Syntheses and fluxional processes of diphenyl(2-thienyl)phosphane derivatives of triosmium clusters

Article abstract of DOI:10.1002/ejic.200501141

Thermal treatment of [Os₃(CO)₁₂] with diphenyl(2-thienyl)-phosphane, Ph₂P(C₄H₃S), results in the formation of [Os₃(CO)_12-x{Ph ₂P(C₄H₃S)}_x] (x = 1-3, 1-3), but no C-H bond activation was observed. Reaction of [H₂Os ₃(CO)₁₀] with diphenyl(2-thienyl)phosphane at ambient temperature affords [HOs₃(μ-H)(CO)₁₀{Ph ₂P(C₄H₃S)}] (4), but when the same reaction is repeated at elevated temperatures, the cyclometallated species [(μ-H)Os ₃(CO)₉{μ₃-Ph₂P(C ₄H₂S)}] (5) and [(μ-H)Os₃(CO) ₈{μ₃-Ph₂P(C₄H₂S)} {Ph₂P(C₄H₃S)}] (6) are formed. In addition, two more products, tentatively assigned as [(μ-H)Os₃(CO) ₆{μ₃-Ph₂P(C₄H₂S)} {μ-Ph₂P(C₄H₃S)}{Ph₂P-(C ₄H₃S)}] (7) and [(μ-H)Os₃(CO) ₇{μ-Ph₂P(C₄H₂S)}{(μ-Ph ₂P(C₄H₃S)}{Ph₂P(C₄H ₃S)}] (8) are obtained. The dynamic behaviours of 2, 5 and 6 have been studied by variable-temperature (VT) ¹H and ³¹P{ ¹H} NMR spectroscopy. The VT ³¹P{¹H} NMR spectra of [Os₃(CO)₁₀{Ph₂P(C₄H ₃S)}₂] (2) demonstrate that a mixture of two isomers, which are in rapid exchange at room temperature, is present and that the less common cis-trans isomer, whose structure has been determined by X-ray crystallography, is favoured for this cluster. The VT ¹H NMR spectra of 5 indicate the presence of two isomers which are proposed to arise from an oscillation of the σ,η²-vinyl group of the thienyl moiety between two metal atoms. A similar fluxional process is proposed to occur in 6 and the assignment of the room-temperature structure(s) of this cluster was confirmed by ¹H-¹⁸⁷Os 2D HMQC spectroscopy. In addition to 2, the solid-state structures of 3, 5 and 6 have been determined by X-ray crystallography. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.

Full text of DOI:10.1002/ejic.200501141

FULL PAPER
DOI: 10.1002/ejic.200501141
Syntheses and Fluxional Processes of Diphenyl(2-thienyl)phosphane Derivatives
of Triosmium Clusters
Nitsa K. Kiriakidou Kazemifar,[a] Marc J. Stchedroff,[a] M. Abdul Mottalib,[a][‡]
Simona Selva,[b] Magda Monari,[b] and Ebbe Nordlander*[a]
Keywords: Cluster / Thienylphosphane / Fluxionality / Hydrodesulfurisation
Thermal treatment of [Os3(CO)12] with diphenyl(2-thienyl)-
phosphane, Ph2P(C4H3S), results in the formation of
[Os3(CO)12–x{Ph2P(C4H3S)}x] (x = 1–3, 1–3), but no C–H bond
activation was observed. Reaction of [H2Os3(CO)10] with di-
phenyl(2-thienyl)phosphane at ambient temperature affords
[HOs3(µ-H)(CO)10{Ph2P(C4H3S)}] (4), but when the same
reaction is repeated at elevated temperatures, the cyclo-
metallated species [(µ-H)Os3(CO)9{µ3-Ph2P(C4H2S)}] (5) and
31P{1H} NMR spectra of [Os3(CO)10{Ph2P(C4H3S)}2] (2) dem-
onstrate that a mixture of two isomers, which are in rapid
exchange at room temperature, is present and that the less
common cis-trans isomer, whose structure has been deter-
mined by X-ray crystallography, is favoured for this cluster.
The VT 1H NMR spectra of 5 indicate the presence of two
isomers which are proposed to arise from an oscillation of
the σ,η2-vinyl group of the thienyl moiety between two metal
atoms. A similar fluxional process is proposed to occur in 6
and the assignment of the room-temperature structure(s) of
this cluster was confirmed by 1H-187Os 2D HMQC spec-
troscopy. In addition to 2, the solid-state structures of 3, 5 and
6 have been determined by X-ray crystallography.
[(µ-H)Os3(CO)8{µ3-Ph2P(C4H2S)}{Ph2P(C4H3S)}]
formed. In addition, two more products, tentatively assigned
as [(µ-H)Os3(CO)6{µ3-Ph2P(C4H2S)}{µ-Ph2P(C4H3S)}{Ph2P-
(C4H3S)}] (7) and [(µ-H)Os3(CO)7{µ-Ph2P(C4H2S)}{µ-
(6)
are
Ph2P(C4H3S)}{Ph2P(C4H3S)}] (8) are obtained. The dynamic
behaviours of 2, 5 and 6 have been studied by variable-tem-
perature (VT) 1H and 31P{1H} NMR spectroscopy. The VT
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2006)
One of the very first reports of the interaction of
thiophene with organometallic compounds described the
desulfurisation of the heterocycle by a metal cluster,
[Fe3(CO)12].[8,9] Rauchfuss and co-workers[10] demonstrated
shortly after, that thiaferroles are easily converted into the
corresponding ferroles on heating and thereby established
that insertion of an iron atom into a C–S bond clearly acti-
vates the heterocycle towards desulfurisation [Scheme 1(a)].
Similarly, the reaction of [Ru3(CO)12] with thiophene pro-
ceeds through C–S bond cleavage, producing the sulfur-free
ferrole-type compound [Ru2(µ-C4H4)(CO)6] and the tetra-
nuclear cluster [Ru4(µ3-S)(µ-C4H4)(CO)11];[11] this is the
first reported example of desulfurisation of a thiophene in
which both the extruded sulfur and the hydrocarbon resi-
due remain coordinated within the same complex
[Scheme 1(b)]. More recently, Angelici and co-workers[12]
have demonstrated [Re2(CO)10]-promoted C–S bond cleav-
age in benzothiophenes.
Despite the above-mentioned examples of C–S bond acti-
vation, C–H bond activation predominates over other types
of oxidative addition in reactions of thiophenes with
[M3(CO)12] (M = Ru, Os) and their derivatives.[7] Thus, the
carbonyltriosmium clusters [Os3(CO)12] and [Os3(CO)10-
(MeCN)2] react with thiophene and thiophene derivatives
through C–H bond cleavage in preference to C–S bond
cleavage to afford the endo- and exo-thienyl isomers of
Introduction
More strict laws concerning sulfur-containing emissions
have intensified the interest in hydrodesulfurisation (HDS)
processes. As a consequence, studies of adsorption and acti-
vation of organosulfur compounds onto metal surfaces is a
rapidly developing area. The objectives of this research are
the understanding of the nature of the active HDS catalysts,
the binding modes and the activation of sulfur-containing
molecules – in particular thiophenes – at the active catalyst
sites, and the improvement of the efficiency of the cata-
lysts.[1–6] Organometallic complexes,[3–5] including transi-
tion-metal clusters,[7] have been used as models for HDS
catalysts because mechanistic information easily can be ex-
tracted by spectroscopic and analytical studies of discrete
molecular complexes.
[a] Inorganic Chemistry, Center for Chemistry and Chemical Engi-
neering, Lund University,
Box 124, 22100 Lund, Sweden
Fax: + 46-46222-4439
E-mail: Ebbe.Nordlander@inorg.lu.se
[b] Dipartimento di Chimica “G. Ciamician”, Università degli
Studi di Bologna,
via Selmi 2, 40126 Bologna, Italy
[‡] On leave from: Bangladesh College of Leather Technology,
Hazaribagh, Dhaka 1209, Bangladesh
Supporting information for this article is available on the
WWW under http://www.eurjic.org or from the author.
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Diphenyl(2-thienyl)phosphane Derivatives of Triosmium Clusters
FULL PAPER
Scheme 1. Examples of desulfurisation of benzothiophene and 2-methylthiophene by carbonyl transition-metal clusters (see text and
references cited therein).
Scheme 2. Room-temperature C–S bond cleavage effected by a carbonyltriosmium cluster (cf. ref.[17]).
[Os3(µ-H)(CO)9(µ-C4H2S)], which are in rapid equilibrium
Results and Discussion
at room temperature.[13–15] Similar results have been ob-
served for 2-methylthiophene, 2,2Ј-bithiophene and
Thermal Treatment of [Os3(CO)12] with Ph2P(C4H3S)
2,2Ј:5Ј,2ЈЈ-terthiophene.[16] The first room-temperature C–S
bond cleavage of a (benzo)thiophene coordinated to a met-
Reaction of [Os3(CO)12] with diphenyl(2-thienyl)phos-
allic cluster was reported by Arce et al.[17] In chloroform at phane, Ph2P(C4H3S), in refluxing toluene yielded, after sep-
room temperature the cluster [Os3(µ-H)(CO)10(µ-C8H5S)], aration by thin layer chromatography, three yellow, substi-
which contains a µ-η2-benzothienyl ligand, undergoes tuted compounds, which were identified as [Os3(CO)11-
C(vinyl)–S bond cleavage to yield the cluster [Os3(CO)10(µ- {PPh2(C4H3S)}] (1) (23%), [Os3(CO)10{PPh2(C4H3S)}2] (2)
C8H6S)], which contains an open benzothiophene ligand (44%), and [Os3(CO)9{PPh2(C4H3S)}3] (3) (8%) on the ba-
coordinated to an open Os3 unit through a µ-S atom and a sis of their IR spectra. They are analogous with those of
µ-η2-vinyl group (Scheme 2).
known mono-, bis-, and tris(phosphane)-substituted tri-
Despite the above-mentioned examples of thiophene co- osmium clusters.[21–24] The FAB mass spectra of all three
ordination and activation, thiophene remains a relatively compounds are also in complete agreement with the pro-
poor ligand for low-valent metal complexes, and thienyl- posed formulas.
1
phosphanes [e.g. diphenyl(2-thienyl)phosphane] have there-
The H NMR spectra of 1–3 display only aromatic reso-
fore been used to bring the heterocycle into the coordina- nances. No hydrido signals could be detected, indicating
tion sphere of transition-metal clusters through the phos- that ortho-metallation had not taken place. The room-tem-
phane moiety of the ligand.[18–20] Treatment of diphenyl(2- perature 31P{1H} NMR spectra show a singlet at δ =
thienyl)phosphane with [Ru3(CO)12] has led to the incorpo- –16.2 ppm for 1, a signal at δ = –17.3 (br.) ppm and doublet
ration of the thiophene ring into tri- and tetraruthenium at δ = –32.7 (JP–P = 6.4 Hz) ppm for 2 (vide infra), and a
clusters by cyclometallation and C–P bond cleavage of the singlet at δ = –17.2 ppm for 3. The 31P{1H} spectra of both
ligand.[20] Here we report the reactions of [Os3(CO)12] 1 and 3 remain unchanged when the temperature is de-
and [H2Os3(CO)10] with diphenyl(2-thienyl)phosphane, creased to –60 °C. This is consistent with the presence of
Ph2P(C4H3S), which have been undertaken in an effort to one isomer of both 1 and 3, in which the phosphane li-
achieve C–P and C–S bond cleavage of the ligand.
gand(s) adopt equatorial positions with respect to the clus-
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E. Nordlander et al.
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ter. However, the low-temperature 31P{1H} NMR spectrum
of 2 indicates the presence of more than one isomer. The
two most reasonable isomers are the cis-trans and trans-
trans isomers (cis or trans with respect to the Os–Os vector)
shown in Figure 1, which have previously been detected for
related [Os3(CO)10(phosphane)2] clusters.[25,26] The 31P{1H}
NMR spectrum at –60 °C (Figure 1) reveals that the pre-
dominant form is the cis-trans isomer with non-equivalent
phosphorus nuclei, represented by two singlets at δ = –18.12
and –21.97 ppm.
Figure 2. Molecular structure of [Os3(CO)10{Ph2P(C4H3S)}2] (2)
(thermal ellipsoids at 30% probability). The carbon atoms of the
carbonyl ligands bear the same numbering as the oxygen atoms.
Hydrogen atoms have been omitted for clarity.
Table 1. Selected bond lengths [Å] and angles [°] for [Os3(CO)10-
(Ph2PC4H3S)2] (2).
Os(1)–Os(2)
Os(1)–Os(3)
Os(2)–Os(3)
Os(1)–P(1)
Os(2)–P(2)
P(1)–C(11)
P(1)–C(17)
P(1)–C(23)
P(2)–C(27)
P(2)–C(31)
2.9104(7)
2.8860(8)
2.9072(6)
2.343(2)
2.333(2)
1.847(3)
1.825(3)
1.828(6)
1.820(6)
1.851(4)
1.833(4)
174.9(2)
92.6(3)
Os(1)–C(1)
Os(1)–C(2)
Os(1)–C(3)
Os(2)–C(4)
Os(2)–C(5)
Os(2)–C(6)
Os(3)–C(7)
Os(3)–C(8)
Os(3)–C(9)
Os(3)–C(10)
1.946(7)
1.887(6)
1.932(6)
1.884(6)
1.948(7)
1.918(7)
1.947(7)
1.920(7)
1.951(7)
1.885(7)
Figure 1. 31P{1H} NMR spectrum (CD2Cl2, 300 MHz) of
[Os3(CO)10(Ph2PC4H3S)2] (2) at –60 °C. The appearance of two
equally intense singlets (δ = –18.12 and –21.97 ppm) is consistent
with the cis-trans isomer and the third singlet (δ = –18.26 ppm) is
attributed to the trans-trans isomer.
P(2)–C(37)
C(1)–Os(1)–C(3)
C(2)–Os(1)–C(3)
P(1)–Os(1)–C(2)
P(1)–Os(1)–Os(2) 106.49(4)
P(1)–Os(1)–Os(3) 166.48(4)
C(2)–Os(1)–Os(2) 157.1(2)
C(5)–Os(2)–C(6)
P(2)–Os(2)–C(4)
P(2)–Os(2)–Os(1) 162.55(4)
P(2)–Os(2)–Os(3)
C(4)–Os(2)–Os(1)
C(4)–Os(2)–Os(3)
C(7)–Os(3)–C(9)
C(8)–Os(3)–C(10)
C(8)–Os(3)–Os(1)
C(8)–Os(3)–Os(2)
104.46(4)
99.1(2)
156.3(2)
173.0(3)
99.6(3)
90.9(2)
151.2(2)
96.0(2)
Until recently, only the trans-trans form of an [Os3-
(CO)10(phosphane)2] cluster had been verified crystallo-
graphically. Leong and Liu[27] have reported the first crys-
tallographic confirmation of a cis-trans structure, that of
cis-trans-[Os3(CO)10(PPh3)2], which can be crystallised in
both isomeric forms. We were able to grow yellow crystals
178.5(3)
97.9(2)
C(10)–Os(3)–Os(1) 169.4(2)
C(10)–Os(3)–Os(2) 109.2(3)
of compound 2 by slow concentration of a dichlorometh- lengthening of the Os(1)–Os(2) and Os(2)–Os(3) interac-
ane/n-hexane solution at 4 °C, and these crystals were some- tions in cis position is observed [2.910(1) and 2.907(1) Å,
what surprisingly found to contain only the cis-trans isomer. respectively, vs. Os(1)–Os(3) 2.886(1) Å]. This trend con-
The molecular structure of 2 is shown in Figure 2; selected firms the similar lengthening of the two Os–Os distances in
bond lengths and angles are listed in Table 1.
cis position in the cis-trans form of the cluster [Os3(CO)10-
The molecule consists of a triangle of osmium atoms (PPh3)2].[27] On the other hand, in trans-trans structures of
with ten carbonyl ligands, four bonded to Os(3) and three [Os3(CO)10(phosphane)2] [phosphane = PPh3, PPh(OMe)2,
to each of Os(1) and Os(2). Two diphenyl(2-thienyl)phos- P(OMe)3] there is no change of Os–Os bond lengths that
phane ligands occupy equatorial coordination sites on can be related to the presence of two phosphane ligands.[31]
Os(1) and Os(2), respectively. The average Os–Os distance The Os(1)–P(1) (2.343 Å) and Os(2)–P(2) [2.333(2) Å] dis-
[2.901(1) Å] is slightly longer than that found in the parent tances are normal and close to those reported for [Os3-
cluster, [Os3(CO)12] [Os–Osave = 2.877(3) Å].[28] In agree- (CO)10(PPh3)2].[27] (cis-trans and trans-trans forms) and the
ment with previous studies indicating that the presence of phosphane-substituted compounds mentioned above. The
a tertiary phosphane ligand tends to lengthen the cis-Os– phosphorus atoms are slightly displaced out of the Os3
Os bond in [Os3(CO)11(phosphane)] clusters,[29,30] some plane [P(1) +0.102(1) and P(2) +0.292(1) Å]. This structure
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Diphenyl(2-thienyl)phosphane Derivatives of Triosmium Clusters
FULL PAPER
determination and the above-mentioned low-temperature the phosphane substituents. In the isomer shown in Fig-
NMR measurements indicate that the cis-trans isomer of 2 ure 3, the two substituents on the same side of the metal
is the thermodynamically favoured compound, as has pre- plane are one phenyl and one thienyl ring for all three phos-
viously been found by Deeming and co-workers for related phane ligands, and the sulfur atom points towards the inner
clusters.[25,26]
part of the phosphane cone. In the other isomer, one phos-
Compound 3 crystallises with two independent mole- phane ligand is rotated so that its thienyl group occupies
cules, which are conformational isomers (vide infra), in the the “other” side of the Os3 plane.
asymmetric unit. The molecular structure of 3 is similar to
Table 2. Selected bond lengths [Å] and angles [°] for [Os3(CO)9-
{Ph2P(C4H3S)}3] (3).
that of previously characterised trisubstituted complexes of
the general formula [M3(CO)9(phosphane)3] [M = Os, Ru
Molecule A
and phosphane = PMe2(CH2Ph), PMe2Ph, PPh(OMe)2,
P(OEt)3, P(OCH2CF3)3 and PPh3].[31] The molecular struc-
Os(1)–Os(2)
2.902(1)
2.877(2)
2.904(1)
2.325(5)
2.333(6)
2.327(6)
1.82(1)
1.81(1)
1.83(2)
1.85(1)
1.82(1)
1.80(2)
172.0(9)
97.7(6)
167.8(2)
110.0(2)
93.0(6)
151.4(6)
172.8(9)
99.0(7)
108.6(1)
P(3)–C(42)
P(3)–C(48)
P(3)–C(54)
Os(1)–C(1)
Os(1)–C(2)
Os(1)–C(3)
Os(2)–C(4)
Os(2)–C(5)
Os(2)–C(6)
Os(3)–C(7)
Os(3)–C(8)
Os(3)–C(9)
P(2)–Os(2)–Os(3)
C(5)–Os(2)–Os(1)
C(5)–Os(2)–Os(3)
C(7)–Os(3)–C(8)
P(3)–Os(3)–Os(1)
P(3)–Os(3)–Os(2)
C(9)–Os(3)–Os(1)
C(9)–Os(3)–Os(2)
1.81(1)
1.83(1)
1.82(2)
1.94(2)
1.94(2)
1.87(1)
1.86(2)
1.88(2)
1.89(3)
1.92(2)
1.86(2)
1.86(3)
165.7(1)
150.6(7)
94.4(7)
170.1(9)
171.2(2)
111.9(1)
91.2(8)
149.9(8)
ture of one of the two crystallographically independent Os(1)–Os(3)
Os(2)–Os(3)
molecules of 3 is shown in Figure 3; selected bond lengths
Os(1)–P(1)
and angles are listed in Table 2. The cluster consists of a
Os(2)–P(2)
triangular Os3 core with nine terminal carbonyl ligands.
Os(3)–P(3)
Three diphenyl(2-thienyl) ligands, each one coordinated to
an osmium atom, occupy equatorial sites in such a way as
to minimize steric interactions. The Os–Os distances
average 2.894 Å, which is slightly longer than that found
for [Os3(CO)12] (vide supra), and the Os–P distances are
P(1)–C(10)
P(1)–C(16)
P(1)–C(22)
P(2)–C(26)
P(2)–C(32)
P(2)–C(38)
comparable to those observed in compound 2. It is worth C(1)–Os(1)–C(2)
P(1)–Os(1)–C(3)
noting that the introduction of the three diphenyl(2-thienyl)-
P(1)–Os(1)–Os(2)
phosphane ligands results in a significant twisting of the
P(1)–Os(1)–Os(3)
Os(CO)3(Ph2PC4H3S) units with respect to the Os3 plane.
C(3)–Os(1)–Os(2)
This distortion towards D3 symmetry, which presumably
occurs to minimize the steric interaction of the large phos-
phane ligands and may be rationalised in terms of more
effective ligand packing, has been observed previously for
related mono-, di- and tri-substituted complexes.[29,31,32]
C(3)–Os(1)–Os(3)
C(4)–Os(2)–C(6)
P(2)–Os(2)–C(5)
P(2)–Os(2)–Os(1)
Molecule B
The usual arrangement of the phosphane substituents, with Os(4)–Os(5)
2.919(1)
2.903(1)
2.912(1)
2.347(5)
2.331(6)
2.342(6)
1.76(2)
1.88(1)
1.82(2)
1.81(1)
1.82(1)
1.82(2)
P(6)–C(101)
P(6)–C(107)
P(6)–C(113)
Os(4)–C(60)
Os(4)–C(61)
Os(4)–C(62)
Os(5)–C(63)
Os(5)–C(64)
Os(5)–C(65)
Os(6)–C(66)
Os(6)–C(67)
Os(6)–C(68)
P(5)–Os(5)–Os(6)
1.83(1)
1.83(1)
1.78(3)
1.85(3)
1.90(2)
1.90(2)
1.90(2)
1.90(2)
1.90(2)
1.87(1)
1.89(2)
1.89(2)
164.4(1)
Os(4)–Os(6)
one lying below the metal plane and the other two lying
Os(5)–Os(6)
above, is found in both of the conformationally distinct
Os(4)–P(4)
molecules that are present in the asymmetric unit. However,
these conformational isomers differ in the orientations of
Os(5)–P(5)
Os(6)–P(6)
P(4)–C(69)
P(4)–C(75)
P(4)–C(81)
P(5)–C(85)
P(5)–C(91)
P(5)–C(97)
C(61)–Os(4)–C(62) 175.6(9)
P(4)–Os(4)–C(60)
P(4)–Os(4)–Os(5)
P(4)–Os(4)–Os(6)
C(60)–Os(4)–Os(5) 101.5(7)
C(60)–Os(4)–Os(6) 159.3(7)
C(63)–Os(5)–C(65) 172.1(9)
96.7(7)
161.7(1)
102.4(1)
C(64)–Os(5)–Os(4) 163.8(7)
C(64)–Os(5)–Os(6) 106.6(7)
P(6)–Os(6)–C(66)
P(6)–Os(6)–Os(4)
P(6)–Os(6)–Os(5)
99.8(7)
154.6(1)
95.3(1)
C(66)–Os(6)–Os(4) 104.8(7)
C(66)–Os(6)–Os(5) 164.9(7)
P(5)–Os(5)–C(64)
P(5)–Os(5)–Os(4)
89.0(7)
105.1(1)
Room-Temperature Reaction of [H2Os3(CO)10] with
(Ph2PC4H3S)
A colour change from purple to yellow was observed im-
mediately upon mixing 1 equiv. of diphenyl(2-thienyl)phos-
phane with [H2Os3(CO)10] in dichloromethane at room
temperature. Comparison of the IR and NMR spectra of
the product to the known [H2Os3(CO)10(L)] clusters,[32]
Figure 3. Molecular structure of one of the two crystallographically
independent molecules of [Os3(CO)9(Ph2PC4H3S)3] (3) (thermal el-
lipsoids at 30% probability). The carbon atoms of the carbonyl
ligands bear the same numbering as the oxygen atoms. Hydrogen
atoms have been omitted for clarity.
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E. Nordlander et al.
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indicated that the product is [HOs3(µ-H)(CO)10-
It was possible to grow crystals suitable for X-ray diffrac-
{Ph2P(C4H3S)}] (4), which was isolated in 26% yield after tion for cluster 5, and single-crystal diffraction studies were
1
TLC purification. The room-temperature H NMR spec- undertaken in order to confirm the structure. The molecu-
trum shows a broad hydrido signal (δ Ϸ –15 ppm) due to lar structure of 5 is shown in Figure 4; selected bond
rapid exchange of the two hydrido ligands, but at –35 °C lengths and angles are listed in Table 3. [Os3(µ-H)(CO)9{µ3-
the exchange is frozen out and two distinct resonances are Ph2P(C4H2S)}] (5) crystallises with two independent slightly
observed in the hydrido region – one for the terminal hyd- different conformers in the asymmetric unit and is
rido ligand at δ = –10.2 ppm and one for the bridging hyd- isostructural with [(µ-H)Ru3(CO)9{µ3-Ph2P(C4H2S)}].[20]
rido ligand at δ = –19.7 ppm. The 31P{1H} NMR spectrum Compound 5 consists of an irregular triangle of osmium
displays one singlet at δ = –16.7 ppm. On the basis of these atoms, each of which is coordinated by three carbonyl li-
NMR spectra we propose that the phosphane ligand in 4 is gands. A triply bridging diphenyl(2-thienyl)phosphane li-
situated trans to the Os–Os bond and cis to the bridging gand and a bridging hydrido ligand complete the coordina-
hydrido ligand, which is reported as the thermodynamically tion sphere of the cluster. The µ3-Ph2P(C4H2S) ligand,
most favourable of the isomers of [HOs3(µ-H)(CO)10(phos- which acts as a five-electron donor, is coordinated through
phane)] that have been identified.[33,34] Earlier investigations the phosphorus atom in axial position to Os(1) and through
have shown that four more isomers have been detected from the ortho-metallated thienyl ring to Os(3) with a C(11)–
the reaction between [H2Os3(CO)10] and phosphanes.[35] In Os(3) σ-bond [Os(3)–C(11) 2.10(1) and 2.09(1) Å in mole-
contrast to those results, we did not observe any additional cule A and B] and to Os(2) with an η2(π)-interaction be-
isomers, even at –75 °C. This lack of observation of isomers tween C(10)–C(11) and Os(2) [Os(2)–C(10) 2.34(1) and
may be related to the relative bulk of the ligand, making 2.36(1) Å, Os(2)–C(11) 2.35(1) and 2.32(1) Å in A and B,
the other possible isomers sterically unfavourable. An alter- respectively]. This σ,η2-vinyl-type interaction is not un-
native explanation is that the populations of (transient) iso- precedented; it has, for example, been observed in [(µ-H)-
mers were too low to be observed.
Ru3(CO)9{µ3-Ph2P(C4H2S)}][20] and [(µ-H)Ru3(CO)9{µ3-
Ph2P(C8H4S)}] (C8H4S
=
benzothienyl),[40] [Os3(µ-H)-
[Os3(µ-H)(CO)9{µ3-PMePh-
(CO)9(µ-Ph2PCH=CH)],[34]
(C6H4)}][41] as well as in the closely related [Os3(µ-H)-
Thermal Treatment of [H2Os3(CO)10] with Ph2P(C4H3S)
(MeSC4H2S)(CO)9],[42] in which the Ph2P unit in 5 is substi-
Reaction of an excess of diphenyl(2-thienyl)phosphane tuted by an SMe group. The C4H2S ring is tilted with re-
with [H2Os3(CO)10] in refluxing toluene for 3 h gives a col- spect to the Os3 plane [dihedral angle between the Os3 and
our change from initial purple colour to yellow, then to C4H2S planes 129.2(3) and 128.5(5)° for A and B, respec-
dark green and ultimately to brown. Separation by TLC led tively] as has previously been noticed for the triruthenium
to the isolation of three products.
analogue [(µ-H)Ru3(CO)9{µ3-Ph2P(C4H2S)}][20] and [Os3(µ-
The first product was isolated in 21% yield. Although IR H)(MeSC4H2S)(CO)9].[42] This tilt of the thienyl ring, which
spectra of isostructural Os and Ru clusters are not always has been found also for the ortho-metallated phenyl ring in
comparable, the product was identified as the cyclometall- [Os3(µ-H)(CO)9{µ3-PMePh(C6H4)}],[41] takes place in order
ated cluster [(µ-H)Os3(CO)9{µ3-Ph2P(C4H2S)}] (5) on the
basis of the similarity of its IR spectrum to that of the
known cluster [Ru3(µ-H)(CO)9{µ3-Ph2P(C4H2S)}].[20] Mass
spectrometric and microanalytical data were found to be
1
consistent with the proposed formula. The H NMR spec-
trum displays a doublet at δ = –18.0 ppm confirming the
presence of a bridging hydrido ligand, which couples to one
phosphorus atom (JP–H = 13.2 Hz). In the phenyl region,
two ortho signals are observed, corresponding to two iso-
mers. This is similar to that previously observed for [Ru3(µ-
H)(CO)9{µ3-Ph2P(C4H2S)}].[20] Unlike the ruthenium ana-
logue, where the ortho-protons are fluxional at 20 °C and
only become static on the NMR timescale at –20 °C, the
ortho-protons of 5 were not fluxional at ambient tempera-
ture. The 31P{1H} NMR spectrum of 5 at 27 °C displays a
singlet at δ = –3.3 (1JP–Os = 147 Hz) ppm, with a small
1
change of shift to δ = –5.3 ppm at –80 °C. The small JP–Os
coupling of 147 Hz is in agreement with axial coordination
Figure 4. Molecular structure of one of the two crystallographically
independent molecules of [(µ-H)Os3(CO)9{µ3-Ph2P(C4H2S)}] (5)
(thermal ellipsoids at 30% probability). The carbon atoms of the
carbonyl ligands bear the same numbering as the oxygen atoms.
All hydrogen atoms except the hydrido ligand have been omitted
for clarity.
of the phosphorus atom with respect to the plane of the
1
metal triangle. Typical equatorial JP–Os couplings are of
the order of 185–225 Hz while axial couplings are much
smaller as the metal–phosphane bond is no longer aligned
with the electron density of the metal triangle.[36–39]
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Diphenyl(2-thienyl)phosphane Derivatives of Triosmium Clusters
Table 3. Selected bond lengths [Å] and angles [°] for [(µ-H)Os3(CO)9{µ3-Ph2P(C4H2S)}] (5). The values in brackets refer to molecule B.
FULL PAPER
Os(1A)–Os(2A)
Os(1A)–Os(3A)
Os(2A)–Os(3A)
Os(1A)–H(1A)
Os(3A)–H(1A)
Os(1A)–P(1A)
Os(2A)–C(11A)
Os(3A)–C(11A)
P(1A)–C(10A)
P(1A)–C(14A)
P(1A)–C(20A)
C(10A)–C(11A)
Os(1A)–C(1A)
Os(1A)–C(2A)
C(2A)–Os(1A)–C(3A)
P(1A)–Os(1A)–C(1A)
P(1A)–Os(1A)–Os(2A)
P(1A)–Os(1A)–Os(3A)
C(2A)–Os(1A)–Os(2A)
C(2A)–Os(1A)–Os(3A)
C(3A)–Os(1A)–Os(2A)
C(3A)–Os(1A)–Os(3A)
C(5A)–Os(2A)–C(6A)
C(5A)–Os(2A)–Os(1A)
2.857(1) [2.859(1)]
3.004(1) [3.020(1)]
2.755(1) [2.762(1)]
1.84(2) [1.83(2)]
1.82(2) [1.83(2)]
2.350(3) [2.344(3)]
2.35(1) [2.32(1)]
2.35(1) [2.32(1)]
2.10(1) [2.09(1)]
1.77(1) [1.78(1)]
1.832(7) [1.831(6)]
1.801(6) [1.827(7)]
1.45(1) [1.43(1)]
1.93(1) [1.93(1)]
95.6(6) [95.7(7)]
170.3(4) [168.5(5)]
73.90(7) [74.53(8)]
86.17(7) [86.03(7)]
167.7(4) [168.5(4)]
119.1(5) [116.4(4)]
90.0(4) [92.5(5)]
145.4(4) [147.9(5)]
94.1(5) [93.9(6)]
95.8(4) [96.0(4)]
S(1A)–C(13A)
C(12A)–C(13A)
S(1A)–C(13A)
C(12A)–C(13A)
Os(1A)–C(3A)
Os(2A)–C(4A)
Os(2A)–C(4A)
Os(2A)–C(4A)
Os(2A)–C(6A)
Os(3A)–C(7A)
Os(3A)–C(8A)
Os(3A)–C(9A)
C(10A)–S(1A)
C(11A)–C(12A)
C(5A)–Os(2A)–Os(3A)
C(6A)–Os(2A)–Os(1A)
C(6A)–Os(2A)–Os(3A)
C(11A)–Os(2A)–Os(3A)
C(7A)–Os(3A)–C(11A)
C(8A)–Os(3A)–C(9A)
C(8A)–Os(3A)–Os(2A)
C(8A)–Os(3A)–Os(1A)
C(9A)–Os(3A)–Os(2A)
C(9A)–Os(3A)–Os(1A)
1.70(1) [1.72(1)]
1.89(1) [1.89(2)]
1.70(1) [1.72(1)]
1.34(2) [1.32(2)]
1.90(2) [1.90(1)]
1.88(1) [1.85(1)]
1.88(1) [1.85(1)]
1.88(1) [1.85(1)]
1.88(1) [1.90(2)]
1.93(1) [1.93(1)]
1.89(1) [1.88(1)]
1.89(1) [1.88(1)]
1.77(1) [1.78(1)]
1.46(2) [1.45(2)]
160.4(4) [160.9(4)]
170.1(4) [169.4(4)]
105.4(4) [105.0(4)]
47.7(3) [47.5(3)]
165.6(5) [166.0(5)]
95.5(7) [94.0(6)]
92.7(5) [95.5(5)]
150.3(5) [152.3(5)]
155.3(4) [151.4(4)]
114.1(5) [113.5(4)]
to favour the η2-interaction. The hydrido ligand which, as explained in terms of an oscillation of the thienyl group
expected, is bridging the longest edge of the cluster, was identical to that observed for 5 (vide supra) except that,
located directly in the electron-density map. In both mole- unlike 5, the isomers of 6 (Figure 6) are observable by
cules, the hydrido ligand is on the same side of the Os3 NMR due to the presence of the terminally coordinated
plane as the µ3-Ph2P(C4H2S) ligand [ca. 0.4 Å above the phosphane ligand, which renders the two hydrido positions
metal plane]. The Os–P bond lengths [Os(3)–P(1) 2.350(3) non-equivalent.
and 2.344(3) Å in A and B, respectively] are similar to those
found in the cyclometallated compounds [Os3(µ-H)(CO)9-
{µ-Ph2P(CH=CH)}][34] [2.361(4) Å] and [Os3(µ-H)(CO)9-
{µ3-PMePh(C6H4)}][41] [2.342(6) Å].
The second product, which was isolated in 34% yield,
was identified as [(µ-H)Os3(CO)8{µ3-Ph2P(C4H2S)}{Ph2P-
(C4H3S)}] (6). The IR spectrum of 6 is similar to that of
[(µ-H)Ru3(CO)8{µ3-Ph2P(C8H4S)}{Ph2P(C8H5S)}][40] and
mass spectrometric and microanalytical data are consistent
with the proposed formula. The variable-temperature 1H
and 31P{1H} NMR spectra of 6 demonstrate that this com-
plex is highly fluxional. The 31P{1H} NMR spectrum of 6
at 20 °C shows two doublets at δ = –0.63 and –1.48 (JP–P
=
16.6 Hz) ppm (Figure 5). This is supported by the bridging
hydrido signal (δ = –17.4 ppm), appearing as a doublet of
doublets due to the coupling to two non-equivalent phos-
phorus ligands. At –100 °C, the spectrum freezes out to
show two distinct isomers in both the 31P{1H} and 1H
NMR spectra, although the 1H spectrum had to be ac-
quired at 600 MHz before the shift differences could be
clearly discerned (Figure 5). The limiting 31P{1H} spectrum
(–100 °C) shows two pairs of doublets centred at δ Ϸ
Figure 5. 31P{1H} and 1H NMR spectra of [(µ-H)Os3(CO)8{µ3-
Ph2P(C4H2S)}{Ph2P(C4H3S)}] (6) at 293 K and 173 K. The low-
temperature 1H NMR spectrum (CD2Cl2, 600 MHz) shows the
very small shift differences between the two isomers.
1
1.2 ppm, while the signal in the hydrido region of the H
spectrum is shifted upfield and split into two doublets of
doublets. It is possible that the two isomers that are ob-
served in solution are related by the relative location of the
terminal phosphane ligand with respect to the hydrido li-
Figure 6. Proposed structures of the two isomers of 6.
The assignment of the room-temperature structure could
gand. This is supported by the observed differences in the be confirmed by the acquisition of a 187Os NMR spectrum
phosphane–hydrido couplings. We believe that this may be by inverse methods.[38] The presence of a P–P coupling
Eur. J. Inorg. Chem. 2006, 2058–2068
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E. Nordlander et al.
FULL PAPER
1
makes it potentially more difficult to extract the JOs–P val-
ues directly from a 31P{1H} spectrum. The 1H-187Os 2D
HMQC spectrum at –100 °C (Figure 7) shows two shifts (δ
= –13965 and –13230 ppm), corresponding to two osmium
centres directly bonded to the bridging hydrido ligands, and
1
it is possible to extract the two JOs–P couplings of 147 Hz
and 211 Hz from the HMQC spectrum. The first coupling
constant corresponds to that observed for 5 (147 Hz) and
the coupling constant of 211 Hz is similar to other known
1JOs–P values for terminal phosphane ligands.[39] The fact
1
that the JOs–P values for the axial phosphane ligands in 5
and 6 are identical is surprising (and may be coincidental),
but it is indicative of the low level of electronic communica-
tion between the metal centres in the clusters.
Figure 8. Molecular structure of [(µ-H)Os3(CO)8{µ3-Ph2P(C4H2S)}-
{Ph2P(C4H3S)}] (6) (thermal ellipsoids at 30% probability). The
carbon atoms of the carbonyl ligands bear the same numbering as
the oxygen atoms. All hydrogen atoms except the hydrido ligand
have been omitted for clarity.
Table 4. Selected bond lengths [Å] and angles [°] for [(µ-H)Os3-
(CO)8{µ3-Ph2P(C4H2S)}{Ph2P(C4H3S)}] (6).
Os(1)–Os(2)
Os(1)–Os(3)
Os(2)–Os(3)
Os(1)–H(1)
Os(2)–H(1)
Os(1)–P(1)
3.0142(6)
2.8626(7)
2.7799(8)
1.84(3)
P(2)–C(37)
C(21)–C(22)
C(21)–S(1)
C(23)–C(24)
Os(1)–C(1)
Os(1)–C(2)
Os(1)–C(3)
Os(2)–C(4)
Os(2)–C(5)
Os(3)–C(6)
Os(3)–C(7)
Os(3)–C(8)
C(22)–C(23)
S(1)–C(24)
1.805(9)
1.45(1)
1.77(1)
1.35(1)
1.93(1)
1.86(1)
1.93(1)
1.92(1)
1.83(1)
1.90(1)
1.91(1)
1.86(1)
1.46(1)
1.69(1)
1.85(3)
2.360(2)
2.325(3)
2.10(1)
2.32(1)
2.33(1)
1.835(5)
1.839(6)
1.793(9)
1.833(5)
1.811(5)
96.4(5)
Os(2)–P(2)
Os(2)–C(22)
Os(3)–C(21)
Os(3)–C(22)
P(1)–C(9)
P(1)–C(15)
P(1)–C(21)
P(2)–C(25)
P(2)–C(31)
C(2)–Os(1)–C(3)
P(1)–Os(1)–C(2)
P(1)–Os(1)–C(3)
Figure 7. 2D 1H-187Os HMQC spectrum of 6 which clearly demon-
strates the two different 187Os-31P couplings for each of the hyd-
rido-bridged osmium centres (cf. Figure 5).
It was possible to grow crystals suitable for X-ray diffrac-
tion for cluster 6, and a single-crystal diffraction study was
undertaken in order to confirm its structure and investigate
whether isomers could be detected also in the solid state.
The structure of [Os3(µ-H)(CO)8{µ3-Ph2P(C4H2S)}{Ph2P-
(C4H3S)}] (6) is shown in Figure 8; selected bond lengths
and angles are listed in Table 4.
As expected, the structure is similar to that of [(µ-H)-
Ru3(CO)8{µ3-Ph2P(C4H2S)}{Ph2P(C4H3S)}][20] and of [(µ-
H)Ru3(CO)8{µ3-Ph2P(C8H4S)}{Ph2P(C8H5S)}].[40] It is also
closely related to [Ru3(µ-H)(CO)8{µ3-Ph2P(CH=CH)}-
{Ph2P(CH=CH2)}][43] and differs from 5 only in the substi-
P(2)–Os(2)–C(22)
P(2)–Os(2)–Os(1)
P(2)–Os(2)–Os(3)
99.9(3)
115.53(6)
153.52(6)
92.3(3)
98.2(3)
P(1)–Os(1)–Os(2) 87.37(6)
P(1)–Os(1)–Os(3) 72.88(6)
C(2)–Os(1)–Os(2) 145.1(4)
C(2)–Os(1)–Os(3) 90.2(4)
C(3)–Os(1)–Os(2) 118.2(3)
C(3)–Os(1)–Os(3) 169.1(3)
C(5)–Os(2)–Os(1) 151.0(3)
C(5)–Os(2)–Os(3) 93.9(3)
C(6)–Os(3)–C(7)
C(7)–Os(3)–C(8)
93.6(6)
99.3(5)
C(6)–Os(3)–Os(1) 169.2(3)
C(6)–Os(3)–Os(2) 105.6(4)
C(7)–Os(3)–Os(1) 95.9(4)
C(7)–Os(3)–Os(2) 160.2(4)
P(2)–Os(2)–C(4)
P(2)–Os(2)–C(5)
93.2(4)
93.3(4)
tution of one carbonyl ligand by one terminal thienylphos- 2.33(1) Å] are very similar to those found in 5 and unaffec-
phane ligand. The cluster consists of a scalene triangle of ted by the presence of the terminal phosphane ligand. The
Os atoms [Os(1)–Os(2) 3.014, Os(1)–Os(3) 2.863 Å, Os(2)– C(21)–C(22) distance [1.45(1) Å] in the bridging thienyl ring
Os(3) 2.780(1) Å] bound to eight terminal carbonyl ligands, is identical to the equivalent interaction in 5 and similar to
a terminal Ph2PC4H3S ligand, a µ3-Ph2PC4H2S and a µ2- the analogous bonds in [(µ-H)Ru3(CO)8{µ3-Ph2P(C4H2S)}-
bridging hydrido ligand. The µ3-Ph2PC4H2S ligand behaves {Ph2P(C4H3S)}][20] [1.425(5) Å]. The terminal diphenyl(2-
as a five-electron donor and interacts with all three metal thienyl)phosphane ligand is coordinated in an equatorial
atoms in the same fashion as observed in 5. The σ- and position, but the phosphorus atom is displaced out of the
η2-interactions of the ortho-metallated thienyl ring [Os(2)– metal plane [P(2) +1.034(2) Å] on the same side of the µ3-
C(22) 2.10(1), Os(3)–C(21) 2.32(1) and Os(3)–C(22) Ph2PC4H2S ligand. The two Os–P interactions [Os(1)–P(1)
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Diphenyl(2-thienyl)phosphane Derivatives of Triosmium Clusters
FULL PAPER
Scheme 3. Possible reaction scheme for the reaction between [H2Os3(CO)10] and Ph2P(C4H3S) in toluene.
2.360(2) and Os(2)–P(2) 2.325(3) Å] are not equivalent; the three non-equivalent phosphorus resonances are observed
Os–P(axial) distance is longer than the Os–P(equatorial) at δ = –3.19 (m), –5.30 (d) and –9.15 (m) ppm. These data
but very similar to the corresponding distance in 5. The suggest that this complex and compound 7 are structurally
bridging hydrido ligand has been directly located along the similar except for one carbonyl ligand. Therefore, we pro-
Os(1)–Os(2) edge which is, as usual, the longest Os–Os in- pose the molecular formula [(µ-H)Os3(CO)7{µ-Ph2P-
teraction.
(C4H2S)}{µ-Ph2P(C4H3S)}{Ph2P(C4H3S)}] for compound
The third product, compound 7, was isolated in 5% 8, containing the µ-Ph2P(C4H2S) ligand bonded through P
yield. The mass spectrometric analysis suggests the stoichio- and a σ-interaction to the osmium triangle, but lacking an
metric formula [Os3(CO)6{Ph2P(C4H3S)}3] for this product, η2-interaction with an osmium atom (cf. Scheme 3).
and microanalytical data are consistent with the proposed
Several colour changes were observed during the reaction
1
formula. The H NMR spectrum displays a signal in the of diphenyl(2-thienyl)phosphane with [H2Os3(CO)10], indi-
(bridging) hydrido region (δ = –16.67 ppm) indicating that cating that the reaction proceeds via a number of intermedi-
an ortho-metallation has taken place. The hydrido signal ates. A possible reaction scheme is shown in Scheme 3. Ad-
appears as a triplet (overlapping doublet of doublets), indi- dition of the ligand to the cluster results in an immediate
cating coupling to two non-equivalent phosphorus atoms. colour change from purple to yellow and formation of
Three signals are observed in the 31P{1H} NMR spectrum, [HOs3(µ-H)(CO)10{Ph2P(C4H3S)}] (4) (indicated by IR
confirming the presence of three non-equivalent phospho- spectroscopy). Cluster 4 then reacts further, possibly under-
rus atoms; a multiplet at δ = 4.50 ppm, a doublet at δ = going a loss of one CO ligand and forming an unsaturated
–1.65 (JP–P = 16 Hz) ppm and a multiplet at δ = –5.98 ppm. intermediate cluster which is likely to be [H2Os3(CO)9-
On the basis of these data, we propose the molecular for- {Ph2P(C4H3S)}]. It has previously been observed, that heat-
mula [(µ-H)Os3(CO)6{µ3-Ph2P(C4H2S)}{µ2-Ph2P(C4H3S)}- ing solutions of compounds of the type [H2Os3(CO)10(L)]
{Ph2P(C4H3S)}] (cf. Scheme 3) for compound 7, containing (L = tertiary phosphane), leads to a loss of one carbonyl
three diphenyl(2-thienyl) ligands coordinated in three dif- ligand giving [H2Os3(CO)9(L)].[33,46] [H2Os3(CO)9{Ph2P-
ferent coordination modes; a µ3-fashion, a µ-(P,S) fashion (C4H3S)}] then presumably undergoes further decarbon-
and a terminal fashion. The µ-(P,S) coordination mode has ylation ultimately giving rise to the four products isolated.
been detected for a diphenyl(2-benzothienyl)phosphane de-
rivative of [Os3(CO)12][44] as well as in thienylphosphane de-
rivatives of [Rh6(CO)16].[45]
Conclusion
The fourth product, compound 8, was isolated in 3%
yield. The mass spectrum of this compound indicates that
In conclusion, the introduction of diphenyl(2-thienyl)-
1
it has one more carbonyl ligand than compound 7. The H phosphane into the coordination sphere of triosmium clus-
NMR spectrum displays, in addition to signals of aromatic ters by direct thermal substitution of carbonyl ligands or
hydrogen atoms, a triplet (overlapping doublet of doublets) room-temperature reaction with the unsaturated cluster
at δ = –17.05 ppm, thus confirming the presence of a single [H2Os3(CO)10] is facile. In all cases surveyed in this study,
bridging hydrido ligand. In the 31P{1H} NMR spectrum, the ligand initially coordinates as a monodentate phos-
Eur. J. Inorg. Chem. 2006, 2058–2068
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E. Nordlander et al.
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decreasing Rf: [HOs3(µ-H)(CO)10{Ph2P(C4H3S)}] (4, 34 mg, 26%,
yellow), uncharacterised product (5 mg, 4%, red).
phane, but further activation/metallation of the ligand is
possible at elevated temperatures, although the osmium
clusters are considerably less reactive than their ruthenium
analogues.[20]
4: C26H15O10Os3PS (1121.12): calcd. C 27.85, H 1.35, P 2.76; found
C 28.86, H 1.38, P 2.72. FAB-MS: m/z = 1120 [M+], [M+ – n CO,
n = 1–10]. IR (CH Cl ): νco = 2106 s, 2090 m, 2086 m, 2068 s, 2052
˜
2
2
s, 2025 s, 1984 m, 1972 m, 1933 sh cm–1. 1H NMR (300 MHz,
CDCl3, 20 °C): δ = 7.79–7.27 (m, 13 H, arom.), –10 to –20 (br. s,
2 H, hydrido) ppm. 1H NMR (300 MHz, CDCl3, –45 °C): δ = 7.8–
7.3 (m, 13 H, arom.), –10.12 (d, JH,H = 3.3 Hz, 1 H, terminal hyd-
rido), –19.72 (dd, JH,H = 3.3 Hz, JP,H = 11 Hz, 1 H, bridging hyd-
rido) ppm. 31P NMR (300 MHz, CDCl3, –45 °C): δ = –16.7 (s, 1
P, terminal phosphane) ppm.
Experimental Section
General Remarks: The clusters [Os3(CO)12][47] and [Os3(µ-H)2-
(CO)10][48–50] and the ligand diphenyl(2-thienyl)phosphane[20] were
synthesised by published methods. Solvents were dried by standard
methods prior to use. TLC was performed on commercial plates
precoated with Merck Kieselgel 60 to 0.5 mm thickness. NMR
spectra were acquired with Bruker DRX300 WB, DRX500 and
DRX600 spectrometers. Gradient-selected 187Os 2D HMQC ex-
periments were carried out with a Bruker DMX600 equipped with
an XYZ 10A gradient amplifier (z-gradient strength 0.05 Tm–1).
Details regarding the experimental setup and acquisition param-
eters for the 187Os 2D HMQC experiments are listed in the Sup-
porting Information (see footnote on the first page of this article).
IR spectra were acquired with a Nicolet Avatar FT-IR spectrome-
ter and FAB-MS (3-nitrobenzyl alcohol matrix) data with a JEOL
SX-102 mass spectrometer.
Thermal Reaction of [H2Os3(CO)10] with Diphenyl(2-thienyl)phos-
phane in Toluene: A solution of [H2Os3(CO)10] (150 mg, 0.18 mmol)
and (Ph2PC4H3S) (95 mg, 0.36 mmol) in toluene (30 mL) was re-
fluxed under nitrogen for 3 h. During the reaction the colour
changed from purple to yellow, to green, and finally to brown. The
products were separated by TLC using dichloromethane/n-hexane
(2:3, v/v) as eluent. Five bands were recovered, in order of decreas-
ing Rf: [H2Os3(CO)10] (purple, trace), [(µ-H)Os3(CO)9{µ3-Ph2P-
(C4H2S)}] (5, intense yellow, 99 mg, 21%), [(µ-H)Os3(CO)8{µ3-
Ph2P(C4H2S)}{Ph2P(C4H3S)}] (6, intense yellow, 197 mg,
34%), [(µ-H)Os3(CO)6{µ3-Ph2P(C4H2S)}{µ-Ph2P(C4H3S)}{Ph2P-
(C4H3S)}] (7, yellow, 32 mg, 5%), [(µ-H)Os3(CO)7{µ-Ph2P(C4H2S)}-
{µ-Ph2P(C4H3S)}{Ph2P(C4H3S)}] (8, intense yellow, 22 mg, 3%).
Direct Thermal Reaction of [Os3(CO)12] and Diphenyl(2-thienyl)-
phosphane in Toluene:
A solution of [Os3(CO)12] (300 mg,
5: C25H13O9Os3PS (1091.1). FAB-MS: m/z = 1092 [M+], [M+ – n
0.33 mmol) and diphenyl(2-thienyl)phosphane (98 mg, 0.37 mmol)
in toluene (40 mL) was refluxed under nitrogen for 2.5 h. The sol-
vent was removed under reduced pressure. Preparative TLC of the
residue, using dichloromethane/n-hexane (3:7, v/v) as eluent gave
four compounds, in order of decreasing Rf: [Os3(CO)12] (pale yel-
low, trace), [Os3(CO)11{Ph2P(C4H3S)}] (1, intense yellow, 96 mg,
23%), [Os3(CO)10{Ph2P(C4H3S)}2] (2, intense yellow, 203 mg,
44%), [Os3(CO)9{Ph2P(C4H3S)}3] (3, orange, 42 mg, 8%).
CO, n = 1–9]. IR (CH Cl ): ν = 2088 s, 2060 s, 2034 s, 2019 s,
˜
2
2
co
1
1989 s, 1974 w, 1965 m cm–1. H NMR (300 MHz, CDCl3, 20 °C):
δ = 7.93–7.07 (m, 12 H, arom.), –18.0 (d, JH,P = 13.2 Hz, 1 H,
bridging hydrido) ppm. 31P NMR (300 MHz, CDCl3, 20 °C): δ =
–3.27 (s, JOs,P = 147 Hz, 1 P, axial phosphorus) ppm.
6: C40H26O8Os3P2S2 (1331.4): calcd. C 36.09, H 1.97, P 4.65; found
C 36.09, H 1.97, P 4.56. FAB-MS: m/z = 1332 [M+], [M+ – n CO,
n = 1–8]. IR (CH Cl ): ν = 2074 s, 2032 s, 2015 s, 1993 sh, 1981
˜
2
2
co
1: C27H13O11Os3PS (1147.12): calcd. C 28.27, H 1.14, P 2.76; found
C 28.19, H 1.33, P 2.76. FAB-MS: m/z = 1148 [M+], [M+ – n CO,
m, 1967 m, 1957 m, 1945 sh cm–1. 1H NMR (300 MHz, CDCl3,
20 °C): δ = 7.86–6.35 (m, 25 H, arom.), –17.4 (dd, JH,P = 15.4 Hz,
JH,P = 11 Hz, 1 H, bridging hydrido) ppm. 31P NMR (300 MHz,
n = 1–11]. IR (CH Cl ): ν = 2108 s, 2056 s, 2031 sh, 2018 sh,
˜
2
2
co
1988 m, 1958 sh cm–1. 1H NMR (300 MHz, CDCl3, 30 °C): δ =
7.9–7.1 (m, 13 H, arom.) ppm. 31P NMR (300 MHz, CDCl3,
30 °C): δ = –16.2 (s, 1 P, terminal phosphane) ppm.
CD2Cl2, 27 °C): δ = –0.70 (d, JP,P = 16.7 Hz, 1 P), –1.22 (d, JP,P
=
16.7 Hz, 1 P) ppm. 31P NMR (300 MHz, CD2Cl2, –90 °C): δ = 1.27
(d, JP,P = 16.8 Hz, 1 P), –0.36 (d, JP,P = 16.8 Hz, 1 P), –0.69 (d,
1
JP,P = 16.5 Hz, 1 P), –2.13 (d, JP,P = 16.4 Hz, 1 P) ppm. H-187Os
2: C42H26O10Os3P2S2 (1387.42): calcd. C 36.36, H 1.89, P 4.46;
found C 36.33, H 1.62, P 4.94. FAB-MS: m/z = 1388 [M+], [M+
–
2D HMQC NMR (600 MHz, CD2Cl2, –100 °C): δ = –13965 (1JOs,P
= 147 Hz), –13230 (1JOs,P = 211 Hz) ppm.
n CO, n = 1–10]. IR (CH Cl ): ν = 2086 w, 2070 s, 2031 s, 1999
˜
co
2
1
2
s, 1970 w, 1956 w cm–1. H NMR (300 MHz, CDCl3, 20 °C): δ =
7.82–7.17 (m, 26 H, arom.) ppm. 31P NMR (300 MHz, CD2Cl2,
–60 °C): δ = –18.12 (s, 1 P, terminal), –18.26 (s, 2 P, terminal),
–21.97 (s, 1 P, terminal) ppm.
7: C54H39O6Os3P3S3 (1543.69). FAB-MS: m/z = 1544 [M+], 1516
[M+ – CO], 1488 [M+ – 2 CO], 1460 [M+ – 3 CO]. IR (CH2Cl2):
ν
= 2068 w, 2058 w, 2025 sh, 2015 m, 1985 s, 1961 sh, 1929 sh
˜
co
cm–1. 1H NMR (300 MHz, CDCl3, 20 °C): δ = 7.85–6.65 (m, 38 H,
arom.), –16.67 [t, JH,P = 11 Hz, 1 H, bridging hydrido] ppm. 31P
NMR (300 MHz, CDCl3, 20 °C): δ = 4.50 (m, 1 P), –1.65 (d, J =
16.18 Hz, 1 P), –5.98 (m, 1 P) ppm.
3: C57H39O9Os3P3S3 (1627.72): calcd. C 42.06, H 2.42, P 5.71:
found C 42.48, H 2.85, P 5.23. FAB-MS: m/z = 1628 [M+], 1600
[M+ – CO]. IR (CH Cl ): ν = 2068 sh, 2034 sh, 2013 w, 1998 m,
˜
co
2
2
1975 m, 1945 w cm–1. 1H NMR (500 MHz, CDCl3, 25 °C): δ = 7.6–
7.12 (m, 39 H, arom.) ppm. 31P NMR (500 MHz, CDCl3, 25 °C): δ
= –17.2 (s, 3 P, terminal) ppm.
8: C55H39O7Os3P3S3 (1571.7). FAB-MS: m/z = 1572 [M+], 1544
[M+ – CO]. IR (CH Cl ): ν = 2061 m, 2040 vs, 2002 s, 1988 m,
˜
2
2
co
1968 w, 1944 m cm–1. 1H NMR (300 MHz, CDCl3, 20 °C): δ =
7.85–6.20 (m, 38 H, arom.), –17.05 [t (dd), JH,P = 14.7 Hz, JH,P
=
Room-Temperature Reaction of [H2Os3(CO)10] with Diphenyl(2-thi-
enyl)phosphane in CH2Cl2: Diphenyl(2-thienyl)phosphane (2 equiv.,
95 mg, 0.36 mmol) was added to [H2Os3(CO)10] (1 equiv., 150 mg,
0.18 mmol) in freshly distilled dichloromethane (30 mL) at room
temperature under nitrogen. Within 5 min, the solution turned
from purple to yellow and the IR spectrum indicated that no start-
ing material had remained unreacted. The solution was concen-
trated and absorbed onto TLC plates using dichloromethane/n-hex-
ane (3:7, v/v) as eluent. Two bands were recovered, in order of
13.2 Hz, 1 H, bridging hydrido] ppm. 1H NMR (300 MHz,
CD2Cl2, –50 °C, hydrido region): δ = –17.16 (t, J = 13.5 Hz,
12.9 Hz, 1 H) ppm. 31P NMR (300 MHz, CDCl3, 20 °C): δ = –3.19
(m), –5.30 (d, J = 17.1 Hz), –9.15 (m) ppm. 31P NMR (300 MHz,
CD2Cl2, –35 °C): δ = –0.58 (d, J = 9.95 Hz, 1 P), –9.5 (2, 1 P),
–11.15 (s, 1 P) ppm.
X-ray Crystallographic Study: Crystals of 2, 3, 5 and 6 were ob-
tained by slow concentration of dichloromethane/n-hexane solu-
2066
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© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2006, 2058–2068

Diphenyl(2-thienyl)phosphane Derivatives of Triosmium Clusters
FULL PAPER
Table 5. Crystal data and experimental details for [Os3(CO)10{Ph2P(C4H3S)}2] (2); [Os3(CO)9{Ph2P(C4H3S)}3] (3); [(µ-H)Os3(CO)9{µ3-
Ph2P(C4H2S)}] (5); [(µ-H)Os3(CO)8{µ3-Ph2P(C4H2S)}{Ph2P(C4H3S)}]( 6).
2
3
5·0.5C6H14
6
Empirical formula
Formula mass
T [K]
C42H26O10Os3P2S2
1387.29
293(2)
C57H42O9Os3P3S3
1630.60
293(2)
C25H13O9Os3PS·0.5C6H14 C40H26O8Os3P2S2
1112.53
293(2)
1331.27
293(2)
λ [Å]
0.71069
0.71069
0.71069
triclinic
0.71069
orthorhombic
P212121 (no. 19)
10.846(4)
14.370(3)
25.455(4)
90
90
90
3967(2)
4
Crystal system
Space group
a [Å]
b [Å]
c [Å]
α [°]
β [°]
triclinic
triclinic
¯
¯
¯
P1 (no. 2)
P1 (no. 2)
P1 (no. 2)
12.461(2)
12.857(4)
14.180(5)
70.69(2)
79.12(2)
88.55(2)
2103.8(9)
2
14.067(2)
18.872(5)
25.004(3)
70.26(2)
75.08(2)
86.97(2)
6033(2)
13.474(3)
13.669(2)
17.309(5)
85.68(2)
77.86(2)
74.05(1)
2996(1)
γ [°]
V [Å3]
Z
4
4
Dcalcd. [Mg·m–3]
µ(Mo-Kα) [mm–1]
F(000)
2.190
9.270
1296
1.795
6.537
3108
2.466
12.863
2.229
9.822
2026
2480
Crystal size [mm]
θ limits [°]
Reflections collected
0.35 × 0.24 × 0.20
2–27
9104 ( h, k, +l)
0.25 × 0.11 × 0.08
2–25
21091 ( h, k, +l)
8123
0.933
0.0766, 0.1544
–
0.27 × 0.25 × 0.20
2–27
13008 ( h, k, +l)
8000
0.989
0.0441, 0.1081
–
0.30 × 0.25 × 0.22
2–27
4801(+h, +k, +l)
4062
Unique observed reflections [I Ͼ 2σ(I)] 6941
Goodness of fit (F2)
1.033
0.0268, 0.0683
–
1.063
R1 (F)[a], wR2 (F2)[b] [I Ͼ 2σ(I)]
Absolute structure parameter
Largest diff. peak/hole [e·Å–3]
0.0249, 0.0601
–0.02(1)
0.925/–0.963
1.340/–0.989
2.055/–2.330
2.204/–2.184
[a] R1 = Σ||Fo| – |Fc||/Σ|Fo|. [b] wR2 = [Σw(Fo – Fc ) /Σw(Fo2)2]1/2, w = 1/[σ2(Fo2) + (aP)2 + bP], P = (Fo + 2Fc )/3.
2
2 2
2
2
tions at 4 °C. Crystal data and other experimental details for all
structures are reported in Table 5. The diffraction experiments were
carried out with an Enraf–Nonius CAD4 diffractometer at room
temperature, using graphite-monochromatized Mo-Kα radiation (λ
= 0.71073 Å). The unit cells were determined by a least-squares
fitting procedure using 25 randomly selected strong reflections. The
diffracted intensities were corrected for Lorentz and polarisation
effects. An empirical absorption correction was applied using the
azimuthal scan method.[51] The positions of the metal atoms were
determined by direct methods (SIR-97[52]) and all non-hydrogen
atoms were located from Fourier difference syntheses. In com-
pounds 5 and 6, the bridging hydrido ligands were also located in
the Fourier map. The phenyl and thienyl H atoms were added in
calculated positions (dC–H 0.93 Å). The final refinement on F2 pro-
charge from The Cambridge Crystallographic Data Centre via
www.ccdc.cam.ac.uk/data_request/cif.
Acknowledgments
This research was supported by grants to E. N. from the Swedish
Research Council (VR) and the European Union (TMR network
Metal Clusters in Catalysis and Organic Synthesis, MECATSYN).
We would like to thank Dr. Jason D. King for his helpful comments
on the variable-temperature NMR spectra, and Prof. Silvio Aime
and Dr. Karl-Erik Bergquist for the use of NMR spectrometers.
M. M. and S. S. thank the University of Bologna and MIUR
(Cofin2003) for financial support.
ceeded by full-matrix least-squares calculations (SHELXL97[53]
)
using anisotropic thermal parameters for all non-hydrogen atoms
in 2, 5 and 6, whereas in 3 only the Os, P and S atoms were treated
anisotropically. The asymmetric units of 3 and 5 contain two inde-
pendent molecules, and the latter contains also one-half of a disor-
dered n-hexane solvent molecule, which is related to the other half
by an inversion centre. The 2-thienyl rings [bound to P(4) and P(5),
respectively] of one of the molecules present in the asymmetric unit
of 3 showed disorder due to a 180° rotation around the P–C axis,
and therefore the sulfur and α-carbon atoms of the rings were re-
fined for the two orientations. The refined occupancy factors of
S(4) and S(5) in the second conformer of the molecule (Figure S3,
Supporting Information) were 52 and 66%, respectively. The
phenyl and thienyl H atoms were assigned isotropic thermal param-
eters 1.2 times Ueq of the carrier carbon atoms. The relatively low
quality of the diffraction data for compound 3 was due to the fact
that good quality crystals could not be obtained despite repeated
crystallisations by different techniques. CCDC-203202 (2), -203203
(3), -203204 (5) and -203205 (6) contain the supplementary crystal-
lographic data for this paper. These data can be obtained free of
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Received: December 22, 2005
Published Online: March 30, 2006
2068
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© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2006, 2058–2068