Synthesis and reactivity of ruthenium tridentate bis-phosphinite ligand complexes

Article abstract of DOI:10.1039/c3dt51065d

The tridentate ligands E(CH₂CH₂OPiPr ₂)₂ (E = NH 1, E = S 2) were employed in the synthesis of a number of ruthenium complexes. Reaction of these ligands with (Ph ₃P)₃RuCl₂ afforded the dimers [Ru(HN(CH ₂CH₂OPiPr₂)₂)Cl(μ-Cl)] ₂ (3) and [(Ru(E(CH₂CH₂OPiPr₂) ₂))₂(μ-Cl)₃][X] (E = NH, X = PF ₆4, E = S, X = Cl 5), respectively. Using (Ph₃P) ₃RuHCl in reactions with 1 gave Ru(NH(CH₂CH ₂OPiPr₂)₂)(PPh₃)HCl (6) while addition of pyridine and 2, gave Ru(S(CH₂CH₂OPiPr ₂)₂)(py)HCl (7). Treatment of 6 or 7 with NaBPh ₄ resulted in the formation of the η⁶-arene complexes RuH(E(CH₂CH₂OPiPr₂)₂) ₂(η⁶-C₆H₅BPh₃) (E = NH 8, E = S 9) while reactions with K[B(C₆F₅)₄] gave the salts [RuH(E(CH₂CH₂OPiPr₂) ₂)(L)][B(C₆F₅)₄] (E = NH, L = PPh₃10, E = S, L = py 12). Compounds 6 and 7 react with CO giving RuH(HN(CH₂CH₂OPiPr₂)₂)(CO)Cl (15) and [RuH(S(CH₂CH₂OPiPr₂)₂(py)(CO)]Cl (16) respectively, while reaction of 6, 10 or 12 with dihydrogen gave RuH(HN(CH₂CH₂OPiPr₂)₂)(H ₂)Cl (18) and RuH(E(CH₂CH₂OPiPr ₂)₂)(L)(H₂)][B(C₆F₅) ₄] (E = NH, L = PPh₃19, E = S, L = py 20). The complexes 4-12, 15 and 16 are shown to catalyze the dehydrogenation of HMe ₂NBH₃.

Full text of DOI:10.1039/c3dt51065d

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Synthesis and reactivity of ruthenium tridentate
bis-phosphinite ligand complexes†
Cite this: DOI: 10.1039/c3dt51065d
Michael J. Sgro and Douglas W. Stephan*
The tridentate ligands E(CH2CH2OPiPr2)2 (E = NH 1, E = S 2) were employed in the synthesis of a number
of ruthenium complexes. Reaction of these ligands with (Ph3P)3RuCl2 afforded the dimers [Ru(HN-
(CH2CH2OPiPr2)2)Cl(μ-Cl)]2 (3) and [(Ru(E(CH2CH2OPiPr2)2))2(μ-Cl)3][X] (E = NH, X = PF6 4, E = S, X = Cl 5),
respectively. Using (Ph3P)3RuHCl in reactions with 1 gave Ru(NH(CH2CH2OPiPr2)2)(PPh3)HCl (6) while
addition of pyridine and 2, gave Ru(S(CH2CH2OPiPr2)2)(py)HCl (7). Treatment of 6 or 7 with NaBPh4
resulted in the formation of the η6-arene complexes RuH(E(CH2CH2OPiPr2)2)2(η6-C6H5BPh3) (E = NH 8, E =
S 9) while reactions with K[B(C6F5)4] gave the salts [RuH(E(CH2CH2OPiPr2)2)(L)][B(C6F5)4] (E = NH, L = PPh3
10, E = S, L = py 12). Compounds 6 and 7 react with CO giving RuH(HN(CH2CH2OPiPr2)2)(CO)Cl (15) and
[RuH(S(CH2CH2OPiPr2)2(py)(CO)]Cl (16) respectively, while reaction of 6, 10 or 12 with dihydrogen gave
RuH(HN(CH2CH2OPiPr2)2)(H2)Cl (18) and RuH(E(CH2CH2OPiPr2)2)(L)(H2)][B(C6F5)4] (E = NH, L = PPh3 19,
E = S, L = py 20). The complexes 4–12, 15 and 16 are shown to catalyze the dehydrogenation of
HMe2NBH3.
Received 23rd April 2013,
Accepted 29th May 2013
DOI: 10.1039/c3dt51065d
www.rsc.org/dalton
PNP analogue,24 PSP complexes have received less
attention.25,26
Introduction
Since the pioneering work by Shaw more than thirty years ago
In our own efforts, we have been exploring both bis-phos-
the field of pincer and more generally tridentate ligand chem- phinite or aminophosphine donors with various neutral
istry has flourished.1–6 Such complexes have found appli- central donors.27–30 For example, Ni complexes of the ligands
cations as sensors, switches and catalysts as well as displaying S(CH2CH2EPiPr2)2 (E = O, NH) have recently been reported to
interesting reactivity including the oxidative addition of both undergo irreversible oxidative addition of the C–S bond to give
C–halogen7–9 and C–H bonds,10,11 the activation of dinitrogen a Ni alkyl-thiolate complex (Scheme 1). In contrast, the corres-
and the homolytic cleavage of H2.12,13 Much of the progress ponding Ni(0) complexes of the ligand HN(CH2CH2EPiPr2)2
made with such systems has been described in published (E = NH) are readily oxidized to give Ni(II)-tridentate chelate
reviews.14–16
hydride complexes. Analogous oxidative addition methods
More recently, Milstein et al. have demonstrated that Ru have also been used to prepare similar Pd and Pt halide,
complexes containing tridentate ligands such as (C5H3N)- hydride, alkyl or aryl-complexes.31 Herein, we report the syn-
(CH2PtBu2)2 or (C5H3N)(CH2PtBu2)(CH2NEt2) are effective in a thesis of a series of Ru-complexes containing bis-phosphinite
variety of catalytic transformations17 including water split-
ting,18 reversible NH activation19 and the hydrogenation of car-
bonates, carbamates and formates.20 In addition, Schneider
et al. have utilized related Ru complexes of the ethyl linked
NP2 ligand for the reduction of N3 to NH3,21 as well as the
−
dehydrogenation of amine-boranes.22,23 While POP complexes
of ruthenium have also received considerable attention and
have exhibited reactivity with amine-boranes similar to the
Department of Chemistry, University of Toronto, Toronto, ON, Canada.
E-mail: dstephan@chem.utoronto.ca
†Electronic supplementary information (ESI) available: Additional data and
spectra are deposition. CCDC 933824–933832. For ESI and crystallographic data
in CIF or other electronic format see DOI: 10.1039/c3dt51065d
Scheme 1 Reactions of aminophosphine tridentate ligands with Ni(COD)2.
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ligands with central NH or S donors. The differing reactivity (CH3)2CH), 1.00 (d of d, 12H, 3JHH 7 Hz, 2JHP 15 Hz, (CH3)2CH).
2
resulting from the change in central donor is explored and the 13C{1H} NMR (CD2Cl2; δ ppm) 72.28 (d, JCP 19 Hz, –CH2–O),
3
1
reactivity of the resulting complexes with CO, H2 and 51.16 (d, JCP 7 Hz, CH2), 28.43 (d, JCP 17 Hz, (CH3)2CH)),
2
2
HMe2NBH3 are probed. The implications of such modifi- 18.16 (d, JCP 21 Hz, (CH3)2CH), 17.17 (d, JCP
9 Hz,
cations for further applications in catalysis are considered.
(CH3)2CH)). 31P{1H} NMR (CD2Cl2; δ ppm) 152.28 (s).
Synthesis of [Ru(NH((CH2)2OPiPr2)2)Cl(μ-Cl)]2 (3). A solu-
tion of 1 and CH2Cl2 (70 mg, 0.209 mmol; 4 mL) was added to
a brown suspension of Ru(PPh3)3Cl2 in CH2Cl2 (200 mg,
0.209 mmol; 4 mL) giving no immediate change. The reaction
mixture was allowed to stir for 12 h before at which point a
Experimental section
General considerations
All preparations were performed under an atmosphere of dry, yellow suspension was obtained. The reaction mixture was
O2-free N2 employing both Schlenk line techniques and inert filtered and the bright yellow solid was washed with hexane
atmosphere glove boxes. Solvents (THF, CH2Cl2, Et2O, hexane (2 × 5 mL) and diethyl ether (1 × 5 mL). The yellow solid was
and pentane) were purified employing a Grubbs’ type column then dried and the product was collected in an 95% yield
system manufactured by Innovative Technology. Solvents were (101 mg, 0.106 mmol). The yellow solid was not soluble
1
stored in the glove box over 4 Å molecular sieves. H, 11B{1H} enough in any solvent to obtain satisfactory NMR spectra, but
13C{1H}, 19F{1H} and 31P{1H} NMR spectra were acquired on a yellow crystals were obtained by adding CH2Cl2 to a sample of
Bruker Avance 400 MHz spectrometer or an Agilent 600 MHz the product, heating it and then allowing it to cool. EA:
spectrometer. 1H and 13C NMR were internally referenced to C32H74O4P4S2Ru2Cl4: Calc’d: C, 37.71; H, 7.32; N, 2.75; Found:
deuterated CD2Cl2 (δ = 5.32 ppm (1H), 53.84 ppm (13C)) and C, 38.05; H, 7.46; N, 3.15. 3: P1, a = 8.7890(8) Å, b = 10.408(1) Å,
ˉ
C6D5Br (δ = 6.94 ppm (1H), 122.167 ppm (13C)) relative to c = 13.796(1) Å, α = 91.428(4)°, β = 106.792(3)°, γ = 114.206(3)°, V
Me4Si. NMR samples were prepared in the glove box, capped = 1087.0(2) Å3, Z = 1, data (>2σ) = 4575, variables = 225, R(>2σ) =
and sealed with parafilm. 11B, 19F and 31P resonances were 0.0208, R(all) = 0.0510, GOF = 1.039.
referenced externally to (BF3·Et2O), CFCl3 and 85% H3PO4,
Synthesis of [(Ru(NH((CH2)2OPiPr2)2))2(μ-Cl)3]2[PF6] (4). A
respectively. H–13C HSQC experiments were carried out using suspension of 3 in CH2Cl2 (100 mg, 0.098 mmol; 4 mL) was
conventional pulse sequences to aid in the assignment of prepared and solid NaPF6 (17 mg, 0.098 mmol) was added
peaks in the 13C{1H} NMR spectroscopy. Coupling constants giving no immediate change. The reaction mixture was stirred
( J) are reported as absolute values. All glassware was dried for 24 h at which point the cloudy yellow mixture was filtered
overnight at 120 °C and evacuated for 1 hour prior to use. through Celite and dried to a yellow solid. The solid was re-dis-
Combustion analyses were performed in-house employing a solved in CH2Cl2 and pentane was layered on top of the yellow
Perkin Elmer 2400 Series II CHNS Analyzer. In cases where the solution. The product was isolated as orange-yellow crystals in
1
1
sensitivity of a compound precluded elemental analysis or an 86% yield (95 mg, 0.084 mmol). H NMR (CD2Cl2, δ ppm)
HRMS, spectral data are deposited in the ESI.† CD2Cl2 and 4.15 (m, 6H, CH2), 3.95 (m, 6H, CH2), 3.75 (m, 2H, 3JHH 7.3 Hz,
3
C6D5Br were purchased from the Cambridge Isotope Labora- CH(CH3)2), 3.66 (m, 2H, JHH 7.3 Hz, CH(CH3)2), 2.99 (bs, 1H,
tories and were dried over CaH2, distilled, degassed and stored NH), 2.96 (bs, 1H, NH), 2.76 (m, 2H, CH2), 2.55 (m, 2H, JHH
under N2 in a glove box. Ru(PPh3)3Cl2 and Ru(PPh3)3HClCO 7 Hz, CH(CH3)2), 2.36 (m, 2H, CH2), 2.29 (m, 2H, JHH 7 Hz,
3
3
3
were obtained from Strem Chemicals Inc. Ru(PPh3)3HCl was CH(CH3)2), 1.35 (m, 42H, CH(CH3)2), 1.14 (m, 6H, JHH 7 Hz,
prepared according to literature procedure.32 ClPiPr2, Et3N, 3JHP 17 Hz, CH(CH3)2). 13C{1H} NMR (CD2Cl2, δ ppm) 64.19 (d,
S(CH2CH2OH)2 were obtained from Aldrich Chemical Co. The JCP 3 Hz, CH2), 63.60 (d, JCP 4 Hz, CH2), 52.74 (d, JCP 4 Hz,
ligand 2 was prepared as previously reported.28
CH2), 52.69 (d, JCP 4 Hz, CH2), 37.80 (d, 1JCP 32 Hz, CH(CH3)2),
1
1
Synthesis of NH((CH2)2OPiPr2)2 (1). A 250 mL round bottom 37.12 (d, JCP 32 Hz, CH(CH3)2), 34.14 (d, JCP 20 Hz,
Schlenk flask was charged with 1.5 mL of 2,2′-thiodiethanol CH(CH3)2), 33.86 (d, JCP 21 Hz, CH(CH3)2), 21.46 (s,
(1.03 g, 9.79 mmol) and 100 mL of THF and stirred under CH(CH3)2), 19.64 (d, JCP 5 Hz, CH(CH3)2), 19.37 (d, JCP 5 Hz,
nitrogen. Et3N (9.98 g, 13.75 mL, 97.96 mmol) was added to CH(CH3)2), 19.14 (d, JCP 7 Hz, CH(CH3)2), 18.70 (d, JCP 7 Hz,
1
2
2
2
2
2
2
the flask and the reaction mixture was stirred for 30 minutes. CH(CH3)2), 17.83 (d, JCP 6 Hz, CH(CH3)2), 17.74 (d, JCP 3 Hz,
Neat iPr2PCl (3.12 mL, 19.6 mmol) was added to the stirring CH(CH3)2), 16.31 (d, JCP 4 Hz, CH(CH3)2). 19F{1H} NMR
2
solution drop wise over 5 minutes giving a cloudy white solu- (CD2Cl2, δ ppm) −74.41 (d, JFP 710 Hz, PF6). 31P{1H} NMR
1
2
2
tion. The reaction mixture was stirred for an additional (CD2Cl2, δ ppm) 177.58 (d, JPP 37 Hz), 171.50 (d, JPP 37 Hz),
24 hours before being dried in vacuo. The white solid was then −144.54 (sept, JPF 710 Hz, PF6); EA: C32H74O4P5N2Ru2Cl3F6:
1
combined with toluene and stirred before being filtered Calc’d: C, 34.04; H, 6.61; N, 2.48; Found: C, 33.77; H, 6.24; N,
through Celite. The clear colourless solution was dried 2.25. 4: P212121, a = 14.310(1)Å, b = 15.520(1) Å, c = 22.333(2) Å,
in vacuo giving the desired product as a liquid in 77% yield α = 90°, β = 90°, γ = 90°, V = 4959.7(7) Å3, Z = 8, data (>2σ) = 10407,
(2.54 g, 7.54 mmol). 1H NMR (CD2Cl2; δ ppm) 3.74 (d of t, 3JHH variables = 527, R(>2σ) = 0.0304, R(all) = 0.0695, GOF = 1.022.
6 Hz, 3JHP 7 Hz, 4H, –CH2–O), 2.73 (t, 4H, 3JHH 6 Hz, 3JHP 7 Hz,
Synthesis of [(Ru(S((CH2)2OPiPr2)2)Cl)2(μ-Cl)]2[Cl] (5). A
–CH2–), 1.66 (sept of d, 4H, JHH 7 Hz, JHP 2 Hz, (CH3)2CH), solution of 2 and CH2Cl2 (74 mg, 0.209 mmol; 2 mL) was
3
2
3
2
1.51 (bs, 1H, NH), 1.05 (d of d, 12H, JHH 7 Hz, JHP 10 Hz, added to a brown suspension of (PPh3)3RuCl2 in CH2Cl2
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(200 mg, 0.209 mmol; 4 mL) immediately giving a clear orange purple suspension of (PPh3)3RuHCl in CH2Cl2 (200 mg,
solution. The reaction mixture was allowed to stir for 12 h 0.216 mmol; 4 mL) giving no immediate change. Neat pyridine
before the solvent was removed in vacuo leaving an orange (0.5 mL) was then added and the solution lightened to a
solid. The crude product was washed with hexane (2 × 5 mL) cloudy green-brown mixture. The mixture was allowed to stir
and diethyl ether (1 × 5 mL). The solid was then crystallized by overnight giving a yellow-orange solution that was dried to a
layering cyclohexane on top of an orange solution of the yellow solid. The crude product was washed with hexane (2 ×
product in CH2Cl2. The product was isolated as yellow-orange 5 mL) and diethyl ether (1 × 5 mL) before the volatiles were
crystals in an 85% yield (93 mg, 0.088 mmol). 1H NMR removed in vacuo. The yellow product was then re-dissolved in
(CD2Cl2, δ ppm) 4.56 (m, 2H, CH2), 4.43 (m, 2H, CH2), 4.27 (m, CH2Cl2 and pentane was layered on top. The purified product
3
2H, CH2), 4.08 (m, 2H, CH2), 3.77 (m, 2H, JHH 7 Hz, was obtained as yellow crystals in 84% yield (104 mg,
3
3
CH(CH3)2), 3.59 (m, 2H, JHH 7 Hz, CH(CH3)2), 2.90 (m, 4H, 0.182 mmol). 1H NMR (CD2Cl2, δ ppm) 10.12 (d, 1H, JHH
3
3
CH2), 2.64 (m, 2H, CH2), 2.56 (m, 2H, CH2), 2.49 (m, 2H, JHH 5 Hz, Ar-H C1), 8.59 (d, 1H, JHH 5 Hz, Ar-H C5), 7.48 (t, 1H,
7 Hz, CH(CH3)2), 2.37 (m, 2H, JHH 7 Hz, CH(CH3)2), 1.33 (m, 3JHH 7 Hz, Ar-H C3), 7.10 (bt, 1H, Ar-H C2), 6.80 (bt, 1H, Ar-H
3
48H, CH(CH3)2). 13C{1H} NMR (CD2Cl2, δ ppm) 64.05 (d, JCP C4), 5.40 (m, 2H, CH2), 4.05 (m, 2H, CH2), 2.69 (m, 2H, CH2),
1
5 Hz, CH2), 63.99 (d, JCP 4 Hz, CH2), 37.77 (d, JCP 30 Hz, 2.56 (m, 2H, CH2), 2.16 (m, 2H, (CH3)2CH), 1.39 (m, 2H,
1
1
CH(CH3)2), 36.57 (d, JCP 25 Hz, CH(CH3)2), 34.49 (d, JCP 26 (CH3)2CH), 1.19 (m, 12H, (CH3)2CH), 1.06 (m, 6H, (CH3)2CH),
Hz, CH(CH3)2), 34.22 (d, JCP 4 Hz, CH2), 34.11 (d, JCP 21 Hz, 0.95 (m, 6H, (CH3)2CH), −20.55 (bs, 1H, Ru–H). 13C{1H} NMR
1
CH(CH3)2), 34.09 (s, CH2), 20.75 (d, 2JCP 2 Hz, CH(CH3)2), 19.74 (CD2Cl2, δ ppm) 160.92 (bs, Ar-C C1), 156.45 (bs, Ar-C C5),
2
2
(d, JCP 7 Hz, CH(CH3)2), 19.42 (d, JCP 1 Hz, CH(CH3)2), 19.37 135.11 (s, Ar-C C3), 124.05 (s, Ar-C C2), 123.35 (s, Ar-C C4),
2
2
(s, CH(CH3)2), 19.26 (d, JCP 6 Hz, CH(CH3)2), 18.43 (d, JCP 66.50 (s, CH2), 39.09 (s, CH2), 32.34 (bs, (CH3)2CH), 30.08 (bs,
2
2
5 Hz, CH(CH3)2), 17.50 (d, JCP 3 Hz, CH(CH3)2), 16.80 (d, JCP (CH3)2CH), 18.22 (bs, (CH3)2CH), 17.80 (bs, (CH3)2CH), 17.50
2 Hz, CH(CH3)2). 31P{1H} NMR (CD2Cl2, δ ppm) 167.83 (d, JPP (bs, (CH3)2CH), 16.46 (bs, (CH3)2CH). 31P{1H} NMR (CD2Cl2,
2
2
34 Hz), 166.14 (d, JPP 34 Hz); EA: C32H72O4P4S2Ru2Cl4. 1/2 δ ppm) 159.18 (s); EA: C21H42O2P2NSRuCl: Calc’d: C, 44.16; H,
C6H12: Calc’d: C, 38.38; H, 7.18; Found: C, 38.54; H, 7.24.
7.41; N, 2.45; Found: C, 44.11; H, 7.64; N, 2.91. 7: Pnma, a =
Synthesis of RuH(NH((CH2)2OPiPr2)2)(PPh3)Cl (6). A solu- 11.0475(2) Å, b = 17.0485(4) Å, c = 17.8434(3) Å, α = 90°, β =
tion of 1 and CH2Cl2 (73 mg, 0.216 mmol; 4 mL) was added to 90°, γ = 90°, V = 2607.31(10) Å3, Z = 4, data (>2σ) = 2625, vari-
a purple suspension of (PPh3)3RuHCl in CH2Cl2 (200 mg, ables = 148, R(>2σ) = 0.0241, R(all) = 0.0577, GOF = 1.043.
0.216 mmol; 4 mL) giving no immediate change. The mixture
Synthesis of RuH(E((CH2)2OPiPr2)2)(η6-C6H5BPh3) E = NH
was allowed to stir overnight giving a slightly cloudy yellow (8), S (9). The preparations of these compounds were com-
orange mixture. The mixture was filtered through Celite and pleted in a similar fashion thus only the preparation of one of
the yellow-orange solution was dried to a yellow solid. The them is described. A yellow solution of 6 in THF was prepared
crude product was washed with hexane (2 × 5 mL) and diethyl (60 mg, 0.081 mmol; 4 mL) and set stirring. Solid NaBPh4 was
ether (1 × 5 mL) before the volatiles were removed in vacuo. added (28 mg, 0.081 mmol) giving a cloudy orange mixture.
The yellow product was then re-dissolved in CH2Cl2 and Within four hours the reaction mixture had lightened to pale
pentane was layered on top. The purified product was obtained yellow. The mixture was allowed to stir for 24 h at which point
1
as yellow crystals in 82% yield (131 mg, 0.177 mmol). H NMR the cloudy colorless solution was dried. The solid was
(CD2Cl2, δ ppm) 8.02 (m, 6H, o-C6H5 PPh3), 7.27 (m, 9H, m,p- extracted with CH2Cl2 and filtered through Celite to remove
C6H5 PPh3), 4.44 (m, 2H, CH2), 4.00 (m, 3H, CH2 and NH), NaCl. The clear colorless solution was then concentrated and
3
3.43 (m, 2H, CH2), 2.46 (m, 2H, CH2), 1.74 (sept, 2H, JHH cyclohexane was layered on top of the CH2Cl2 layer. The
3
7.1 Hz, CH(CH3)2), 1.11 (sept, 2H, JHH 7 Hz, CH(CH3)2), 0.98 product was obtained as white blocks in 87% yield (54 mg,
3
3
(m, 12H, JHH 7 Hz, CH(CH3)2), 0.89 (m, 6H, JHH 7 Hz, 0.071 mmol) after the solution was decanted to remove PPh3.
CH(CH3)2), 0.85 (m, 6H, JHH 7 Hz, CH(CH3)2), −17.48 (q, 1H, 8: 1H NMR (CD2Cl2, δ ppm) 7.42 (d, 6H, JHH 7 Hz, o-C6H5
3
3
3JHP 22 Hz, Ru–H). 13C{1H} NMR (CD2Cl2, δ ppm) 140.72 (d, JCP BPh4), 7.08 (t, 6H, JHH 7 Hz, m-C6H5 BPh4), 6.96 (t, 3H, JHH
3
3
38 Hz, Cipso PPh3), 136.18 (d, JCP 10 Hz, o-C PPh3), 129.26 (d, 7 Hz, p-C6H5 BPh4), 5.83 (d, 1H, JHH 6 Hz, p-C6H5(η6-Ph)
3
JCP 2 Hz, p-C PPh3), 127.16 (d, JCP 8 Hz, m-C PPh3), 65.36 (s, BPh4), 5.76 (t, 2H, 3JHH 6 Hz, m-C6H5(η6-Ph) BPh4), 5.52 (d, 2H,
CH2), 47.24 (bs, CH2), 34.62 (t, JCP 14 Hz, CH(CH3)2), 33.02 (t, 3JHH 6 Hz, o-C6H5(η6-Ph) BPh4), 3.88 (m, 2H, CH2), 3.54 (m,
3
JCP 7 Hz, CH(CH3)2), 18.51 (s, CH(CH3)2), 18.27 (s, CH(CH3)2), 2H, CH2), 2.82 (m, 4H, CH2), 2.08 (m, 2H, JHH 7.1 Hz,
17.29 (t, JCP 3 Hz, CH(CH3)2), 17.35 (s, CH(CH3)2). 31P{1H} CH(CH3)2), 1.72 (m, 2H, JHH 7 Hz, CH(CH3)2), 1.26 (m, 6H,
3
NMR (CD2Cl2, δ ppm) 164.66 (d, JPP 28 Hz, OP(CH(CH3)2)2), 3JHH 7 Hz, CH(CH3)2), 1.21 (m, 6H, JHH 7 Hz, CH(CH3)2), 1.08
2
3
2
3
3
60.29 (t, JPP 28 Hz, PPh3); EA: C34H53O2P3NRuCl: Calc’d: (m, 6H, JHH 7 Hz, CH(CH3)2), 0.60 (m, 6H, JHH 7 Hz,
C, 55.37; H, 7.25; N, 1.90; Found: C, 55.62; H, 7.54; N, 1.87. 6: CH(CH3)2), −10.20 (t, 1H, 3JHP 35 Hz, Ru–H). NH not observed.
C2/c, a = 21.9644(8) Å, b = 17.3583(8) Å, c = 20.1248(9) Å, V = 11B{1H} NMR (CD2Cl2, δ ppm) −8.17 (s, BPh4). 13C{1H} NMR
7672.8(6) Å3, Z = 8, data (>2σ) = 5894, variables = 383, R(>2σ) = (CD2Cl2, δ ppm) 136.60 (s, BPh4), 126.46 (s, BPh4), 123.54 (s,
0.0431, R(all) = 0.0917, GOF = 0.936.
BPh4), 96.26 (bs, (η6-Ph) BPh4), 92.86 (bs, (η6-Ph) BPh4), 89.10
Synthesis of RuH(S((CH2)2OPiPr2)2)(py)Cl (7). A solution of (bs, (η6-Ph) BPh4), 69.90 (m, CH2), 51.38 (m, CH2), 36.98 (t, 1JCP
1
2 and CH2Cl2 (77 mg, 0.216 mmol; 4 mL) was added to a 14 Hz, CH(CH3)2), 33.71 (t, JCP 12 Hz, CH(CH3)2), 18.90 (s,
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1
CH(CH3)2), 18.73 (s, CH(CH3)2), 18.46 (bs, CH(CH3)2) Cipso for δ ppm) −16.64 (s). 13C{1H} (CD2Cl2, δ ppm) 148.17 (dm, JCF
1
either type of Ph on BPh4 not located. 31P{1H} NMR (CD2Cl2, 240 Hz, o-C6F5), 138.94 (dm, JCF 250 Hz, p-C6F5), 136.47 (dm,
δ ppm) 174.57 (s, OP(CH(CH3)2)2). EA: C40H58BNO2P2Ru: 1JCF 237 Hz, m-C6F5), 134.04 (d, JCP 12 Hz, Ar-C PPh3), 131.38
Calc’d: C, 63.32; H, 7.71; N, 1.85; Found C, 63.36; H, 7.83; N, (bs, Ar-C PPh3 (a)), 131.10 (bs, Ar-C PPh3 (b)), 129.31 (d, JCP 10
1.95. 8: P21/n, a = 13.6707(6) Å, b = 13.3994(5) Å, c = 21.0170(8) Hz, Ar-C PPh3(a)), 128.75 (d, JCP 9 Hz, Ar-C PPh3 (b)), 67.05 (s,
Å, α = 90°, β = 93.096(1)°, γ = 90°, V = 3844.3(3) Å3, Z = 4, data CH2 (a)), 66.70 (s, CH2 (b)), 52.84 (s, CH2 (a)), 52.65 (s, CH2
(>2σ) = 7230, variables = 436, R(>2σ) = 0.0288, R(all) = 0.0711, (b)), 32.91 (bm, CH(CH3)2 (a)), 31.85 (t, JCP 12 Hz, CH(CH3)2
GOF = 1.023.
(b)), 30.90 (t, JCP 14 Hz, CH(CH3)2 (b)), 19.57 (s, CH(CH3)2),
9: The product was obtained as white blocks in 53% yield 19.28 (s, CH(CH3)2), 18.80 (s, CH(CH3)2), 18.71 (s, CH(CH3)2),
(45 mg, 0.056 mmol) after the purple solution was decanted 18.44 (s, CH(CH3)2), 17.38 (s, CH(CH3)2), 16.97 (s, CH(CH3)2),
off to remove the colored by-product. 1H NMR (CD2Cl2, δ ppm) 16.67 (s, CH(CH3)2). 19F{1H} (CD2Cl2, δ ppm) −134.13 (bs, o-F),
3
3
7.43 (d, 6H, JHH 7.34 Hz, o-C6H5 BPh4), 7.09 (t, 6H, JHH 7 Hz, 164.62 (t, 3JFF 21 Hz, p-F), −168.50 (bt, 3JFF 18 Hz, m-F). 31P{1H}
3
m-C6H5 BPh4), 6.97 (t, 3H, JHH 7 Hz, p-C6H5 BPh4), 5.81 (d, (CD2Cl2, δ ppm) isomer (a) (major) 184.21 (m, OP(CH(CH3)2)2),
3H, p/m-C6H5(η6-Ph) BPh4), 5.54 (d, 2H, 3JHH 5.4 Hz, o-C6H5(η6- 43.40 (m, PPh3); isomer (b) (minor) 172.97 (m, OP(CH(CH3)2)2),
Ph) BPh4), 3.98 (m, 2H, CH2), 3.83 (m, 2H, CH2), 2.80 (m, 2H, 55.90 (m, PPh3). ESI-TOF HI-RES MS [C34H53O2P3NRu]+ m/z =
3
CH2), 2.69 (m, 2H, CH2), 2.09 (m, 2H, JHH 7 Hz, CH(CH3)2), 702.2327 (theoretical 702.2359).
1.71 (m, 2H, JHH 7 Hz, CH(CH3)2), 1.26 (m, 12H, JHH 7 Hz,
3
3
12: Red solid was obtained in 83% yield (133 mg,
3
1
3
CH(CH3)2), 1.10 (m, 6H, JHH 7 Hz, CH(CH3)2), 0.65 (m, 6H, 0.109 mmol). H (CD2Cl2, δ ppm) 8.43 (d, 2H, JHH 7 Hz, o-Ar-
3JHH 7 Hz, CH(CH3)2), −10.29 (t, 1H, JHP 35 Hz, Ru–H). 11B H Py), 7.75 (t, 1H, 3JHH 7 Hz, p-Ar-H Py), 7.28 (d, 2H, 3JHH 7 Hz,
3
{1H} NMR (CD2Cl2, δ ppm) −8.23 (s, BPh4). 13C{1H} NMR m-Ar-H Py), 4.23 (m, 4H, CH2), 2.78 (m, 2H, CH2), 2.32 (m, 2H,
3
3
(CD2Cl2, δ ppm) 136.55 (s, BPh4), 126.48 (s, BPh4), 123.62 (s, CH2), 2.23 (m, 2H, JHH 7 Hz, CH(CH3)2), 1.56 (m, 2H, JHH
BPh4), 96.33 (bs, η6-BPh4), 93.27 (t, JCP 4 Hz, η6-BPh4), 89.02 7 Hz, CH(CH3)2), 1.23 (m, 6H, JHH 7 Hz, CH(CH3)2), 1.10 (m,
3
(m, η6-BPh4), 68.94 (t, JCP 5 Hz, CH2), 37.07 (t, JCP 12 Hz, 12H, JHH 7 Hz, CH(CH3)2), 0.93 (m, 6H, JHH 7 Hz, CH(CH3)2),
1
3
3
CH(CH3)2), 35.19 (t, JCP 4 Hz, CH2), 34.16 (t, JCP 13 Hz, −29.71 (bm, 1H, Ru–H). 11B{1H} (CD2Cl2, δ ppm) −16.64 (s).
1
CH(CH3)2), 19.02 (s, CH(CH3)2), 18.82 (d, JCP 3 Hz, CH(CH3)2), 13C{1H} (CD2Cl2, δ ppm) 148.60 (dm, JCF 238 Hz, o-C6F5),
1
1
18.56 (s, CH(CH3)2). Cipso for either type of Ph on BPh4 138.68 (dm, JCF 247 Hz, p-C6F5), 137.94 (s, Ar-C Py), 136.79
not located. 31P{1H} NMR (CD2Cl2,
δ
ppm) 174.88 (s, (dm, JCF 250 Hz, m-C6F5), 125.91 (s, Ar-C Py), 68.95 (s, CH2),
1
OP(CH(CH3)2)2). EA: C40H57BSO2P2Ru·1/2C6H12: Calc’d: C, 39.03 (s, CH2), 31.07 (t, JCP 11 Hz, CH(CH3)2), 29.23 (t, JCP
ˉ
63.12; H, 7.77; Found C, 63.03; H, 7.96. 9: P1, a = 13.117(2) Å, 14 Hz, CH(CH3)2), 18.46 (t, JCP 5 Hz, CH(CH3)2), 18.04 (s, CH
b = 13.357(2) Å, c = 13.641(2) Å, α = 86.498(6)°, β = 86.588(6)°, (CH3)2), 17.86 (s, CH(CH3)2), 16.11 (s, CH(CH3)2). 19F{1H}
3
γ = 71.613(6)°, V = 2261.7(5) Å3, Z = 2, data (>2σ) = 6684, vari- (CD2Cl2, δ ppm) −134.15 (bs, o-F), 164.55 (t, JFF 18 Hz, p-F),
3
ables = 476, R(>2σ) = 0.0315, R(all) = 0.0760, GOF = 1.051.
−168.47 (bt, JFF 16 Hz, m-F). 31P{1H} (CD2Cl2, δ ppm) 163.82
Synthesis of [RuH(E((CH2)2OPiPr2)2)(L)][B(C6F5)4] E = NH, (s, OP(CH(CH3)2)2). ESI-TOF HI-RES MS [C21H42O2P2NSRu]+
L = PPh3 (10), E = S, L = py (12). The preparations of these m/z = 536.1449 (theoretical 536.1434).
compounds were completed in a similar fashion thus only the
Synthesis
of
[RuH(NH((CH2)2OPiPr2)2)(PPh3)(CH3CN)]
preparation of one of them is described. A pale yellow solution [B(C6F5)4] (11). An orange solution of 10 and CH2Cl2 was pre-
of 6 and THF (75 mg, 0.102 mmol; 4 mL) was prepared and pared (70 mg, 0.051 mmol; 2 mL) and set stirring in a 4 dram
solid K[B(C6F5)4] (73 mg, 0.102 mmol) was added. No immedi- vial. Neat acetonitrile (2.09 mg, 0.051 mmol) was added giving
ate change is observed but after approximately 4 h a cloudy no immediate change. The reaction mixture was stirred for
orange solution is obtained. The reaction mixture was stirred 24 h at which point a pale yellow solution was obtained. The
for 24 h at which point the solvent was removed in vacuo. The stir bar was removed and pentane was layered on top of the
solid was extracted with CH2Cl2 and filtered through a plug of CH2Cl2 mixture. 11: The product was obtained as very faint
Celite. The clear orange solution was dried and the foamy yellow to colorless crystals once the solvent was decanted in
1
solid was washed with hexane (3 × 5 mL). 10: The orange solid 62% yield (45 mg, 0.032 mmol). H (CD2Cl2, δ ppm) 7.59 (m,
1
was obtained in 78% yield (109 mg, 0.079 mmol). H (CD2Cl2, 6H, o-Ar-H PPh3), 7.41 (m, 3H, p-Ar-H PPh3), 7.36 (m, 6H,
3
δ ppm) isomer (a) 7.59 (m, 5H, Ar-H PPh3), 7.46 (m, 10H, Ar-H m-Ar-H PPh3), 4.43 (m, 2H, CH2), 4.04 (m, 2H, JHH 6.4 Hz,
PPh3), 4.01 (m, 2H, CH2), 3.91 (m, 2H, CH2), 3.53 (m, 2H, CH2), 3.48 (bs, 1H, NH), 2.98 (m, 2H, CH2), 2.68 (m, 2H, CH2),
3
CH2), 3.29 (m, 2H, CH2), 2.01 (m, 2H, CH(CH3)2), 1.35 (m, 2H, 2.10 (bs, 3H, CH3CN), 1.77 (m, 2H, JHH 7 Hz, CH(CH3)2), 1.57
3
3
CH(CH3)2), 1.17 (m, 12H, CH(CH3)2), 0.76 (m, 12H, CH(CH3)2), (m, 2H, JHH 7 Hz, CH(CH3)2), 1.00 (m, 18H, JHH 7 Hz,
2
3
−30.04 (d of t, 1H, JHP 30, 20 Hz, Ru–H); isomer (b) 7.59 (m, CH(CH3)2), 0.77 (m, 6H, JHH 7 Hz, CH(CH3)2), −14.36 (q, 1H,
5H, Ar-H PPh3), 7.46 (m, 10H, Ar-H PPh3), 3.91 (m, 2H, CH2), 3JHP 21 Hz, Ru–H). 11B{1H} (CD2Cl2, δ ppm) −16.6 (s). 13C{1H}
1
3.43 (m, 2H, CH2), 3.13 (m, 1H, CH2 and 1H CH(CH3)2), 2.59 (CD2Cl2, δ ppm) 148.58 (dm, JCF 237 Hz, o-C6F5), 138.65 (dm,
(m, 2H, CH2), 2.57 (m, 1H, CH(CH3)2), 2.31 (m, 1H, CH2), 1.35 1JCF 247 Hz, p-C6F5), 136.67 (dm, JCF 239 Hz, m-C6F5), 134.70
1
(m, 12H, CH(CH3)2 and 2H, CH(CH3)2), 0.99 (m, 12H, (d, JCP 10 Hz, Ar-C PPh3), 130.50 (d, JCP 2 Hz, Ar-C PPh3),
2
CH(CH3)2) −30.04 (d of t, 1H, JHP 29.6 and 19.8 Hz, Ru–H). 128.07 (d, JCP 9 Hz, Ar-C PPh3), 63.95 (s, CH2), 47.52 (s, CH2),
1
1
Both NMR above are partial assignment. 11B{1H} (CD2Cl2, 34.90 (t, JCP 14 Hz, CH(CH3)2), 32.49 (t, JCP 9 Hz, CH(CH3)2),
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18.94 (t, JCP 2 Hz, CH(CH3)2), 18.32 (s, CH(CH3)2), 17.76 (s, 237 Hz, o-C6F5), 138.84 (dm, 1JCF 244 Hz, p-C6F5), 138.62 (s, Ar-
1
CH(CH3)2), 17.51 (t, JCP 2 Hz, CH(CH3)2), 4.92 (bs, CH3CN). 19
F
C, Py), 136.87 (dm, JCF 240 Hz, m-C6F5), 126.71 (b, Ar-C, Py),
{1H}(CD2Cl2, δ ppm) −134.06 (bs, o-F), −164.65 (t, JFF 21 Hz, 126.34 (b, Ar-C, Py), 66.98 (b, CH2), 38.32 (b, CH2), 31.42 (b,
3
p-F), −168.53 (bt, JFF 18 Hz, m-F). 31P{1H} (CD2Cl2, δ ppm) (CH3)2CH), 18.16 (b, (CH3) CH), 16.72 (b, (CH3)2CH). 19F {1H}
3
2
165.13 (d, JPP 26 Hz, OP(CH(CH3)2)2), 61.96 (d, JPP 26 Hz, NMR (CD2Cl2, δ ppm) −133.09 (bd, o-F), −163.66 (t, 3JFF 21 Hz,
2
2
3
PPh3). EA: C60H56O2P3N2RuF20B: Calc’d: C, 50.65; H, 3.97; N, p-F), −167.53 (bt, JFF 18 Hz, m-F). 31P{1H} NMR (CD2Cl2,
ˉ
1.97; Found C, 50.23; H, 4.10; N, 2.06. 11: P1, a = 12.7350(6) Å,
δ . EA:
ppm) 165.86 (bs, PiPr2). IR (CO); 1953 cm−1
b = 14.0486(7) Å, c = 16.8712(9) Å, α = 92.955(2)°, β = 92.820(2)°, C46H42O3P2SRuF20NB·2CH2Cl2: Calc’d: C, 40.79; H, 3.28; N,
γ = 92.267(2)°, V = 3008.1(3) Å3, Z = 2, data (>2σ) = 9277, 0.99; Found C, 41.05; H, 2.72; N, 0.81.
variables = 807, R(>2σ) = 0.0542, R(all) = 0.1271, GOF = 1.024.
Synthesis of RuH(NH((CH2)2OPiPr2)2)(CO)Cl (15). A solution
Synthesis of [RuH(HN((CH2)2OPiPr2)2)(CO)2][B(C6F5)4] of 1 and CH2Cl2 (89 mg, 0.262 mmol; 4 mL) was added to a
(13). An orange solution of 10 in THF (140 mg, 0.102 mmol; gray suspension of RuH(PPh3)3(CO)Cl in CH2Cl2 (250 mg,
4 mL) was prepared in a 25 mL bomb. The solution was 0.262 mmol; 4 mL) giving no immediate change. After approxi-
degassed using three freeze–pump–thaw cycles and was mately five minutes a very pale yellow solution was obtained.
charged with 1 atm of CO. The solution fades from red to pale The reaction mixture was stirred for 12 h at which point the
yellow over 12 h at which point the solvent was removed giving mostly colourless, clear solution was dried. The white solid
an off white solid. The sample was re-dissolved in CH2Cl2 and was washed with hexane (3 × 5 mL) and the remaining volatiles
pentane was layered on top of the pale yellow solution. The were removed in vacuo. The white product was obtained in
product was obtained as colorless crystals in 87% yield 88% yield (116 mg, 0.230 mmol). 1H NMR (CD2Cl2, δ ppm))
(104 mg, 0.088 mmol). Two isomers observed by NMR major 4.16 (m, 2H, CH2), 4.01 (m, 2H, CH2), 3.46 (bs, 1H, NH), 2.74
1
(a), minor (b) in 8 : 2 ratio. H NMR (CD2Cl2, δ ppm) 4.24 (m, (m, 6H, CH2, CH(CH3)2), 2.19 (m, 2H, CH2), 1.36 (m, 12H, 3JHH
3
2H, 3JHH 7 Hz, CH2), 3.99 (m, 2H, 3JHH 7 Hz, CH2), 2.85 (m, 2H, 7 Hz, CH(CH3)2), 1.24 (m, 6H, JHH 7 Hz, CH(CH3)2), 1.11 (m,
3
3
3
3JHH 7 Hz, CH2), 2.73 (m, 3H, JHH 7 Hz, CH2, NH), 2.53 (m, 6H, JHH 7 Hz, CH(CH3)2), −14.68 (t, 1H, JHP 22 Hz, Ru–H).
2H, JHH 7 Hz, JHP 7 Hz, (CH3)2CH), 2.28 (sept, 2H, JHH 7 Hz, 13C{1H} NMR (CD2Cl2, δ ppm) 205.38 (t, JCP 16 Hz, CO), 66.51
3
3
2
3
(CH3)2CH), 1.32 (m, 24H, JHH 7 Hz, (CH3)2CH), −5.39 (t, 1H, (s, CH2), 57.22 (t, JCP 4 Hz, CH2), 31.65 (t, JCP 10 Hz,
2JHP 20 Hz, Ru–H (a)), −5.69 (t, 1H, JHP 21 Hz, Ru–H (b)). CH(CH3)2), 30.27 (t, JCP 18 Hz, CH(CH3)2), 18.27 (s, CH(CH3)2),
2
11B{1H} (CD2Cl2, δ ppm) −16.62 (s). 13C{1H} NMR (CD2Cl2, 17.79 (t, JCP 3 Hz, CH(CH3)2), 17.41 (s, CH(CH3)2), 16.84
δ ppm) 197.34 (m, CO), 197.04 (m, CO), 148.74 (dm, JCF 240 (s, CH(CH3)2). 31P{1H} NMR (CD2Cl2, δ ppm) 160.98 (s,
1
Hz, o-C6F5), 138.84 (dm, JCF 245 Hz, p-C6F5), 136.90 (dm, JCF OP(CH(CH3)2)2). IR (CO); 1930 cm−1. EA: C17H38O3P2NRuCl:
249 Hz, m-C6F5), 67.80 (s, CH2 (a)), 67.29 (s, CH2 (b)), 57.17 (t, Calc’d: C, 40.58; H, 7.62; N, 2.79; Found C, 41.02; H, 7.61; N, 2.77.
JCP 4 Hz, CH2 (a)), 55.70 (t, JCP 4 Hz, CH2 (b)), 33.08 (t, JCP 14: C2/c, a = 18.4105(7) Å, b = 20.4109(8) Å, c = 15.1460(6) Å, α =
14 Hz, (CH3)2CH), 32.10 (t, JCP 18 Hz, (CH3)2CH), 18.23 (t, JCP 90°, β = 126.075(1)°, γ = 90°, V = 4600.1(3) Å3, Z = 8, data (>2σ) =
1 Hz, (CH3)2CH (a)), 17.47 (t, JCP 5 Hz, (CH3)2CH (b)) 17.09 (t, JCP 4698, variables = 230, R(>2σ) = 0.0198, R(all) = 0.0489, GOF = 1.023.
1
1
4 Hz, (CH3)2CH (a)), 16.87 (t, JCP 3 Hz, (CH3)2CH (a)). 19F{1H}
Synthesis of [RuH(S((CH2)2OPiPr2)2)(py)CO][Cl] (16). A
3
NMR (CD2Cl2, δ ppm) −133.13 (bd, o-F), −163.60 (t, JFF 21 Hz, sample of 7 was dissolved in CH2Cl2 (100 mg, 0.187 mmol;
p-F), −167.50 (bt, JFF 18 Hz, m-F). 31P{1H} (CD2Cl2, δ ppm) 5 mL) and transferred to a 50 mL tube bomb. The yellow solu-
3
166.34 (s, PiPr2 (b)), 162.35 (s, PiPr2 (a)). IR stretching Frequency tion was degassed using three the freeze–pump–thaw cycles.
CO; 2055 cm−1, 2001 cm−1. EA: C42H38O4P2NRuBF20: Calc’d: C, The solution was thawed and 1 atm of CO was added immedi-
42.92; H, 3.26; N, 1.19; Found C, 42.67; H, 3.25; N, 1.12.
ately giving a pale yellow solution. The mixture was stirred
Synthesis of [RuH(S((CH2)2OPiPr2)2)(py)CO][B(C6F5)4] under CO for 12 h at which point the very pale yellow solution
(14). A red solution of 12 in THF (100 mg, 0.082 mmol; 4 mL) was concentrated and pentane was layered on top of the
was prepared in a 25 mL bomb. The solution was degassed CH2Cl2 solution. The product was obtained as white crystals in
using three freeze–pump–thaw cycles and was charged with 79% yield (89 mg, 0.148 mmol). 1H NMR (CD2Cl2, δ ppm))
3
1 atm of CO. The solution fades from red to pale yellow over 8.70 (bs, 1H, Ar-H Py), 8.65 (d, 1H, JHH 5 Hz, Ar-H Py), 7.85
3
12 h at which point the solvent was removed giving an off (bt, 1H, JHH 8 Hz, Ar-H Py), 7.28 (bs, 2H, Ar-H Py), 4.39 (m,
white solid. The sample was re-dissolved in CH2Cl2 and 4H, CH2), 2.73 (m, 4H, CH2), 2.42 (m, 2H, CH2), 1.43 (m, 2H,
pentane was layered on top of the pale yellow solution. The (CH3)2CH), 1.26 (m, 18H, (CH3)2CH), 0.94 (m, 6H, (CH3)2CH),
2
product was obtained as colorless crystals in 83% yield (85 mg, −4.25 (t, 1H, JHP 21 Hz, Ru–H). 13C{1H} NMR (CD2Cl2, δ ppm)
0.068 mmol). 1H NMR (CD2Cl2, δ ppm)) 8.80 (bs, 1H, Ar-H Py), 202.41 (bm, CO), 159.99 (b, Ar-C, Py), 157.34 (b, Ar-C,
3
8.77 (b, 1H, Ar-H Py), 8.64 (d, 1H, JHH 5 Hz, Ar-H Py) 7.73 (t, Py), 138.66 (s, Ar-C, Py), 126.39 (b, Ar-C, Py), 67.55 (b, CH2),
3
1H, JHH 8 Hz, Ar-H Py), 7.21 (b, 2H, Ar-H Py), 4.34 (m, 4H, 38.02 (b, CH2), 31.40 (b, (CH3)2CH), 16.71 (b, (CH3)2CH),
CH2), 2.65 (m, 2H, (CH3)2CH), 2.51 (m, 4H, CH2), 1.25 (m, 20H, 15.48 (b, (CH3)2CH). 31P{1H} NMR (CD2Cl2, δ ppm) 165.05 (s).
(CH3)2CH and (CH3)2CH), 0.93 (m, 6H, (CH3)2CH), −4.26 (t, IR (CO); 1966 cm−1. EA: C22H42O3P2SRuClN·0.5CH2Cl2: Calc’d:
2
1H, JHP 22 Hz, Ru–H). 11B{1H} NMR (CD2Cl2, δ ppm) C, 42.11; H, 6.76; N, 2.18; Found C, 41.64; H, 6.31; N, 2.13.
−16.6 (s). 13C{1H} NMR (CD2Cl2, δ ppm) 202.16 (m, CO),
160.21 (b, Ar-C, Py), 157.60 (b, Ar-C, Py), 148.79 (dm, JCF pale yellow solution of 16 in CH2Cl2 (50 mg, 0.084 mmol;
Synthesis of [RuH(S((CH2)2OPiPr2)2)(py)CO][PF6] (17). A
1
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4 mL) was prepared in a 4 dram vial and was wrapped in Al- 3.01 (m, 2H, CH2), 2.88 (m, 2H, CH2), 2.32 (m, 2H, CH(CH3)2),
foil. Solid AgPF6 (21 mg, 0.084 mmol) was added to the stirring 1.57 (m, 2H, CH(CH3)2), 1.30 (m, 6H, CH(CH3)2), 1.08 (m, 6H,
3
solution immediately giving a cloudy gray mixture. The reac- CH(CH3)2), 0.99 (m, 6H, CH(CH3)2), 0.56 (m, 6H, JHH 7 Hz,
tion was stirred for 12 h at which point it was filtered through CH(CH3)2), −12.10 (bm, 3H, Ru–H and Ru–H2). 11B{1H} NMR
Celite to a pale yellow solution and dried. The sample was re- (CD2Cl2, δ ppm) −16.6 (s). 13C{1H} NMR (CD2Cl2, δ ppm)
1
1
dissolved in CH2Cl2 and pentane was layered on top of the 148.16 (dm, JCF 238.13 Hz, o-C6F5), 138.24 (dm, JCF 248 Hz,
1
pale yellow solution. The product was obtained as colorless p-C6F5), 136.30 (dm, JCF 248 Hz, m-C6F5), 133.36 (b, Ar-C
crystals in 87% yield (52 mg, 0.073 mmol). H NMR (CD2Cl2, PPh3), 130.92 (b, Ar-C PPh3), 129.22 (b, Ar-C PPh3), 66.12 (bm,
δ ppm) 8.80 (bs, 1H, Ar-H Py), 8.70 (d, 1H, JHH 5 Hz, Ar-H Py), CH2), 59.04 (bm, CH2), 33.71 (bm, CH(CH3)2), 30.60 (bm,
7.83 (bt, 1H, JHH 8 Hz, Ar-H Py), 7.29 (bs, 2H, Ar-H Py), 4.42 CH(CH3)2), 19.69 (bm, CH(CH3)2), 18.48 (bm, CH(CH3)2), 17.65
1
3
3
(m, 4H, CH2), 2.63 (m, 4H, CH2), 2.41 (m, 2H, CH2), 1.29 (m, (bm, CH(CH3)2), 17.07 (bm, CH(CH3)2), 16.12 (bm, CH(CH3)2).
3
20H, (CH3)2CH and (CH3)2CH), 0.99 (m, 6H, (CH3)2CH), −4.20 19F{1H} NMR (CD2Cl2, δ ppm) −133.09 (bs, o-F), 163.72 (t, JFF
2
3
(t, 1H, JHP 21.0 Hz, Ru–H). 13C{1H} NMR (CD2Cl2, δ ppm) 21 Hz, p-F), −167.57 (bt, JFF 17 Hz, m-F). 31P{1H} NMR
160.00 (b, Ar-C, Py), 157.38 (b, Ar-C, Py), 138.54 (s, Ar-C, Py), (CD2Cl2, δ ppm) 162.13 (m, OP(CH(CH3)2)2), 36.49 (m, PPh3).
126.34 (b, Ar-C, Py), 67.06 (b, CH2), 38.07 (b, CH2), 31.02 (b,
20: The solution quickly changes from red to a very pale
(CH3)2CH), 16.56 (b, (CH3)2CH), 15.79 (b, (CH3)2CH). Could orange once thawed and the product is observed in quantitat-
1
3
not locate CO by 13C. 19F{1H} NMR (CD2Cl2, δ ppm) −74.37 (d, ive yield by NMR. H NMR (CD2Cl2, δ ppm) 8.93 (d, 2H, JHH
1JFP 710 Hz, PF6). 31P{1H} (CD2Cl2, δ ppm) 165.72 (bs, PiPr2), 6 Hz, o-Ar-H Py), 7.86 (t, 1H, 3JHH 6 Hz, p-Ar-H Py), 7.37 (d, 2H,
−144.50 (sept, JPF 710 Hz, PF6). IR (CO); 1975 cm−1. EA: 3JHH 6 Hz, m-Ar-H Py), 4.33 (m, 2H, JHH 6 Hz, CH2), 4.27 (m,
1
3
3
3
C22H42O3P3SRuF6N: Calc’d: C, 37.27; H, 5.98; N, 1.98; Found 2H, JHH 6 Hz, CH2), 3.03 (m, 2H, JHH 6 Hz, CH2), 2.68 (m,
C, 36.73; H, 5.78; N, 1.92. 16: P1, a = 8.830(2) Å, b = 13.451(2) 2H, JHH 6 Hz, CH2), 2.13 (m, 2H, JHH 6 Hz, CH(CH3)2), 1.74
3
3
ˉ
3
3
Å, c = 15.359(2) Å, α = 81.154(7)°, β = 74.718(7)°, γ = 74.475(7)°, (m, 2H, JHH 6.1 Hz, CH(CH3)2), 1.13 (m, 6H, JHH 6 Hz,
V = 1688.7(5) Å3, Z = 2, data (>2σ) = 4520, variables = 361, CH(CH3)2), 1.05 (m, 6H, JHH 6 Hz, CH(CH3)2), 0.77 (m, 6H,
3
3
R(>2σ) = 0.0896, R(all) = 0.2672, GOF = 1.047.
3JHH 6 Hz, CH(CH3)2), 0.67 (m, 6H, JHH 6 Hz, CH(CH3)2),
Synthesis of RuH(NH((CH2)2OPiPr2)2)(H2)Cl (18). A sample −11.31 (t, 3H, JHP 12 Hz, Ru–H). 11B{1H} NMR (CD2Cl2,
2
of 6 was dissolved in CD2Cl2 and transferred to a J-Young NMR δ ppm) −15.0 (s). 13C{1H} NMR (CD2Cl2, δ ppm) 156.26 (bs,
1
1
tube. The yellow solution was degassed using three freeze– Ar-C Py), 148.63 (dm, JCF 244 Hz, o-C6F5), 138.66 (dm, JCF
pump–thaw cycles. The solution was frozen once more in 250 Hz, p-C6F5), 138.65 (s, Ar-C Py), 136.86 (dm, JCF 253 Hz,
1
liquid nitrogen and H2 was added. The solution quickly m-C6F5), 128.72 (s, Ar-C Py), 126.42 (s, Ar-C Py), 66.99 (s, CH2),
changes from yellow to colorless once thawed and the product 38.96 (t, JCP 3 Hz, CH2), 30.20 (t, JCP 17 Hz, CH(CH3)2), 29.96 (t,
is observed in quantitative yield by NMR. 1H NMR (CD2Cl2, JCP 11 Hz, CH(CH3)2), 18.54 (s, CH(CH3)2), 17.00 (t, JCP 5 Hz,
3
3
δ ppm)) 4.12 (m, 2H, JHH 7 Hz, CH2), 3.99 (m, 2H, JHH 7 Hz, CH(CH3)2), 16.53 (s, CH(CH3)2), 15.74 (s, CH(CH3)2). 19F{1H}
CH2), 3.58 (m, 1H, NH), 2.97 (m, 4H, CH2), 2.58 (sept, 2H, 3JHH NMR (CD2Cl2, δ ppm) −133.17 (bs, o-F), 163.55 (t, JFF 21 Hz,
3
7 Hz, CH(CH3)2), 1.93 (sept, 2H, 3JHH 7 Hz, CH(CH3)2), 1.27 (m, p-F), −167.46 (bt, JFF 17 Hz, m-F). 31P{1H} NMR (CD2Cl2,
3
3
3
6H, JHH 7 Hz, CH(CH3)2), 1.15 (m, 6H, JHH 7 Hz, CH(CH3)2), δ ppm) 169.87 (s, OP(CH(CH3)2)2).
3
3
1.09 (m, 6H, JHH 7 Hz, CH(CH3)2), 0.90 (m, 6H, JHH 7 Hz,
3
Procedure for catalytic dehydrogenation reactions
CH(CH3)2), −12.52 (t, 3H, JHP 17 Hz, Ru–H(H2)). 13C{1H} NMR
(CD2Cl2, δ ppm) 65.93 (s, CH2), 59.11 (t, JCP 3.05 Hz, CH2), A sample of HMe2NBH3 (7.4 mg, 0.126 mmol) was weighed
29.58 (t, JCP 9.16 Hz, CH(CH3)2), 28.06 (t, JCP 17 Hz, CH(CH3)2), out in a 2 dram push top vial and 1 mL of C6D5Br was added.
18.88 (s, CH(CH3)2), 18.50 (bs, CH(CH3)2), 17.86 (t, JCP 5 Hz, The solution was added to the appropriate amount of ruthe-
CH(CH3)2), 16.03 (s, CH(CH3)2). [Free PPh3 also observed]. nium complex in a two dram push top vial equipped with a
31P{1H} NMR (CD2Cl2, δ ppm) 173.51 (s, OP(CH(CH3)2)2). If the magnetic stir bar and the reaction mixture stirred for 24 h in a
sample is heated or allowed to stand for extended periods of N2 glovebox. The reaction was transferred to a NMR tube and
time decomposition to 3 is observed.
immediately frozen in Liq-N2. The sample was thawed at the
Synthesis of [RuH(E((CH2)2OPiPr2)2)(L)(H2)][B(C6F5)4] E = NMR spectrometer and 11B NMR was used to monitor reaction
NH, L = PPh3 (19), E = S, L = py (20). The preparations of 19 progress. Analogous reactions were run in tandem and one of
and 20 were completed in a similar fashion thus only the the samples was quenched with 0.5 mL of CH3CN before freez-
preparation of one of them is described. 19: A sample of 10 ing. The productivities obtained in either fashion were found
was dissolved in CD2Cl2 and transferred to a J-Young NMR to be in good agreement. For the reactions followed at varying
tube. The orange solution was degassed 3 times using the intervals the mixture was transferred to a sealed J-Young NMR
freeze–pump–thaw method. The solution was frozen once tube and frozen until the first NMR experiment was ready to
more in liquid nitrogen and H2 was added. The solution be run.
quickly changes from orange to a very pale yellow once thawed
X-ray crystallography
and the product is observed in quantitative yield by NMR
1
spectroscopy. 19: H NMR (CD2Cl2, δ ppm) 7.52 (m, 15H, Ar-H Crystals were coated in Paratone-N oil in the glovebox,
PPh3), 4.26 (m, 2H, CH2), 4.06 (m, 2H, CH2), 3.89 (bs, 1H, NH), mounted on a MiTegen Micromount and placed under an N2
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stream, thus maintaining a dry, O2-free environment for each
crystal. The data were collected on a Bruker Apex II and Bruker
SMART diffractometers employing Mo Kα radiation (λ =
0.71073 Å). Data collection strategies were determined using
Bruker Apex software and optimized to provide >99.5% com-
plete data to a 2θ value of at least 55°. The data were collected
at 150( 2) K for all crystals. The frames were integrated with
the Bruker SAINT software package using a narrow-frame
algorithm. Data were corrected for absorption effects using the
empirical multi-scan method (SADABS). Non-hydrogen atomic
scattering factors were taken from the literature tabulations.33
The heavy atom positions were determined using direct
methods employing the SHELXTL direct methods routine. The
remaining non-hydrogen atoms were located from successive
difference Fourier map calculations. The refinements were
carried out by using full-matrix least squares techniques on F,
minimizing the function ω(Fo − Fc)2 where the weight ω is
2
2
defined as 4Fo /2σ(Fo ) and Fo and Fc are the observed and
calculated structure factor amplitudes, respectively. In the
final cycles of each refinement, all non-hydrogen atoms were
assigned anisotropic temperature factors in the absence of dis-
order or insufficient data. In the latter cases atoms were
treated isotropically. C–H atom positions were calculated and
allowed to ride on the carbon to which they are bonded assum-
ing a C–H bond length of 0.95 Å. H-atom temperature factors
were fixed at 1.20 times the isotropic temperature factor of the
C-atom to which they are bonded. The H-atom contributions
were calculated, but not refined. The locations of the largest
peaks in the final difference Fourier map calculation as well as
the magnitude of the residual electron densities in each case
were of no chemical significance.
Scheme 2 Synthesis of 3–5.
Fig. 1 POV-ray depiction of the molecular structure of 3. C: black, O: red, P:
orange, N: aquamarine, Cl: green, H: gray, Ru: salmon; all H-atoms except the
NH are omitted for clarity.
Results and discussion
The tridentate ligands HN(CH2CH2OPiPr2)2 (1) and S(CH2-
CH2OPiPr2)2 (2) are readily prepared in high yields from the
reaction of ClPiPr2 with a mixture of the corresponding diol
and triethylamine in THF.28 Following work-up, the ligands
can be used without further purification. Reaction of a solu-
tion of 1 in CH2Cl2 with Ru(PPh3)3Cl2 yielded a yellow suspen-
sion. The product (3) was insoluble and could not be
characterized by NMR spectroscopy at room temperature.
However, slow cooling of a hot suspension of the solid in
CH2Cl2 afforded single crystals of 3. The solid state structure
revealed that 3 is the dimer [Ru(NH(CH2CH2OPiPr2)2)Cl(μ-Cl)]2
comprised of two equivalent Ru centers bridged by two chlor-
ide atoms (Scheme 2, Fig. 1). Of the four remaining coordi-
nation sites, three are filled by the ligand 1 in a facial
coordination mode and one is occupied by a terminal chloride.
The most notable feature of the molecule is the close contact
of 2.52(1) Å between the terminal Cl and the NH proton of the
adjacent Ru. This lies within the sum of the van der Waals
radii of the atoms and suggests Cl⋯HN hydrogen bonding.
Addition of NaPF6 to a suspension of 3 in CH2Cl2 allowed
for the isolation of [(Ru(NH(CH2CH2OPiPr2)2))2(μ-Cl)3][PF6] 4
as a yellow solid in 86% yield (Scheme 2). The 31P{1H} spec-
trum shows two doublets at 177.6 ppm and 171.5 ppm with a
coupling constant of 37 Hz suggesting two inequivalent phos-
phorus environments with a cis disposition. The 1H NMR spec-
trum was consistent with an asymmetric ligand environment
as each methylene group of the ethyl linkers are inequivalent.
Similarly, the methine resonances of the iso-propyl groups are
inequivalent. Single crystals of 4 were analyzed by X-ray diffrac-
tion revealing a C2 symmetric dimeric structure similar to 3
but with three chlorine atoms bridging the two metal centres
(Fig. 2). The overall charge of the bimetallic cation is balanced
by a PF6 counter-ion.
The analogous combination of 2 and (PPh3)3RuCl2 in
CH2Cl2 gives the orange solid [(RuS(CH2CH2OPiPr2)2))2(μ-Cl)3]-
[Cl] (5) in 85% yield (Scheme 2). The 31P{1H} and 1H NMR
spectra are similar to those observed for 4 with the most
notable features being the two doublets centred at 167.8 ppm
and 166.1 ppm with a coupling constant of 34 Hz in the
31P{1H} NMR spectrum. These data are consistent with the for-
mulation of 5 as the S analogue of 4.
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Fig. 2 POV-ray depiction of the molecular structure of the cation of 4. C: black,
O: red, P: orange, N: aquamarine, Cl: green, H: gray, Ru: salmon; hydrogen
atoms are omitted for clarity.
The combination of a solution of 1 with a purple suspen-
sion of Ru(PPh3)3HCl in CH2Cl2 affords the yellow solid Ru(NH-
(CH2CH2OPiPr2)2)(PPh3)HCl 6 in 82% yield (Scheme 3). The
31P{1H} NMR spectrum of 6 shows a doublet at 164.7 ppm and
a triplet at 60.3 ppm, in a 2 : 1 ratio, with a coupling constant
of 28 Hz, consistent with the presence of three phosphine
1
donors in two inequivalent environments. The H NMR spec-
trum contains a pseudo quartet (a doublet of triplets) centred
at −17.5 ppm, four resonances arising from inequivalent
geminal protons of the ethyl linkers, two signals for the
methine protons and four signals for the methyl protons of
the iso-propyl groups. In addition, the 1H resonance for the
NH proton was observed at 4.00 ppm while aryl protons were
observed at 8.02 and 7.27 ppm consistent with the presence of
PPh3. A single crystal X-ray study of 6 confirmed coordination
of 1 to Ru in a meridional fashion, with a hydride occupying
the position trans to a chloride and a PPh3 completing the
coordination sphere, trans to the central NH (Fig. 3). The Ru–
H and Ru–Cl distances were found to 1.56(3) Å and 2.5785(8)
Å, respectively while the Ru–N distance of 2.234(2) Å, lies in
the range expected for PNP systems.34,35 The iso-propyl groups
of the phosphines are sterically crowded by the PPh3 ligand
resulting in a P–Ru–P bite angle of 159.08(3)°. Additionally,
the proton from the central NH is located on the same side of
the molecule as the chloride group with a Cl⋯HN distance of
2.93(1) Å, just within the sum of the van der Waals radii indi-
cating the possibility of a weak hydrogen bonding interaction
locking the molecule in one conformation.
Scheme 3 Synthesis of 6–13 and 15.
Fig. 3 POV-ray depiction of the molecular structure of 6. C: black, O: red, P:
orange, N: aquamarine, Cl: green, H: gray, Ru: salmon; hydrogen atoms except
the Ru–H are omitted for clarity. Ru–PiPr2 distances: 2.3595(9) Å, 2.3526(9) Å;
Ru–PPh3 distance: 2.2838(8) Å.
The corresponding reaction of
2 with Ru(PPh3)3HCl
afforded a complex mixture of products. However, addition of
pyridine to the mixture gave Ru(S(CH2CH2OPiPr2)2)(py)HCl (7) structure very similar to 6 where PPh3 has been replaced by
in 84% yield (Scheme 3). This species gave rise to a 31P{1H} pyridine (Fig. 4). The Ru–H distance (1.49(3) Å) is shorter
1
NMR signal at 159.2 ppm and a H resonance at −20.6 ppm. than in 6. In contrast, the Ru–Cl distance of 2.5979(7) Å is
An additional feature of the 1H NMR spectrum is a set of slightly longer than in 6. The most notable feature of 7 is the
five resonances each integrating to one proton from P–Ru–P bite angle is 164.30(3)°. The larger bite angle in 7 com-
6.80–10.12 ppm characteristic of coordinated pyridine. Results pared to 6 may result from the larger central donor S in combi-
from single crystal X-ray diffraction of 7 yielded a molecular nation with the smaller pyridine ligand.
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Fig. 6 POV-ray depiction of the molecular structure of 9. C: black, O: red,
P: orange, S: yellow, H: gray, B: Pink, Ru: light-blue; hydrogen atoms except the
Ru–H are omitted for clarity. Ru–P distances: 2.2656(7) Å, 2.2939(7) Å.
Fig. 4 POV-ray depiction of the molecular structure of 7. C: black, O: red,
P: orange, S: yellow, N: aquamarine, Cl: green, Ru: salmon; hydrogen atoms except
the Ru–H are omitted for clarity. The Ru–P distances: 2.3098(5) Å, 2.3099(5) Å.
8, a single resonance is observed in the in the 31P{1H} NMR
spectrum at 174.9 ppm while the 11B{1H} NMR shows a singlet
1
at −8.3 ppm. Additionally, the H spectrum shows resonances
The addition of NaBPh4 to a solution of 6 in THF gave rise
to a white solid, 8 (Scheme 3). The 31P{1H} NMR spectrum of 8
shows a single resonance at 174.6 ppm consistent with the
loss of PPh3, while the 11B{1H} spectrum shows a upfield
shifted singlet at −8.2 ppm arising from the BPh4 counter-ion.
The 1H NMR spectrum shows a triplet hydride resonance at
−10.2 ppm, downfield with respect to that of 6, and 15 aro-
matic protons between 6.96 ppm and 7.42 ppm as well as
three new signals at 5.83 ppm, 5.76 ppm and 5.52 ppm. A
single crystal X-ray diffraction study confirmed the formulation
of 8 as RuH(HN(CH2CH2OPiPr2)2)(η6-C6H5BPh3). 8 has a zwit-
terionic piano-stool-type geometry with a cationic Ru centre co-
ordinated to the two P centers of the ligand (1), a hydride and
an η6-bound phenyl ring of the BPh4 anion (Fig. 5). The Ru–C
bond distances range from 2.245(2) Å to 2.430(2) Å and are in
accord with other examples of Ru complexes with η6-bound
BPh4.36 The Ru–H distance (1.55(2) Å) remains essentially
unchanged relative to 6.
at 5.81 ppm and 5.54 ppm indicative of an η6-arene bound to
Ru, and a corresponding triplet at −10.3 ppm for the hydride.
The formulation of 9 was confirmed using single crystal X-ray
diffraction (Fig. 6). The metrics within 9 were similar to those
in 8 with the Ru–C distances ranging from 2.255(2) Å to
2.362(2) Å, and a Ru–H distance of 1.59(3) Å.
The corresponding reaction of 6 with K[B(C6F5)4] was
carried out and yielded an orange solid [RuH(HN(CH2CH2O-
PiPr2)2)(PPh3)][B(C6F5)4] (10) (Scheme 3). The 31P{1H} NMR
spectrum of 10 exhibited two sets of resonances attributable to
two isomers present in a 70 : 30 ratio. The more abundant
isomer consisted of resonances at 184.2 ppm and 43.4 ppm in
a 2 : 1 ratio, while the minor product showed similar peaks at
1
173.0 ppm and 55.9 ppm. The H, 13C{1H} and 31P{1H} NMR
spectra all revealed resonances consistent with the presence of
two isomers, but surprisingly only one hydride resonance, a
doublet of triplets at −30.0 ppm, was observed. The two iso-
meric forms observed are thought to arise from differing con-
formations of the central NH relative to the position of the
Ru–H. The presence of two isomers of 10 contrasts with 6 and
may result from the absence of hydrogen bonding between the
NH and chloride noted for 3 and 6. While 10 was not charac-
terized in the solid state, high resolution mass spectrometry
was consistent with the above formulation of the cation. Fur-
thermore, addition of MeCN to 10 afforded the species [RuH-
(HN(CH2CH2OPiPr2)2)(PPh3)(NCMe)][B(C6F5)4] (11) as evi-
The analogous reaction of 7 with NaBPh4 proceeds in a
similar manner to give white blocks of [RuH(S(CH2CH2O-
PiPr2)2)(η6-C6H5BPh3)] (9) in 53% yield (Scheme 3). Similar to
1
denced by 31P{1H} and H NMR spectroscopic data which are
similar to that of 10. The most noteworthy changes in the
1
NMR spectra are the new signal at 2.10 ppm in the H NMR
spectrum attributable to bound MeCN and the large downfield
shift from −30.0 ppm to −14.4 ppm for the hydride. The latter
shift is consistent with the change from a vacant site trans to
the H− to one that is occupied by MeCN. The molecular struc-
ture of 11 was confirmed using X-ray crystallography (Fig. 7).
The bond distances for the coordinated ligands distances are
similar to those in 6. Thus, despite the cationic nature of 10,
Fig. 5 POV-ray depiction of the molecular structure of 8. C: black, O: red,
P: orange, N: aquamarine, H: gray, B: pink, Ru: salmon; hydrogen atoms except
the Ru–H are omitted for clarity. The Ru–P distances: 2.2670(5) Å, 2.3037(5) Å.
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Fig. 7 POV-ray depiction of the molecular structure of the cation of 11.
C: black, O: red, P: orange, N: aquamarine, H: gray, Ru: salmon; hydrogen atoms
except the Ru–H are omitted for clarity. Ru–PiPr2 distances: 2.3297(9) Å, 2.355(1) Å,
Ru–PPh3 2.302(1) Å.
Scheme 4 Formation of the CO-complexes 13–17.
These data support the formulation of 14 as [RuH(S(CH2CH2O-
PiPr2)2)(py)(CO)] [B(C6F5)4].
the metrical parameters are essentially unchanged likely a
result of the sterics preventing stronger Ru–P bond formation.
The Ru–N for the PNP ligand was found to be 2.240(3) Å while
the MeCN donor gives rise to a Ru–N of 2.131(3) Å while the
P–Ru–P bite angle is 156.46(4)°.
Compounds 6 and 7 also react with CO to yield the new
species 15 and 16. The 31P{1H} spectra show resonances at
161.0 and 165.1 ppm respectively. In the former case, liberated
PPh3 was also evidenced by the signal at −4 ppm. These pro-
ducts were isolated in 83 and 79% respectively. 13C{1H} NMR
resonances at 205.4 and 202.4 ppm as well as IR absorptions
at 1930 and 1965 cm−1 respectively are consistent with co-
ordinated CO. The hydrides of 15 and 16 give rise to reson-
Reactivity with CO
Compound 10 reacts with 1 atm of CO resulting in a slow
colour change from orange to pale yellow. In situ NMR experi-
ments show three peaks in the 31P{1H} spectrum, two singlets
at 166.3 ppm and 162.4 ppm in a 4 : 1 ratio, and one at
−4.0 ppm, consistent with the liberation of PPh3. The 1H NMR
spectrum displays two triplets in the hydride region at
−5.4 ppm and −5.7 ppm in the same 4 : 1 ratio observed in the
31P{1H} NMR spectrum. These data infer the formation of two
isomeric complexes related by inversion at nitrogen. Following
work-up, a white solid 13 is obtained in 87% yield. The down-
field shift compared to 10 is an indication of the coordination
of a ligand trans to the hydride, with the chemical shift
suggesting the trans ligand is CO. The IR spectrum of 13
which displays two equal intensity signals at 2055 and
2001 cm−1, indicating inequivalent carbonyl ligands, suggests
the formulation of 13 as [RuH(HN(CH2CH2OPiPr2)2)(CO)2]-
[B(C6F5)4] (Scheme 4). While single crystals of 13 were
obtained, hydride-carbonyl disorder precluded a satisfactory
refinement (see ESI†).
1
ances at −14.7 and −4.3 ppm in H NMR spectra. These data
are consistent with the formulation of 15 as RuH(HN-
(CH2CH2OPiPr2)2)(CO)Cl, where CO occupies the position trans
to nitrogen, and 16 as [RuH(S(CH2CH2OPiP2)2)(py)(CO)]Cl,
where CO is trans to the hydride (Scheme 4). Single crystal
X-ray studies confirmed the formulation of 15 (Fig. 8). The
Ru–P bond distances are shorter than those observed in 6 and
The corresponding reaction between 12 and CO undergoes
a similar colour change over 12 h. Following work-up, com-
1
pound 14 can be obtained in 83% yield. In this case, H NMR
data affirm that the bound pyridine is not displaced by CO,
although the IR absorption at 1953 cm−1 demonstrates coordi-
nation of CO to the metal centre. The 31P{1H} NMR spectrum
shows only a single singlet at 165.9 ppm indicating the two
Fig. 8 POV-ray depiction of 15; C: black, O: red, P: orange, N: aquamarine,
Cl: green, H: gray, Ru: salmon; hydrogen atoms except the Ru–H are omitted for
phosphines are bound in a symmetric manner, and the
1
hydride signal in the H NMR spectrum is seen at −4.3 ppm. clarity. Ru–P distances: 2.3249(4) Å, 2.3282(4) Å.
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Fig. 9 POV-ray depiction of the cation of 17; C: black, O: red, P: orange,
S: yellow, N: aquamarine, hydrogen atoms are omitted for clarity. Ru–P dis-
tances: 2.359(2) Å, 2.360(2) Å.
11 presumably a result of the presence of the π-accepting CO
ligand. The corresponding P–Ru–P bite angle is increased to
166.82(2)° in comparison to 6. The Ru–N distance of 2.218(1) Å
is slightly longer than the analogous distance in 6 while the
Ru–Cl distance in 15 is 2.5477(4) Å and the CO bond length is
1.154(2) Å.
Scheme 5 Reactions with H2 or D2.
Anion metathesis with AgPF6 allowed the conversion of 16
to [RuH(S(CH2CH2OPiPr2)2)(py)(CO)]PF6 17 in 87% yield
(Scheme 4). This species was crystallographically characterized
(Fig. 9). In this case, the Ru–S distance is 2.360(3) Å and the
CO bond length is 1.15(1) Å. The cationic species 15 and 17
are similar to Ru(PNP)(CO) complexes reported by Jia et al.37
The reactivity of 6 and 7 with CO differs in that PPh3 is dis-
placed from 6 whereas for 7 chloride is liberated and pyridine
remains bound to the metal center. The presence of a weaker
central donor in the tridentate ligand in 7 presumably com-
bines with the diminished steric demands of pyridine to result
in the retention of the pyridine ligand.
in 18 (Scheme 5). The selective incorporation of deuterium at
one of the methylene sites indicates that the reaction occurs
from only one face of the molecule. It is also noted that deuter-
ium is not incorporated into the NH group illustrating that the
amine proton is not involved in the process. The H–D coupling
constant of 5.4 Hz observed for 18 is relatively small and
similar to values previously described for complexes in which
dihydrogen ligands exchange with hydrides, suggesting the
formation of isotopomers.42 Using an analysis of these data
described by Morris,43 these data suggest a dihydrogen
complex (see ESI†). While exchange precluded resolution of
hydride and dihydrogen resonances even on cooling to
−80 °C, T1(min) measurements for 18 were carried out and
Reactivity with H2/D2
Exposure of 6 to 1 atm of H2 results in the quantitative for- showed T1(min) of 86 ms at −60 °C on a 600 MHz spectro-
mation of RuH(HN(CH2CH2OPiPr2)2)(H2)Cl (18) (Scheme 5) as meter. While these data further affirm the hydride-dihydrogen
evidenced by the 31P{1H} spectrum which shows two singlets, nature of 18, attempts to obtain an analytically pure sample
one at 173.5 ppm and one at −4 ppm for free PPh3. It is worth were unsuccessful, presumably due to the facile loss of H2
noting, that while the displacement of PPh3 by H2 has pre- upon work-up.
1
viously been observed in other systems, it is rare.38–41 The H
Reaction of the cationic species 10 and 12 with H2 proceed
NMR spectrum of 18 reveals a triplet at −12.5 ppm integrating to give [RuH(E(CH2CH2OPiPr2)2)(L)(H2)][B(C6F5)4] (E = NH, L =
to three protons. This suggests rapid exchange between the PPh3 (19), E = S, L = py (20)) respectively (Scheme 5). The
bound H2 molecule and the hydride, an observation further hydride resonance for 19 was observed at −12.1 ppm, consist-
supported by the analogous reaction with D2 which resulted in ent with coordination of a ligand trans to the hydride. A
1
deuterium incorporation into the hydride position. In similar shift was observed in the H NMR spectrum of 20 for
addition, the selective incorporation of D into one of the the hydride resonance shifts to −11.3 ppm. The formation of
geminal positions of the methylene groups adjacent to N was the analogous species 19-d and 20-d from the reactions with
also observed (Fig. S3, ESI†). As hydride abstraction from the D2 showed deuterium incorporation in the ligand backbones
methylene groups adjacent N in related PNP systems34 has similar to that described for 18 (Scheme 5). In the case of 20,
been reported, as similar mechanism is proposed to account the H–D coupling experiments showed JHD of 7.4 Hz
for the incorporation of deuterium into the corresponding site suggesting a dihydrogen complex similar to that reported for
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Dalton Transactions
Table 1 TON of HMe2NBH3 to [Me2NBH2]2 for Ru-catalysts 4–10, 12, 15 and
16 in 24 h
Catalyst
mol% Ru
TON
4
5
5
5
14
2
6
7
8
9
1
1
1
5
57
99
49
4
10
12
15
16
1
2.5
5
67
14
2
5
2
related POP complexes.44 Although variable temperature NMR
experiments for both 19 and 20 failed to resolve the dihydro-
gen and hydride signals, T1(min) values of 44 ms (−35 °C) and
55 ms (−65 °C) were observed respectively, consistent with the
dihydrogen complex formulations.
Fig. 10 Concentration–time plots for B-containing products of dehydrogena-
tion using 2.5 mol% 10 and 0.18 M HMe2NBH3. Key: HMe2NBH3 (circles),
Me2NBH2 (diamonds), [Me2NBH2]2 (squares), HMe2NBH2NMe2BH3 (triangles).
Conclusions
Reactivity with HMe2NBH3
The ruthenium complexes 4–12, 15 and 16 were all shown to
effect the dehydrogenation of HMe2NBH3 to [Me2NBH2]2 in a
fashion similar to that previously described for the complexes
RuH((C5H4PPh2)2Fe)(ICy)Cl (ICy = (CyN)2C3H2)16 and RuH(N-
(CH2CH2PiPr2)2)(PMe3).23,24 However, the catalytic competence
of the present complexes was shown to vary dramatically
(Table 1). To gain a better understanding of the differences in
catalysis, the reactions of 6, 8, 10 and 12 with HMe2NBH3 were
monitored using 31P{1H} NMR spectroscopy. In the cases of 6,
10 and 12, the spectra showed the formation of 18, 19 and 20
respectively under catalytically relevant conditions. This
suggests that these dihydrogen complexes are formed and are
intermediates in the release of H2 from the amine-borane.
Interestingly the consumption of HMe2NBH3 by 10 as fol-
lowed by 11B NMR spectroscopy was shown to yield the pro-
ducts of dehydrogenation including Me2NBH2, [Me2NBH2]2
and Me2NBH2NMe2BH3 as evidenced by the known 11B NMR
signals, reported by Weller et al.45 (Fig. 10). The consumption
HMe2NBH3 is rapid at the beginning of the reaction and slows
towards the end. Me2NBH2 is an intermediate that is formed
and consumed while the species HMe2NBH2NMe2BH3 shows
only very slow consumption over the course of 10 h in a sealed
vessel, but is completely consumed in an open system. These
results are analogous to those described in several other
studies and suggest a similar mechanism of dehydrogenation
in which HMe2NBH2NMe2BH3 is an intermediate en route to
[Me2NBH2]2.24,46–50 The general trend in reactivity (Table 1)
indicates that complexes containing NH as the central donor
demonstrate greater activity than the S-substituted analogues.
Interestingly even in the cases where the central donor was not
coordinated (8 and 9), an amine-based ligand imparts greater
reactivity. This suggests the possibility of participation of the
NH fragment in the activation of HMe2NBH3. Nonetheless,
this view is contradicted by the observation that 7 catalyzes the
dehydrogenation more effectively than 6.
A series of Ru complexes derived from tridentate bis-phosphi-
nite ligands have been prepared and characterized. The reactiv-
ity of these species with CH3CN, CO, H2 and HMe2NBH3 has
been described. The resulting Ru-carbonyl complexes and
dihydrogen complexes have been characterized. These com-
plexes are also shown to act as catalyst for the dehydrogenation
of HMe2NBH3. Generally this reactivity demonstrates the
subtle influences that steric demands of the donors and the
electronic nature of the central donor can have on reactivity of
these tridentate ligand complexes. The utility of these com-
pounds as catalyst precursors for other processes of interest is
continuing to be studied in our laboratories.
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