Synthesis and ligand substitution reactions of κ4-B,S,S′,S′′-ruthenaboratranes

Article abstract of DOI:10.1039/c8dt04278k

A range of ruthenaboratranes of the form [Ru(CO)L{κ⁴-B,S,S′,S′′-B(mt)₃}] (mt = N-methylmercaptoimidazolyl) have been prepared either by substitution of the PPh₃ ligand in [Ru(CO)(PPh₃){κ⁴-B,S,S′,S′′-B(mt)₃}] by L (L = PMe₂Ph, PMe₃, P(OMe)₃, P(OEt)₃, P(OPh)₃) or reactions of [RuCl(R)(CO)L_n] (R = Ph, CH═CHPh; n = 2, L = PCy₃; n = 3, L = P(OMe)₃, PMe₂Ph) with Na[HB(mt)₃].

Full text of DOI:10.1039/c8dt04278k

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Synthesis and ligand substitution reactions of
κ4-B,S,S’,S’’-ruthenaboratranes†
Cite this: Dalton Trans., 2019, 48,
209
Mark R. St.-J. Foreman, a Anthony F. Hill, *b Chenxi Ma,b Never Tshabangb,c and
Andrew J. P. Whited
A range of ruthenaboratranes of the form [Ru(CO)L{κ4-B,S,S’,S’’-B(mt)3}] (mt = N-methylmercaptoimidazolyl)
have been prepared either by substitution of the PPh3 ligand in [Ru(CO)(PPh3){κ4-B,S,S’,S’’-B(mt)3}] by L (L =
PMe2Ph, PMe3, P(OMe)3, P(OEt)3, P(OPh)3) or reactions of [RuCl(R)(CO)Ln] (R = Ph, CHvCHPh; n = 2, L =
PCy3; n = 3, L = P(OMe)3, PMe2Ph) with Na[HB(mt)3].
Received 26th October 2018,
Accepted 23rd November 2018
DOI: 10.1039/c8dt04278k
rsc.li/dalton
strongest σ-bases and best able to stabilise the Lewis acidic
Introduction
boron through Z-type polar-covalent bonding.14 We therefore
Metallaboratranes1 are cage structures in which a transannular contend that the scarcity of group 8 (M→B)8 metallabora-
dative (polar covalent,2 M→B) bond between a transition tranes15 is an historical oversight rather than any reflection on
metal and boron is supported by two or three buttressing their stability or accessibility. Accordingly, we describe herein
bridges (Chart 1). Metallaboratranes with N-heterocyclic but- the synthesis of a range of new ruthenaboratranes for the
tresses are known for all the elements of groups 8,3,4q 9,4 105 purpose of assessing the varying impact of co-ligands upon
and 11,6 with the majority of studies involving the heavier the (Ru→B)8 dative interaction.
elements of group 9.4 In contrast, despite the archetype
[Ru(CO)(PPh3){κ4-B,S,S′,S″-B(mt)3}] (1a mt = N-methyl-2-mer-
captoimidazolyl),3b,7 being based on ruthenium, very few
Results and discussion
further examples have been described within group 8, these
being limited to Parkin’s ferraboratrane [Fe(CO)2{B(mttBu)3}],3a
The first metallaboratrane, 1a, arose from the unexpected reac-
the osmaboratrane analogue of 1a,3f the ruthenaboratranes
tion of [RuCl(R)(CO)(PPh3)2] (R = Ph, CHvCHPh) with Na[HB
[Ru(CS)(PPh3){κ4-B,S,S′,S″-B(mt)3}] (2) and [Ru(CO)(CNR){B
(mt)3] via activation of the borohydride group and elimination
t
(mt)3}] (R = Bu 1c, C6H3Me2-2,6 1d, C6H2Me3-2,4,6 1e),4c and
of benzene or styrene.3b,c The B–H activation step is presumed
to proceed via coordination of this group to the ruthenium
centre via a 3 centre 2-electron B–H⋯Ru association, isolable
related examples of which include the complexes [RuH(CO)
(PPh3){κ3-H,S,S′-HB(mt)3}]3d [RuH(PPh3)2{κ3-H,S,S′-H2B(mt)2}]16a
and [RuX(CO)(PPh3){κ3-H,S,S′-H2B(mt)2}] (X = H, Cl, SePh,
SiCl3, SiMe3, BO2C6H4).16b The factors that dictate why in some
but by no means all cases this coordination mode proceeds to
B–H activation and metallaboratane formation are not well
delineated, though the reverse process, i.e., migration of a
hydride ligand to a cis M→B bond has been observed on rare
the N-chlorophenyl analogue of 1a.4d
The poly(2-phosphinophenyl)borane scaffold pioneered by
Bourissou8 has been applied to metals from groups 9,8,9 1010
and 1111 but it is with iron, as developed by Peters,12 that the
ligand system has enjoyed the most intense study, rewarded
with impressive results in supporting inter alia the stoichio-
metric reduction of CO and the catalytic reduction of N2.
This dearth of group 8 metallaboratranes is perhaps
counter-intuitive in that of all the late transition metals, those
of group 8 in the formally zerovalent state13 are likely to be the
aDepartment of Chemistry and Chemical Engineering, Nuclear Chemistry and
Industrial Materials Recycling, Chalmers University of Technology, Göteborg, Sweden
bResearch School of Chemistry, Australian National University, Acton, Canberra,
A.C.T., Australia. E-mail: a.hill@anu.edu.au
cDepartment of Chemistry, University of Botswana, Gaborone, Botswana
dChemical Crystallography Laboratory, Department of Chemistry, Imperial College
London White City Campus, UK, W12 0BZ
†Electronic supplementary information (ESI) available. CCDC 1874175–1874179.
For ESI and crystallographic data in CIF or other electronic format see DOI:
10.1039/c8dt04278k
Chart 1 The metallaboratrane motif.
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occasions for platina-,5c,i rhoda-4r,9e and ferraboratranes.12 It
may well be therefore that this process does indeed surrepti-
tiously operate more widely and reversibly but not to spectro-
scopically determinable extents.
Perhaps surprisingly, the phosphine ligand in 1a was
shown to be labile under mild conditions, being reversibly dis-
placed by CO to provide [Ru(CO)2{κ4-B,S,S′,S″-B(mt)3}] (1b)
which however reverted to 1a under vacuum. Irreversible sub-
stitution however ensued with isonitriles to provide [Ru(CO)
(L){κ4-B,S,S′,S″-B(mt)3}] (L = CNtBu 1c, CNC6H3Me2-2,6 1d,
CNC6H2Me3-2,4,6 1e).3c The syntheses of new ruthenabora-
tranes to be described herein therefore take one of two
different approaches; either (i) ligand substitution reactions of
1a with a range of phosphines or (ii) pre-installation of the
phosphine prior to ruthenaboratrane assembly.
Treating a solution of 1a with a slight excess of PMe2Ph in
dichloromethane at room temperature results in complete
phosphine substitution with the formation of [Ru(CO)
(PMe2Ph){κ4-B,S,S′,S″-B(mt)3}] (1f, Scheme 1).
Alternatively, 1f may be prepared by installing PMe2Ph prior
to the ruthenaboratrane assembly. Mawby has described the
synthesis of mer-[RuCl(Ph)(CO)(PMe2Ph)3] via the reaction of
Fig. 1 Molecular structure of 3 (most hydrogen atoms omitted, phenyl
groups simplified, 50% displacement ellipsoids). Selected bond lengths
(Å) and angles (°): Ru1–Cl1 2.4815(8), Ru1–P1 2.3573(9), Ru1–P2 2.4148
(9), Ru1–P3 2.3971(9), Ru1–C1 1.818(4), Ru1–C2 2.106(3), C2–C3 1.329
(5), C3–C4 1.483(5), Cl1–Ru1–P1 86.33(3), Cl1–Ru1–P2 93.18(3), P1–
Ru1–P2 97.53(3), Cl1–Ru1–P3 83.66(3), P1–Ru1–P3 163.10(3), P2–Ru1–
P3 96.59(3), P1–Ru1–C1 92.59(12), P2–Ru1–C1 87.82(11), P3–Ru1–C1
97.18(12), Cl1–Ru1–C2 88.6(1), P1–Ru1–C2 82.4(1), P3–Ru1–C2 83.73
(9), C1–Ru1–C2 90.44(15), Ru1–C2–C3 130.1(3), C2–C3–C4 126.9(3).
[RuCl(Ph)(CO)(PPh3)2] with excess PMe2Ph17 and a similar pro- between these two Ru–P bonds (Ru1–P1 = 2.3573(9), Ru1–P3 =
tocol converts [RuCl(CHvCHPh)(CO)(PPh3)2]18 to mer-[RuCl 2.3971(9) Å) is itself noteworthy given their spectroscopic
(CHvCHPh)(CO)(PMe2Ph)3] 3 in 79% yield (Scheme 1). The chemical equivalence. A search for inter- or intramolecular
characterisation of 3 included a crystallographic analysis close-contacts failed to identify any interactions that might be
(Fig. 1) and is generally unremarkable other than to note that responsible, leading us to conclude that this is simply a
(i) the mer-RuP3 geometry is confirmed both crystallographi- response to meridionally accommodating the three irregularly
cally and from 31P{1H} NMR data (CDCl3: δP = −8.80 t, −1.17 shaped phosphines.
dt, 2JPP = 23.1 Hz) and (ii) The σ-styryl ligand, as expected for a
Heating 3 with Na[HB(mt)3] in THF under reflux for
σ-organyl, exerts a discernible trans influence upon the unique 12 hours returns 1f in 51% yield. The phosphine associated
phosphine (Ru1–P2 = 2.4148(9) Å) relative to the mutually trans resonance which appear at δP = −13.3 (CDCl3) in the 31P{1H}
disposed pair of phosphines, however the significant disparity NMR spectrum of 1f is conspicuously broad consistent with
coordination trans to the quadrupolar boron of the metallabor-
atrane. The 11B{1H} NMR spectrum comprises an apparent
singlet resonance (CDCl3: δB = 15.4), the broadness of which
2
precluded the resolution of JPB. The molecular geometry of 1f
is depicted in Fig. 2 and geometric features will be discussed
collectively alongside other examples to follow.
Whilst the replacement of PPh3 in 1a by the more compact
and strongly σ-basic phosphine PMe2Ph proceeded quickly
under mild conditions, the same reaction involving the more
sterically demanding phosphine PCy3 did not proceed to com-
pletion but rather afforded an equilibrium mixture of 1a and
[Ru(CO)(PCy3){κ4-B,S,S′,S″-B(mt)3}] (1g, Scheme 2).
This mixture proved too problematic to separate and
accordingly the alternative pre-installation approach was
found to be preferable. Aerobic decomposition of Grubbs’ cata-
lyst [RuCl2(vCHPh)(PCy3)2] has been shown to provide [RuCl
(Ph)(CO)(PCy3)2] (4),19 but in the present work 4 was more con-
veniently obtained in 80% yield simply by heating [RuCl(Ph)
(CO)(PPh3)2] with excess PCy3. The reaction of 4 with Na[HB
(mt)3] in dichloromethane proceeds to completion within
2 hours to cleanly provide 1g in 77% yield, obviating the PPh3
and 1a contamination problems encountered in the initial
Scheme 1 Alternative syntheses of [Ru(CO)(PMe2Ph){B(mt)3}] (1f).
210 | Dalton Trans., 2019, 48, 209–219
route. The molecular structure of 1g is shown in Fig. 3, from
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Fig. 2 Molecular structure of 1f (hydrogen atoms omitted, phenyl and
methimazolyl groups simplified, 50% displacement ellipsoids). Inset =
view along Ru1⋯P1 vector. Selected bond lengths (Å) and angles (°): B1–
Ru1 2.174(3), B1–N1 1.561(4), B1–N3 1.580(4), B1–N5 1.561(4), Ru1–S1
2.3881(7), Ru1–S2 2.4938(7), Ru1–S3 2.4071(8), Ru1–P1 2.4170(7), Ru1–
B1–N1 110.41(18), Ru1–B1–N3 110.57(18), N1–B1–N3 105.7(2), Ru1–B1–
N5 109.74(18), N1–B1–N5 114.5(2), N3–B1–N5 105.7(2) B1–Ru1–S1
83.44(8), B1–Ru1–S2 85.21(8), S1–Ru1–S2 90.92(3), B1–Ru1–S3
82.84(8).
Fig. 3 Molecular structure of 1g in a crystal of 1g·CH2Cl2 (hydrogen
atoms and solvent omitted, cyclohexyl and methimazolyl groups sim-
plified, 50% displacement ellipsoids). Selected bond lengths (Å) and
angles (°): B1–Ru1 2.168(3), B1–N1 1.568(4), B1–N3 1.568(4), B1–N5
1.560(5), Ru1–S1 2.4188(8), Ru1–S2 2.4922(8), Ru1–S3 2.4084(8), Ru1–
P1 2.4894(7), Ru1–B1–N1 110.4(2), Ru1–B1–N3 110.2(2), N1–B1–N3
105.6(2), Ru1–B1–N5 111.2(2), N1–B1–N5 112.6(3), N3–B1–N5 106.6(3),
B1–Ru1–S1 81.45(10), B1–Ru1–S2 85.49(10), S1–Ru1–S2 89.83(3), B1–
Ru1–S3 83.36(10), S1–Ru1–S3 164.73(3), S2–Ru1–S3 90.59(3).
Scheme 2 Alternative syntheses of [Ru(CO)(PCy3){B(mt)3}] (1g).
which the steric bulk of the PCy3 ligand is immediately
obvious relative to that of the phosphines in 1a and 1f
(vide infra, Fig. 7).
Fig. 4 Molecular structure of 1h in a crystal (hydrogen atoms and
solvent omitted, 50% displacement ellipsoids). Selected bond lengths (Å)
and angles (°): Ru1–B1 2.157(6), Ru1–S2 2.3929(17), Ru1–S1 2.4068(17),
Ru1–P1 2.423(7), Ru1–S3 2.5103(15), B1–N2 1.558(7), B1–N8 1.559(8),
B1–N14 1.587(8), B1–Ru1–S2 83.35(17), B1–Ru1–S1 82.90(17), B1–Ru1–
S3 85.45(17), N2–B1–N8 114.0(4), N2–B1–N14 104.6(4), N8–B1–N14
105.3(4). The PMe3 ligand was disordered over three positions (ca. 46,
32 and 22% occupancy) with the major occupancy isotropically refined
components shown.
In contrast to the steric encumbrance and high σ-basicity of
the PCy3 ligand in 1g, the more compact derivative [Ru(CO)
(PMe3){B(mt)3}] (1h) was obtained via simple substitution of
PPh3 in 1a by PMe3. The molecular geometry of 1h is shown in
Fig. 4 and data are discussed collectively below. Notably, in
contrast to the reversible reaction of 1a with CO to provide 1b
and its irreversible reaction with CNtBu, to afford 1c, the PMe3
ligand in 1h is displaced by neither CO nor CNtBu under
ambient conditions (CH2Cl2, 12 h).
Of the three phosphines in 1a, 1f, 1g and 1h, PCy3 has the within the region typical of zerovalent ruthenium complexes.
lowest Tolman electronic parameter20 which is also reflected Having prepared two ruthenaboratranes with strongly σ-basic
in 1g having the lowest νCO value (CH2Cl2: 1876 cm−1), well phosphines with small (PMe3, θT = 118°) and large (PCy3: θT =
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Chart 2 Distribution of phosphines employed across Tolman steric (θT)
and electronic (νT) space.
170°) Tolman cone angles20 we next turned to phosphorus
ligands with modest steric profiles but reduced donor
strength, i.e., phosphites (Chart 2) to broaden the ligand space
under consideration.
Both synthetic approaches described above proved success-
ful, though in both cases more forcing conditions and
extended reaction times were required to complete the conver-
sions. Thus 1a reacted with P(OMe)3 to provide modest yields
of [Ru(CO){P(OMe)3}{B(mt)3}] (1i, Scheme 3) when heated for
16 hours in refluxing hexane (59%) or THF (49%).
Fig. 5 Molecular structure of 1j (hydrogen atoms omitted, groups sim-
plified, 50% displacement ellipsoid). Selected bond lengths (Å) and
angles (°): Ru1–B1 2.172(6), Ru1 P1 2.360(6), Ru1–S2 2.4018(16), Ru1–S1
2.4306(19), Ru1–S3 2.4781(17), B1–N8 1.559(8), B1–N2 1.560(8), B1–N14
1.571(8), B1–Ru1–S2 83.45(18), B1–Ru1–S1 80.79(19), B1–Ru1–S3 85.33
(18), N8–B1–N2 112.6(5), N8–B1–N14 104.9(5), N2–B1–N14 107.8(5).
Each OEt group suffers position disorder, with only the major occu-
pancy components shown.
Similar results were obtained for the formation of triethyl
(1j) and triphenyl (1k) analogues. Complex 1i failed to provide
crystallographic grade crystals however both 1j (Fig. 5) and 1k
(Fig. 6) were structurally characterised and their structural fea-
tures are discussed below. Passing a stream of CO through a
dichloromethane solution of 1i results in ca. 30% conversion
to [Ru(CO)2{B(mt)3}] (1b: 2020, 1994 cm−1) which was however
cleanly converted back to 1i when the CO stream was replaced
with a nitrogen purge, or the sample simply left to evaporate.
Alternatively, mer-[RuCl(CHvCHPh)(CO){P(OMe)3}3] (5) was
prepared by heating [RuCl(CHvCHPh)(CO)(PPh3)2]18 with
excess P(OMe)3 in hexane under reflux for 16 hours as
described previously for the synthesis of [RuCl(Ph)(CO)
{P(OMe)3}3].17 Although the yield of this conversion was spec-
troscopically quantitative, the high solubility compromised the
isolated yield (59%). Reduced reaction times provide samples
Fig. 6 Molecular structure of 1k (hydrogen atoms omitted, phenyl
groups simplified, 50% displacement ellipsoids). Selected bond lengths
(Å) and angles (°): Ru1–B1 2.184(6), Ru1–P1 2.314(4), Ru1–S2 2.4048(14),
Ru1–S1 2.4167(13), Ru1–S3 2.4776(14), B1–N14 1.564(7), B1–N8 1.568(7),
B1–N2 1.568(7), B1–Ru1–S2 82.88(15), B1–Ru1–S1 81.54(15), B1–Ru1–
S3 85.02(15), N14–B1–N8 107.3(4), N14–B1–N2 104.8(4), N8–B1–N2
113.5(4). Each OPh group suffers position disorder, with only the major
occupancy components shown.
contaminated with mer-trans-[RuCl(CHvCHPh)(CO)(PPh3)2{P
(OMe)3}] (6) which could be acquired in pure form via reaction
of [RuCl(CHvCHPh)(CO)(PPh3)2] with one equivalent of
P(OMe)3 at room temperature. The mer-RuP3 geometry of 5 was
confirmed by 31P{1H} NMR spectroscopy (AB2: δP = 128.9 d,
Scheme 3 Alternative syntheses of [Ru(CO){P(OR)3}{B(mt)3}] (R = Me 1i,
Et 1j, Ph 1k).
2
142.4 t, JAB = 43.0 Hz). Heating 6 with Na[HB(mt)3] in reflux-
212 | Dalton Trans., 2019, 48, 209–219
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Table 1 Tolman steric (θT) and electronic (νT) parameters for phos-
phines and selected structural data for ruthenaboratranes [Ru(CO)(L){B
(mt)3}] (1)
L
θT
νT
νCO
δB
rRuB
rRuP
PCy3
PPh3
170
145
128
122
118
108
107
102a
2056.4
2068.9
2085.3
2065.3
2064.1
2076.3
2079.5
2071.3b
1876
1894
1923
1887
1885
1904
1907
1894
15.4
17.1
13.0
15.4
14.6
14.0
14.5
14.6
2.168(3)
2.161(5)
2.184(6)
2.174(3)
2.157(6)
2.172(6)
—
2.4894(7)
2.435(1)
2.314(4)
2.4170(7)
2.423(7)
2.360(6)
—
P(OPh)3
PMe2Ph
PMe3
P(OEt)3
P(OMe)3
CNtBu
2.176(7)
—
a Taken from ref. 21. b [Ni(CNtBu)(CO)3] has not been reported, the
value given here is for [Ni(CNnBu)(CO)3].22
Chart 4 Relationship between Ru–B bond length and νCO for ruthena-
boratranes (1).
comparable to that of the CNtBu and P(OEt)3 derivatives, but
considerably longer than found in the PMe3 derivative (1i)
despite PMe3 and PMe2Ph having rather similar νT values.
Although PCy3 is considered more electron releasing than
PMe3, the Ru–B bond length in the PCy3 derivative 1g is inter-
mediate between those for the PMe3 (1h) and PMe2Ph (1f)
derivatives (Chart 4), presumably due to the more pronounced
inter ligand repulsion in the PCy3 complex. Steric factors
should be more pronounced in octahedral ruthenium com-
plexes than in tetrahedral [Ni(CO)3(PR3)] and the selection of
phosphines spans a wide range (107 < θT < 170°). Fig. 7 pre-
sents space filling representations for the phosphines con-
sidered in addition to the two previously reported isonitrile
ing THF for 12 hours afforded 1i in 59% yield. As with the
other derivatives, the resonance for the phosphite in the 31P
{1H} NMR spectrum was broadened (δP = 159.1) indicating
coupling between the 31P and quadrupolar 11B nuclei, however
the 11B resonance (δB = 15.4) was not much moved from those
for derivatives with more σ-basic (less π-acidic) phosphines.
These and other spectroscopic data are collated in Table 1.
The comparative π-acidity of the phosphite relative to phos-
phines is, however, indirectly manifested in the νCO values
(CH2Cl2: 1i 1907, 1k 1923 cm−1) being the highest for the
series. Taking the range of ruthenaboratranes together,
Table 1 collates the two key structural features, i.e., the bond
lengths between ruthenium and phosphorus or boron, contex-
tualised by the Tolman steric and electronic parameters.20
Despite Tolman’s electronic parameter being derived from
the A1 vibrational mode for C3v-[Ni(CO)3(PR3)] complexes,20
there is good correlation between this and the single νCO value
for the complexes 1 (Chart 3).
t
derivatives [Ru(CO)(CNR){B(mt)3}] (R = Bu, C6H2Me3-2,4,6).3c
Whilst isonitriles are clearly more slender ligands than the
vast majority of phosphines, they also present a variable
Chart 4 presents Ru–B bond lengths in relation to the νCO
values for ruthenaboratranes. The isonitrile and phosphite
ligands have the capacity to act as π-acceptors and the three
derived complexes display the longest Ru–B bond lengths,
however the PMe2Ph derivative 1f has a Ru–B bond length
Chart 3 Correlation of νCO for ruthenaboratranes (1) vs. Tolman’s elec-
tronic parameter νT. [Ni(CNtBu)(CO)3] has not been reported, the value
used here is for [Ni(CNnBu)(CO)3].22
Fig. 7 Space-filling representations of ligands bound to the ‘Ru(CO){B
(mt)3}’ viewed along the unique Ru–C vector with associated Tolman
cone angles (θT).
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‘cone angle’ estimated to be comparable (116°) to PMe3 (118°)
although somewhat less electron releasing due to a degree of
synergic σ-donor/π-acceptor bonding.
We are therefore at this stage forced to resort to the
chemists’ standard conclusion; a subtle interplay of steric and
electronic factors.
Experimental
General considerations
Unless otherwise stated, all experimental work was carried out
at room temperature under a dry and oxygen-free nitrogen
atmosphere using standard Schlenk, vacuum line and inert
atmosphere (argon) dry-box techniques. Solvents tetrahydro-
furan, toluene, pentane and hexane were dried and distilled
Chart 5 Relationship of ruthenaboratrane Ru–B bond length towards
θT for phosphines (1).
under
a nitrogen atmosphere from benzophenone and
degree of π-acidity depending on the nature of the alkyl or aryl
substituent (Chart 5).
sodium. Dichloromethane was dried and distilled under a
nitrogen atmosphere from calcium hydride. The silica gel used
for chromatography was dried in an oven at 100 °C, evacuated
and saturated with nitrogen prior to use. Once isolated, com-
pounds were generally stored as solids under a nitrogen or
argon atmosphere at −20 °C. NMR spectra were obtained at
25 °C on Jeol JNM EX 270 (1H at 270.0, 13C at 67.9 MHz, 11B at
86.6, 31P at 109.3 MHz), Bruker AVANCE 400 (1H at 399.9 MHz),
Bruker AVANCE 600 (1H at 600.0, 13C NMR at 150.9 MHz) or
Bruker AVANCE 800 (1H at 800.1, 13C NMR at 201.0 MHz) spec-
trometers. Chemical shifts (δ) are reported in ppm and refer-
enced to the solvent peaks or external standards (31P: 70%
H3PO4; 11B: BF3·OEt2). The multiplicities of NMR resonances
are denoted by the abbreviations s (singlet), d (doublet), t
(triplet), m (multiplet) and combinations thereof for more
highly coupled systems. Infrared spectra were obtained using a
PerkinElmer 1720-X or Spectrum One FT-IR spectrometers.
FAB mass spectra were obtained from 3-nitrobenzylalocohol
matrices with Kratos MS-80 or Autospec-Q instrument.
Electrospray ionisation mass spectrometry (ESI-MS) was per-
formed by the ANU Research School of Chemistry mass spec-
trometry service with acetonitrile as the matrix. With the excep-
tion of complexes 1h, 1j and 1k, data for X-ray crystallography
were collected on Nonius Kappa KappaCCD, Oxford
Diffraction Xcalibur or SuperNova diffractometers. Diffraction
data for complexes 1h, 1j and 1k were collected some years ago
at room temperature on a Siemens P4 diffractometer using
sealed tube X-ray sources and single point counter detectors.
As such, the data beyond 2θ ca. 120° with copper radiation, or
ca. 45° with molybdenum radiation was typically too weak and
diffuse to be observable in a sensible time frame, and so the
standard data collections did not proceed beyond these angles.
The compounds [RuCl(R)(CO)(PPh3)2] (R = Ph,17 CHvCHPh18)
were prepared according to published procedures. All other
reagents were obtained from commercial sources.
Finally, it may be noted that there is no useful correlation
between the Ru–S bond lengths and either the Tolman cone
angle or the Ru–B bond length (see ESI, Chart S1†), as might
be expected given the comparatively narrow ranges spanned
(trans-S-Ru–S: 2.478–2.510
=
0.032 Å; trans-L-Ru–S:
2.398–2.417 = 0.02 Å; Ru–B: 2.157–2.184 = 0.027 Å) and the
typical precision in these bond lengths (6 × e.s.d. = ca.
0.004–0.011 (Ru–S) and 0.018–0.036 Å). In all cases, however,
the unique Ru–S bond length is significantly longer
(ca. 0.08 Å) than the average of the two mutually trans disposed
Ru–S bonds.
Conclusions
Despite significantly extending the range of known ruthena-
boratranes and acquiring both spectroscopic and crystallo-
graphic data for many, not a single parameter emerges as a
definitive measure of the variable degree of Ru→B interaction.
The Tolman steric and electronic parameters are independent
variables that may reinforce or counteract each other with
respect to the Ru–B bond length (and by implication, bond
strength). Whilst the bridgehead boron nuclei give rise to
resonances in a region of the 11B NMR spectra appropriate
for four-coordinate boron, these span a remarkably small
range and are exacerbated by the typically broad appearance of
resonances. Each example includes a carbonyl ligand co-
ordinated cis to both the variable phosphine and the borane
boron, however other than correlating, as expected with the
Tolman electronic parameter,20 the values for νCO, which span
almost 50 cm−1 for the series, show no significant correlation
with geometric parameters such as rRuB. There is a rather loose
inverse correlation between rRuB and rRuP, however this may
well be a response to steric rather than electronic factors. That
said, the shortest Ru–B separation observed amongst the phos-
phine/phosphite series corresponds to the smallest and most
Synthesis of [Ru(CO)(PMe2Ph){B(mt)3}] (1f)
σ-basic PMe3 derivative. The shortest case overall however Method 1: To a solution of [Ru(CO)(PPh3){B(mt)3}] (1a: 0.50 g,
involves the isonitrile CNC6H2Me3-2,4,6 which has a Tolman 0.68 mmol) in dichloromethane (50 mL) was added an excess
214 | Dalton Trans., 2019, 48, 209–219
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of PMe2Ph (0.12 g, 0.12 mL, 0.87 mmol) under an inert atmo- Synthesis of [Ru(CO)(PCy3){B(mt)3}] (1g)
sphere. The mixture was stirred for 1 hour and then the
A mixture of [RuCl(Ph)Cl(CO)(PCy3)2] (4: 0.50 g, 0.62 mmol)
and Na[HB(mt)3] (0.23 g, 0.62 mmol) was stirred in CH2Cl2
(30 mL) for 2 hours. The clear yellow solution was filtered
through diatomaceous earth and the solvent volume of the fil-
trate was reduced to ca. 5 mL. Hexane (20 mL) was added and
the total volume reduced slowly to provide a pale yellow pre-
cipitate. The product was isolated by filtration and recrystal-
lised from a mixture of CH2Cl2 and ethanol, isolated by fil-
tration, washed with diethyl ether (20 mL) and dried in vacuo.
Yield = 0.36 g (77%). IR (cm−1) Nujol: 1872 νCO, 1554w, 1181vs,
solvent was reduced and a yellow precipitate was formed on
addition of ethanol (20 mL). The product was isolated by fil-
tration, washed with ethanol (2 × 10 mL) and hexane (10 mL)
and dried in vacuo. Yield = 0.31 g (0.51 mmol, 74%). Method 2:
A mixture of [Ru(CHvCHPh)Cl(CO)(PMe2Ph)3] (3: 0.41 g,
0.60 mmol) and Na[HB(mt)3] (0.23 g, 0.61 mmol) was heated
under reflux in THF (30 mL) for 12 hours. The mixture was
allowed to cool and then filtered. The filtrate was concentrated
under reduced pressure (ca. 5 mL) and then diluted with
hexane (20 mL) resulting in the formation of a yellow precipi-
tate. The product was filtered off and washed with diethyl
ether (2 × 20 mL) and further recrystallised from a mixture of
CH2Cl2 and ethanol. The resulting product was washed with
petroleum ether (60–80 °C) (20 mL) and then diethyl ether
(10 mL) dried in vacuo. Yield = 0.19 g (0.31 mmol, 51%).
[NB: The reaction does not proceed to completion at room
temperature]. IR (cm−1) Nujol: 1883 νCO, 1552w, 1181s, 1041m,
1090m 920w. CH2Cl2: 1876 νCO. ATR: 2923w, 2847w, 1871 νCO
.
1H NMR (300.7 MHz, CDCl3): δH = 1.23–2.05 (m.br., 33 H,
C6H11), 3.46 (s, 6 H, NCH3), 3.50 (s, 3 H, NCH3), 6.33, 6.48 (d ×
2, 2 H, 3JHH = 1.8, NCHvCHN), 6.66, 6.93 (d × 2, 3JHH = 2.0 Hz,
4H, NCHvCHN) ppm. 1H NMR (700 MHz, CDCl3): δH
=
1.30–2.07 (sets of m, 33 H, C6H11), 3.46 (s, 3 H, NCH3), 3.48 (s,
6 H, NCH3), 6.37 (d, 1 H, 3JHH = 2.1, NCHvCHN), 6.50 (d, 1 H,
3
3JHH = 1.7, NCHvCHN), 6.70 (d, 2 H, JHH = 1.8, NCHvCHN),
1
937m, 897m. ATR: 3115, 2970, 1882 νCO. CH2Cl2: 1887 νCO. H
3
6.99 (d, 1 H, JHH = 2.0, NCHvCHN). 13C{1H} APT NMR
2
NMR (300.7 MHz, CDCl3): δH = 2.01 (d, 6 H, JPH = 5, PCH3),
2
(100 MHz, CDCl3): δC = 26.9 [CH2(C6H11)], 28.1 [d, JPC = 9.4,
3.65 (s, 6 H, NCH3), 3.73 (s, 3 H, NCH3), 6.14, 6.39 (d × 2, 2 H ×
2
CH2(C6H11)], 29.9 [d, JPC = 2.2, CH2(C6H11)], 33.9, 34.4
3
3
2, JHH = 1.9, NCHvCHN), 6.48, 6.70 (d × 2, 1 H × 2, JHH
=
1
4
(NCH3), 35.3 [d, JPC = 6.3, PCH(C6H11)], 116.3 (d, JPC = 1.8,
1.9 Hz, NCHvCHN), 7.11, 7.24, 7.54 (m × 3, 5 H, C6H5).
4
NCHvCHN), 116.5 (d, JPC = 1.2, NCHvCHN), 121.9, 122.0
1
13C{1H} NMR (75.4 MHz, CDCl3): δC = 18.40 (d, JPC = 15.4,
3
3
(NCHvCHN), 166.8 (d, JPC = 17.8, CS), 171.0 (d, JPC = 13.5
Hz, CS), 208.2 (CO). 31P{1H} NMR (283 MHz, CDCl3): δP = 28.2
(br s). 11B{1H} NMR (128 MHz, CDCl3): δB = 15.4 (br s). ESI-MS
(+) m/z: 760.2 [M]+, 783.2 [M + Na]+. Accurate mass: Found
760.1951 [M]+, Calcd for C31H4811BN6OPS3102Ru 760.1926.
PCH3), 33.7 (2C, NCH3), 34.2 (1C, NCH3), 116.3, 117.4
3
(NCHvCHN), 120.8, 122.1 [C4(C6H5)], 127.9 [d, JPC = 4.6,
2
C3,5(C6H5)], 128.0 [C4(C6H5)], 130.3 [d, JPC = 12.8, C2,6(C6H5)],
1
142.3 [d, JPC = 19.8, C1(C6H5)], 170.9 (1C, CS), 171.1 (2C, CS),
1
206.5 (RuCO). 13C{1H} (176 MHz, CDCl3): δC 18.6 (d, JPC
=
Found
783.1813
[M
+
Na]+,
Calcd
for
4
C31H4811BN6O23NaPS3102Ru 783.1824. Anal. Found: C, 49.24;
H, 6.36; N, 11.16%. Calcd for C31H48BN6OPS3Ru: C, 49.00; H,
6.37; N, 11.06%. Crystals suitable for crystallographic analysis
were obtained from slow evaporation of a concentrated solu-
tion in dichloromethane/n-pentane over one day. Crystal data
for C31H48BN6OPRuS3·CH2Cl2 (150 K): Mw = 844.75, triclinic,
15.8, PCH3), 33.7, 34.2 (NCH3), 116.5 (d, JPC
= 2.3,
4
NCHvCHN), 116.6 (d, JPC
= 1.7, NCHvCHN), 122.2
3
[C4(C6H5)], 128.0, 128.1 (NCHvCHN), 128.0 [d, JPC = 7.9,
2
1
C3,5(C6H5)], 130.3 [d, JPC = 12.3, C2,6(C6H5)], 142.2 [d, JPC
=
19.4, C1(C6H5)], 166.8 (d, JPC = 22.9, CS), 170.1 (d, JPC = 17.6,
3
3
CS), 206.7 (d, JPC = 5.3 Hz, CO). 31P{1H} NMR (283 MHz,
2
CDCl3): δP = –13.3 (br s). 11B{1H} NMR (128 MHz, CDCl3): δB =
15.4 (br s). FAB-MS: m/z (%): 619(25) [M]+, 591(10%)[M − CO]+,
452(40%)[M − CO − PMe2Ph]+. ESI-MS (+) m/z: 618.0 [M]+.
Accurate mass: Found 618.0201 [M]+, Calcd for
C21H2611BN6OPS3102Ru 618.0204; Found 641.0121 [M + Na]+,
ˉ
P1 (no. 2), a = 11.5008(5), b = 12.1448(5), c = 14.2700(4) Å, α =
82.893(3), β = 81.948(3), γ = 75.012(4)°, V = 1898.38(5) Å3, Z = 2,
Dcalcd. = 1.478 Mg m−3, μ(Cu Kα) = 6.86 mm−1, T = 150(2) K,
colourless needle, 0.28 × 0.06 × 0.04 mm, 7649 independent
reflections, F2 refinement, R1 = 0.041, wR2 = 0.106 for 6878
reflections (I > 2.0σ(I), 2θmax. = 144°), 442 parameters, 0
restraints CCDC 1874176.†
Calcd
for
C21H2611BN6O23NaPS3102Ru
Na]+. Calcd for
641.0102;
Found 1258.0226 [M
−
H
+
C42H5111B2N12O223NaP2S6102Ru2 1258.0228. Anal. Found: C,
40.91; H, 4.18; N, 13.49%. Calcd for C21H26BN6OPRuS3: C,
40.85; H, 4.24; N, 13.61%.
Synthesis of [Ru(CO)(PMe3){B(mt)3}] (1h)
Crystals suitable for crystallographic analysis were obtained A solution of [Ru(CO)(PPh3){B(mt)3}] (1a: 1.005 g, 1.36 mmol)
from slow evaporation of a concentrated solution in dichloro- in CH2Cl2 (20 mL) was treated with a solution of PMe3 (0.12 g,
methane/n-pentane over one day. Crystal data for 1.50 mmol) in THF (10 mL) and the mixture stirred for
C21H26BN6OPRuS3: Mw
=
617.53, monoclinic, P21/c,
a
=
16 hours. Diethyl ether (40 mL) was added to provide a pale
14.4644(2), b = 14.2915(2), c = 13.0253(1) Å, β = 102.2830(13)°, yellow precipitate which was freed of supernatant by cannula
V = 2630.93(2) Å3, Z = 4, Dcalcd. = 1.559 Mg m−3, μ(Cu Kα) = filtration. The residue was recrystallised from a mixture of di-
7.84 mm−1, T = 150(2) K, yellow block, 0.39 × 0.19 × 0.09 mm, chloromethane and ethanol. Yield 0.625 g (1.12 mmol, 83%).
5301 independent reflections. F2 refinement, R1 = 0.035, wR2 = IR (cm−1) Nujol: 1993 νCO, 1554w, 1181s, 944.9m. IR (cm−1
)
1
0.095 for 4954 reflections (I > 2.0σ(I), 2θmax = 144°), 307 para- CH2Cl2: 1885 νCO. H NMR (270 MHz, CDCl3); δ = 1.43 (d, 9 H,
meters, 42 restraints, CCDC 1874175.†
2JPH = 5.4 Hz, PCH3) 3.42 (s, 3 H; NCH3), 3.43 (s, 6 H, NCH3),
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6.36, 6.54 (d × 2, 1 H × 2, 3JHH not resolved, NHCvCHN), 6.70, dried in vacuo. Yield: 0.080 g (0.133 mmol, 49%). IR (cm−1
)
3
6.96 (d × 2, 2 H × 2, JHH not resolved, NHCvCHN) ppm. 13C CH2Cl2: 1907 νCO. Nujol: 1883 νCO, 1552w, 1181s, 1041m,
{1H} NMR (67.9 MHz, CDCl3): δC = 19.51 (d, 1JPC = 15.5, PCH3), 937m, 897m. ATR: 3164w, 3114w, 1894 νCO, 1556m, 1184s,
1
33.7, 34.2 (NCH3), 116.5, 122.1 (NCHCHN), 171.3, 171.6 (CS), 1011v. H NMR (300.7 MHz, CDCl3) δH = 3.72 (s, 6 H, NCH3),
206.9 (RuCO). 31P{1H} NMR (72.9 Hz, CDCl3): δP = −25.2 (s.br.). 3.73 (s, 3 H, NCH3), 3.92 (d, 3JPH = 11.5, 9 H, OCH3), 6.34, 6.57
3
11B{1H} NMR (86.6 MHz, CDCl3): δB = 14.6 (br.). LR-FAB-MS (d × 2, JHH = 1.8, 2 H, NCHvCHN), 6.64, 6.72 (d × 2, 2 H
3
(nba matrix): m/z = 556(12) [M]+, 528(29) [M − CO]+, 452(53) 3JHH = 1.8, NCHvCHN), 7.00, 7.25 (d × 2, 2 H, JHH = 2.0 Hz,
[M − CO − PMe3]+. Anal. Found; C, 34.23; H, 4.59; N, 14.88%. NCHvCHN) ppm. 13C{1H} NMR (176 MHz, CDCl3): δC = 33.8,
4
Calc. for C16H24BN6OPRuS3: C, 34.58; H, 4.36; N, 34.3 (NCH3), 50.8 (OCH3), 116.6 (d, JPC = 3.2, NCHvCHN),
4
15.13%: crystals suitable for crystallographic analysis were 116.7 (d, JCP = 2.6, NCHvCHN), 122.5, 122.7 (NCHvCHN),
3
3
obtained from slow evaporation of
a
concentrated 167.3 (d, JPC = 27.2, CS), 171.0 (d, JPC = 22.1, CS), 206.0 (d,
solution in dichloromethane/n-pentane. Crystal data for 1h: 2JPC = 7.1 Hz, CO). 31P{1H} NMR (283 MHz, CDCl3): δP = 159.1
C16H24BN6OPRuS3, Mw = 555.44, monoclinic, P21/c (no. 14), (br s). 11B{1H} NMR (128 MHz, CDCl3): δB = 14.5 (br s).
a = 13.763(2), b = 12.5156(18), c = 13.792(3) Å, β = 95.727(14)°, LR FAB-MS (nba): m/z (%) = 603(15) [M]+, 575(19) [M − CO]+,
V = 2364.0(7) Å3, Z = 4, Dcalcd. = 1.561 Mg m−3, μ(Mo-Kα) = 452(44) [M − CO − P(OMe)3]+. ESI-MS (+) m/z: 604.0 [HM]+,
1.016 mm−1, T = 293 K, yellow prisms, 3079 independent 627.0 [M + Na]+. Accurate mass: Found 603.9898 [M]+,
measured reflections (Rint = 0.0333), F2 refinement, R1
0.0390, wR2 = 0.0871, 2362 independent observed absorption- 626.9792 [M + Na]+, Calcd for C16H2411BN6O423NaPS3102Ru
corrected reflections [|Fo| 4σ(|Fo|), completeness to 626.9793. Found 1230.9668 [2M
Na]+, Calcd for
θfull(22.5°)
100.0%], 295 parameters. CCDC 1874177.† C32H4811B2N12O823NaP2S6102Ru2 1230.9688. Anal. Found; C
=
Calcd
for
C16H2411BN6O4PS3102Ru
603.9895.
Found
>
+
=
The trimethyl phosphine group in the structure of 1h was 31.94; H, 4.12; N, 13.84%. Calcd For C16H24O4N6BPRuS3; C,
found to be disordered. Three orientations were identified of 31.85; H, 4.01; N, 13.93%.
ca. 46, 32 and 22% occupancy, their geometries were
optimised, the thermal parameters of adjacent atoms were
restrained to be similar, and only the three partial occupancy
Synthesis of [Ru(CO){P(OEt)3}{B(mt)3}] (1j)
phosphorus atoms were refined anisotropically (the carbon As described for 1i above (Method 1, 1a: 1.005 g, 1.36 mmol).
and hydrogen atoms of all three orientations were refined Yield 0.756 g (1.17 mmol, 86%). IR (cm−1) Nujol: 1898 νCO
,
isotropically).
1553w, 1179s, 1030s, 921m. IR (cm−1) CH2Cl2: 1904 νCO
.
1H
NMR (270 MHz, CDCl3); δ = 1.30 (dt, 9 H, 2JHH = 7.1, 4JPH = 0.8,
Synthesis of [Ru(CO){P(OMe)3}{B(mt)3}] (1i)
3
3
CCH3), 3.46 (s, 9 H; NCH3), 4.03 (dq, 6 H, JPH ∼ JHH = 7.1,
3
Method 1: A mixture of [Ru(CO)(PPh3){B(mt)3}] (1a: 0.500 g, OCH2), 6.34, 6.54 (d × 2, 1 H × 2, JHH = 1.8 Hz, NHCvCHN),
0.675 mmol) and P(OMe)3 (0.08 mL, 0.72 mmol) was heated 6.69, 6.93 (s × 2, 2 H × 2, JHH not resolved, NHCvCHN) ppm.
3
3
under reflux in hexane (30 mL) for 16 h, during which time a 13C{1H} NMR (67.9 MHz, CDCl3): δC = 16.8 (d, JPC = 6.1,
colour change from yellow to orange was observed. The solvent CCH3), 33.7 (2C), 34.3 (1C, NCH3), 59.31 (OCH2), 116.6 (3C),
was reduced and petroleum spirit added (80–100 °C, 20 mL). 122.4 (1C), 122.5 (2C, NCHCHN), 170 (br., CS, onset of fluxion-
The solvent volume was further reduced to yield an off-white ality). 31P{1H} NMR (72.9 Hz, CDCl3): δP = 156.7 (s.br.). 11B{1H}
precipitate. The solid was filtered off, washed with petroleum NMR (86.6 MHz, CDCl3): δB = 14.0 (br.). LR-FAB-MS (nba
spirit (60–80 °C, 2 × 20 mL) and dried in vacuo. Yield = 0.27 g matrix): m/z = 646(18) [M]+, 618(32) [M − CO]+, 480(3) [M −
(0.45 mmol, 62%). Method 2: A mixture of [Ru(CHvCHPh)Cl P(OEt)3]+, 452(100)[M − CO − P(OEt)3]+. Anal. Found; C, 34.12;
(CO){P(OMe)3}3] (5: 0.23 g, 0.36 mmol) and Na[HB(mt)3] H, 4.93; N, 12.92%. Calc. for C19H30BN6O4PRuS3: C, 34.34; H,
(0.14 g, 0.36 mmol) was heated under reflux in THF (30 mL) 4.69; N, 13.02%. Crystal data for 1j: C19H30BN6O4PRuS3, Mw
for 12 hours. The mixture was allowed to cool and the clear 645.52, orthorhombic, Pbca (no. 61), a = 13.3878(11), b =
yellow solution was filtered through diatomaceous earth. The 16.5415(9), c = 25.3837(14) Å, V = 5621.3(6) Å3, Z = 8, Dcalcd.
=
=
filtrate was concentrated under reduced pressure to ca. 5 mL 1.525 Mg m−3, μ(Cu-Kα) = 7.445 mm−1, T = 293 K, yellow
and then hexane added (20 mL). The total volume was further prisms, 4170 independent measured reflections (Rint = 0.0656),
reduced and the resulting yellow precipitate was allowed to F2 refinement, R1 = 0.0532, wR2 = 0.1470, 3276 independent
settle and the mother-liquor decanted off. The remaining solid observed absorption-corrected reflections [|Fo| > 4σ(|Fo|), com-
was washed with petroleum-ether (60–80 °C, 20 mL) and pleteness to θfull(60.0°) = 100.0%], 365 parameters. CCDC
diethyl-ether (10 mL) and then dried in vacuo. Yield = 0.130 g 1874178.† The triethyl phosphite group in the structure of 1j
(0.22 mmol, 59%). NB: This resulting solid is susceptible to was found to be disordered. Two orientations were identified
forming a gum when the THF solvent is not completely of ca. 68 and 32% occupancy, their geometries were optimised,
removed during the work-up process. Method 3: A solution of the thermal parameters of adjacent atoms were restrained to
[Ru(CO)(PPh3){B(mt)3}] (1a: 0.202 g, 0.27 mmol) and P(OMe)3 be similar, and only the two partial occupancy phosphorus
(0.20 mL, 1.64 mmol) in THF (20 mL) was heated under reflux atoms and the carbon atoms of the major occupancy orien-
for 16 h. The bright yellow precipitate was separated from the tation were refined anisotropically (the rest were refined
supernatant by cannula filtration, washed with n-pentane and isotropically).
216 | Dalton Trans., 2019, 48, 209–219
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Synthesis of [Ru(CO){P(OPh)3}{B(mt)3}] (1k)
681(10) [M]+, 579(40) [M − HCCHPh]+, 544(35) [M − Cl −
HCCHPh]+, 516(55) [M − CO − Cl − HCCHPh]+, 377(100) [Ru
(PMe2Ph)2]+. Anal. Found: C, 58.37; H, 6.02%. Calcd for
C33H40ClOP3Ru: C, 58.09; H, 5.91%. Single crystals suitable for
X-ray crystallography were obtained by layering pentane upon a
CH2Cl2 solution of the complex. Crystal data: C33H40ClOP3Ru;
Mr = 682.127, monoclinic, P21/c, a = 15.3727(2), b = 12.4583(2),
c = 17.6126 (3) Å, β = 105.0989(7)°, V = 3256.68(9) Å3, Z = 4;
Dcalcd. = 1.391 Mg m−3, μ (Mo-Kα) = 0.74 mm−1, T = 200(2) K,
yellow prism 0.26 × 0.16 × 0.14 mm, 7457 independent
measured reflections, F refinement, R1 = 0.031, wR2 = 0.038,
4016 independent observed absorption corrected reflections
(I > 3σ(I), 2θ ≤ 55°), 353 parameters.
As described for 1i above (Method 1, 1a: 1.000 g, 1.35 mmol).
Yield 0.937 g (1.19 mmol, 88%). IR (cm−1) Nujol: 1923 νCO
,
1590w, 1185s, 901m, 871m. IR (cm−1) CH2Cl2: 1923 νCO 1H
.
NMR (270 MHz, CDCl3); δ = 3.37 (s, 6 H; NCH3), 3.40 (s, 3 H,
NCHvCHN), 6.35, 6.61 (d × 2, 1 H × 2, JHH = 1.8 Hz,
NHCvCHN), 6.73, 6.93 (d 2, 2 H × 2, JHH not resolved,
3
3
NHCvCHN), 7.05–7.15, 7.23–7.31 (m × 2, 15 H, C6H5) ppm.
13C{1H} NMR (67.9 MHz, CDCl3): δC = 33.6(2C), 34.0 (1C,
3
NCH3), 116.6 (3C), 121.7 [d, JPC = 4.3, C2,6(C6H5)], 122.5 (2C),
122.7 (1C, NCHCHN), 123.6 [C4(C6H5)], 129.2 [C3,5(C6H5)],
2
152.4 [d, JPC = 5.4, C1(C6H5)], 170.2, 170.5 (CS). 31P{1H} NMR
(72.9 Hz, CDCl3): δP = 136.5 (s.br.). 11B{1H} NMR (86.6 MHz,
CDCl3): δB = 13.0 (br.). LR-FAB-MS (nba matrix): m/z = 790(71)
[M]+, 762(26) [M − CO]+, 452(70)[M − CO − P(OPh)3]+. Anal.
Found; C, 47.01; H, 3.94; N, 10.92%. Calcd for
C31H30BN6O4PRuS3: C, 47.14; H, 3.83; N, 10.65%.
Synthesis of [RuCl(Ph)(CO)(PCy3)2] (4)
A mixture of [RuCl(Ph)(Cl)(CO)(PPh3)2] (3.00 g, 3.92 mmol)
and PCy3 (3.37 g, 12.0 mmol) was dissolved THF (40 mL) and
heated under reflux in a N2 atmosphere for 4 hours. The solu-
tion was allowed to cool to room temperature and then diluted
with ethanol (40 mL) and concentrated to a minimum under
reduced pressure to provide a red microcrystalline precipitate
which was isolated by filtration. The product was washed with
ethanol (2 × 20 mL), dried in vacuo and stored under an
Crystals of a dichloromethane solvate 1k·2CH2Cl2 suitable
for crystallographic analysis were obtained from slow evapor-
ation of a concentrated solution in dichloromethane/hexane.
Crystal data for 1k·2CH2Cl2: C31H30BN6O4PRuS3·2(CH2Cl2), Mw
ˉ
= 959.49, triclinic, P1 (no. 2), a = 11.8771(4), b = 12.3847(4), c =
16.6567(5) Å, α = 93.569(2), β = 108.863(3), γ = 114.826(2)°, V =
2047.58(12) Å3, Z = 2, Dcalcd. = 1.556 Mg m−3, μ(Cu-Kα) =
7.671 mm−1, T = 293 K, pale yellow platy needles, 5612 inde-
pendent measured reflections (Rint = 0.0528), F2 refinement, R1
= 0.0501, wR2 = 0.1345, 4828 independent observed absorp-
tion-corrected reflections [|Fo| > 4σ(|Fo|), completeness to
θfull(60.0°) = 92.3%], 504 parameters. CCDC 1874179.† The tri-
phenylphosphite group in the structure of 1k was found to be
disordered. Two orientations were identified of ca. 79 and 21%
occupancy, their geometries were optimized, the thermal para-
meters of adjacent atoms were restrained to be similar, and
only the two partial occupancy phosphorus atoms and the
carbon atoms of the major occupancy orientation were refined
anisotropically (the rest were refined isotropically).
oxygen- and moisture-free atmosphere. Yield
= 2.52 g
(3.13 mmol, 80%). IR (cm−1) Nujol: 1897 νCO. CH2Cl2: 1901
1
νCO. H NMR (300.7 MHz, CDCl3): δH = 1.16–1.72 (m.br, 66 H,
C6H11), 6.58–6.61, 7.24–7.68 (m, 5 H, C6H5) ppm. 31P{1H} NMR
(121.4 MHz, CDCl3): δP = 24.8. FAB-MS: m/z (%) 805.2(10)[M]+,
767.1(100)[M − Cl]+. Anal. Found: C, 63.91; H, 9.14%. Calcd
for C43H71ClOP2Ru: C, 64.36; H, 8.92%. This complex
with comparable spectroscopic data, has previously been
obtained via the adventitious hydrolysis of Grubbs’ catalyst
[Ru(vCHPh)Cl2(PCy3)2].19
Synthesis of [Ru(CHvCHPh)Cl(CO){P(OMe)3}3] (5)
A
mixture of [Ru(CHvCHPh)Cl(CO)(PPh3)2] (0.55 g,
0.60 mmol) and three equivalents of P(OMe)3 (0.21 mL,
1.8 mmol) was heated under reflux in hexane (50 mL) for
16 hours during which time the colour faded from red to col-
Synthesis of mer-[Ru(CHvCHPh)Cl(CO)(PMe2Ph)3] (3)
A
mixture of [Ru(CHvCHPh)Cl(CO)(PPh3)2] (1.00 g, ourless. The solution was allowed to cool and the solvent
1.30 mmol) and three equivalents of dimethylphenyl- removed in vacuo. The white product was recrystallised from
phosphine (0.54 mL, 0.52 g, 3.80 mmol) was stirred in CH2Cl2 CH2Cl2 (10 mL) and petroleum spirit (10 mL). This is a very
(50 mL) for 1 hour. The solvent volume was reduced under soluble compound, which compromises the isolated yield
reduced pressure and ethanol (20 mL) added to precipitate the though the reaction is spectroscopically quantitative. Yield =
white crystalline product. The precipitate was filtered off and 0.23 g (59%). IR (cm−1) Nujol: 1969 νCO. CH2Cl2: 1969 νCO
.
31P
2
washed with ethanol (20 mL) and hexane (10 mL). Yield = {1H} NMR (121.4 MHz, C6D6): δP = 128.9 [d, JAB = 42.3, 2 P,
1
2
0.68 g (79%). IR (cm−1) Nujol: 1919 νCO. CH2Cl2: 1918 νCO. H trans-P(OMe)3], 142.4 [t, JAB = 43.0 Hz, 1 P, cis-P(OMe)3] ppm.
NMR (300.7 MHz, CDCl3): δH = 1.09 (d, JPH = 7.2, 6 H, cis- FAB-MS: m/z (%): 639.9(3)[M]+, 607.0(4)[M − Cl]+, 583.7(20)
2
PMe2Ph), 1.48 (tv, JPH = 6.4, 6 H, trans-PMe2), 1.62 (tv, 6 H, [M − CO − Cl]+. Anal. Found C, 33.81; H, 5.18%. Calc. for
JPH = 4.92 Hz, trans-PMe2), 6.70 (dd, 1 H, CHβPh, not resolved), C18H34O4ClP3Ru: C, 33.78; H, 5.32%.
8.35 (ddt, 1 H, RuCHα), 7.08–7.49 (m, 20 H, C6H5) ppm. 13C
Synthesis of [Ru(CHvCHPh)Cl(CO){P(OMe)3}(PPh3)2] (6)
{1H} NMR (75.4 MHz, CDCl3): δC = 203.9 (dt, not resolved,
RuCO), 163.7 [C1(C6H5)], 140.0 [C2,6(C6H5)], 128.7 [C3,5(C6H5)], To
a solution of [Ru(CHvCHPh)Cl(CO)(PPh3)2] (0.55 g,
124.4 [C4(C6H5)], 14.38 (PCH3) ppm. 31P{1H} NMR (121.4 MHz, 0.60 mmol) in CH2Cl2 (60 mL) was added P(OMe)3 (0.25 cm3,
2
CDCl3): δP = −8.80 (t, JPP = 23.1, 1 P, cis-PMe2Ph), −1.17 1.8 mmol). The mixture was stirred at room temperature and
2
[d, JPP = 23.1 Hz, 2 P, trans-(PMe2Ph)2] ppm. FAB-MS m/z (%): an instant colour change from red to light yellow was observed,
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Dalton Trans., 2019, 48, 209–219 | 217

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however the reaction was left to stir for further two hours. The
CH2Cl2 solvent was reduced to a minimum (ca. 10 mL) and
ethanol (20 mL) added and the total volume further reduced
slowly under reduced pressure to provide an off-white precipi-
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tate of the desired complex. Yield = 0.82 g (42%). IR (cm−1
)
Nujol: 1955 νCO. 1H NMR (300.7 MHz, C6D6): δH = 3.32 (d, 9 H,
3JPH = 10.1, POCH3), 5.70 (dd, 1 H, CHβPh), 8.35 (m = ddt, not
resolved, 1 H, RuCHα), 7.24–7.26, 7.74–7.80 (m, 35 H, C6H5)
ppm. 31P{1H} NMR (121.4 MHz, C6D6); δP = 127.7 [t, 2JPP = 43.6,
2
P(OMe)3], 22.6 [d, JPP = 43.6 Hz, 2 P, trans-PPh3] ppm. Anal.
Found: C, 63.21; H, 5.36%. Calcd for C48H46ClO4P3Ru: C,
62.90; H, 5.06%.
Conflicts of interest
The authors declare no conflicts of interest.
Acknowledgements
This work was supported by the Australian Research Council
(DP170102695).
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