Rhodium(I) and iridium(I) complexes containing bidentate phosphine-imidazolyl donor ligands as catalysts for the hydroamination and hydrothiolation of alkynes

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Rhodium(I) and iridium(I) complexes containing bidentate phosphine-

imidazolyl donor ligands as catalysts for the hydroamination and

hydrothiolation of alkynes†

Leslie D. Field,^aBarbara A. Messerle,*^aKhuong Q. Vuong^aand Peter Turner^b

Received 27th November 2008, Accepted 16th February 2009

First published as an Advance Article on the web 13th March 2009

DOI: 10.1039/b821188d

A series of novel cationic and neutral rhodium and iridium complexes containing bidentate

phosphine-imidazolyl donor ligands of the general formulae [M(ImP)(COD)]BPh₄(M = Rh, ImP =

ImP2, 3; ImP1a, 4a; ImP1b, 4b and M = Ir, ImP = ImP2, 5; ImP1a, 6a and ImP1b, 6b),

[Ir(ImP)(CO)₂]BPh₄(ImP = ImP2, 7; ImP1a, 8a and ImP1b, 8b), [Rh(ImP1b)(CO)₂]BPh₄(10b) and

[M(ImP)(CO)Cl] (M = Rh, ImP = ImP2, 11; ImP1b, 12 and M = Ir, ImP = ImP2, 13; ImP1b, 14) where

COD = 1,5-cyclooctadiene, ImP2 = 1-methyl-2-[(2-(diphenylphosphino)ethyl]imidazole, 1; ImP1a =

1-methyl-2-[(diphenylphosphino)methyl]imidazole, 2a and ImP1b = 2-[(diisopropylphosphino)methyl]-

1-methylimidazole, 2b were successfully synthesised. The solid state structures of 3, 6a, 11 and 12 were

determined by single crystal X-ray diffraction analysis. A number of these complexes are effective as

catalysts for the intramolecular hydroamination of 4-pentyn-1-amine to 2-methyl-1-pyrroline. The

cationic complexes are signiﬁcantly more effective than analogous neutral complexes. The cationic

iridium complex 8b, containing the phosphine-imidazolyl ligand with the bulky isopropyl groups on the

phosphorus donor, is more efﬁcient than analogous complexes with the phenyl substituents on the

phosphorus donor atom, 7 and 8a. The complexes 7–8b are also moderately effective in catalysing the

addition of thiophenol to a range of terminal alkynes. In contrast to the hydroamination reaction,

placement of the isopropyl group on the phosphorus donor leads to a decrease in the reactivity of the

resulting metal complexes as catalysts for the hydrothiolation reaction.

of alkenes⁶and imines.⁸These metal complexes have not been

widely used as catalysts for the addition of X–H bonds to C–C

unsaturated bonds.⁹

Introduction

Metal complexes containing hybrid P-N donor ligands have

been extensively investigated due to their potential hemilability.

Phosphorus, being a soft donor, is capable of stabilising transition

metal centres at low or medium oxidation states, whereas nitrogen,

as a harder donor, is more suitable for stabilising metals in higher

oxidation states. In a catalytic cycle the oxidation state of the metal

centre can undergo change, and at any stage of the cycle one donor

atom of a mixed donor ligand may be more strongly bound than

the other so that a wide range of possible reactive intermediates

could be formed and stabilised in the catalytic system using

hemilabile ligands.¹Many metal complexes with mixed donor

ligands containing phosphorus as well as sp²-N donors within

heterocycles are known.¹The main focus has been on ligands with

phosphine-pyridine²and phosphine-oxazoline donors,³and only

a limited number of complexes containing bidentate phosphine-

imidazolyl^4,5or phosphine-imidazoline^6–8donors have been re-

ported. Applications of metal complexes containing phosphine-

imidazolyl or phosphine-imidazoline donor ligands in catalysis

include the Heck coupling reactions⁴and the hydrogenation

Transition metal catalysed addition of X–H bonds (X = N, O, S)

to alkynes is a direct method for the construction of C–N, C–O

and C–S bonds. This is potentially important in the synthesis of

biologically active compounds as well as organic building blocks,

new materials and ﬁne chemicals. These simple addition reactions

can be performed, in principle, with 100% atom efﬁciency with few

byproducts. Many valuable alkenyl organic compounds, including

sulﬁdes, and different oxygen and nitrogen containing compounds,

can be formed using this approach and this scheme provides a more

efﬁcient and “greener” entry to compounds containing C–N, C–O

and C–S bonds than other available methods.^10,11In addition, the

intramolecular version of the addition reactions provides one of

the most straightforward routes to nitrogen-, oxygen- and sulfur-

containing heterocycles.^10,12

Imines/enamines and amines are highly important in organic

synthesis as well as in ﬁne chemical production.^10,13Hydroamina-

tion of alkynes and alkenes is the most straightforward method for

the synthesis of imines and amines. Lanthanide¹⁴and both early¹⁵

and late^16–18transition metal complexes facilitate the hydroamina-

tion of alkynes and alkenes. While lanthanide and early transition

metal complexes have high reactivity for hydroamination, their

sensitivity to oxygen and moisture has restricted their more general

application. On the other hand, hydroamination catalysts based on

late transition metals are generally more functional group tolerant

and less sensitive towards oxygen or moisture.^10,13c,d

^aSchool of Chemistry, University of New South Wales, Kensington, Sydney,

NSW 2052, Australia. E-mail: b.messerle@unsw.edu.au; Fax: (+612)

93856141

^bCrystal Structure Analysis Facility, School of Chemistry, University of

Sydney, Camperdown, Sydney, NSW 2006, Australia

† CCDC reference numbers 711455–711458. For crystallographic data in

CIF or other electronic format see DOI: 10.1039/b821188d

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Compounds containing C–S bonds commonly exhibit biolog-

ical activity,^19,20and are reactive and versatile intermediates in

organic chemistry,^20,21and a general and efﬁcient method for the

construction of the C–S bond could signiﬁcantly improve synthetic

routes to sulfur containing compounds. In contrast to the extensive

research in the area of catalytic hydroamination, the metal catal-

ysed addition of thiols or alkynes/alkenes (hydrothiolation) has

not been investigated to any signiﬁcant extent.¹⁰This is possibly

due to the misconception that thiols bind strongly to the metal cen-

tre and therefore render the catalyst ineffective.^10,22Since the early

1990s, several hydrothiolation catalytic systems have been reported

including palladium,^23,24,25rhodium^23,26and nickel²⁷complexes.

We have reported the synthesis of a number of rhodium

and iridium complexes containing phosphine-pyrazolyl biden-

tate donor ligands and their application as catalysts for

the hydroamination,²⁸hydrothiolation²⁹and hydroalkoxylation³⁰

reactions.³¹Rhodium and iridium complexes containing hybrid

phosphine-pyrazolyl bidentate donor ligands are, in general,

better catalysts for these reactions than analogous complexes

containing bidentate N–N donor ligands (N–N = bis(pyrazolyl)

or bis(imidazolyl).^28,29,31,32In this paper, we report the synthe-

sis of a range of cationic and neutral rhodium and iridium

complexes containing hybrid phosphine-imidazolyl donor ligands

[Rh(ImP)(COD)]BPh₄(ImP = ImP2, 3; ImP1a, 4a; ImP1b, 4b),

[Ir(ImP)(COD)]BPh₄(ImP = ImP2, 5; ImP1a, 6a; ImP1b, 6b),

[Ir(ImP)(CO)₂]BPh₄(ImP = ImP2, 7; ImP1a, 8a and ImP1b,

8b), [Rh(ImP1b)(CO)₂]BPh₄(10b), [Rh(ImP)(CO)Cl] (ImP =

ImP2, 11; ImP1b, 12) and [Ir(ImP)(CO)Cl] (ImP = ImP2,

13, ImP1b, 14) where ImP2 = 1-methyl-2-[(2-(diphenylphos-

phino)ethyl]imidazole (1), ImP1a = 1-methyl-2-[(diphenylphos-

phino)methyl]imidazole (2a) and ImP1b = 2-[(diisopropyl-

phosphino)methyl]-1-methylimidazole (2b). The solid state struc-

tures of 3, 6a, 11 and 12 were established by single X-ray

diffraction analysis. A selection of these complexes were used as

catalysts for hydroamination and hydrothiolation. Variations of

the substituents on the phosphorus atom as well as the length of

the carbon linker bridge between the phosphine and imidazolyl

donors affected the catalytic efﬁciency of the corresponding

metal complexes. The catalytic activity of complexes containing

phosphine-imidazolyl donor ligands is compared with that of the

analogous complexes with phosphine-pyrazolyl ligands.

Results and discussion

Ligand synthesis

The synthesis of 1-methyl-2-[(diphenylphosphino)ethyl]imidazole,

ImP2, (1) was carried out in 3 steps from 1-methylimidazole

(Scheme 1). Ring opening of ethylene glycol cyclic sulfate with

1-methylimidazol-2-yllithium at -78 ^◦C led to the formation

of the lithium sulfate intermediate. Subsequent nucleophilic

-

displacement of the sulfate moiety with PPh₂afforded 1 as a

waxy solid in excellent yield (89%). 1-Methylimidazol-2-yllithium

and LiPPh₂were conveniently generated in situ by the reaction

of 1-methylimidazole and diphenylphosphine with n-butyllithium

respectively. Recently, Jalil and Hui³³have reported the synthesis

of the same compound using a related approach. Werner and

co-workers³⁴have also reported the use of 1,2-cyclic sulfates

as versatile intermediates in the construction of a number of

unsymmetrical bidentate phosphine or arsine ligands.

The preparation of analogous phosphine-imidazolyl ligands

containing a one-carbon linker 1-methy-2-[(diphenylphosphino)-

methyl]limidazole, ImP1a (2a) and 2-[(diisopropylphosphino)-

methyl]-1-methylimidazole, ImP1b, (2b) was performed accord-

ing to a published procedure (Scheme 2).^5aThe 1-methyl-[2-

(trimethylsilyl)methyl]imidazole intermediate was generated by

the reaction of 1,2-dimethylimidazole and n-butyllithium at

◦

-78 C. The desired ligands 2a and 2b were then formed by the

solventless reaction of the silyl intermediate with the appropriate

phosphinous chloride.

Scheme 2

Scheme 1

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Table 1 Selected bond lengths and bond angles^afor the inner coordination sphere of [Rh(ImP2)(COD)]BPh₄(3) and [Ir(ImP1a)(COD)]BPh₄(6a)

[Rh(ImP2)(COD)]BPh₄(3)

[Ir(ImP1a)(COD)BPh₄(6a)

˚

Atoms

Bond Lengths (A)

Atoms

Bond Lengths (A)

Rh(1)–P(1)

Rh(1)–N(1)

Rh(1)–C(1)

Rh(1)–C(2)

Rh(1)–C(5)

Rh(1)–C(6)

C(1)–C(2)

C(5)–C(6)

2.2821(8)

2.1340(19)

2.237(2)

2.259(2)

2.134(2)

2.144(2)

1.371(3)

1.396(3)

Bond Angles (^◦)

89.35(5)

90.32(7)

93.24(7)

91.20(8)

95.16(8)

95.87(9)

80.37(9)

80.17(9)

87.22(9)

Ir(1)–P(1)

Ir(1)–N(1)

Ir(1)–C(1)

Ir(1)–C(2)

Ir(1)–C(5)

Ir(1)–C(6)

C(1)–C(2)

C(5)–C(6)

2.2747(7)

2.061(2)

2.193(3)

2.206(3)

2.128(3)

2.127(3)

1.374(4)

1.396(5)

Atoms

Bond Angles (^◦)

81.94(6)

P(1)–Rh(1)–N(1)

P(1)–Rh(1)–C(5)

P(1)–Rh(1)–C(6)

N(1)–Rh(1)–C(1)

N(1)–Rh(1)–C(2)

C(1)–Rh(1)–C(5)

C(1)–Rh(1)–C(6)

C(2)–Rh(1)–C(5)

C(2)–Rh(2)–C(6)

P(1)–Ir(1)–N(1)

P(1)–Ir(1)–C(5)

P(1)–Ir(1)–C(6)

N(1)–Ir(1)–C(1)

N(1)–Ir(1)–C(2)

C(1)–Ir(1)–C(5)

C(1)–Ir(1)–C(6)

C(2)–Ir(1)–C(5)

C(2)–Ir(2)–C(6)

96.92(9)

95.08(8)

95.40(9)

94.69(10)

94.59(12)

81.52(11)

80.93(13)

91.37(12)

^aStandard deviations are given in parentheses.

Synthesis of rhodium and iridium metal complexes

The complexes with mixed phosphine-imidazolyl bidentate

ligands and COD as co-ligands are ﬂuxional at ambient tem-

perature on the NMR time scale. At room temperature, the

¹H resonances due to the alkenyl CHs of COD were observed

as broad peaks at approximately 5.0 ppm (trans to P) and

3.0 ppm (cis to P, 3 and 5) or 3.8 ppm (cis to P, 4a, 4b,

6a and 6b). In the cases of complexes [M(ImP2)(COD)]BPh₄

(M = Rh, 3; M = Ir, 5) and [Ir(ImP1a)(COD)]BPh₄(6a) at

room temperature, exchange between the alkenyl protons of

COD that are trans to P and those trans to N was observed

(a) Synthesis of [Rh(ImP)(COD)]BPh₄(ImP = ImP2, 3; ImP1a,

4a and ImP1b, 4b) and [Ir (ImP) (COD)] BPh₄(ImP = ImP2,

5; ImP1a, 6a and ImP1b, 6b). A series of metal complexes

[M(ImP)(COD)]BPh₄(M = Rh, 3–4b and Ir, 5–6b) was success-

fully synthesised (Scheme 3) by reaction of a methanol solution of

the ligand with the metal precursor [M(m-Cl)(COD)]₂in methanol.

The products were isolated by precipitation as their methanol-

insoluble tetraphenylborate salts. The rhodium complexes 3–4b

were collected as yellow solids and the iridium complexes

5–6b were collected as orange solids, after ﬁltration and washing

the crude products with a small quantity of methanol to remove

sodium chloride by-product.

1

on the NMR time scale using phase sensitive H NOESY. The

¹H NOESY NMR spectra of the complexes with bidentate

phosphine-imidazolyl donor ligands in CDCl₃or CD₂Cl₂contain

NOE cross-peaks between the resonances of the protons due

-

All the complexes were fully characterised by multinuclear 1D

to BPh₄and the metal bound ligands. This demonstrates that

1

(¹H, ³¹P{ H} and ¹³C{ H}) and 2D (COSY, NOESY, HMQC)

there is strong ion-pairing in solution as a result of interionic

NMR, IR, MS and elemental analysis. In the ³¹P{ H} NMR

1

-

interactions between the BPh₄anion and the metal cationic

spectra, the signiﬁcant shift of the ³¹P resonance to lower ﬁeld

and the appearance of a ¹J(Rh-P) coupling in the phosphorus res-

onance of the rhodium complexes 3–4b conﬁrm the coordination

of the phosphine donor to the metal centres. The binding of the

imidazolyl sp²-N donor to the metal centre is illustrated by changes

in the ¹H chemical shifts of the imidazolyl H4 and H5 resonances

relative to those in the free ligands, and also by the observation of

²J(Rh-C2) couplings in the ¹³C resonances due to the C2 carbon

of the imidazolyl heterocycles.

fragment.

X-Ray quality crystals of [Rh(ImP2)(COD)]BPh₄(3) and

[Ir(ImP1a)(COD)]BPh₄(6a) were obtained by layering of

dichloromethane solutions of the complexes with n-hexane and

diethyl ether respectively. ORTEP diagrams containing the atom

numbering schemes of the solid state structures of 3 and 6a are

shown in Fig. 1. Selected bond lengths and bond angles are

included in Table 1. Crystallographic data are provided in Table 6

(Experimental section). Both complexes crystallised in the space

Scheme 3

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which is possibly due to the decrease in ﬂexibility of the smaller

ring system (Table 1).

The M–C (COD) bonds (M = Rh, Ir) that are trans to P (M(1)-

C(1) and M(1)-C(2)) are slightly longer than the M–C bonds

that are trans to N (M(1)-C(5) and M(1)-C(6)) (Table 1). This

observation was expected as the phosphine donor has a stronger

trans inﬂuence than the sp²-N donor. Similar observations have

also been made in the solid state structures of analogous rhodium

and iridium complexes with bidentate phosphine-pyrazolyl biden-

tate ligands.^28,29,31The trans inﬂuence of phosphorus is also

manifested in the fact that the alkenyl bond C(1)–C(2) (trans

to P) is slightly shorter than C(5)–C(6) (trans to N). The M–

N(1) distances are similar to those reported in the literature

for rhodium,³⁵and iridium^5d,32b,36complexes with imidazolyl and

imidazolinyl ligands.^6,8Other bond lengths observed for 3 and

6a are similar to those reported in the literature for similar

complexes.^5d,6,36b,37

(b) Synthesis of [Ir(ImP)(CO)₂]BPh₄(ImP = ImP2, 7; ImP1a,

8a and ImP1b, 8b) and [Rh(ImP1b)(CO)₂]BPh₄(10b). Cationic

iridium complexes with bidentate phosphine-imidazolyl ligands

and carbonyls as co-ligands, [Ir(ImP)(CO)₂]BPh₄(7, 8a and

8b with ImP = ImP2, 1; ImP1a, 2a and ImP1b, 2b respec-

tively) were prepared by the displacement of COD from the

[Ir(ImP)(COD)]BPh₄(5–6b) complexes under an atmosphere of

carbon monoxide (Scheme 4). These reactions were performed

in a 2-phase methanol/n-hexane or n-pentane suspension un-

der an atmosphere of carbon monoxide. The displaced COD

stays in the hydrocarbon layer and is therefore prevented from

re-coordinating to the metal centre. [Ir(ImP2)(CO)₂]BPh₄(7)

and [Ir(ImP1a)(CO)₂]BPh₄(8a) are yellow-orange solids and

[Ir(ImP1b)(CO)₂]BPh₄(8b) is a bright yellow solid. All of the

complexes, 7–8b, are mildly air sensitive in the solid state but

are rather unstable in solution.

Fig. 1 ORTEP depictions of the cationic fragment of (a) [Rh(ImP2)-

(COD)]BPh₄(3) and (b) [Ir(ImP1a)(COD)]BPh₄(6a) at 50% thermal

ellipsoids for the non-hydrogen atoms.

Scheme 4

group P2₁/c(#14). The metal coordination spheres are slightly

distorted square planar typical of 4-coordinate iridium(I) and

rhodium(I) complexes.

The complexes 7–8b were characterised by IR, NMR spec-

troscopy, ESI-MS and elemental analysis. The IR spectra of each

complex showed two strong absorption bands of approximately

equal intensities at around 2000 cm^-1, characteristic of cis dicar-

bonyl metal complexes.

The 6-membered metallacycle deﬁned by P(1)-Rh(1)-N(1)-

C(11)-C(12)-C(13) in 3 adopts a highly puckered ring confor-

mation and does not show a preference for either a chair or

boat conformation. Similar conformations have been observed for

the solid state structures of iridium(I) complexes with bidentate

phosphine-imidazoline ligands.^6,8The 5-membered metallacyclic

ring of 6a is relatively ﬂat, with the carbon bridge lying slightly

above the ring coordination plane. The P(1)-M(1)-N(1) bite angles

are 89.35(5)^◦and 81.94(6)^◦for complexes 3 and 6a respectively

(Table 1). The bite angle in 3 is very close to the ideal value of 90^◦,

indicating a very low level of ring strain associated with the six

membered metallacyclic ring upon chelation. On the other hand,

the bite angle P(1)-Ir(1)-N(1) in 6a deviates signiﬁcantly from 90^◦,

1

In the ¹³C{ H} NMR spectra at ambient temperature, reso-

nances due to the CO groups for 7–8b were not observed. This was

attributed to broadening of the resonances due to the exchange

of the two carbonyl groups at ambient temperature. The exchange

process possibly occurs via a Berry pseudo-rotation with a solvent

or residual water molecule mediated ﬁve coordinate transition

1

state.³⁸When the ¹³C{ H} spectrum of [Ir(ImP1b)(CO)₂]BPh₄(8b)

was obtained with the sample kept under an atmosphere of carbon

monoxide, a single averaged broad resonance due to CO was

observed at 179.0 ppm indicating that the two metal bound COs

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and free CO are in exchange. This has also been observed for a

similar system.³⁹

The metal complexes 11, 12, 13 and 14 were characterised by

multinuclear NMR, IR and elemental analysis. The spectroscopic

data i.e. the IR stretching frequencies of the carbonyl groups,

Attempts at preparing the analogous rhodium complexes

[Rh(ImP2)(CO)₂]BPh₄and [Rh(ImP1a)(CO)₂]BPh₄using the

same method as that previously used in the synthesis of iridium

complexes were unsuccessful. The IR spectra of the solids

formed immediately after the reactions with CO showed IR

stretching bands due to metal bound carbonyls. However, the

complexes were too unstable to be isolated or fully characterised.

In contrast, when the bulky isopropyl substituents are present

on the phosphorus donor atom, the cationic rhodium complex

[Rh(ImP1b)(CO)₂]BPh₄(10b) was successfully isolated and char-

acterised by NMR, IR and elemental analysis. The complex is a

pale yellow, mildly air sensitive solid and decomposed slowly (ca.

30 h) in CD₂Cl₂under nitrogen. Two very strong CO stretches at

frequencies of 2092 and 2025 cm^-1in the IR spectrum (KBr disc)

clearly indicate the presence of two metal bound cis-COs. A single

resonance due to the phosphorus was observed as a doublet at

71.1 (¹J(Rh-P) = 119.1 Hz) ppm in the ³¹P NMR spectrum. On

1

2

the ³¹P{ H}, CO ¹³C{ H} NMR chemical shifts and the J(P-

CO) coupling constant (Table 2) all demonstrate clearly that the

phosphine and CO ligands are arranged in a cis fashion around

the metal centre of each of the complexes 11–14.^37a,40

In the IR spectra (KBr disc), all of the complexes 11–14

display a single strong absorption band for CO (Table 2). The

frequencies observed for complexes with ImP1b (2b), 12 and 14,

are signiﬁcantly lower than the values found for analogous metal

complexes with the ImP2 (1) ligand, 11 and 13. The difference in

nCO can be attributed to the stronger s-electron donating ability

and poorer p-accepting ability of the trialkyl phosphine donor of

ImP1b (2b) when compared with the diaryl alkylphosphine donor

in ImP2 (1).

1

The ³¹P{ H} NMR spectra of the neutral complexes 11–14 each

contain a single resonance for the metal bound phosphine atom.

1

The J(Rh-P) values of 171.2 Hz and 162.8 Hz for 11 and 12

1

analysis of the ¹³C{ H} spectrum, only a very broad resonance at

are similar to those values observed in similar complexes with

2

d 187.1 ppm could be attributed to the CO ligands, possibly due to

the exchange of the two carbonyl groups at ambient temperature

as has been observed previously for analogous iridium complexes,

7, 8a and 8b.

phosphine-pyrazolyl ligands.^28,29,31The chemical shifts, J(P-CO)

1

and ¹J(Rh-C) constants for CO ¹³C{ H} NMR resonances are also

similar to those that have been reported for similar compounds.

2

The small J(P-CO) values (<20 Hz) of the ¹³C resonances due

to the metal bound carbonyls observed for the neutral complexes

11–14 are consistent with the cis arrangement of phosphorus and

carbonyl around the metal centres.⁴⁰

(c) Synthesis of [Rh(ImP)(CO)Cl] (ImP = ImP2, 11; ImP1b, 12)

and [Ir(ImP)(CO)Cl] (ImP = ImP2, 13; ImP1b, 14). Several neu-

tral rhodium and iridium complexes with mixed donor phosphine-

imidazolyl ligands were synthesised using similar methods to those

used for the synthesis of analogous complexes with phosphine-

pyrazolyl donor ligands (Scheme 5).^28,31The reactions were carried

out by slow addition of a solution of ligand to a solution of

[M(m-Cl)(CO)₂]₂in methanol (M = Rh) or acetonitrile (M =

Ir) to form [Rh(ImP2)(CO)Cl] (11), [Rh(ImP1b)(CO)Cl] (12),

[Ir(ImP2)(CO)Cl] (13) and [Ir(ImP1b)(CO)Cl] (14) in good to

excellent yields.

Crystals suitable for X-ray diffraction analysis of 11 and 12

were obtained by careful layering of dichloromethane solutions

of the compounds with n-hexane at room temperature. Both

complexes crystallised in the same space group P2₁/c(#14), where

each asymmetric unit contains only one complex molecule of 11

and 12 respectively. ORTEP depictions including atom numbering

schemes of both compounds are shown in Fig. 2. Selected bond

lengths and bond angles are presented in Table 3. Crystallographic

data can be found in Table 6 (experimental section).

The coordination around the metal centres is square planar for

both complexes (Fig. 2). The sums of the four angles P(1)-Rh(1)-

N(1), N(1)-Ir(1)-Cl(1), Cl(1)-Rh(1)-C(1), and C(1)-Rh(1)-P(1) are

almost exactly 360^◦respectively for 11 and 12, conﬁrming the

square planar geometry around the metal centres. The bite angle

P(1)-Rh(1)-N(1) of 89.51(4)^◦in [Rh(ImP2)(CO)Cl] (11) is very

close to the ideal 90^oangle for square planar Rh(I) complexes, and

this indicates a very low ring strain associated with the chelation

of the ligand to rhodium which leads to the formation of a six

membered ring. The angle observed in [Rh(ImP1b)(CO)Cl] (12)

(81.27(5)^◦) on the other hand deviates very signiﬁcantly from

Scheme 5

1

Table 2 IR stretching frequencies^a(nCO), ¹³C{ H} (¹³CO resonances) and³¹P{ H}NMR chemical shifts for neutral rhodium(I) and iridium(I) complexes

(11–14) with phosphine-imidazolyl ligands

Complex

nCO/cm^-1

d

¹³C (CO)/ppm (¹J(Rh-C), ²J(P-CO) Hz)

d

³¹P/ppm (¹J(Rh-P) Hz)

[[Rh(ImP2)(CO)Cl] (11)

[Rh(ImP1b)(CO)Cl] (12)

[Ir(ImP2)(CO)Cl] (13)

[Ir(ImP1b)(CO)Cl] (14)

1975

1957

1975

1946

188.8^b(dd, 69.8, 18.0)

190.4^b(dd, 69.8, 17.4)

176.0^c(d, 13.8)

41.4^b(d, 171.2)

84.4^b(d, 162.8)

12.9^c

178.5^c(d, 12.1)

56.2^c

^aSpectra were acquired using KBr discs. ^bSpectra were acquired in CDCl₃. ^cSpectra were acquired in CD₂Cl₂.

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Table 3 Selected bond lengths and bond angles for the inner coordination

sphere of [Rh(ImP2)(CO)Cl] (11) and [Rh(ImP1b)(CO)Cl] (12)^a

suggesting there should be no steric effect due to this interaction

in determining the value of the bite angle. The trans L-Rh-L¢

(P(1)-Rh(1)-Cl(1) and N(1)-Rh(1)-C(1)) angles deviate slightly, in

11, and signiﬁcantly, in 12, from 180^◦(Table 3). The values for

these trans angles are much smaller in 12 than those in 11 as

the geometry of 12 is much more distorted than the geometry of

11. As was observed for the ring conformation in the solid state

structure of [Rh(ImP2)(COD)]BPh₄(3), the metallacycle in 12 is

highly puckered and does not show any real preference for either a

boat or chair conformation. The 5 membered metallacyclic ring of

11 is relatively ﬂat with the carbon of the bridge puckered up only

slightly from the coordination plane. The Rh–N bond distances

of 12 and 11 are similar to the values reported for similar metal

complexes.^37a,40,41

[Rh(ImP2)(CO)Cl] (11) [Rh(ImP1b)(CO)Cl] (12)

˚

Atoms

Bond Lengths (A)

Rh(1)–P(1)

Rh(1)–N(1)

Rh(1)–Cl(1)

Rh(1)–C(1)

2.2144(6)

2.1319(16)

2.4062(6)

1.807(2)

2.2217(7)

2.0882(17)

2.3986(7)

1.804(2)

C(1)–O(1)

Atoms

1.150(3)

1.154(3)

Bond Angles (^◦)

89.51(4)

Bond Angles (^◦)

81.27(5)

P(1)–Rh(1)–N(1)

N(1)–Rh(1)–Cl(1)

Cl(1)–Rh(1)–C(1)

C(1)–Rh(1)–P(1)

N(1)–Rh(1)–C(1)

Cl(1)–Rh(1)–P(1)

91.81(4)

86.70(6)

91.98(6)

178.41(7)

178.515(16)

90.13(5)

95.51(7)

93.13(6)

174.33(7)

170.608(19)

^aStandard deviations in the least signiﬁcant ﬁgures are given in

parentheses.

Catalysis

Catalysed intramolecular hydroamination. The intramolecular

hydroamination of alkynes leading to the formation of cyclic

imines is a signiﬁcant transformation due to the prevalence of these

heterocycles in many biologically active compounds. The use of

late transition metal complexes as catalysts for the intramolecular

hydroamination of alkynes has received increased attention re-

cently, with the focus of research being mainly on second and third

row metals of groups VIII, X and XI, with little attention on group

IX.^10,12,16,42We have previously reported that rhodium and irid-

ium complexes containing bidentate bis-pyrazolyl, bis-imidazolyl,

bis-N-heterocyclic carbene (NHC) or mixed phosphine-NHC,

phosphine-pyrazolyl donor ligands^28,32,39,43are effective as catalysts

for the intramolecular hydroamination of aliphatic as well as

aromatic alkynes. The efﬁciency of the catalyst changes signif-

icantly even with a small change to the ligand donor set.^31,32

Here we investigated the activity of a number of metal complexes

containing phosphine-imidazolyl donor ligands as catalysts for the

intramolecular hydroamination of 4-pentyn-1-amine (Scheme 6,

Table 4).

Scheme 6

Table 4 Catalytic efﬁciency of a number of rhodium and iridium

complexes containing phosphine-imidazolyl donor ligands for the catal-

ysed cyclisation of 4-pentyn-1-amine to 2-methyl-1-pyrroline in CDCl₃

at 60 ^◦

C

Time at > 98%

conversion (h)

Catalyst^b

N_t(h^-1)

a

[Ir(ImP2)(CO)₂]BPh₄(7)

[Ir(ImP1a)(CO)₂]BPh₄(8a)

[Ir(ImP1b)(CO)₂]BPh₄(8b)

[Rh(ImP1b)(CO)₂]BPh₄(10b)

[Ir(ImP2)(COD)]BPh₄(5)

[Rh(ImP2)(COD)]BPh₄(3)

[Ir(ImP2)(CO)Cl] (13)

17

9

31

59

24

3

22

44

17

18

Fig. 2 ORTEP depictions of (a) [Rh(ImP2)(CO)Cl] (11) and (b)

[Rh(ImP1b)(CO)Cl] (12) at 50% thermal ellipsoids for the non-hydrogen

atoms.

27

64 (94%)

48 (81%)

45 (92%)

1

2

[Rh(ImP2)(CO)Cl] (11)

90^◦. This deviation could be a result of the strain associated

with the formation of the ﬁve membered metallacyclic ring. The

intramolecular distances between the CH₃of the two isopropyl

groups and the metal bound carbonyl in 12 are quite large,

^aTurn-over number N_t= (mol of product)/((mol of catalyst) h), typically

calculated at 50% conversion. ^b1.5 mol% catalyst was used, except for 8a

where 1.3 mol% was used and 13 and 11 where 1.4 mol% was used.

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The catalytic efﬁciency of iridium complexes with carbonyls

as co-ligands (7–8b) for the cyclisation of 4-pentyn-1-amine is

affected by the changes in the steric and electronic properties

of the ligands. Reducing the length of the carbon bridge in the

phosphine-imidazolyl ligands (ImP2, 1 and ImP1a, 2a) led to a

decrease in catalytic performance of the corresponding complexes

7 and 8a, with N_tfor complex 8a nearly halved and the time

taken to reach complete conversion doubled in comparison to

the catalytic activity of complex 7 with a two carbon bridge

in the phosphine-imidazolyl donor ligand. On the other hand,

replacing the mildly electron withdrawing phenyl groups on the

phosphorus atom by the bulkier and electron donating iso-

propyl groups led to a signiﬁcant enhancement in the reactivity

of the resulting metal complex 8b, with the turnover rate N_t

more than tripled and the time to reach complete conversion

reduced to a third when compared to those of complex 8a with

phenyl groups on the phosphorus atom of the phosphine donor.

Complexes 7–8b are moderately more reactive for this cyclisa-

tion than the iridium complex containing a bidentate nitrogen

donor ligand [Ir(bim)(CO)₂]BPh₄(bim = bis(N-methylimidazol-

2-yl)methane)³²and the iridium complex containing a phos-

phine-pyrazolyl bidentate ligand [Ir(PyP)(CO)₂]BPh₄(PyP =

1-[(2-diphenylphosphino)ethyl]pyrazole).^28,31In summary, varia-

tion in the ligand donors signiﬁcantly inﬂuenced the catalytic

efﬁciency of the metal complexes.

Catalysed intermolecular hydrothiolation of alkynes. The addi-

tion of thiols to alkynes is one of the most straightforward routes

to vinyl sulﬁdes, which are important synthetic intermediates.^21,44

Hydrothiolation reactions with alkynes, in general, provide alkenyl

sulﬁdes at better yields and complementary or better selectivities

when compared with the radical addition reactions (yielding

the anti-Markovnikov products) or with the non-catalysed nu-

cleophilic addition of thiolate anion (yielding the Markovnikov

products), where longer reaction times and harsher conditions are

essential.^22,45

We have previously demonstrated that the cationic irid-

ium complex containing bidentate phosphine-pyrazolyl donor

ligand [Ir(PyP)(CO)₂]BPh₄(PyP = 1-[(2-di-phenylphosphino-

ethyl)]pyrazole) is a much better catalyst for the catalysed

addition of thiophenol to alkynes than either the analogous

rhodium complex [Rh(PyP)(CO)₂]BF₄or complexes with biden-

tate nitrogen donor digands [M(N-N)(CO)₂]BPh₄(M = Rh, Ir;

N-N = bis(1-pyrazol-1-yl)methane or bis(N-methylimidazol-2-

yl)methane) and neutral complexes [M(PyP)(CO)Cl] (M = Rh,

Ir).²⁹Here, the catalytic activity of cationic iridium complexes

[Ir(ImP)(CO)₂]BPh₄(ImP = ImP2, 7; ImP1a, 8a and ImP1b,

8b) for the addition of thiophenol to a range of alkynes was

investigated (Scheme 7). Possible products from these reactions

include the E and Z isomers of the anti-Markovnikov products

and the Markovnikov products.

The cationic rhodium complex [Rh(ImP1b)(CO)₂]BPh₄(10b),

which has the bulky isopropyl substituents on the phospho-

rus donor, gave the highest turnover rate of 59 h^-1of all

the catalysts with a phosphine-imidazolyl ligand, however the

time to reach complete conversion (>98%) is slightly longer in

comparison to the iridium complex [Ir(ImP1b)(CO)₂]BPh₄(8b).

This is possibly due to the instability of 10b in solution as

noted above. The fact that [Rh(ImP)(CO)₂]BPh₄where ImP =

ImP2, 9 and ImP1a, 10a, were too unstable to be isolated

has prevented a systematic investigation into the effect of the

nature of the ligands on the catalytic efﬁciency of these rhodium

complexes.

The iridium complex with COD as co-ligand [Ir(ImP2)(COD)]-

BPh₄(5) was slightly more effective as a catalyst for hydro-

amination (Scheme 5) than the complex with carbonyl co-

ligands [Ir(ImP2)(CO)₂]BPh₄(7). Complex [Ir(ImP2)(COD)]BPh₄

(5) does not, however, possess catalytic ability comparable

to that of the analogous complex with phosphine-pyrazolyl

ligand [Ir(PyP)(COD)]BPh₄, with the turnover rate found to

be approximately 50 fold slower than that observed for the

[Ir(PyP)(COD)]BPh₄promoted reaction (N_t= 1200 h^-1).^28,31This

result again shows that a relatively small change in the donor

ability of the ligand can result in signiﬁcant alteration in the

catalytic efﬁciency of the metal complex. The reaction promoted

by [Rh(ImP2)(COD)]BPh₄(3) had a very low turnover rate and

did not reach completion.

Scheme 7

In a similar outcome to that observed previously,²⁹when

using the complexes with phosphine-imidazolyl ligand as cat-

alysts for the hydrothiolation reaction, in most cases only the

anti-Markovnikov addition products were observed and the

total conversion was highly substrate dependent. The iridium

complexes [Ir(ImP)(CO)₂]BPh₄(7–8b) are not as effective as

the analogous complex with phosphine-pyrazolyl donor ligand

[Ir(PyP)(CO)₂]BPh₄. With complexes 7–8a, very good conversions

of substrates to products were achieved only with phenylacetylene

and the conversions with propargyl alcohol, 1-pentyne and

(trimethylsilyl)acetylene are poor (Table 5).

While changing the length of the carbon bridge of the

phosphine-imidazolyl ligands from two carbons to one carbon,

e.g. [Ir(ImP2)(CO)₂]BPh₄(7) to [Ir(ImP1a)(CO)₂]BPh₄(8a), led to

a decrease in efﬁciency of 8a when compared with that of 7 for

the catalysed hydroamination reaction, complex 8a was in general

slightly more effective than 7 in promoting the hydrothiolation

reaction (Table 5).

While most of the cationic complexes are effective for the

cyclisation of 4-pentyn-1-amine, the neutral rhodium and iridium

complexes [M(ImP2)(CO)Cl] (M = Rh, 11; and M = Ir, 13)

were ineffective in promoting this transformation. This result

further conﬁrmed previous ﬁndings that neutral rhodium and

iridium complexes are signiﬁcantly less active as catalysts for

hydroamination^28,31,32and hydrothiolation^29,31when compared with

their cationic analogues.

Of the phosphine-imidazolyl ligands, on switching the mildly

electron withdrawing phenyl substituents of the phosphine donor

to the electron donating and more bulky isopropyl group, the

activity of the corresponding metal complex decreases slightly

for hydrothiolation. Again, this is in contrast to the observed

efﬁciency of these complexes as catalysts for hydroamination

(Table 4 above). These results further showed that a small change

in the ligand can alter the catalytic efﬁciency of the corresponding

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Table 5 Efﬁciency of cationic iridium complexes with bidentate phosphine-imidazolyl ligands [Ir(ImP2)(CO)₂]BPh₄(7), [Ir(ImP1a)(CO)₂]BPh₄(8a) and

[Ir(ImP1b)(CO)₂]BPh₄(8b) (1.0 mol%) as catalysts for the addition of thiophenol to alkynes in CDCl₃

Product conversion (%)

Alkyne

Catalyst

Time/h

anti-Mar. (E/Z)

Mar.

Phenyl acetylene^a

[Ir(ImP2)(CO)₂]BPh₄(7)

[Ir(ImP1a)(CO)₂]BPh₄(8a)

[Ir(ImP1b)(CO)₂]BPh₄(8b)

[Ir(ImP2)(CO)₂]BPh₄(7)

[Ir(ImP1a)(CO)₂]BPh₄(8a)

[Ir(ImP1b)(CO)₂]BPh₄(8b)

[Ir(ImP2)(CO)₂]BPh₄(7)

[Ir(ImP1a)(CO)₂]BPh₄(8a)

[Ir(ImP2)(CO)₂]BPh₄(7)

[Ir(ImP1a)(CO)₂]BPh₄(8a)

74.0

17.0

18.0

24.0

26.0

74.0

21.0

23.0

20.0

16.0

92 (26/74)

93 (26/74)

93 (22/78)

18^c

0

Propargyl alcohol^b

27 (70/30)

4^d

6^c

1-Pentyne^e

27 (53/47)

14 (33/67)

5 (60/40)

19 (92/8)

0

(Trimethylsilyl)acetylene^f

^aReactions were conducted at room temperature. ^bReactions were conducted at 55 ^◦C. ^cProducts resulting from intermolecular addition of OH to the

terminal alkynes were also observed; and a complicated mixture of products was obtained. ^dConversion of th_◦e allylic alcohol product to the corresponding

aldehyde was also observed see reference 29 for more detailed discussion. ^eReactions were conducted at 40 C. ^fReactions were conducted at 55 ^◦C.

metal complexes. A correlation between ligand variation and

catalytic reactivity for either hydroamination or hydrothiolation

needs further investigation.

complexes for the cyclisation of 4-pentyn-1-amine is: 8b > 7 > 8a

while the opposite trend is observed in the catalysed hydrothiol-

ation reaction: 8a > 7 > 8b.

Conclusions

Experimental

A series of novel rhodium(I) and iridium(I) complexes with biden-

tate phoshine-imidazolyl ligands [M(ImP)(COD)]BPh₄(M = Rh,

ImP = ImP2, 3; ImP1a, 4a and ImP1b, 4b; and M = Ir, ImP =

ImP2, 5; ImP1a, 6a; ImP1b, 6b), [Ir(ImP)(CO)₂]BPh₄(ImP =

ImP2, 7; ImP1a, 8a; ImP1b, 8b), [Rh(ImP1b)(CO)₂]BPh₄(10b)

and [M(ImP)(CO)Cl] (M = Rh, ImP = ImP2, 11 and ImP1b,

12; and M = Ir, ImP = ImP2, 13 and ImP1b, 14), have been

synthesised and fully characterised. The solid state structures of 3,

6a, 11 and 12 were determined by single crystal X-ray diffraction.

The solid state structures of [Rh(ImP2)(COD)]BPh₄(3) and

[Ir(ImP1a)(COD)]BPh₄(6a) show a slightly distorted square pla-

nar coordination around the metal centres. The cationic complexes

[Ir(ImP)(CO)₂]BPh₄(ImP = ImP2, 7; ImP1a, 8a and ImP1b,

8b) were synthesised by the displacement of COD by carbon

monoxide from 5, 6a and 6b respectively. The analogous reaction

with rhodium complexes resulted in the successful preparation

of [Rh(ImP1b)(CO)₂]BPh₄(10b); the other expected rhodium

complexes [Rh(ImP2)(CO)₂]BPh₄(9) and [Rh(ImP1a)(CO)₂]BPh₄

(10a) are too unstable in solution to be spectroscopically charac-

terised.

The efﬁciency of a number of rhodium and iridium complexes

with phosphine-imidazolyl ligands as catalysts for the cyclisation

of 4-pentyn-1-amine was only moderate. The cationic complexes

were more effective than their analogous neutral complexes

[M(ImP2)(CO)Cl] (M = Rh, 11; Ir, 12) for this transformation.

The cationic complexes [Ir(ImP)(CO)₂]BPh₄(7–8b) were, however,

less effective when compared with the analogous complex with

phosphine-pyrazolyl ligand [Ir(PyP)(CO)₂]BPh₄for the catalysed

addition of thiophenol to a range of terminal alkynes.

General considerations

All manipulations of metal complexes and air sensitive reagents

were carried out using standard Schlenk techniques, or in

a nitrogen-ﬁlled dry box. All solvents were distilled under

an atmosphere of nitrogen or argon. Diethyl ether, tetrahy-

drofuran (THF), n-hexane, n-pentane and benzene were dis-

tilled from sodium/benzophenone ketyl. Dichloromethane was

distilled from calcium hydride. Methanol was distilled from

dimethoxymagnesium. CDCl₃and CD₂Cl₂were dried over cal-

cium hydride and vacuum distilled before use. All compressed

gases were obtained from British Oxygen Company (BOC

gases) and Linde Gas Pty. Ltd. Nitrogen (>99.5%) and carbon

monoxide (>99.5%) were used as supplied without puriﬁcation.

1-Methylimidazole, 1,5-cyclooctadiene (COD), cis-cyclooctene

(COE), sodium ethoxide and sodium tetraphenylborate were

obtained from Aldrich or Lancaster and used without fur-

ther puriﬁcation. Iridium(III) chloride hydrate and rhodium(III)

chloride hydrate were obtained from Precious Metals On-

line PMO P/L and were used without further puriﬁcation.

1,3,2-Dioxathiolane 2,2-dioxide (ethylene glycol cyclic sulfate)

was either synthesised using literature methods⁴⁶or purchased

from Aldrich. [Ir(m-Cl)(COD)]₂,⁴⁷[Rh(m-Cl)(COD)]₂,⁴⁸[Rh(m-

Cl)(CO)₂]₂,⁴⁹[Ir(m-Cl)(COE)₂]₂,⁴⁷diphenylphosphine,⁵⁰[Rh(m-

OEt)(COD)]₂and 4-pentyn-1-amine⁵¹were prepared by liter-

43b

ature methods. Thiophenol, phenylacetylene, propargyl alcohol,

(trimethylsilyl)acetylene, propargyl alcohol and 1-pentyne were

dried by standard methods and degassed via three freeze-pump-

thaw cycles prior to use.

Variation in the length of the carbon linker bridge or the

substituents on the phosphorus donor led to opposing trends

in catalytic efﬁciency in hydroamination and hydrothiolation of

complexes [Ir(ImP2)(CO)₂]BPh₄(7), [Ir(ImP1a)(CO)₂]BPh₄(8a)

and [Ir(ImP1b)(CO)₂]BPh₄(8b). The trend for activity of these

¹H, ³¹P and ¹³C NMR spectra were recorded on Bruker

DPX300 or DMX500 spectrometers, operating at 300 or 500 MHz;

121 MHz (³¹P); 75 or 125 MHz (¹³C). All spectra were recorded

at 298 K unless otherwise speciﬁed. ¹H NMR and ¹³C NMR

chemical shifts were referenced internally to residual solvent

3606 | Dalton Trans., 2009, 3599–3614

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resonances. ³¹P NMR was referenced externally using H₃PO₄

(85% in D₂O) in a capillary. Electrospray mass spectra were

recorded on a Finnigan LQC or a Finnigan Micromass QToF

mass spectrometer. Melting points were recorded using a Mel-

Temp apparatus and are uncorrected. IR spectra were recorded

using an ATI Mattson Genesis Series F.T.I.R. spectrometer

or an Avatar370 FTIR spectrometer. Elemental analyses were

performed by the Campbell Microanalytical Laboratory at the

University of Otago, New Zealand. Complexes were typically

recrystallised from dichloromethane/hexanes before submission

for elemental analyses. Single crystal X-ray structure analyses were

carried out at the X-Ray Crystallography Centre, the University

of Sydney, Australia.

1

ppm. ³¹P{ H} NMR (121 MHz, C₆D₆): d -15.3 ppm. ¹³C{ H}

NMR (75 MHz, C₆D₆,): d 148.0 (d, ³J(P-C) = 15.6 Hz, C2), 138.0

(d, ¹J(P-C) = 12.8 Hz, ipso-C of PPh₂), 132.7 (d, ²J(P-C) = 18.8 Hz,

o-C of PPh₂), 128.7 (s, p-C of PPh₂), 128.6 (d, ³J(P-C) = 6.4 Hz,

m-C of PPh₂), 126.9 (s, C4), 120.5 (s, C5), 32.4 (CH₃), 25.9 (d,

¹J(P-C) = 12.0 Hz, PCH₂), 23.2 (d, J(P-C) = 20.7 Hz, C2CH₂)

2

ppm. IR (KBr disc): n 2967 (w), 1522 (w), 1497 (w), 1478 (w),

1433 (m), 1414 (w), 1278 (m), 1128 (w), 1025 (w), 996 (w), 939 (w),

923 (w), 759 (m), 746 (ms), 732 (s), 699 (s) cm^-1.

Synthesis of 1-methyl-[2-(trimethylsilyl)methyl]imidazole. n-

Butyllithium (1.60 M in hexanes, 32.0 mL, 51.2 mmol) was added

to a solution of 1,2-dimethylimidazole (4.91 g, 50.0 mmol) in

THF (100 mL) at -78 ^◦C. During the addition the temperature

Procedures for catalytic hydroamination²⁸and hydrothiolation²⁹

have been previously reported.

◦

was kept below -75 C and the reaction mixture was stirred for

3 hours at -78 ^◦C. The solution was then transferred slowly using

a cold cannula (wrapped in dry-ice) to a solution of trime_◦thylsilyl

chloride (6.35 mL, 50.0 mmol) in THF (20 mL) at -78 C over

45 minutes. The reaction mixture was then stirred for 30 minutes

at -78 ^◦C. The reaction mixture was then warmed up to room

temperature over 1 hour and the solvent was removed in vacuo to

give an orange liquid. Benzene (75 mL) and water (50 mL) were

added and the aqueous layer was separated, extracted with another

portion of benzene (75 mL). The combined organic layer was dried

over calcium chloride, ﬁltered and the solvent was removed under

vacuum to afford 1-methyl-[2-(trimethylsilyl)methyl]imidazole as

a pale yellow oil (7.25 g, 87%). The compound, with greater than

Synthesis of ligands, rhodium complexes and iridium complexes

Synthesis of 1-methyl-[2-(diphenylphosphino)ethyl]imidazole (1).

n-Butyllithium(1.40 Minhexanes, 7.15mL, 10.0mmol)was added

dropwise to a solution of 1 methylimidazole (0.80 mL, 10.0 mmol)

in tetrahydrofuran (THF, 20 mL) at -78 ^◦C. During the addition,

the temperature was kept below -60 ^◦C and the reaction mixture

was stirred at -75 ^◦C for one hour. The solution obtained was

added dropwise to a solution of 1,3,2-dioxathiolane 2,2-dioxide

(1.24 g, 10.0 mmol) in THF (30 mL) at -78 ^◦C, and the temperature

◦

was kept below -60 C during the addition. A white suspension

1

97% purity as determined by H NMR spectroscopy, was used

formed and the reaction mixture was maintained at -78 ^◦C for

a further 30 minutes. The temperature was then slowly raised to

0 ^◦C over 1 hour.

1

in subsequent reactions without further puriﬁcation. H NMR

(300 MHz, CDCl₃): d 6.87 (d, ³J(H5-H4) = 1.1 Hz, 1H, H4), 6.71

3

(d, J(H5-H4) = 1.1 Hz, 1H, H5), 3.49 (s, 3H, NCH₃), 2.11 (s,

Lithium diphenylphosphide was prepared by the addition of

n-butyllithium (1.40 M in hexanes, 7.15 mL, 10.0 mmol) to a

solution of diphenylphosphine (1.74 mL, 10.0 mmol) at 0 ^◦C. The

resulting solution was stirred at 0 ^◦C for 1 hour before being

transferred slowly into the ﬁnal solution of Step 1 at 0 ^◦C. The

reaction mixture was stirred for 30 minutes at 0 ^◦C, 1 hour at

room temperature and it was then heated at reﬂux under nitrogen

overnight. During this time, the colour of the slurry changed

from orange to yellow then colourless. The solvent was removed

in vacuo giving a pale yellow oil. Deoxygenated water (40 mL)

was added, followed by deoxygenated diethyl ether (100 mL),

the organic layer was separated and washed with deoxygenated

water (2 ¥ 15 mL). The organic layer was dried over anhydrous

magnesium sulfate, ﬁltered and the solvent removed in vacuo. All of

the volatile components were removed under vacuum (1.5 mmHg,

130 ^◦C, 4 hours). The resulting oil was cooled to room temperature

and anhydrous diethyl ether (10 mL) was added to this oil. Slow

evaporation of solvent under an inert atmosphere afforded a

white solid which was collected by ﬁltration, washed with ice

cold diethyl ether (2 ¥ 2 mL) and dried in vacuo. 1-Methyl-[2-

(diphenylphosphino)ethyl]imidazole, ImP2, (1) was collected as

a mildly air sensitive, white waxy solid (2.62 g, 89%), mp 51–

2H, CH₂), 0.08 (s, 9H, Si(CH₃)₃) ppm. ¹³C{ H} NMR (75 MHz,

1

CDCl₃): d 144.7 (C2), 126.3 (C4), 120.2 (C5), 32.5 (NCH₃), 30.7

(CH₂), 1.8 (Si(CH₃)₃) ppm. IR (neat, NaCl plates): n 2956 (w),

1650 (m), 1532 (w), 1507 (m), 1475 (w), 1439 (m), 1414 (m),

1281 (m), 1145 (m), 989 (m), 744 (s), 677 (m) cm^-1.

Synthesis of 1-methyl-[2-(diphenylphosphino)ethyl]imidazole hy-

drobromide, ImP1a·HBr, (2a·HBr). p-Chlororodiphenylpho-

sphine (3.60 mL, 20.0 mmol) was added dropwise over 10 min-

utes to 1-methyl-[2-(trimethylsilyl)-methyl]imidazole (3.37 g,

20.0 mmol) at room temperature. An exothermic_◦reaction took

place and the reaction mixture was heated at 100 C for 6 hours

under nitrogen. All the volatile components were removed in vacuo

(80 ^◦C, 2 mmHg for approximately 2 hours) and the reaction

mixture was cooled to room temperature. Deoxygenated aqueous

hydrobromic acid (2.35 mL, 48 (wt)%, 20.0 mmol) was then added

and the reaction mixture was stirred for further 45 minutes at

room temperature, during which time a white solid formed. Water

was then removed in vacuo and ethanol (12 mL) was added to

dissolve the solid. Diethyl ether was then added to the ethanol

solution until it became slightly cloudy. The solution was cooled

on ice for approximately 30 minutes, the colourless crystalline

solid product formed was collected by ﬁltration, washed with ice

cold ethanol: ether (1:4 (v/v), 4 ¥ 10 mL) and dried in vacuo

(5.23 g, 72%), mp 205–207 ^◦C. Anal. Found: C, 56.52; H, 5.17;

N, 7.70. C₁₇H₁₇N₂P·HBr requires: C, 56.53; H, 5.02; N, 7.76%.

¹H NMR (300 MHz, D₂O): d 7.42–7.32 (m, 10H, CH of PPh₂),

◦

53 C. MS (EI), m/z (%): 295.2 (38) [M + H]⁺, 217.3 (100)

[M - Ph]⁺. HRMS found: 294.1281. C₁₈H₁₉N₂P requires: 294.1286.

Anal. Found: C, 73.41; H, 5.76; N, 9.25. C₁₈H₁₉N₂P requires: C,

73.45; H, 6.18; N, 9.72%. ¹H NMR (300 MHz, C₆D₆): d 7.47–7.42

(m, 4H, o-CH of PPh₂), 7.32–7.28 (m, 6H, m & p-CH of PPh₂), 6.90

(d, ³J(H5-H4) = 1.1 Hz, 1H, H4), 6.70 (d, ³J(H4-H5) = 1.1 Hz, 1H,

H5), 3.37 (s, 3H, CH₃), 2.71 (m, 2H, C2CH₂), 2.52 (m, 2H, PCH₂)

3

7.18 (d, J(H4-H5) = 2.3 Hz, 1H, H5), 7.15 (d, J(H5-H4) =

2

2.3 Hz, 1H, H4), 3.8 (d, J(P-H) = 2.3 Hz, 2H, PCH₂), 3.42 (s,

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Dalton Trans., 2009, 3599–3614 | 3607

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164.3 (q, ¹J(B-C) = 49.1 Hz, ipso-C of BPh₄), 146.9 (d, ³J(P-C) =

5.5 Hz, C2), 136.4 (s, o-C of BPh₄), 133.5 (d, J(P–C) = 11.3 Hz,

o or m-C of PPh₂), 131.9 (s, p-C of PPh₂), 129.3 (d, J(P–C) =

10.5 Hz, m or o-C of PPh₂), 128.5 (d, ¹J(P-C) = 57.0 Hz, ipso-C

of PPh₂), 125.7 (q, ⁴J(B-C) = 2.9 Hz, m-C of BPh₄), 125.3 (s, C4),

122.6 (s, C5), 121.9 (s, p-C of BPh₄), 93.7 (d, ²J(P-C) = 12.4 Hz,

CH (trans to P) of COD), 60.6 (s, CH (cis to P) of COD), 34.1

1

3H, NCH₃) ppm. ³¹P{ H} NMR (121 MHz, D₂O): d -14.5 ppm.

¹³C{ H} NMR (75 MHz, D₂O): d 143.3 (d, ²J(P-C) = 6.5 Hz, C2),

1

134.1 (d, ¹J(P-C) = 11.6 Hz, ipso-C of PPh₂), 132.5 (d, ²J(P-C) =

19.6 Hz, o-C of PPh₂), 130.1 (s, p-C of PPh₂), 129.0 (d, ³J(P-C) =

7.3 Hz, m-C of PPh₂), 123.1 (s, C5), 117.8 (s, C4), 33.8 (d, ⁴J(P–

1

C) = 3.6 Hz, NCH₃), 24.4 (d, J (P-C) = 21.1 Hz, PCH₂) ppm.

IR (KBr disc): n 3076 (w), 2873 (w), 1599 (m), 1524 (w), 1505 (w),

1484 (w), 1434 (m), 1333 (w), 1279 (m), 1226 (w), 1093 (m),

1028 (w), 929 (m), 851 (w), 841 (m), 823 (m), 772 (w), 748 (s),

734 (s), 691 (s), 661 (m) cm^-1.

3

(s, CH₃), 32.7 (d, J(P-C) = 2.9 Hz, CH₂(trans to P) of COD),

1

29.5 (s, CH₂of COD (cis to P), 21.7 (s, C2CH₂), 20.9 (d, J(P-

C) = 33.4 Hz, PCH₂) ppm. IR (KBr disc): n 3053 (w), 2831 (w),

1579 (w), 1479 (m), 1434 (m), 1424 (w), 1127 (w), 1100 (w), 849 (m),

744 (m), 732 (m), 704 (s), 612 (w) cm^-1.

Synthesis of [2-(diisopropylphosphino)methyl]-1-methylimida-

zole, ImP1b, (2b). p-Chlorodiisopropylphosphine (3.20 mL,

20.0 mmol) was added dropwise to 1-methyl-[2-(trimethylsilyl)-

methyl]imidazole (3.37 g, 20.0 mmol) and the reaction mixture

was heated under nitrogen for 6 hours at 100 ^◦C. All the volatile

by-products were removed under vacuum to give the crude

product as a pale brown oil. [2-(diisopropyl-phosphino)methyl]-1-

methylimidazole (2b) was obtained as colourless oil by vacuum

distillation of the _◦crude product (3.15 g, 74%), bp 80 ^◦C/

Synthesis of [Ir(ImP1a)(COD)]BPh₄(6a). Methanol (10 mL)

was added to

a

mixture of 1-methyl-[2-(diphenylpho-

sphino)methyl]imidazole hydrobromide (2a.HBr, 0.181 g,

0.501 mmol) and sodium ethoxide (95%, 0.051 g, 0.712 mmol)

and the reaction mixture was stirred for 10 minutes at room

temperature until all of the solids dissolved. The solution was

added slowly to a suspension of [Ir(m-Cl)(COD)₂]₂(0.170 g,

0.253 mmol) in methanol (10 mL) over 10 minutes and the reaction

mixture was stirred for a further 15 minutes at room temperature.

Sodium tetraphenylborate (0.188 g, 0.549 mmol) was added and

an orange solid formed. The reaction mixture was stirred for a

further 30 minutes at room temperature. Approximately 25% of

methanol was removed in vacuo and the solid was collected by

ﬁltration, washed with methanol (4 ¥ 3 mL), n-pentane (3 ¥ 5 mL)

and dried in vacuo (0.318 g, 71%), mp 176–179 ^◦C (decomp.).

ESI-MS (MeOH/dcm), m/z (%): ES⁺, 581.9 (100) [M]⁺; ES^-,

1

1.5 mmHg; lit. 80 C/1 mmHg. H NMR (300 MHz, CDCl₃):

d 6.69 (s, 1H, H4), 6.61 (s, 1H, H5), 3.51 (s, 3H, NCH₃), 2.72

(s, 2H, CH₂), 1.71–1.61 (m, ³J(CH-CH₃) = 7.2 Hz, 2H, 2 ¥

CH(CH₃)₂), 0.92 (dd, ³J(P-H) = 12.1 Hz, ³J(CH-CH₃) = 7.2 Hz,

6H, CH(CH₃)(CH₃)), 0.89 (dd, ³J(P-H) = 13.9 Hz, ³J(CH-CH₃) =

7.2 Hz, 6H, CH(CH₃)(CH₃)) ppm. ³¹P{ H} NMR (121 MHz,

1

CDCl₃): d 0.8 ppm. ¹³C{ H} NMR (75 MHz, CDCl₃): d 145.5 (d,

1

²J(P-C) = 6.9 Hz, C2), 126.6 (s, C4), 120.5 (s, C5), 33.1 (d, ⁴J(P-

1

C) = 9.5 Hz, NCH₃), 23.3 (d, J(P-C) = 14.2 Hz, CH(CH₃)₂),

1

2

-

21.0 (d, J(P-C) = 22.5 Hz, CH₂), 19.2 (d, J(P-C) = 14.2 Hz,

319.7 (100) BPh₄. Anal. Found: C, 62.00; H, 5.22; N, 3.19.

2

CH(CH₃)(CH₃)), 18.5 (d, J(P-C) = 14.2 Hz, CH(CH₃)(CH₃))

C₄₉H₄₉BIrN₂P·0.75CH₂Cl₂requires: C, 62.01; H, 5.28; N, 3.16%.

¹H NMR (300 MHz, CD₂Cl₂): d 7.60–7.47 (m, 10H, CH of PPh₂),

7.31 (br m, 8H, o-CH of BPh₄), 6.96 (m, 8H, m-CH of BPh₄),

ppm.

Synthesis of [Ir(ImP2)(COD)]BPh₄(5).

A solution of

3

6.86 (d, J(H5-H4) = 1.9 Hz, 1H, H4), 6.82 (m, 4H, p-CH of

1-methyl-[2-(diphenylphosphino)ethyl]imidazole (1, 0.404 g,

1.37 mmol) in methanol (15 mL) was added slowly to a sus-

pension of [Ir(m-Cl)(COD)]₂(0.465 g, 0.692 mmol) in methanol

(25 mL) over 15 minutes and the reaction mixture was stirred for

45 minutes at room temperature. Sodium tetraphenylborate

(0.470 g, 1.37 mmol) was added and an orange precipitate formed.

The reaction mixture was stirred for another hour at room

temperature, the solvent was evaporated under reduced pressure to

approximately 25 mL. The orange solid product was collected by

ﬁltration, washed with methanol (3 ¥ 5 mL), n-pentane (3 ¥ 7 mL)

and dried under vacuum. The crude product was recrystallised

by layering n-hexane (55 mL) over a dichloromethane solution

(25 mL) of the crude product and allowing to stand at 4 ^◦C

overnight. [Ir(ImP2)(COD)]BPh₄(5) was collected as a dark

orange crystalline solid by ﬁltration and dried under vacuum

(1.15 g, 92%), mp 165–167 ^◦C (decomp.). ESI-MS (MeOH/dcm),

BPh₄), 6.82 (1H, H5) (last two signals overlap), 5.26 (br m, 2H,

CH (trans to P) of COD)), 3.45 (br m, 2H, CH (cis to P) of COD),

3.26 (d, ²J(P-H) = 10.6 Hz, 2H, PCH₂), 3.22 (s, 3H, NCH₃), 2.29

(br m, 4H, 4 x CHH of COD), 2.09 (br m, 4H, 4 x CHH of COD)

1

ppm. ³¹P{ H} NMR (121 MHz, CD₂Cl₂): d 29.2 ppm. ¹³C{ H}

1

NMR (75 MHz, CD₂Cl₂): d 164.6 (q, J(B-C) = 49.4 Hz, ipso-

2

C of BPh₄), 156.4 (d, J(P-C) = 16.0 Hz, C2), 136.4 (s, o-C of

BPh₄), 133.8 (d, J(P - C) = 12.4 Hz, o or m-C of PPh₂), 132.8 (d,

⁴J(P-C) = 2.2 Hz, p-C of PPh₂), 130.0 (d, J(P-C) = 11.6 Hz, m or

o-C of PPh₂), 128.9 (d, ¹J(P-C) = 53.0 Hz, ipso-C of PPh₂), 126.2

(q, ³J(B–C) = 2.2 Hz, m-C of BPh₄), 125.6 (s, C4), 124.2 (s, C5),

122.3 (s, p-C of BPh₄), 93.7 (d, ²J(P-C) = 11.6 Hz, C (trans to P) of

COD), 63.1 (s, C (cis to P) of COD)), 36.2 (s, NCH₃), 33.2 (d, ³J(P-

C) = 3.6 Hz, CH₂(trans to P) of COD), 30.0 (d, ¹J(P-C) = 31.2 Hz,

PCH₂), 29.9 (d, ³J(P-C) = 2.2 Hz, CH₂(cis to P) of COD) ppm.

IR (KBr disc): n 3052 (w), 2958 (w), 1579 (w), 1558 (w), 1479 (w),

1435 (w), 1385 (w), 1127 (w), 1101 (w), 1031 (w), 734 (s), 705 (s),

612 (m) cm^-1.

m/z (%): ES⁺, 595.2 (100) [M]⁺; ES^-, 319.7 (100) BPh₄. Anal.

-

Found: C, 62.37; H, 5.52; N, 3.23. C₅₀H₅₁BIrN₂P·075CH₂Cl₂

requires: C, 62.35; H, 5.41; N, 2.87%. ¹H NMR (300 MHz, CDCl₃):

d 7.53–7.40 (m, 18H, o-CH of BPh₄(8H) and CH of PPh₂(10H)),

6.96 (m, 8H, m-CH of BPh₄), 6.82 (m, 4H, p-CH of BPh₄), 6.76 (d,

Synthesis of [Ir(ImP1b)(COD)]BPh₄(6b). A solution of [2-

(diisopropylphosphino)methyl]-1-methylimidazole (2b, 0.313 g,

1.47 mmol) in methanol (12 mL) was added slowly to a suspension

of [Ir(m-Cl)(COD)]₂(0.495 g, 0.737 mmol) in methanol (20 mL)

and the resulting orange solution was stirred at room temperature

for 45 minutes. Sodium tetraphenylborate (0.504 g, 1.47 mmol)

was added and the reaction mixture was stirred for another hour

³J(H5-H4) = 1.9 Hz, 1H, H4), 6.5 (d, J(H4-H5) = 1.9 Hz, 1H,

3

H5), 5.07 (br s, 2H, CH (trans to P) of COD), 2.92 (br s, 2H, (cis

to P) CH of COD), 2.76 (s, 3H, CH₃), 2.32–1.88 (m, 12H, CH₂

of COD (8H), PCH₂(2H) and C2CH₂(2H)) ppm. ³¹P{ H} NMR

1

(121 MHz, CDCl₃): d 12.3 ppm. ¹³C{ H} (75 MHz, CDCl₃): d

1

3608 | Dalton Trans., 2009, 3599–3614

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©

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at room temperature. About half of the solvent was removed under

reduced pressure and the orange solid product was collected by

ﬁltration, washed with methanol (3 ¥ 4 mL), n-pentane (2 ¥ 6 mL)

and dried in vacuo (1.03 g, 84%), mp 164–166 ^◦C (decomp.).

ESI-MS (MeOH/dcm), m/z (%): ES⁺, 513.2/511.3/509.2/507.2

³J(B-C) = 1.5 Hz, o-C of BPh₄), 133.2 (d, J(P-C) = 11.3 Hz, o or

m-C of PPh₂), 131.6 (d, ⁴J(P-C) = 2.2 Hz, p-C of PPh₂), 130.8 (d,

¹J(P-C) = 45.4 Hz, ipso-C of PPh₂), 129.3 (d, J(P-C) = 10.2 Hz,

3

o or m-C of PPh₂), 125.7 (q, J(B-C) = 2.5 Hz, m-C of BPh₄),

125.6 (s, C4), 122.3 (s, C5), 121.8 (s, p-C of BPh₄), 105.6 (br m,

(66/100/76/24) [M]⁺; ES^-, 319.6 (100) BPh₄. Anal. Found: C,

¹J(Rh-C) = 10.2 Hz, C (trans to P) of COD), 75.8 (br d, J(Rh-

-

1

61.63; H, 6.48, N, 3.58. C₄₃H₅₃BIrN₂P requires: C, 62.08; H, 6.42,

N, 3.37%. ¹H NMR (300 MHz, CDCl₃): d 7.42 (m br, 8H, o-CH of

BPh₄), 7.00 (m, 8H, m-CH of BPh₄), 6.86 (m, 4H, p-CH of BPh₄),

6.6 (d, ³J(H5-H4) = 1.9 Hz, 1H, H4), 6.47 (s, ³J(H4-H5) = 1.9 Hz,

1H, H5), 4.93 (m br, 2H, CH (trans to P) of COD), 3.91 (m br, 2H,

CH (cis to P) of COD)), 2.78 (s, 3H, NCH₃), 2.27 (d, ²J(P-C) =

9.0 Hz, 2H, C2CH₂), 2.35–2.03 (m, 8H, 2 ¥ CH₂(cis to P) of COD

(4 H), 2 ¥ CHH (trans to P) of COD (2H) and 2 ¥ CH(CH₃)₂(2H)),

1.90 (m, 2H, 2 ¥ CHH (trans to P) of COD)), 1.14 (dd, ³J(P-H) =

17.0 Hz, ³J(CH-CH₃) = 7.2 Hz, 6H, CH(CH₃)(CH₃))), 1.00 (dd,

³J(P-H) = 15.5 Hz, ³J(CH-CH₃) = 6.8 Hz, 6H, CH(CH₃)(CH₃)₂))

C) = 10.5 Hz, C (cis to P) of COD), 33.8 (s, CH₃), 32.4 (s, CH₂

1

of COD), 28.8 (s, CH₂of COD), 28.2 (s, C2CH₂), 21.8 (d, J(P-

C) = 30.2 Hz, PCH₂) ppm. IR (KBr disc): n 3053 (w), 2831 (w),

1579 (w), 1479 (m), 1434 (m), 1424 (w), 1127 (w), 1100 (w), 849 (m),

744 (m), 732 (m), 704 (s), 612 (w) cm^-1.

Synthesis of [Rh(ImP1a)(COD)]BPh₄(4a). A solution of

1-methyl-[2-(diphenylphosphino)methyl]imidazole hydrobromide

(2a·HBr, 0.094 g, 0.260 mmol) in methanol (6 mL) was added

dropwise over 5 minutes to a suspension of [Rh(m-OEt)(COD)]₂

(0.069 g, 0.135 mmol) in methanol (5 mL) and the reaction

mixture was stirred for 20 minutes at room temperature. Sodium

tetraphenylborate (0.093 g, 0.270 mmol) was added and a bright

yellow precipitate formed. The reaction mixture was stirred for

20 minutes at room temperature and approximately 25% of

methanol was removed in vacuo. The solid product was collected by

ﬁltration, washed with methanol (3 ¥ 2.0 mL), n-pentane (3 ¥ 4 mL)

and dried under vacuum (0.148 g, 70%), mp 167–169 ^◦C (decomp.).

ESI-MS (MeOH/dcm), m/z (%): ES⁺, 492.1/491.0 (100/82) [M]⁺.

Anal. Found: C, 72.13; H, 5.83; N, 3.49. C₄₉H₄₉BN₂PRh requires:

1

ppm. ³¹P{ H} NMR (121 MHz, CDCl₃): d 46.5 ppm. ¹³C{ H}

1

NMR (75 MHz, CDCl₃): d 164.3 (q, J(B-C) = 49.4 Hz, ipso-C

2

of BPh₄), 157.1 (d, J(P-C) = 13.8 Hz, C2), 136.4 (br s, o-C of

3

BPh₄), 125.7 (q, J(B-C) = 2.9 Hz, m-C of BPh₄), 124.3 (s, C4),

123.7 (s, C5), 121.9 (s, p-C of BPh₄), 90.5 (d, ²J(P-C) = 11.5 Hz,

CH (trans to P) of COD), 60.2 (s, CH (cis to P) of COD), 35.6 (s,

NCH₃), 33.6 (d, ³J(P-C) = 2.3 Hz, CH₂(cis to P) of COD), 29.0

(d, ³J(P-C) = 2.3 Hz, CH₂(trans to P) of COD), 25.1 (d, ¹J(P-C) =

27.0 Hz, CH(CH₃)₂), 19.1 (d, ¹J(P-C) = 25.9 Hz, C2CH₂), 18.5 (d,

²J(P-C) = 2.3 Hz, CH(CH₃)(CH₃)), 18.1 (br s, CH(CH₃)(CH₃))

ppm. IR (KBr disc): n 3054 (w), 2950 (w), 1656 (w), 1558 (m),

1479 (w), 1425 (w), 1249 (w), 1031 (w), 733 (s), 705 (s) cm^-1.

1

C, 72.60; H, 6.09; N, 3.46%. H NMR (300 MHz, CD₂Cl₂): d

7.64–7.54 (m, 6H, o & p-CH of PPh₂), 7.51–7.45 (m, 4H, m-CH

of PPh₂), 7.31 (br m, 8H, o-CH of BPh₄), 6.98 (m, 8H, m-CH of

BPh₄), 6.84 (m, 4H, p-CH of BPh₄), 6.79 (d, ³J(H4-H5) = 1.9 Hz,

3

1H, H5), 6.65 (d, J(H5-H4) = 1.9 Hz, 1H, H4), 5.51 (very br,

Synthesis of [Rh(ImP2)(COD)]BPh₄(3).

A solution of

2H, CH (trans to P) of COD), 3.80 (very br, 2H, CH (cis to P)

1-methyl-[2-(diphenylphosphino)ethyl]imidazole, (1, 0.181 g,

0.604 mmol) in methanol (5 mL) was added slowly into a solution

of [Rh(m-Cl)(COD)]₂(0.154 g, 0.312 mmol) in methanol (15 mL)

under nitrogen. The colour of the solution changed from orange to

yellow, all the [Rh(m-Cl)(COD)]₂solid dissolved and the reaction

mixture was stirred for a further 30 minutes at room temperature.

Sodium tetraphenylborate (0.208 g, 0.608 mmol) was added, a

bright yellow precipitate formed and the reaction was stirred for a

further 45 minutes at room temperature. The solvent was reduced

in vacuo to ca. 5 mL. The product was collected by ﬁltration,

washed with methanol (3 ¥ 3.5 mL), n-pentane (3 ¥ 5 mL) and

dried in vacuo. The crude product was recrystallised by layering a

dichloromethane (12 mL) solution of 3 with n-hexane (40 mL) and

allowing to stand at 4 ^◦C overnight. [Rh(ImP2)(COD)]BPh₄(3)

was collected as a bright yellow needle-like crystals (0.450 g, 90%),

mp 166–168 ^◦C (decomp.). ESI-MS (MeOH/dcm), m/z (%): ES⁺,

2

of COD), 3.28 (d, J(P-H) = 10.2 Hz, 2H, PCH₂), 3.26 (s, 3H,

NCH₃), 2.45 (br m, 4H, 4 ¥ CHH of COD), 2.23 (br m, 4H,

1

4 ¥ CHH) ppm. ³¹P{ H} NMR (121 MHz, CD₂Cl₂): d 36.5 (d,

1

¹J(Rh-P) = 154.4 Hz) ppm. ¹³C{ H} NMR (75 MHz, CD₂Cl₂): d

164.5 (q, ¹J(B-C) = 49.4 Hz, ipso-C of BPh₄), 151.4 (dd, ²J(P-C) =

2

19.6 Hz, J(Rh-C) = 2.9 Hz, C2), 136.4 (q, J (B-C) = 1.5 Hz,

2

o-C of BPh₄), 133.5 (d, J (P-C) = 12.4 Hz, o-C of PPh₂), 132.5

(d, ⁴J(P-C) = 2.2 Hz, p-C of PPh₂), 130.1 (d, ³J(P-C) = 10.5 Hz,

m-C of PPh₂), 129.6 (dd, ¹J(P-C) = 44.3 Hz, ²J(Rh-C) = 1.4 Hz,

ipso-C of PPh₂), 128.8 (s, p-C of BPh₄), 126.2 (q, ³J(B-C) = 2.9 Hz,

m-C of BPh₄), 125.7 (s, C4), 123.8 (s, C5), 122.3 (s, p-C of BPh₄),

ca. 105 (very br, CH (trans to P) of COD), ca.75 (very br, CH

(cis to P) of COD), 35.9 (s, NCH₃), 30.7 (br, CH₂of COD), 30.1

1

(d, J(P-C) = 25.4 Hz, PCH₂), 29.3 (br, CH₂of COD) ppm. H

and ¹³C resonances of COD, in particular ¹³C resonances, are very

1

broad due to ﬂuxionality. H NMR (500 MHz, CD₂Cl₂, 220 K):

-

505.1 (100) [M]⁺; ES^-, 319.6 (100) BPh₄. Anal. Found: C, 68.66;

d 7.5–7.52 (m, 6H, o & p-CH of PPh₂), 7.47–7.44 (m, 4H, m-CH

of PPh₂), 7.26 (br s, 8H, o-CH of BPh₄), 6.95 (m, 8H, m-CH of

BPh₄), 6.82 (m, 4H, p-CH of BPh₄), 6.80 (s, 1H, H5), 6.61 (s, 1H,

H4), 5.51 (br s, 2H, CH (trans to P) of COD), 3.64 (br s, 2H, CH

(cis to P) of COD), 3.13 (d, ²J(P-H) = 10.1 Hz, 2H, PCH₂), 3.31

(s, 3H, NCH₃), 2.40 (br m, 4H, 4 ¥ CHH of COD), 2.19 (br m,

4H, 4 ¥ CHH of COD) ppm. IR (KBr disc): n 3055 (w), 2957 (w),

1579 (w), 1558 (w), 1480 (w), 1426 (w), 1386 (w), 1128 (w), 735 (m),

706 (m) cm^-1.

H, 5.88; N, 3.24. C₅₀H₅₁BN₂PRh·0.75CH₂Cl₂requires: C, 68.42;

H, 5.96; N, 3.15%. ¹H NMR (300 MHz, CDCl₃): d 7.50–7.39 (m,

18H, CH of PPh₂(10H) and o-CH of BPh₄(8H)), 6.97 (m, 8H, m-

CH of BPh₄), 6.83 (m, 4H, p-CH of BPh₄), 6.50 (d, ³J(H5-H4) =

1.5 Hz, 1H, H4), 6.45 (d, ³J(H4-H5) = 1.5 Hz, 1H, H5), 5.40 (br s,

2H, CH (trans to P) of COD), 3.24 (br s, 2H, CHs (cis to P) of

COD), 2.82 (s, 3H, CH₃), 2.42–1.97 (m, 12H, CH₂of COD (8H),

1

PCH₂(2H) and C2CH₂(2H)) ppm. ³¹P{ H} NMR (121 MHz,

1

CDCl₃): d 26.7 (d, J(Rh-C) = 151.7 Hz) ppm. ¹³C{ H} NMR

(75 MHz, CDCl₃): d 164.4 (q, ¹J(B-C) = 49.4 Hz, ipso-C of BPh₄),

Synthesis of [Rh(ImP1b)(COD)]BPh₄(4b). A solution of [2-

(diisopropylphosphino)methyl]-1-methylimidazole (2b, 0.338 g,

3

2

146.5 (dd, J(P-C) = 1.5 Hz, J(Rh-C) = 6.9 Hz, C2), 136.4 (q,

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1.47 mmol) in methanol (15 mL) was added dropwise to a sus-

pension of [Rh(m-Cl)(COD)]₂(0.393 g, 0.797 mmol) in methanol

(25 mL) and the resulting yellow solution was stirred at room

temperature for 30 minutes. Sodium tetraphenylborate (0.548 g,

1.60 mmol) was added and the reaction mixture was stirred for

further 30 minutes at room temperature. The solvent was reduced

in vacuo to approximately 5 mL. The yellow solid was collected

by ﬁltration, washed with methanol (3 ¥ 5 mL), n-pentane (3 ¥

6 mL) and dried under vacuum (1.08 g, 91%), mp 160–161 ^◦C (de-

comp.). ESI-MS (MeOH/dcm), m/z (%): ES⁺, 424.1/423.1/421.1

122.4 (s, p-C of BPh₄), 34.8 (s, CH₃), 21.2 (d, ¹J(P-C) = 34.5 Hz,

PCH₂), 21.1 (s, C2CH₂) ppm. IR (KBr disc): n 2100 (s, CO), 2025

(s, CO) cm^-1.

Synthesis of [Ir(ImP1a)(CO)₂]BPh₄(8a). n-Hexane (10 mL)

and methanol (1 mL) were added to a ﬂask containing

[Ir(ImP1a)(COD)]BPh₄(6a) (0.075 g, 0.083 mmol). The suspen-

sion was degassed via three freeze-pump-thaw cycles and the

reaction mixture was placed under an atmosphere of carbon

monoxide for 2 hours 30 minutes at room temperature, during

which time the colour of the solid changed from orange-red

to orange-yellow. The solid product was collected by ﬁltration,

washed with methanol (3 ¥ 0.6 mL), n-pentane (3 ¥ 4 mL) and

dried in vacuo (0.053 g, 83%), mp 136–138 ^◦C (decomp.). ESI-MS

(MeOH/dcm), m/z (%): ES⁺, 519.1 (25) [M - CO + H₂O]⁺, 517.1

(17), [M - CO + H₂O]⁺, 501.07/499.07 (9/5) [M - CO]⁺. Anal.

Found: C, 60.44; H, 4.40, N, 3.43. C₄₃H₃₇BIrN₂O₂P requires: C,

60.92; H, 4.40, N, 3.30%. ¹H NMR (500 MHz, CD₂Cl₂): d 7.65–

7.55 (m, 10H, CH of PPh₂), 7.29 (br s, 8H, o-CH of BPh₄), 7.14

(23/100/65) [M]⁺; ES^-, 319.6 (100) BPh₄. Anal. Found: C, 66.91,

-

H, 6.55, N, 3.74. C₄₃H₅₃BN₂PRh.0.5CH₂Cl₂requires: C, 66.55; H,

1

6.93; N, 3.57%. H NMR (300 MHz, CDCl₃): d 7.42 (br m, 8H,

o-CH of BPh₄), 7.01 (m, 8H, m-CH of BPh₄), 6.87 (m, 4H, p-CH

of BPh₄), 6.48 (d, ³J(H4-H5) = 1.5 Hz, 1H, H5), 6.37 (d, ³J(H5-

H4) = 1.5 Hz, 1H, H4), 5.27 (br s, 2H, CH (trans to P) of COD),

4.23 (br s, 2H, CH (cis to P) of COD), 2.90 (s, 3H, NCH₃), 2.36 (d,

²J(P-H) = 9.4 Hz, 2H, C2CH₂), 2.45-2.06 (br, 8H, CH₂of COD),

2.07 (m, 2H, 2 x CH(CH₃)₂), 1.16 (dd, ³J(P-H) = 16.6 Hz, ³J(CH-

CH₃) = 7.2 Hz, 6H, CH(CH₃)(CH₃)), 1.07 (dd, ³J(P-H) = 15.1 Hz,

3

(s, 1H, H4/H5), 6.92 (t, J = 7.5 Hz, 8H, m-CH of BPh₄), 6.82

(s, 1H, H5/H4), 6.80 (t, ³J = 7.5 Hz, 4H, p-CH of BPh₄), 3.09 (s,

1

³J(CH-CH₃) = 7.2 Hz, 6H, CH(CH₃)(CH₃)) ppm. ³¹P{ H} NMR

2

1

NCH₃), 3.08 (d, J(P-H) = 14.5 Hz, PCH₂) ppm. ³¹P{ H}NMR

(202 MHz, CD₂Cl₂): d 34.2 ppm. IR (KBr disc): n 2089 (s, CO),

2017 (s, CO) cm^-1.

1

(121 Hz, CDCl₃): d 53.5 (d, ¹J(Rh-P) = 148.0 Hz) ppm. ¹³C{ H}

1

NMR (75 MHz, CDCl₃): d 164.3 (q, J(B-C) = 49.4 Hz, ipso-C

2

of BPh₄), 152.3 (d, J(P-C) = 19.3 Hz, C2), 136.4 (s br, o-C of

3

BPh₄), 125.7 (q, J(B-C) = 2.6 Hz, m-C of BPh₄), 124.3 (s, C4),

Synthesis of [Ir(ImP1b)(CO)₂]BPh₄(8b). n-Hexane (16 mL)

and methanol (2 mL) were added into a ﬂask containing

[Ir(ImP1b)(COD)]BPh₄(6b, 0.182 g, 0.219 mmol) under an

atmosphere of nitrogen. The suspension was degassed via three

freeze-pump-thaw cycles and the reaction mixture was placed

under an atmosphere of carbon monoxide for one hour. During

which time the colour of the solid changed from orange to

yellow. The solid product was collected by ﬁltration, washed with

methanol (3 ¥ 1 mL), n-pentane (3 ¥ 3 mL) and dried in vacuo

(0.148 g, 87%), mp 159–161 ^◦C (decomp.). ESI-MS (MeOH/dcm),

m/z, (%): ES⁺, 461.06 (80) [M]⁺, 431.02 (94) [M - CO]⁺. Anal.

Found: C, 56.71; H, 5.56; N, 3.54. C₃₇H₄₁BIrN₂O₂P requires: C,

123.2 (s, C5), 121.8 (s, p-C of BPh₄), 101.9 (br m, CH (trans to P)

of COD)), 74.8 (br m, CH (cis to P) of COD)), 35.3 (s, NCH₃),

32.8 (br s, CH₂(cis to P) of COD)), 28.5 (br s, CH₂(trans to

1

2

P) of COD)), 24.8 (dd, J(P-C) = 21.3 Hz, J(Rh-C) = 1.4 Hz,

1

2

CH(CH₃)₂), 19.5 (d, J(P-C) = 21.0 Hz, C2CH₂), 18.7 (d, J(P-

C) = 3.7 Hz, CH(CH₃)(CH₃)), 18.1 (br s, CH(CH₃)(CH₃)) ppm.

IR (KBr disc): n 3052 (w), 2953 (w), 1579 (w), 1558 (w), 1479 9w),

1425 (w), 1386 (w), 732 (s), 705 (s) cm^-1.

Synthesis of [Ir(ImP2)(CO)₂]BPh₄(7). Methanol (1.5 mL)

and n-hexane (15 mL) were added to a ﬂask containing

[Ir(ImP2)(COD)]BPh₄(5) (0.212 g, 0.232 mmol) under nitrogen.

The suspension was degassed via three freeze-pump-thaw cycles

and the reaction mixture was placed under an atmosphere of

carbon monoxide using a balloon for 3.5 h, during which time

the colour of the suspension changed to yellow-orange. The

solid product was collected by ﬁltration, washed with methanol

(3 ¥ 1 mL), n-pentane (3 ¥ 4 mL) and dried in vacuo (0.180 g,

90%), mp 162–163 ^◦C (decomp.). ESI-MS (MeOH/dcm), m/z

(%): ES⁺, 546.5 (27) [M-CO + MeOH]⁺, 485.2 (100) [M-2CO]⁺;

1

56.99; H, 5.30; N, 3.59%. H NMR (300 MHz, CD₂Cl₂, under

3

CO): d 7.34 (br m, 8H, o-CH of BPh₄), 7.07 (d, J(H5-H4) =

1.9 Hz, 1H, H4), 7.01 (m, 8H, m-CH of BPh₄), 6.86 (m, 4H, p-

CH of BPh₄), 6.78 (d, ³J(H5-H4) = 1.9 Hz, 1H, H4), 3.18 (s, 3H,

NCH₃), 2.65 (d, ²J(P-H) = 10.2 Hz, 2H, CH₂), 2.48 (m, 2H, 2 ¥

CH(CH₃)₂), 1.30 (dd, ³J(P-H) = 18.8 Hz, ³J(CH-CH₃)= 7.2 Hz,

6H, CH(CH₃)(CH₃)), 1.12 (dd, ³J(P-H) = 17.0 Hz, ³J(CH-CH₃) =

1

7.2 Hz, 6H, CH(CH₃)(CH₃)) ppm. ³¹P{ H} NMR (121 MHz,

1

CD₂Cl₂, under CO): d 61.3 ppm. ¹³C{ H} NMR (75 MHz, CD₂Cl₂,

ES^-, 319.5 (100) BPh₄. Anal. Found: C, 61.11; H, 4.66; N, 3.44.

-

under CO): d 179.0 (br, COs exchanging with free CO), 164.6 (q,

¹J(B-C) = 48.9 Hz, ipso-C of BPh₄), 156.4 (d, ²J(P-C) = 13.2 Hz,

C2), 135.5 (br q, ²J(B-C) = 1.4 Hz, o-C of BPh₄), 131.2 (d, ³J(P-

C) = 1.7 Hz, C4), 126.3 (q, ³J(B-C) = 2.9 Hz, m-C of BPh₄), 125.1

(s, C5), 122.4 (br s, p-C of BPh₄), 36.7 (s, NCH₃), 26.2 (d, ¹J(P-C) =

31.6 Hz, CH(CH₃)₂), 19.2 (d, ²J(P-C) = 2.3 Hz, CH(CH₃)(CH₃)),

C₃₄H₃₉BIrN₂O₂P requires: C, 61.32; H, 4.56; N, 3.25%. ¹H NMR

(300 MHz, CD₂Cl₂): d 7.64–7.54 (m, 10H, CH of PPh₂), 7.32 (br s,

8H, o-CH of BPh₄), 7.2 (s, ³J(H5-H4) = 1.9 Hz, 1H, H4), 6.95 (m,

8H, m-CH of BPh₄), 6.82 (m, 4H, p-CH of BPh₄), 6.77 (d, ³J(H4-

H5) = 1.9 Hz, 1H, H5), 3.12 (s, CH₃), 2.31 (m, 2H, C2CH₂),

1

2.13 (m, 2H, PCH₂) ppm. ³¹P{ H} NMR (121 MHz, CD₂Cl₂): d

1

2

19.0 (d, J(P-C) = 28.5 Hz, CH₂), 18.6 (d, J(P-C) = 1.4 Hz,

CH(CH₃)(CH₃)) ppm. IR (KBr disc): n 2079 (s, CO), 2012 (s,

CO) cm^-1.

1

14.0 ppm. ¹³C{ H} NMR (75 MHz, CD₂Cl₂): d resonances from

1

COs were not observed, 164.6 (q, J(B-C) = 48.6 Hz, ipso-C of

3

BPh₄), 147.9 (d, J(P-C) = 5.8 Hz, C2), 136.5 (s, o-C of BPh₄),

134.5 (s, C4), 134.0 (d, J(P-C) = 11.5 Hz, o or m-C of PPh₂),

Synthesis of [Rh(ImP1b)(CO)₂]BPh₄(10b). n-Hexane (12 mL)

and methanol (1.2 mL) were added into a ﬂask containing

[Ir(ImP1b)(COD)]BPh₄(4b, 0.225 g, 0.316 mmol) under an

atmosphere of nitrogen. The suspension was degassed via three

4

133.5 (d, J(P-C) = 2.3 Hz, p-C of PPh₂), 130.3 (d, J(P - C) =

11.5 Hz, m or o-C of PPh₂), 128.2 (d, ¹J(P-C) = 60.6 Hz, ipso-C

of PPh₂), 126.2 (q, ³J(B-C) = 2.6 Hz, m-C of BPh₄), 123.9 (s, C5),

3610 | Dalton Trans., 2009, 3599–3614

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freeze-pump-thaw cycles and then placed under an atmosphere of

carbon monoxide using a balloon for 3 hours at room temperature.

The pale yellow solid product was collected by ﬁltration, washed

with methanol (3 ¥ 1mL), n-pentane (3 ¥ 7 mL) and dried in vacuo

(0.182 g, 87%), mp 122–124 ^◦C (decomp). ESI-MS (MeOH/dcm),

m/z (%): ES⁺, 343.0 (23) [M - CO]⁺, 301.1 (100) [M- -CO - iPr]⁺;

monoxide for 5 minutes, all the [Ir(m-Cl)(COE)₂]₂dissolved and

a yellow green solution formed almost immediately. [2-(Diiso-

propylphosphino)methyl]-1-methylimidazole (2b, 0.222 g,

1.046 mmol) in acetronitrile (15 mL) was added dropwise over

15 minutes and the reaction mixture was stirred for further

15 minutes at room temperature. The solution was ﬁltered to

remove any undissolved solid and the solvent was removed under

vacuum until about 2 mL of solvent was left. The yellow solid

that formed was collected by ﬁltration, washed with acetronitrile

(2 ¥ 1.5 mL), n-pentane (3 ¥ 5mL) and dried in vacuo giving

the product as a yellow solid (0.483 g, 73%); mp 226–228 ^◦C

(decomp). ESI-MS (MeOH/dcm), m/z (%): ES⁺, 433.1 (27) [M -

Cl]⁺. Anal. Found: C, 31.27; H, 4.79; N, 5.51. C₁₂H₂₁ClIrN₂OP

requires: C, 30.80; H, 4.52; N, 5.99%. ¹H NMR (300 MHz,

CD₂Cl₂): d 7.59 (d, ³J(H5-H4) = 1.9 Hz, 1H, H4), 6.89 (d, ³J(H4-

ES^-, 319.48 (100) BPh₄. Anal: Found: C, 64.36; H, 6.17; N, 3.97.

-

C₃₇H₄₁BN₂O₂PRh requires: C, 64.37; H, 5.99; N, 4.06%. ¹H NMR

(500 MHz, CD₂Cl₂): d 7.36 (br m, 8H, o-CH of BPh₄), 7.01 (m, 8H,

m-CH of BPh₄), 6.87 (m, 5H, p-CH of BPh₄& H4), 6.78 (s, 1H,

H5), 3.21 (s, 3H, NCH₃), 2.68 (d, ²J(P-H) = 10.1 Hz, 2H, CH₂),

2.33 (m, 2H, 2 x CH(CH₃)₂), 1.28 (dd, ³J(P-H) = 19.4 Hz, ³J(CH-

CH₃) = 7.2 Hz, 6H, CH(CH₃)(CH₃)), 1.08 (dd, ³J(P-H) = 16.7 Hz,

1

³J(CH-CH₃) = 6.8 Hz, 6H, CH(CH₃)(CH₃)) ppm. ³¹P{ H}NMR

1

(202 MHz, CD₂Cl₂): d 71.7 (d, ¹J(Rh-P) = 119.1 Hz) ppm. ¹³C{ H}

NMR (125 MHz, CD₂Cl₂): d 187.1 (br, CO), 164.6 (q, ¹J(B-C) =

49.2 Hz, ipso-C of BPh₄), 152.5 (d, ²J(P-C) = 16.5 Hz, C2), 136.4

(s, o-C of BPh₄), 130.3 (s, C4), 126.2 (q, ⁴J(B-C) = 2.5 Hz, m-C of

BPh₄), 124.4 (s, C5), 122.4 (s, p-C of BPh₄), 36.4 (s, NCH₃), 25.8 (d,

¹J(P-C) = 27.6 Hz, CH₂), 19.6 (d, ¹J(P-C) = 23.7 Hz, CH(CH₃)₂),

19.2 (d, ²J(P-C) = 3.4 Hz, CH(CH₃)₂), 18.5 (s br, CH(CH₃)₂) 18.3

(d, ¹J(P-C) = 21.6 Hz, P(CH)(CH₃)₂) ppm. IR (KBr disc): n 2092

(s, CO), 2025 (s, CO) cm^-1.

H5) = 1.9 Hz 1H, H5), 3.72 (s, 3H, NCH₃), 2.92 (d, J(P-C) =

2

9.0 Hz, 2H, CH₂), 2.33–2.16 (m, ³J(CH₃-CH) = 7.2 Hz, 2H, 2 ¥

CH(CH₃)₂), 1.24 (dd, ³J(P-H) = 17.7 Hz, ³J(CH-CH₃) = 7.2 Hz,

6H, CH(CH₃)(CH₃), 1.13 (dd, ³J(P-H) = 15.4 Hz, ³J(CH-CH₃) =

1

7.2 Hz, 6H, CH(CH₃)(CH₃) ppm. ³¹P{ H} NMR (121 MHz,

1

CD₂Cl₂): d 56.2 ppm. ¹³C{ H} NMR (75 MHz, CD₂Cl₂): d

2

178.5 (d, J(P-C) = 12.1 Hz, CO), 154.3 (d, J(P-C) = 13.2 Hz,

1

C2), 125.5 (C4), 121.5 (s, C5), 35.8 (s, CH₃), 26.4 (d, J(P-C) =

1

36.8 Hz, CH(CH₃)₂), 20.3 (d, J(P-C) = 26.4 Hz, CH₂), 18.9 (d,

Synthesis of [Ir(ImP2)(CO)Cl] (13). A suspension of [Ir(m-

Cl)(COE)₂]₂(0.521 g, 0.581 mmol) in acetronitrile (35 mL) was

stirred under nitrogen for 10 minutes. The suspension was placed

under an atmosphere of carbon monoxide and the remaining [Ir(m-

Cl)(COE)₂]₂solid dissolved immediately to give a clear yellow

green solution. Carbon monoxide was replaced by nitrogen, and

a solution of 1-methyl-[2-(diphenylphosphino)ethyl]imidazole (1,

0.340 g, 1.16 mmol) in acetonitrile (15 mL) was added dropwise

over 15 minutes into the iridium carbonyl precursor solution.

During the addition, the colour of the solution changed to yellow

and the reaction mixture was stirred for a further 30 minutes. Most

of the solvent was removed under vacuum until about 2 mL of

acetronitrile was left, the solid product which formed was collected

by ﬁltration, washed with acetonitrile (2 ¥ 1 mL), n-pentane (3 ¥

4 mL) and dried in vacuo (0.472 g, 74%), mp 234–236 ^◦C (decomp).

ESI-MS (MeOH), m/z (%): ES⁺, 546.7 (34) [M - Cl + MeOH]⁺,

515.0 (28) [M - Cl]⁺, 485.2 (31) [M - CO - Cl]⁺. Anal. Found:

C, 39.82; H, 3.62; N, 4.86. C₁₉H₁₉ClIrN₂PO·0.5CH₂Cl₂requires:

²J(P-C)= 2.9 Hz, CH(CH₃)(CH₃)), 18.3 (d, J(P-C) = 1.7 Hz,

2

CH(CH₃)(CH₃)) ppm. IR (KBr disc): n 1946 (s, CO) cm^-1.

Synthesis of [Rh(ImP2)(CO)Cl] (11). 1-Methyl-[2-(diphe-

nylphosphino)ethyl]imidazole (1, 0.213 g, 0.714 mmol) in

methanol (10 mL) was added dropwise into a solution of [Rh(m-

Cl)(CO)₂]₂(0.150 g, 0.386 mmol) in methanol (12 mL). The

solution turned yellow-green and the green solution was stirred

for 30 minutes at room temperature. About half of the solvent

was removed under reduced pressure, a precipitate formed and

was collected by ﬁltration, washed with methanol (3 ¥ 3mL), n-

pentane (3 ¥ 5mL) and dried in vacuo. [Rh(ImP2)(CO)Cl] (11) was

◦

collected as a pale yellow solid (0.292 g, 87.0%), mp 213–217 C

(decomp). ES-MS (MeOH/dcm), m/z (%): ES⁺, 456.6 (56) [M -

Cl - MeOH]⁺, 425.0 (100) [M - Cl]⁺. Anal. Found: C, 49.51; H,

4.24; N; 6.00. C₁₉H₁₉ClN₂OPRh requires: C, 49.53; H, 4.16; N,

1

3

6.08%. H NMR (CDCl₃, 500 MHz): d 8.02 (d, J(H5-H4) =

1.7 Hz, 1H, H4), 7.80–7.76 (m, 4H, o-CH of PPh₂), 7.45–7.38 (m,

6H, m- & p-CH of PPh₂), 6.69 (d, ³J(H4-H5) = 1.7 Hz, 1H, H5),

3.55 (s, 3H, CH₃), 2.90 (m, 2H, C2CH₂), 2.57 (m, 2H, PCH₂) ppm.

1

C, 39.53; H, 3.40; N, 4.73%. H NMR (300 MHz, CD₂Cl₂): d

3

8.07 (d, J(H5-H4) = 1.9 Hz, 1H, H4), 7.86–7.78 (m, 4H, o-CH

of PPh₂), 7.49–7.45 (m, 6H, m & p-CH of PPh₂), 6.81 (d, ³J(H4-

H5) = 1.9 Hz, 1H, H5), 3.60 (s, 3H, CH₃), 2.98 (m, 2H, C2CH₂),

³¹P{ H} NMR (CDCl₃, 202 MHz): d 41.4 (d, J(Rh-P) = 171.2

1

Hz) ppm. ¹³C{ H} NMR (CDCl₃, 125 MHz): d 188.8 (dd, ¹J(Rh-

1

2.62 (m, 2H, PCH₂) ppm. ³¹P{ H} NMR (121 MHz, CD₂Cl₂): d

CO) = 69.8 Hz, ²J(P C) = 18.0 Hz, CO), 145.9 (dd, ²J(Rh-C) =

1

2

3

1

12.9 ppm. ¹³C{ H} NMR (75 MHz, CD₂Cl₂,): d 176.0 (d, J(P-

6.0 Hz, J(P-C) = 2.0 Hz, C2), 133.8 (d, J(P - C) = 50.9 Hz,

ipso-C of PPh₂), 133.2 (d, ²J(P-C) = 12.0 Hz, o-C of PPh₂), 130.9

(d, ⁴J(P-C) = 2.0 Hz, p-C of PPh₂), 128.8 (d, ³J(P-C) = 10.0 Hz,

m-C of PPh₂), 128.6 (s, C4), 119.8 (s, C5), 33.7 (s, CH₃), 24.4 (d,

¹J(P-C) = 27.9 Hz, PCH₂), 20.8 (C2CH₂) ppm. IR (KBr disc): n

1975 (s, CO) cm^-1.

3

CO) = 13.8 Hz, CO), 147.4 (d, J(P-C) = 4.6 Hz, C2), 134.1 (d,

¹J(P-C) = 60.9 Hz, ipso-C of PPh₂), 133.7 (d, ²J(P-C) = 10.9 Hz,

o-C of PPh₂), 131.3 (d, ⁴J(P-C) = 2.9 Hz, p-C of PPh₂), 129.0 (d,

³J(P-C) = 10.9 Hz, m-C of PPh₂), 127.9 (s, C4), 120.3 (s, C5), 34.4

1

2

(s, CH₃), 23.7 (d, J(P-C) = 35.6 Hz, PCH₂), 21.8 (d, J(P-C) =

1.1 Hz, C2CH₂) ppm. IR (KBr disc): n 1975 (vs, CO), 1975 (vs,

CO) cm^-1.

Synthesis of [Rh(ImP1b)(CO)Cl] (12). A solution of [2-

(diisopropylphosphino)methyl]-1-methylimidazole (2b, 0.371 g,

1.75 mmol) in methanol (15 mL) was added dropwise over

20 minutes into a solution of [Rh(m-Cl)(CO)₂]₂(0.350 g,

0.900 mmol) in methanol (20 mL) and the resulting yellow solution

was stirred for 30 minutes at room temperature. Methanol was

Synthesis of [Ir(ImP1b)(CO)Cl] (14). A suspension of [Ir(m-

Cl)(COE)₂]₂(0.475 g, 0.533 mmol) in acetonitrile (40 mL) was

stirred under an atmosphere of nitrogen for 10 minutes. The

suspension was then placed under an atmosphere of carbon

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Table 6 Crystallographic data for solid state structures of [Rh(ImP2)(COD)]BPh₄(3), Ir(ImP1a)(COD)]BPh₄(6a), [Rh(ImP2)(CO)Cl] (11) and

[Rh(ImP1b)(CO)Cl] (12)

3

6a

11

12

Empirical formula

M (g mol^-1)

C₅₁H₅₃BCl₂N₂PRh

909.54

C₄₉H₄₉BIrN₂P

899.88

C₁₉H₁₉ClN₂OPRh

460.69

Monoclinic

P2₁/c(#14)

13.989(3)

8.913(2)

16.393(4)

111.975(4)

1895.5(8)

1.614

C₁₂H₂₁ClN₂OPRh

378.64

Monoclinic

P2₁/c(#14)

16.711(7)

7.318(3)

12.865

98.043

1557.7(11)

1.614

4

150(2)

0.71073

1.361

0.445 ¥ 0.146 ¥ 0.038

yellow

blade

0.629, 0.948

56.58

Crystal system

Space group

Monoclinic

P2₁/c(#14)

14.459(4)

27.437(3)

11.669(3)

108.354(5)

4394(2)

1.375

4

150(2)

0.71073

0.585

0.468 ¥ 0.247 ¥ 0.030

yellow

plate

0.800, 0.982

56.66

-19 18, -25 36, -15 15

42551

Monoclinic

P2₁/c(#14)

13.971(3)

9.6981(18)

29.840(6)

96.844(3)

4014.3(13)

1.489

˚

a (A)

˚

b (A)

˚

c (A)

b (^◦)

3

˚

V (A )

D_c(g cm^-3)

Z

4

T (K)

150(2)

0.71073

3.403

0.326 ¥ 0.145 ¥ 0.139

orange

prism

0.414, 0.651

56.58

-18 18, -12 12, -38 38

39147

9556 (R_merge0.0389)

8112

1.316

0.0243

0.0528

150(2)

0.71073

1.135

0.372 ¥ 0.250 ¥ 0.097

yellow

prism

0.923, 1.00

56.66

-18 18, -11 11, -21 21

17968

4508 (R_merge0.0375)

3902

1.162

0.0218

0.0595

˚

l Mo K_a(A)

m Mo K_a(mm^-1)

Crystal size (mm)

Crystal colour

Crystal habit

T (Gaussian)_min,max

2q_max(^◦)

hkl range

N

N_ind

-22 22, -9 9, -17 17

14330

3710 (R_merge0.0462)

3181

1.168

0.0215

0.0531

10445 (R_merge0.0616)

7358

1.020

0.0328

0.0774

N

_obs(I > 2s(I))

GoF(all data)

R1^a(F, I > 2s(I))

wR2^b(F², all data)

^aR1 = RꢀF_o| - |Fꢀ/R|F_o| for F_o> 2s(F_o); wR2 = (Rw(F_o- F_o²)²/R(wF_o²)²)^1/2all reﬂections. ^bw = 1/[s (Fo²) + (XP)²+ YP] where P = (F_o

+

2

2F_o²)/3; X = 0.03, Y = 0 for 3.28; X = 0.02, Y = 0 for 6a; X = 0.03, Y = 0.5 for 11; X = 0.02, Y = 0.0 for 12.

removed under reduced pressure until about 10 mL was left and

the yellow precipitate was collected by ﬁltration, washed with

methanol (2 ¥ 5 mL), n-pentane (3 ¥ 5 mL) and dried in vacuo

(0.483 g, 73%), mp 230–231 ^◦C (decomp.). ESI-MS (MeOH/dcm),

m/z (%): ES⁺, 343.03 (100) [M - Cl]⁺. Anal. Found: C, 37.46, H,

5.32; N, 6.94. C₁₂H₂₁ClN₂OPRh requires: C, 38.06; H, 5.59; N,

located between 4 and 56^◦2q. The data integration and reduction

were undertaken with SAINT and XPREP,⁵²and subsequent

computations were carried out with the WinGX⁵³and XTAL⁵⁴

graphical user interfaces. A Gaussian absorption correction^52,55

was applied to the data collected from 3, 6a and 12, and a

multi-scan absorption correction determined with SADABS⁵⁶was

applied to the data collected from 11.

1

3

7.40%. H NMR (300 MHz, CDCl₃): d 7.45 (d, J(H5-H4) =

3

1.1 Hz, 1H, H4), 6.78 (d, J(H4-H5) = 1.1 Hz, 1H, H5), 3.73

The structures were solved by direct methods with SIR97,⁵⁷

and extended and reﬁned with SHELXL-97.⁵⁸The non-hydrogen

atoms were modelled with anisotropic displacement parameters,

and in general a riding atom model was used for the hydrogen

atoms. In general the non-hydrogen atoms were modelled with

anisotropic displacement parameters, and a riding atom model

with group displacement parameters was used for the hydrogen

atoms. The alkene hydrogen sites for 6a were located and modelled

with isotropic displacement parameters. ORTEP⁵⁹depictions of

the molecules with 50% displacement ellipsoids are provided in

Fig. 1 and 2.

2

(s, 3H, NCH₃), 2.94 (d, J(P-H) = 9.0 Hz, 2H, CH₂), 2.26–2.10

3

(m, 2H, 2 ¥ CH(CH₃)₂), 1.29 (dd, J(P-H) = 17.7 Hz, J(CH-

CH₃) = 7.2 Hz, 6H, CH(CH₃)(CH₃)), 1.16 (dd, ³J(P-H) = 15.4 Hz,

1

³J(CH-CH₃) = 7.2 Hz, 6H, CH(CH₃)(CH₃)) ppm. ³¹P{ H} NMR

1

(121 MHz, CDCl₃): d 84.4 (d, ¹J(Rh-P) = 162.8 Hz) ppm. ¹³C{ H}

NMR (75 MHz, CDCl₃): d 190.4 (dd, ¹J(Rh - C) = 69.8 Hz, ²J(P-

C) = 17.4 Hz, CO), 150.2 (dd, ²J(Rh-C) = 16.9 Hz, ²J(Rh-C) or

³J(P-C) = 4.7 Hz, C2), 126.4 (s, C4), 121.0 (s, C5), 35.3 (s, CH₃),

1

2

26.1 (dd, J(P-C) = 29.1 Hz, J(Rh-C) = 2.3 Hz, CH(CH₃)₂),

1

2

20.7 (d, J(P-C) = 20.3 Hz, CH₂), 18.9 (d, J(P-C) = 3.5 Hz,

CH(CH₃)(CH₃)), 18.2 (d, ²J(P-C) = 1.2 Hz, CH(CH₃)(CH₃)) ppm.

IR (KBr disc): n 1957 (s, CO) cm^-1.

Acknowledgements

X-Ray crystal structure determination details

Data were collected at 150(2) K from crystals quenched in a cold

nitrogen gas stream from an Oxford Cryosystems Cryostream.

A Bruker SMART 1000 CCD diffractometer employing graphite

monochromated Mo Ka radiation generated from a sealed tube

was used for the data collection. Cell constants were obtained

from a least squares reﬁnement against more than 900 reﬂections

Financial support from the Australian Research Council (ARC)

and the University of New South Wales (UNSW) is gratefully

acknowledged. We thank Dr Keith Fisher (University of Sydney)

and Dr Russ Pickford (Bioanalytical Mass Spectrometry Facility,

UNSW) for obtaining electrospray mass spectra. K. Q. V. would

like to thank the Australian government for an Endeavour

3612 | Dalton Trans., 2009, 3599–3614

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The Royal Society of Chemistry 2009

©

View Article Online

International Postgraduate Research Scholarship (EIPRS) and the

School of Chemistry for a Postgraduate Teaching Fellowship.

26 (a) C. S. Cao, L. R. Fraser and J. A. Love, J. Am. Chem. Soc., 2005,

127, 17614; (b) Y. Misumi, H. Seino and Y. Mizobe, J. Organomet.

Chem., 2006, 691, 3157; (c) A. Sabarre and J. Love, Org. Lett., 2008,

10, 3941; (d) S. Shoai, P. Bichler, B. Kang, H. Buckley and J. A. Love,

Organometallics, 2007, 26, 5778; (e) L. R. Fraser, J. Bird, Q. M. Wu,

C. S. Cao, B. O. Patrick and J. A. Love, Organometallics, 2007, 26,

5602.

27 (a) V. P. Ananikov, D. A. Malyshev, I. P. Beletskaya, G. G. Aleksandrov

and I. L. Eremenko, Adv. Synth Catal, 2005, 347, 1993; (b) L.-B. Han,

C. Zhang, H. Yazawa and S. Shimada, J. Am. Chem. Soc., 2004, 126,

5080.

28 L. D. Field, B. A. Messerle, K. Q. Vuong, P. Turner and T. Failes,

Organometallics, 2007, 26, 2058.

29 S. Burling, L. D. Field, B. A. Messerle, K. Q. Vuong and P. Turner,

Dalton Trans., 2003, 4181.

30 (a) B. A. Messerle and K. Q. Vuong, Pure Appl. Chem., 2006, 78,

385; (b) B. A. Messerle and K. Q. Vuong, Organometallics, 2007, 26,

3031.

31 K. Q. Vuong, PhD Thesis, The University of New South Wales, 2006.

32 (a) S. Burling, L. D. Field and B. A. Messerle, Organometallics, 2000,

19, 87; (b) S. Burling, L. D. Field, B. A. Messerle and P. Turner,

Organometallics, 2004, 23, 1714; (c) S. Burling, L. D. Field, B. A.

Messerle and S. L. Rumble, Organometallics, 2007, 26, 4335.

33 M. A. Jalil and E. B. Hui, Tetrahedron Lett., 2006, 47, 1473.

34 (a) G. Fries, J. Wolf, M. Pfeiffer, D. Stalke and H. Werner, Angew.

Chem., Int. Ed., 2000, 39, 564; (b) G. Fries, J. Wolf, K. Ilg, B. Walfort,

D. Stalke and H. Werner, Dalton Trans., 2004, 1873.

References

1 C. S. Slone, D. A. Weinberger and C. A. Mirkin, Prog. Inorg. Chem.,

1999, 48, 233.

2 (a) P. Espinet and K. Soulantica, Coord. Chem. Rev., 1999, 195, 499–

556; (b) G. R. Newkome, Chem. Rev., 1993, 93, 2067.

3 (a) G. Helmchen and A. Pfaltz, Acc. Chem. Res., 2000, 33, 336; (b) P. J.

Guiry and C. P. Saunders, Adv. Synth. Catal., 2004, 346, 497; (c) K. N.

Gavrilov and A. I. Polosukhin, Russ. Chem. Rev., 2000, 69, 721; (d) P.

Braunstein, G. Clerc, X. Morise, R. Welter and G. Mantovani, Dalton

Trans., 2003, 1601.

4 (a) T. Ru¨ther, M. C. Done, K. J. Cavell, E. J. Peacock, B. W. Skelton

and A. H. White, Organometallics, 2001, 20, 5522; (b) S. T. Henriksen,

P. O. Norrby, P. Kaukoranta and P. G. Andersson, J. Am. Chem. Soc.,

2008, 130, 10414.

5 (a) M. A. Jalil, S. Fujinami, H. Senda and H. Nishikawa, J. Chem.

Soc., Dalton Trans., 1999, 1655; (b) M. A. Jalil, S. Fujinami and H.

Nishikawa, J. Chem. Soc., Dalton Trans., 2001, 1091; (c) M. A. Jalil, T.

Yamada, S. Fujinami, T. Honjo and H. Nishikawa, Polyhedron, 2001,

20, 627; (d) C. Tejel, M. Ciriano, S. Jimenez, L. Oro, C. Graiff and

A. Tiripicchio, Organometallics, 2005, 24, 1105; (e) G. Espino, F. A.

Jalon, M. Maestro, B. R. Manzano, M. Perez-Manrique and A. C.

Bacigalupe, Eur. J. Inorg. Chem., 2004, 2542.

35 (a) S. Elgaﬁ, L. D. Field, B. A. Messerle, P. Turner and T. Hambley,

J. Organomet. Chem., 1999, 588, 69; (b) F. Bonati, L. A. Oro, M. T.

Pinillos, C. Tejel, M. C. Aareda, C. Foces-Foces and F. H. Cano,

J. Organomet. Chem., 1989, 369, 253; (c) K. T. K. Chan, L. P.

Spencer, J. D. Masuda, J. S. J. McCahill, P. Wei and D. W. Stephan,

Organometallics, 2004, 23, 381.

36 (a) C. Tejel, R. Bravi, M. A. Ciriano, L. A. Oro, M. Bordonaba, C.

Graiff, A. Tiripicchio and A. Burini, Organometallics, 2000, 19, 3115–

3119; (b) C. Tejel, M. A. Ciriano, R. Bravi, L. A. Oro, C. Graiff, R.

Galassi and A. Burini, Inorg. Chim. Acta, 2003, 347, 129.

37 (a) M. P. Anderson, A. L. Casalnuovo, B. J. Johnson, B. M. Mattson,

A. M. Mueting and L. H. Pignolet, Inorg. Chem., 1988, 27, 1649;

(b) D. R. Hou, J. Reibenspies, T. J. Colacot and K. Burgess, Chem.–

Eur. J., 2001, 7, 5391; (c) S. I. Pascu, K. S. Coleman, A. R. Cowley,

M. L. H. Green and N. H. Rees, J. Organomet. Chem., 2005, 690,

1645.

6 F. Menges, M. Neuburger and A. Pfaltz, Org. Lett., 2002, 4, 4713.

7 C. A. Busacca, D. Grossbach, R. C. So, E. M. O’Brien and E. M.

Spinelli, Org. Lett., 2003, 5, 595–598.

8 E. Guiu, C. Claver, J. Benet-Buchholz and S. Castillo´n, Tetrahedron:

Asymm., 2004, 15, 3365.

9 (a) D. B. Grotjahn and D. A. Lev, J. Am. Chem. Soc., 2004, 126, 12232;

(b) D. B. Grotjahn, C. D. Incarvito and A. L. Rheingold, Angew. Chem.,

Int. Ed., 2001, 40, 3884.

10 F. Alonso, I. P. Beletskaya and M. Yus, Chem. Rev., 2004, 104, 3079.

11 P. T. Anastas and M. M. Kirchhoff, Acc. Chem. Res., 2002, 35, 686.

12 I. Nakamura and Y. Yamamoto, Chem. Rev., 2004, 104, 2127.

13 (a) T. E. Mu¨ller, K. C. Hultzsch, M. Yus, F. Foubelo and M. Tada,

Chem. Rev., 2008, 108, 3795–3892; (b) R. Severin and S. Doye, Chem.

Soc. Rev., 2007, 36, 1407; (c) J. J. Brunet, and D. Neibecker, in Catalytic

Heterofunctionalization, ed. A. Togni, and H. Gru¨tzmacher, Wiley-

VCH, Weinheim, 2001, pp. 91; (d) T. E. Mu¨ller and M. Beller, Chem.

Rev., 1998, 98, 675; (e) K. C. Hultzsch, Adv. Synth. Catal., 2005, 347,

367.

14 (a) S. Hong and T. J. Marks, Acc. Chem. Res., 2004, 37, 673; (b) G. A.

Molander and J. A. C. Romero, Chem. Rev., 2002, 102, 2161.

15 (a) F. Pohlki and S. Doye, Chem. Soc. Rev., 2003, 32, 104; (b) A. L.

Odom, Dalton Trans., 2005, 225.

16 T. E. Mu¨ller and A.-K. Pleier, J. Chem. Soc., Dalton Trans., 1999, 583.

17 (a) J. F. Hartwig, Pure Appl. Chem., 2004, 76, 507; (b) R. A. Widenhoefer

and X. Q. Han, Eur. J. Org. Chem., 2006, 4555.

18 (a) M. Lutete, I. Kadota and Y. Yamamoto, J. Am. Chem. Soc.,

2004, 126, 1622; (b) C. G. Hartung, A. Tillack, H. Trauthwein and

M. Beller, J. Org. Chem., 2001, 66, 6339; (c) T. Kondo, T. Okada, T.

Suzuki and T. Mitsudo, J. Organomet. Chem., 2001, 622, 149; (d) J. J.

Brunet, M. Cadena, N. C. Chu, O. Diallo, K. Jacob and E. Mothes,

Organometallics, 2004, 23, 1264.

19 J. B. Press, Chem. Heterocycl. Compd., 1991, 44, 397.

20 R. J. Cremlyn, An Introduction to Organosulfur Chemistry, 1^stedn., John

Wiley & Sons, Chichester, 1996.

21 (a) M. B. Smith, and J. March, March’s Advanced Organic Chemistry:

Reactions, Mechanisms, and Structure, 5^thedn., John Wiley & Sons,

Inc., New York, 2001; (b) O. De, Lucchi and L. Padquato, Tetrahedron,

1988, 44, 6755.

22 (a) A. Ogawa, J. Organomet. Chem., 2000, 611, 463–474; (b) T. Kondo

and T. Mitsudo, Chem. Rev., 2000, 100, 3205; (c) M. Beller, J. Seayad,

A. Tillack and H.-J. Jiao, Angew. Chem., Int. Ed., 2004, 43, 3368; (d) H.

Kuniyasu, in Catatytic Heterofunctionalization, ed. A. Togni, and H.

Gru¨tzmacher, Wiley-VCH, Weinheim, 2001, pp. 217.

23 (a) H. Kuniyasu, A. Ogawa, K. I. Sata, I. Ryu, N. Kambe and N.

Sonoda, J. Am. Chem. Soc., 1992, 114, 5902; (b) A. Ogawa, T. Ikeda,

K. Kimura and T. Hirao, J. Am. Chem. Soc., 1999, 121, 5108.

24 J. E. Ba¨ckvall and A. Ericsson, J. Org. Chem., 1994, 59, 5850.

25 A. Kondoh, H. Yorimitsu and K. Oshima, Org. Lett., 2007, 9, 1383.

38 R. H. Crabtree, The Organometallic Chemistry of the Transition Metals,

3^rdedn., John Wiley & Sons, Inc., New York, 2001.

39 L. D. Field, B. A. Messerle, K. Q. Vuong and P. Turner,

Organometallics, 2005, 24, 4241.

40 A. Schnyder, A. Togni and U. Wiesli, Organometallics, 1997, 16, 255.

41 M. P. Anderson, C. C. Tso, B. M. Mattson and L. H. Pignolet, Inorg.

Chem., 1983, 22, 3267.

42 (a) S. Cacchi and G. Fabrizi, Chem. Rev., 2005, 105, 2873; (b) J. Penzien,

R. Q. Su and T. E. Mu¨ller, J. Mol. Catal. A: Chem., 2002, 182, 489.

43 (a) S. Burling, L. D. Field, H. L. Li, B. A. Messerle and A. Shasha,

Aust. J. Chem., 2004, 57, 677; (b) S. Burling, L. D. Field, H. L. Li, B. A.

Messerle and P. Turner, Eur. J. Inorg. Chem., 2003, 3179.

44 (a) B. M. Trost and P. L. Ornstein, Tetrahedron Lett., 1981, 22, 3463;

(b) M. Yus, A. Gutie´rrez and F. Foubelo, Tetrahedron, 2001, 57, 4411;

(c) S. Watanabe, E. Mori, H. Nagai, T. Iwamura, T. Iwama and T.

Kataoka, J. Org. Chem., 2000, 65, 8893; (d) C. G. Bates, P. Saejueng,

M. Q. Doherty and D. Venkataraman, Org. Lett., 2004, 6, 5005.

45 (a) W. E. Truce and J. A. Simms, J. Am. Chem. Soc., 1956, 78, 2756;

(b) R. Medel, M. I. Monterde, J. Plumet and J. K. Rojas, J. Org. Chem.,

2005, 70, 735.

46 (a) J. E. Baldwin, R. M. Adlington, D. W. Gollins and C. R. A. Godfrey,

Tetrahedron, 1995, 51, 5169; (b) G. Caron, G. W.-M. Tseng and R. J.

Kazlauskas, Tetrahedron: Asymm., 1994, 5, 83.

47 J. L. Herde, J. C. Lambert and C. V. Senoff, Inorg. Synth., 1974, 14, 18.

48 G. C. Giordano and R. H. Crabtree, Inorg. Synth., 1990, 28, 88.

49 J. A. McCleverty and G. Wilkinson, Inorg. Synth., 1990, 28, 84.

50 V. D. Bianco and S. Doronzo, Inorg. Synth., 1976, 16, 161.

51 L. D. Field, and J. Morgan, manuscript in preparation.

52 Bruker, SMART, SAINT and XPREP. Area, detector control and

data integration and reduction software, Bruker Analytical X-ray

Instruments Inc., Madison, WI, USA, 1995.

53 L. J. Farrugia, WinGX, J. Appl. Crystallogr., 1999, 32, 837.

This journal is

The Royal Society of Chemistry 2009

Dalton Trans., 2009, 3599–3614 | 3613

©

View Article Online

54 S. R. Hall, D. J. du Boulay, and R. Olthof-Hazekamp, (Editors), Xtal3.6

System, University of Western Australia, 1999.

57 A. Altomare, M. C. Burla, M. Camalli, G. L. Cascarano, C. Giacov-

azzo, A. Guagliardi, A. G. G. Moliterni, G. Polidori and R. Spagna,

J. Appl. Crystallogr., 1999, 32, 115.

58 G. M. Sheldrick, SHELX97 Programs for Crystal Structure Analysis,

University of Go¨ttingen. Institu¨t fu¨r Anorganische Chemie der Uni-

versita¨t, Tammanstrasse 4, D-3400 Go¨ttingen, Germany, 1998.

59 C. K. Johnson, ORTEPII. Report, ORNL-5138, Oak Ridge National

Laboratory, Oak Ridge, TN, 1976.

55 P. Coppens, L. Leiserowitz and D. Rabinovich, Acta Crystallogr., 1965,

18, 1035.

56 (a) R. H. Blessing, Acta Crystallogr. Section A, 1995, 51, 33–

38; (b) G. M. Sheldrick, SADABS Emperical absorption correction

program for area detector data. University of Go¨ttingen, Germany,

1996.

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The Royal Society of Chemistry 2009

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Article Doi

Rhodium(I) and iridium(I) complexes containing bidentate phosphine-imidazolyl donor ligands as catalysts for the hydroamination and hydrothiolation of alkynes

DOI: 10.1039/b821188d

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Article abstract of DOI:10.1039/b821188d

Full text of DOI:10.1039/b821188d

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