further complexes of Budppat were synthesised to
investigate the change in ligand behaviour. Reaction
with [Pd(l-Cl)(g3-C3H6)]2] generated the now expected
monodentate complex [PdCl(g3-C3H6)(b-dppat-P)] (17)
with the ligand bound by the phosphorus; d(P) 58.3
ppm and v(C–N) 1527 cmꢀ1, which is only 2 cmꢀ1 from
the value seen for the free ligand, indicating monoden-
tate coordination.
night giving
a white solid (yield: 2.5 g, 37%).
C15H13N2 SP requires: C, 63.2; H, 4.51; N, 9.86.
Found: C, 62.2; H, 3.68; N, 9.32%. vmax/cmꢀ1: 3076,
1541, 1492, 1432, 1150, 999. 31P NMR (CDCl3) d
1
41.3 ppm. H NMR (CDCl3); 7.9 (1H, bs, N–H), 7.5–
7.2 (10H, m, aromatic), 6.7 (1H, dd, J = 1; 4 Hz, thia-
zoyl), 6.5 (1H, d, J = 4 Hz, thiazoyl).
Reaction with [{RuCl(l-Cl)(g6-p-cymene)}2] gave
[RuCl2 (g6-p-cymene)(b-dppat-P)] (18), again it is a

H.L. Milton et al. / Inorganica Chimica Acta 358 (2005) 1393–1400
1397
3.2. 2-(diphenylphosphino)aminothiazole sulfide (2)
until the solid was dissolved, this mixture was then al-
lowed to return to room temperature. An orange precip-
itate was formed during cooling and this was filtered
isolating the product as an orange solid, (yield: 73 mg,
33%). C30H26N4S2P2Br2Pd requires: C, 43.2; H, 3.14;
Sulfur (23 mg, 0.7 mmol) was added to 2-(diph-
enylphosphino)aminothiazole (200 mg, 0.7 mmol) and
the mixture refluxed in toluene (10 cm3) for 30 min.
The resulting solution was stored at 4 °C overnight gen-
erating a white solid. The product was filtered and iso-
N, 6.71. Found: C, 43.4; H, 2.78; N, 6.72%. vmax
/
cmꢀ1: 2938, 2799, 1570, 1542, 1483, 1433, 1156, 998,
381. 31P NMR (CDCl3); d 82.0 ppm(2JP–P = 18.78 Hz),
51.5 ppm (2JP–P = 18.78 Hz). 1H NMR (CDCl3); d
10.5 (1H, s, N–H), 10.4 (1H, bs, N–H) 7.8-6.9 (21H,
m, aromatic), 6.4 (1H, d, J = 5 Hz, thiazoyl), 6.2 (1H,
d, J = 5 Hz, thiazoyl), 5.7 (1H, d, J = 5 Hz, thiazoyl).
lated as
a white solid (yield: 184 mg, 83%).
C15H13N2S2P requires: C, 56.9; H, 4.14; N, 8.85. Found:
C, 56.8; H, 4.15; N, 8.88%. vmax/cmꢀ1: 3141, 3097, 3050,
1576, 1432, 1412, 947. 31P NMR (CDCl3) d 50.2 ppm.
1H NMR (CDCl3); d 8.1–7.9 (4H, m, aromatic), 7.3–
7.5 (6H, m, aromatic), 6.35 (1H, d, J = 4 Hz, thiazoyl),
6.2 (1H, dd, J = 2, 4 Hz, thiazoyl).
3.6. [Pd(g3-C3H6)(dppat-P,N)][Cl] (6)
3.3. [PtCl(dppat-P)(dppat-P,N)][Cl] (3)
Dppat (78 mg, 0.28 mmol) and [{Pd(l-Cl)(g3-
C3H6)}2] (50 mg, 0.14 mmol) were weighed into a round
bottomed flask. Acetonitrile (5 cm3) was added and the
mixture heated until the entire solid was dissolved, this
mixture was then allowed to return to room tempera-
ture. A yellow precipitate was formed during cooling
and this was filtered isolating the product as a yellow so-
lid (yield: 60 mg, 46%). C18H19N2 SPClPd requires: C,
46.2; H, 4.10; N, 6.00. Found: C, 45.3; H, 3.27; N,
6.08%. vmax/cmꢀ1: 2928, 2589, 1474, 1433, 1164, 1104,
Dppat (301 mg, 1 mmol) and [PtCl2(cod)] (200 mg, 1
mmol) were weighed into a round bottomed flask and
acetonitrile (10 cm3) added. This mixture was stirred
for 2 h, and a colourless precipitate was generated.
The solid was filtered and isolated as a colourless solid
(yield: 333 mg, 80%). C30H26N4S2P2Cl2Pt requires: C,
43.2; H, 3.15; N, 6.72. Found: C, 42.3; H, 2.80; N,
6.49%. vmax/cmꢀ1: 3054, 2786, 1577, 1551, 1481, 1435,
1159, 1103, 998, 249. 31P NMR (CDCl3); d 65.1
1
997, 252. 31P NMR (CDCl3); d 84.4 ppm. H NMR
1
(2JP–P = 14 Hz, JPt–P = 4060 Hz), 23.9 (2JP–P = 14 Hz,
(CDCl3) 7.9–7.7 (4H, m, aromatic), 7.5–7.3 (6H, m, aro-
matic), 7.15 (1H, d, J = 4 Hz, thiazoyl), 6.6 (1H, dd,
J = 2, 4 Hz, thiazoyl), 5.7 (1H, m, allyl), 4.9 (1H, bs, al-
lyl), 3.8 (1H, bs, allyl), 3.5 (2H, bs, allyl).
1
1JPt–P = 3650 Hz). H NMR (CDCl3) d 11.1 (1H, bs,
N–H), 10.4 (1H, s, N–H), 7.6–7.4 (4H, m, aromatic),
7.3–6.9 (16H, m, aromatic), 6.5 (1H, d, J = 1 Hz, thia-
zoyl), 6.0 (1H, d, J = 1 Hz, thiazoyl), 5.5 (1H, d, J = 1
Hz, thiazoyl), 5.0 (1H, s, thiazoyl).
3.7. [RhCl(dppat-P,N)(g-C5Me5)][Cl] (7)
3.4. [PdCl(dppat-P)(dppat-P,N)][Cl] (4)
Dppat (49 mg, 0.17 mmol) and [{RhCl(l-Cl)(g-
C5Me5)}2] (53 mg, 0.17 mmol) were weighed into a
round bottomed flask. Acetonitrile (5 cm3) was added
and the mixture heated until the entire solid was dis-
solved, this mixture was then allowed to return to room
temperature. A red precipitate was formed during cool-
ing and this was filtered isolating the product as a red
solid (yield: 94 mg, 94%). C25H28N2SPCl2 Rh requires:
C, 50.7; H, 4.77; N, 4.73. Found: C, 50.4; H, 4.62; N,
4.81%. vmax/cmꢀ1: 3052, 2432, 1487, 1434, 1146, 1101,
998, 234. 31P NMR (CDCl3); d 94.2 (1JRh–P = 141 Hz).
1H NMR (CDCl3); d 7.9 (2H, m, aromatic), 7.6–7.4
(6H, m, aromatic), 7.3–7.2 (2H, m, aromatic), 7.0 (1H,
d, J = 4 Hz, thiazoyl), 6.8 (1H, dd, J = 2.2 Hz, thiazoyl),
1.55 (15H, d, J = 3.7 Hz, C5Me5).
Dppat (100 mg, 0.34 mmol) and [PdCl2(cod)] (50 mg,
0.17 mmol) were weighed into a round bottomed flask.
Acetonitrile (5 cm3) was added and the mixture heated
until the entire solid was dissolved, this mixture was then
allowed to return to room temperature. An orange pre-
cipitate was formed during cooling and this was filtered
isolating the product as an orange solid (yield: 94 mg,
74%). C30H26N4S2P2Cl2Pd requires: C, 48.3; H, 3.52;
N, 7.53. Found: C, 47.8; H, 3.05; N, 7.31%. vmax
/
cmꢀ1: 2923, 2719, 1542, 1482, 1434, 1158, 1103, 996,
279. 31P NMR (CDCl3); d 83.0 (2JP–P = 14.1 Hz), 50.0
(2JP–P = 14.1 Hz). 1H NMR (CDCl3); d 10.3 (1H, s,
N–H), 10.1 (1H, bs, N–H) 7.0–6.4 (21H, m, aromatic),
6.2 (1H, d, J = 4 Hz, thiazoyl), 5.7 (1H, d, J = 4 Hz, thi-
azoyl), 5.3 (1H, d, J = 5 Hz, thiazoyl).
3.8. [RuCl(p-Cymene)(dppat-P,N)][Cl] (8)
3.5. [PdBr(dppat-P)(dppat-P,N)][Br] (5)
Dppat (56 mg, 0.19 mmol) and [{RuCl(l-Cl)(g6-p-
cymene)}2] (61 mg, 0.95 mmol) were weighed into a
round bottomed flask and dcm (10 cm3) added. This
mixture was stirred for 2 h, and a red precipitate was
generated. The solid was filtered and isolated as a red
Dppat (76 mg, 0.27 mmol) and [PdBr2(cod)] (50 mg,
0.135 mmol) were weighed into a round bottomed flask.
Acetonitrile (5 cm3) was added and the mixture heated

1398
H.L. Milton et al. / Inorganica Chimica Acta 358 (2005) 1393–1400
solid (yield: 86 mg, 77%). C25H27N2SPCl2 Ru requires:
C, 50.8; H, 4.61; N, 4.75. Found: C, 49.8; H, 3.92; N,
4.60%. vmax/cmꢀ1: 3043, 2957, 1523, 1474, 1434, 1130,
1000. 31P NMR (CDCl3); d 62.7 ppm. 1H NMR
(CDCl3); 8.0 (4H, m, aromatic), 7.5–7.2 (6H, m, aro-
matic), 6.8 (1H, bs, thiazoyl), 6.4 (1H, bs, thiazoyl),
5.3–5.1 (4H, m, p-Cy (aromatic)) 2.5 (1H, m, –CMe2-
H) 1.6 (3H, s, Me–H) 1.0–0.8 (6H, bs, Me–H).
58.2; H, 4.58; N, 8.48. Found: C, 56.8; H, 4.45; N,
8.14%. vmax/cmꢀ1: 3098, 1577, 1554, 1433, 1401, 1112,
1018. 31P NMR (CDCl3); d 48.2 ppm. 1H NMR
(CDCl3); d 8.1–7.9 (4H, m, aromatic), 7.5–7.2 (6H, m,
aromatic), 5.7 (1H, d, J = 3 Hz, thiazoyl) 2.0 (3H, s,
Me).
3.12. [PtCl(Medppat-P)(Medppat-P,N)][Cl] (12)
3.9. [RuCl2(g3:g3-C10H16)(dppat-P)] (9)
Me-dppat (80 mg, 0.27 mmol) and [PtCl2(cod)] (50
mg, 0.135 mmol) were weighed into a round bottomed
flask and acetonitrile (5 cm3) added. This mixture was
stirred for 2 h, and a colourless precipitate was gener-
ated. The solid was filtered and isolated as a colourless
solid, (yield: 71 mg, 62%). C32H30N4S2P2Cl2Pt requires:
C, 44.5; H, 3.51; N, 6.49. Found: C, 44.0; H, 3.42; N,
6.42%. vmax/cmꢀ1: 3093, 2790, 2551, 1576, 1555, 1480,
1437, 1147, 1105, 999. 31P NMR (CDCl3); d 62.0
Dppat (46 mg, 0.17 mmol) and [{RuCl(l-Cl)(g3:g3-
C10H16)}2] (50 mg, 0.085 mmol) were weighed into a
round bottomed flask. Acetonitrile (5 cm3) was added
and the mixture heated until the entire solid was dis-
solved, this mixture was then allowed to return to room
temperature. A brown precipitate was formed during
cooling and this was filtered isolating the product as a
brown solid (yield: 36 mg, 36 %). C25H29N2SPCl2 Ru re-
quires: C, 50.4; H, 5.58; N, 4.70. Found: C, 51.2; H,
4.49; N, 4.70%. vmax/cmꢀ1: 3173, 1519, 1474, 1438,
1
(2JP–P = 9 Hz; JPt–P = 4090 Hz), 20.9 (2JP–P = 9 Hz;
1
1JPt–P = 3805 Hz). H NMR (CDCl3); d 7.8–7.2 (22H,
m, aromatic), 6.9 (1H, bs, thiazoyl), 5.6 (1H, bs, thia-
zoyl), 1.6 (3H, bs, Me), 1.2 (3H, bs, Me).
1420, 1134, 996. 31P NMR (CDCl3); d 42.5 ppm. H
1
NMR (CDCl3); d 8.5 (1H, d, J = 15 Hz, N–H), 8.1–7.9
(4H, m, aromatic), 7.5–7.3 (6H, m, aromatic), 7.1 (1H,
d, J = 4 Hz, thiazoyl), 6.5 (1H, d, J = 4 Hz, thiazoyl),
5.0 (2H, m, allyl), 3.7 (2H, d, J = 9 Hz, allyl), 3.4 (2H,
m, allyl), 3.00 (2H, d, J = 4 Hz, allyl), 2.6 (2H, m, allyl),
2.0, (6H, s, allyl-Me).
3.13. [PdCl(Medppat-P)(Mdppat-P,N)][Cl] (13)
Me-dppat (104 mg, 0.35 mmol) and [PdCl2(cod)] (50
mg, 0.175 mmol) were weighed into a round bottomed
flask. Acetonitrile (5 cm3) was added and the mixture
heated until the solid was dissolved, this mixture was
then allowed to return to room temperature. An orange
precipitate was formed during cooling and this was fil-
tered isolating the product as an orange solid (yield:
86 mg, 63%). C32H30N4S2P2Cl2 Pd requires: C, 49.6;
H, 3.91; N, 7.24. Found: C, 48.8; H, 3.71; N, 7.07%.
vmax/cmꢀ1: 3085, 2914, 2570, 1574, 1551, 1477, 1434,
1101, 998. 31P NMR (CDCl3); d 80.1 (2JP–P = 23 Hz),
3.10. 2-(diphenylphosphino)amino-4-methylthiazole(Medp-
pat) (10)
Chlorodiphenylphosphine (3.93 cm3, 22 mmol) in 40
cm3 of thf was added dropwise to a mixture of 2-amino-
4-methylthiazole (2.5 g, 22 mmol), DMAP (268 mg, 2.2
mmol) and triethylamine (3.36 cm3, 24 mmol) in 80 cm3
of thf at ꢀ78 °C. After addition was complete the mix-
ture was allowed to warm to room temperature over-
night. The resultant white precipitate was filtered and
the filtrate reduced to dryness in vacuo over the course
of five days to give the desired product (yield: 4.3 g,
69%). C15H13N2SP requires: C, 64.3; H, 5.07; N, 9.39.
Found: C, 62.9; H, 5.31; N, 9.18%. vmax/cmꢀ1: 3068,
1524, 1480, 1432, 1135, 986. 31P NMR (CDCl3); d 40.2
1
50.6 (2JP–P = 23 Hz). H NMR (CDCl3); d 10.5 (2H, s,
N–H), 7.7-6.6 (20H, m, aromatic), 5.8 (1H, s, aromatic),
5.1 (1H, s, aromatic), 2.2 (3H, s, Me), 1.6 (3H, s, Me).
3.14. [RuCl(p-Cymene)(Medppat-P,N)][Cl] (14)
Me-dppat (68 mg, 0.23 mmol) and [{RuCl(l-Cl)(p-
cymene)}2] (70 mg, 0.115 mmol) were weighed into a
round bottomed flask. Acetonitrile (5 cm3) was added
and the mixture heated until the solid was dissolved, this
mixture was then allowed to return to room tempera-
ture. A red precipitate was formed during cooling and
this was filtered isolating the product as a red solid
(yield: 97 mg, 70%). C26H29N2 SPCl2 Ru requires: C,
51.6; H, 4.84; N, 4.63. Found: C, 51.1; H, 5.21; N,
4.78%. vmax/cmꢀ1: 3046, 2961, 1578, 1561, 1482, 1435,
1
ppm. H NMR (CDCl3); d 7.5–7.2 (10H, m, aromatic),
6.1 (1H, d, J = 1 Hz, thiazoyl), 2.0 (3H, s, Me).
3.11. 2-(diphenylphosphino)amino-4-methylthiazole sul-
fide (11)
Sulfur (21 mg, 0.67 mmol) was added to 2-amino-4-
methylthiazole (200 mg, 0.7 mmol) and the mixture
refluxed in toluene (10 cm3) for 30 min. The resulting
solution was stored at 4 °C overnight generating a white
solid. The product was filtered and isolated as a white
solid (yield: 175 mg, 79%). C16H15N2S2P requires: C,
1
1101, 994. 31P NMR (CDCl3);d 99.9 ppm. H NMR
(CDCl3);d 10.2 (1H, s, N–H), 8.1–7.9 (4H, m, aromatic
(ligand)), 7.6–7.1 (6H, m, aromatic (ligand)), 6.4 (1H, s,
thiazoyl), 5.3–5.1 (2H, m, aromatic (p-cymene)), 2.3

H.L. Milton et al. / Inorganica Chimica Acta 358 (2005) 1393–1400
1399
(1H, m, –CMe2-H), 1.9 (3H, s, Ar–Me), 1.0–0.7 (15H,
t
m, Me and Bu–H).
3.18. [RuCl2 (p-Cymene)(Budppat-P)] (18)
Budppat (78 mg, 0.23 mmol) and [{RuCl(l-Cl)(p-
cymene)}2] (70 mg, 0.115 mmol) were weighed into a
round bottomed flask. DCM (5 cm3) was added and
the mixture stirred for 1 hour. The solvent was reduced
in vacuo to approx. 1 cm3 and the product precipitated
with petroleum ether (15 cm3), this solid was subse-
quently filtered to isolate a red solid (yield: 83 mg,
78%). C30H35N2SPCl2Ru requires: C, 54.6; H, 5.36; N,
3.15.
(Budppat) (15)
2-(diphenylphosphino)amino-4-tert-butylthiazole
Chlorodiphenylphosphine (2.80 cm3, 16 mmol) in 40
cm3 of thf was added dropwise to a mixture of 2-amino-
4-tert-butylthiazole (2.5 g, 16 mmol), DMAP (191 mg,
1.6 mmol) and triethylamine (2.34 cm3, 17 mmol) in
100 cm3 of thf at ꢀ78 °C. After addition was complete
the mixture was allowed to warm to room temperature
overnight. The resultant white precipitate was filtered
and the filtrate reduced to dryness in vacuo over the
course of five days to give the desired product (yield:
3.4 g, 63%). C19H21N2SP. vmax/cmꢀ1: 3343, 2959, 1525,
1479, 1432, 1241, 1202, 1098, 996. 31P NMR (CDCl3);
39.7 ppm. 1H NMR (CDCl3); 8.2 (1H, d, J = 7 Hz,
N–H), 7.5–7.2 (10H, m, aromatic), 6.1 (1H, s, thiazoyl),
4.25. Found: C, 53.6; H, 5.29; N, 4.28%. vmax/cmꢀ1
:
2690, 1532, 1435, 1100. 31P NMR (CDCl3); d 62.3
ppm. H NMR (CDCl3); 8.1–8.0 (4H, m, aromatic (lig-
1
and)), 7.5–7.2 (6H, m, aromatic (ligand)), 5.9 (1H, s, thi-
azoyl), 5.3 (2H, m, aromatic (p-cymene)), 5.2 (2H, m,
aromatic (p-cymene)), 2.5 (1H, m, –CMe2-H), 1.9 (3H,
t
s, Ar–Me), 1.0–0.7 (15H, m, Me and Bu–H).
3.19. Crystallography
t
1.2 (9H, s, Bu–H).
SMART diffractometer Mo Ka radiation, 293 K.
Hemisphere of data. All data corrected for Lorentz,
polarisation and absorption. Solution and refinement
using SHELXTL [22], all non hydrogen atoms refined
ansiotropically. 9 C25H29Cl2N2PSRu, M = 592.50, Tri-
3.16. [PtCl2 (tBudppat-P)2] (16)
tBudppat (99 mg, 0.29 mmol) and [PtCl2(cod)] (54
mg, 0.145 mmol) were weighed into a round bottomed
flask. Acetonitrile (5 cm3) was added and the mixture
heated until the solid was dissolved, this mixture was
then allowed to return to room temperature. The solvent
was removed in vacuo and diethyl ether (5 cm3) added
and the resultant solution cooled to ꢀ4 °C to generate
a solid, this solid was subsequently filtered to isolate a
expected colourless solid (yield: 72 mg, 53%).
C38H42N4S2P2Cl2Pt requires: C, 48.2; H, 4.46; N, 5.91.
Found: C, 46.9; H, 4.55; N, 5.24%. vmax/cmꢀ1: 3055,
2964, 1623, 1592, 1561, 1479, 1435, 1104, 1017, 997.
ꢀ
clinic P1, a = 9.2030(8), b = 10.2156(8), c = 17.6444(15)
˚
A, a = 96.892(2), b = 101.409(2), c = 114.1880(10)°,
3
3
ꢀ1
,
˚
V = 1445.3(2) A , Dc = 1.361 Mg/m , l = 0.869 mm
5182
independent
reflections
[Rint
=
0.0177],
R1[I > 2r(I)] = 0.0493, wR2 = 0.1298. 12 C32H30Cl2
N4P2PtS2, M = 862.65, orthorhombic, Pbcn, a =
˚
15.1534(10), b = 15.1619(10), c = 30.1776(19) A,
3
3
ꢀ1
˚
V = 6933.4(8) A , Dc = 1.653 Mg/m , l = 4.443 mm
,
6273 independent reflections 5182 [Rint = 0.163],
R1[I > 2r(I)] = 0.0492, wR2 = 0.0749. Full lists of struc-
ture refinement data, atomic coordinates, bond lengths
and angles, anisotropic displacement parameters and
hydrogen atom parameters have been deposited as sup-
plementary material, CCDC Nos. 239471, 239472 at the
Cambridge Crystallographic Data Centre, 12 Union
Road, Cambridge CB2 1EZ, UK [fax: +44-1223-
336033; e-mail: deposit@ccdc.cam.ac.uk].
31P NMR (CDCl3); d 53.9 ppm (1JPt–P = 4040 Hz). H
NMR (CDCl3); d 11.2 (2H, bs, N–H), 8.0–7.1 (20H,
m, aromatic), 5.9 (2H, s, thiazoyl), 1.3 (9H, s, Bu–H).
1
t
3.17. [Pd(g-C3H6)(Budppat-P,N)][Cl] (17)
Budppat (93 mg, 0.27 mmol) and [{Pd(l-Cl)(g-
C3H6)}2] (50 mg, 0.135 mmol) were weighed into a
round bottomed flask. DCM (5 cm3) was added and
the mixture stirred for 1 h. The solvent was reduced in
vacuo to approx. 1 cm3 and the product precipitated
with petroleum ether (15 cm3), this solid was subse-
quently filtered to isolate a pale yellow solid (yield: 34
mg, 24%). C22H27N2 SPClPd requires: C, 50.4; H,
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