Subtle reactivity patterns of non-heteroatom-substituted manganese alkynyl carbene complexes in the presence of phosphorus probes

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F U L L P A P E R

Subtle reactivity patterns of non-heteroatom-substituted manganese

alkynyl carbene complexes in the presence of phosphorus probes

Yannick Ortin, Noe¨l Lugan* and Rene´ Mathieu

Laboratoire de Chimie de Coordination du CNRS, 205 route de Narbonne, 31077 Toulouse

Cedex 4, France. E-mail: lugan@lcc-toulouse.fr; Fax: +33 5 61 55 30 03; Tel: +33 5 61 33 31 71

Received 21st January 2005, Accepted 15th March 2005

First published as an Advance Article on the web 1st April 2005

5

ꢀ

=

The non-heteroatom-substituted manganese alkynyl carbene complexes (g -MeC₅H₄)(CO)₂Mn C(R)C≡CR (3; 3a:

R = R^ꢀ= Ph, 3b: R = Ph, R^ꢀ= Tol, 3c: R = Tol, R^ꢀ= Ph) have been synthesised in high yields upon treatment of the

5

corresponding carbyne complexes [(g -MeC₅H₄)(CO)₂Mn≡CR][BPh₄] ([2][BPh₄]) with the appropriate alkynyllithium

reagents LiC≡CR^ꢀ(R^ꢀ= Ph, Tol). The use of tetraphenylborate as counter anion associated with the cationic carbyne

5

=

complexes has been decisive. The X-ray structures of (g -MeC₅H₄)(CO)₂Mn C(Tol)C≡CPh (3c), and its precursor

5

=

[(g -MeC₅H₄)(CO)₂Mn CTol][BPh₄] ([2b](BPh₄]) are reported. The reactivity of complexes 3 toward phosphines has

been investigated. In the presence of PPh₃, complexes 3 act as a Michael acceptor to afford the zwitterionic r-allenyl-

phosphonium complexes (g -MeC₅H₄)(CO)₂MnC(R) C C(PPh₃)R (5) resulting from nucleophilic attack by the

phosphine on the remote alkynyl carbon atom. Complexes 5 exhibit a dynamic process in solution, which has been

5

ꢀ

= =

rationalized in terms of a fast [NMR time-scale] rotation of the allene substituents around the allene axis; metrical

5

= =

features within the X-ray structure of (g -MeC₅H₄)(CO)₂MnC(Ph) C C(PPh₃)Tol (5b) support the proposal. In the

presence of PMe₃, complexes 3 undergo a nucleophilic attack on the carbene carbon atom to give zwitterionic

5

r-propargylphosphonium complexes (g -MeC₅H₄)(CO)₂MnC(R)(PMe₃)C≡CR^ꢀ(6). Complexes 6 readily isomerise in

5

ꢀ

= =

solution to give the r-allenylphosphonium complexes (g -MeC₅H₄)(CO)₂MnC(R ) C C(PMe₃)R (7) through a 1,3

5

shift of the [(g -MeC₅H₄)(CO)₂Mn] fragment. The nucleophilic attack of PPh₂Me on 3 is not selective and leads to a

mixture of the r-propargylphosphonium complexes (g -MeC₅H₄)(CO)₂MnC(R)(PPh₂Me)C≡CR^ꢀ(9) and the r-allen-

5

ꢀ

= =

ylphosphonium complexes (g -MeC₅H₄)(CO)₂MnC(R) C C(PPh₂Me)R (10). Like complexes 6, complexes 9

5

ꢀ

= =

readily isomerize to give the r-allenylphosphonium complexes (g -MeC₅H₄)(CO)₂MnC(R ) C C(PPh₂Me)R (10 ).

Upon gentle heating, complexes 7, and mixtures of 10 and 10^ꢀcyclise to give the r-dihydrophospholium complexes

5

ꢀ

5

=

(g -MeC₅H₄)(CO)₂MnC C(R )PMe₂CH₂CH(R) (8), and mixtures of complexes (g -MeC₅H₄)(CO)₂MnC C(Ph)-

5

ꢀ

=

PPh₂CH₂CH(Tol) (11) and (g -MeC₅H₄)(CO)₂MnC C(Tol)PMe₂CH₂CH(Ph) (11 ), respectively. The reactions of

complexes 3 with secondary phosphines HPR¹₂(R¹= Ph, Cy) give a mixture of the g -allene complexes (g -MeC₅H₄)-

2

5

2

1

ꢀ

4

5

= =

(CO)₂Mn[g -{R PC(R) C C(R )H}] (12), and the regioisomeric g -vinylketene complexes (g -MeC₅H₄)(CO)Mn-

2

4

1

ꢀ

5

4

1

ꢀ

=

= =

=

= =

[g -{R PC(R) CHC(R ) C O}] (13) and (g -MeC₅H₄)(CO)Mn[g -{R PC(R ) CHC(R) C O}] (13 ). The

2

5

2

5

4

= =

solid-state structure of (g -MeC₅H₄)(CO)₂Mn[g -{Ph₂PC(Ph) C C(Tol)H}] (12b) and (g -MeC₅H₄)(CO)Mn[g -

=

= =

{Cy₂PC(Ph) CHC(Ph) C O}] (13d) are reported. Finally, a mechanism that may account for the formation of the

species 12, 13 and 13^ꢀis proposed.

The most obvious potential drawback of this synthetic proce-

Introduction

dure rested in the use of air-, moisture- and temperature-sensitive

Within the past ten years, heteroatom-substituted alkynyl car-

5

cationic carbyne complexes. The tetrachloroborate salt [(g -

bene complexes have become extremely valuable building blocks

MeC₅H₄)(CO)₂MnCPh][BCl₄], for instance, must be synthesised

in organic synthesis.¹By contrast, the chemistry of their non-

◦

and handled below −30 C,^6awhile the tetrabromoborate salt

heteroatom-substituted counterparts has been little explored.^2,3

5

[(g -MeC₅H₄)(CO)₂MnCPh][BBr₄] is said to be even more difﬁ-

Pursuing our investigations of low-cost manganese carbene

cult to handle since it decomposes_◦explosively on exposure to air

complexes deriving from methylcyclopentadienyl manganese

and can be stored only below −70 C for a short period of time.⁷

tricarbonyl (MMT),⁴we envisioned that non-heteroatom-

As shown in the ﬁrst part of the present paper, we were prompted

substituted alkynyl carbene complexes should be readily acces-

5

to consider the salts [(g -MeC₅H₄)(CO)₂Mn≡CR][BPh₄] as a

sible upon treatment of cationic carbyne complexes of the type

more suitable starting material. Actually, these salts exhibited

5

[(g -MeC₅H₄)(CO)₂Mn≡CR][BX₄] with an appropriate alkynyl–

a totally unexpected stability in the solid state as they could be

metal reagent (Scheme 1). Indeed, the reaction of cationic group

washed with water, in air, at room temperature (!). With large

7 carbyne complexes with nucleophiles has been shown to

quantities of such a stable precursor in hand,⁸it became possible

constitute a particularly versatile route to carbene complexes,⁵

to prepare in high yield a series of non-heteroatom-substituted

manganese alkynylcarbene complexes, and to start examining

including non-heteroatom substituted-ones.⁶

their chemistry.

We have investigated the reactivity of the non-heteroatom-

substituted manganese carbene complexes following two di-

rections. We have ﬁrst assessed the possibility of inducing

remote activation of the carbene function upon coordination

of an ancillary metal fragment to the alkyne function. This

led to polynuclear species exhibiting unprecedented dynamic

behaviour,⁹including the occurrence of a dynamic equilibrium

Scheme 1

1 6 2 0

D a l t o n T r a n s . , 2 0 0 5 , 1 6 2 0 – 1 6 3 6

T h i s j o u r n a l i s

T h e R o y a l S o c i e t y o f C h e m i s t r y 2 0 0 5

©

View Article Online

1

2

5

between g -carbene and g -alkyne moieties within the [(g -

solution the carbyne complex [2a]⁺remains extremely reactive.

In dichloromethane, for instance, it reacts instantaneously with

water to give a species showing two IR m_CObands 1951 and

1885 cm⁻¹, which then decomposes to give, among other

MeC₅H₄)(CO)₂Mn]₂[l-g -PhCCCPh] binuclear complex.^9aSec-

3

ond, in light of the reactivity trends of group 6 alkynyllalkoxy

carbene complexes¹⁰and parallel studies developed by Casey

et al. on the rhenium congeners,¹¹we were led to explore

the reactivity of these carbene complexes in the presence of

nucleophiles, including phosphines. The corresponding results

constitute the main part of the present article.

5

products, benzaldehyde and (g -MeC₅H₄)(CO)₃Mn. Although

the decomposition mechanism was not investigated in depth,

we assume that the carbyne [2a]⁺reacts with water to give

a hydroxycarbene complex, which further rearranges through

2

an acid–base process to a g -benzaldehyde complex that ulti-

5

mately decomposes into (g -MeC₅H₄)(CO)₃Mn and benzalde-

Results and discussion

hyde (Scheme 3).¹³

Synthesis of manganese alkynyl carbene complexes

5

ꢀ

=

(g -MeC₅H₄)(CO)₂Mn C(R)C≡CR (3) from carbyne

precursors

Preliminary observations. Our ﬁrst attempts to synthesise

non-heteroatom-substituted Mn–alkynyl carbene complexes

upon reaction of cationic carbyne precursors with alkynyl-

lithium reagents were quite disappointing. Indeed, the carbyne

5

complex [(g -MeC₅H₄)(CO)₂Mn≡CPh][BCl₄], [2a][BCl₄], gener-

(1a) and BCl₃,^6awas found to react in a quantitative manner

5

ated in situ by reaction of (g -MeC₅H₄)(CO)₂Mn≡C(OEt)Ph

Scheme 3

5

The carbyne salt [(g -MeC₅H₄)(CO)₂Mn≡CTol][BPh₄], [2b]-

with lithium phenylacetylide, and we could get evidence for

5

=

5

[BPh₄], was synthesised from (g -MeC₅H₄)(CO)₂Mn C(OEt)-

the formation of the expected alkynyl carbene complex (g -

Tol (1b) following the same procedure, and it exhibits the same

remarkable stability in the solid state.

=

MeC₅H₄)(CO)₂Mn C(Ph)C≡CPh (3a); however, the yields

after puriﬁcation on an alumina column were totally erratic

(Scheme 2). Yet, once isolated, 3a was found to be stable in solu-

tion, and we could check that it was not decomposed by contact

with alumina. We soon realised that extensive decomposition of

3a occurred at the very beginning of chromatographic workup,

and this was likely induced by the decomposition of [Li][BCl₄],

which is a by-product of the reaction, on contact with water

contained within the alumina.¹²We then envisioned that the use

of the tetraphenylborate as counter anion might circumvent the

problem.

Structure of [(g⁵-MeC₅H₄)(CO)₂Mn≡CTol][BPh₄] ([2b]-

[BPh₄]). Crystals of [2b][BPh₄] suitable for an X-ray structure

determination could be obtained from a dichloromethane solu-

tion in the cold. An ORTEP drawing of [2b]⁺is shown in Fig. 1.

Relevant crystallographic data are set out in Table 5. The cation

Synthesis of the carbyne complexes [(g⁵-MeC₅H₄)(CO)₂-

5

Mn≡CR][BPh₄] ([2][BPh₄]). The salt [(g -MeC₅H₄)(CO)₂Mn≡

CPh][BPh₄] ([2a][BPh₄]) was obtained by a simple metathesis

reaction between [2a][BCl₄] and [Na][BPh₄] in a THF–hexane

mixture, and isolated in 86–92% yield (based on the carbene

precursor 1a). In contrast to [2a][BX₄] (X = F, Cl, Br), [2a][BPh₄]

is remarkably stable in the solid state. It can be manipulated in

air without any problem and is totally insensitive to water. As a

matter of fact, one step of our puriﬁcation protocol consists of

dropping portion-wise the metathesis products [2a][BPh₄] and

[Na][BCl₄] in a large quantity of water, in an open beaker,

under vigorous stirring (see Experimental section). Once in

5

Fig.

1

A

perspective view of the complex [(g -MeC₅H₄)(CO)₂-

Mn≡CTol]⁺([2b]⁺). Thermal ellipsoids are shown at the 50% probability

◦

˚

level. Selected bond lengths (A) and angles ( ): C1–Mn1 1.831(3),

C2–Mn1 1.818(4), C3–Mn1 1.663(3), C3–C21 1.415(4), C3–Mn1

1.663(3); C21–C3–Mn1 175.3(2).

Scheme 2

D a l t o n T r a n s . , 2 0 0 5 , 1 6 2 0 – 1 6 3 6

1 6 2 1

View Article Online

[2b]⁺shows a typical pseudo-octahedral piano-stool geometry

around manganese, the three angles C1–Mn–C2 (92.7(1)^◦), C1–

Mn–C3 (95.2(1)^◦) and C2–Mn–C3 (94.6(1)^◦) being each close

to 90^◦. The manganese carbon bond distance Mn1–C3 is rather

◦

˚

Table 1 Bond lengths (A) and angles ( ) for complex 3c

C(3)–C(4)

C(3)–C(21)

C(3)–Mn(1)

1.417(3)

1.489(3)

1.905(2)

C(4)–C(5)

C(5)–C(31)

1.205(3)

1.425(3)

˚

short (1.663(3) A), thus reﬂecting triple bond character. It falls

C(4)–C(3)–C(21)

C(4)–C(3)–Mn(1)

C(21)–C(3)–Mn(1)

C(5)–C(4)–C(3)

112.92(18)

117.16(15)

129.91(16)

178.0(2)

C(4)–C(5)–C(31)

C(1)–Mn(1)–C(2)

C(1)–Mn(1)–C(3)

C(2)–Mn(1)–C(3)

178.3(2)

91.84(10)

94.32(9)

89.56(9)

within the range of Mn≡C triple bond distances (ꢁMn≡Cꢂ =

X-ray diffraction data are available.¹⁴The environment of the

carbyne carbon is quasi linear with a Mn–C3–C21 angle of

175.3(2)^◦.

˚

1.673 A) for relevant manganese carbyne complexes for which

Synthesis and spectroscopic characterisation of the alkynyl

5

ꢀ

=

carbene complexes (g -MeC₅H₄)(CO)₂Mn C(R)C≡CR (3).

5

The carbyne complexes [(g -MeC₅H₄)Mn(CO)₂Mn≡CR][BPh₄]

([2][BPh₄]) appeared to be excellent precursors for the non-

heteroatom-substituted alkynyl carbene complexes we were

looking for. Indeed, upon reaction with the alkynyllithium

5

reagents R^ꢀC≡CLi (R^ꢀ

=

Ph, Tol), the complexes (g -

ꢀ

=

MeC₅H₄)(CO)₂Mn C(R)C≡CR (3; 3a: R = R = Ph; 3b: R =

Ph, R^ꢀ= Tol, 3c: R = Tol, R^ꢀ= Ph) were obtained in gratifying

82–85% isolated yields (Scheme 2).^15a

Complexes 3 were characterised by the usual spectroscopic

methods, and for 3c by X-ray diffraction. The IR spectra of

5

3 show the two m_CObands characteristic of the (g -MeC₅H₄)-

(CO)₂MnL fragment at signiﬁcantly higher wave numbers than

those of their parent alkylalkoxy carbene complexes 1: 1969,

1905 cm⁻¹for 3a vs. 1947, 1875 cm⁻¹for 1a (CH₂Cl₂soln.). This

indicates a higher p-acceptor capability of the non-heteroatom-

substituted alkynyl carbene moiety. The m_C≡Cstretch appears at

5

Fig.

2

A

perspective view of the complex (g -MeC₅H₄)(CO)₂-

=

Mn C(Tol)C≡CPh (3c). Thermal ellipsoids are shown at the 50%

probability level.

1

ca. 2120 cm⁻¹as a very weak band. In the ¹³C{ H} NMR spectra,

in heteroatom-substituted Mn–alkoxy-¹⁸or Mn–amino-carbene

the carbene carbon atom appears at very low ﬁeld, ca. d 301 ppm.

The sp C_band C_ccarbon atoms of the alkynyl moieties appear

at d 98–106 ppm and d 113–126 ppm, respectively. Finally, the

carbon atoms of the carbonyl ligands are observed at ca. d

complexes.^4d,fThe C3–C4 bond (1.417(3) A) is slightly shorter

˚

2

19

˚

than a typical C(sp )–C(sp) single bond (1.427 A), while the

C4–C5 bond, (1.205(3) A), is slightly longer than an isolated

˚

19

˚

5

C≡C triple bond (1.189 A). Such structural feature may

234 ppm, whereas the (g -MeC₅H₄) ligand gives four signals,

=

indicate some degree of conjugation of the Mn C and C≡C

namely, a singlet at ca. d 107 ppm for the ipso carbon atom, two

singlets centred at ca. d 94 ppm for the CH groups, and a singlet

at high ﬁeld, ca. d 14 ppm, for the methyl group.

bonds. In addition, the phenyl and tolyl rings sit close to

the carbene plane ({C4–C3–C21–C22} = 8.7^◦; {C21–C3–C31–

C32} = 17.7^◦), offering the possibility of conjugation through

the entire alkynyl carbene moiety. All this could account for the

stability of type 3 complexes.

We have to mention that along with complexes 3, chro-

matographic workups erratically show trace amounts of the

5

dimanganese ene-diyne complexes [(g -MeC₅H₄)(CO)₂Mn][l-

4

ꢀ

In passing, it is worth noting that the carbene ligand in 3c is

oriented in such a way that it lies approximately in the mirror

=

g -(E)-RC≡C(R ) C(R )C≡CR] (4; 4a: R = R = Ph; 4b: R =

Ph, R^ꢀ= Tol, 4c: R = Tol, R^ꢀ= Ph). Casey et al. have

reported that thermal activation (65 ^◦C, 19 h) of complexes

3b,c and analogous Cp derivatives can produce ene-diyne

complexes as mixtures of stereo- and regioisomers.^15bHowever,

in separate work, we have shown that, upon controlled potential

electrolysis (−1.30 V vs. SCE, 20 ^◦C), complexes 3 undergo an

electrocatalytic dimerization by coupling at the remote alkynyl

carbon atom to afford 4 in a quantitative and stereoselective

manner.¹⁶In view of that, we assume the formation of traces

amount of 4 in the reaction conditions shown in Scheme 2 results

from a dimerization of 3 triggered by the alkynyllithium reagent,

acting then as reducing agent.

5

plane of the (g -MeC₅H₄)(CO)₂Mn fragment ({cnt–Mn1–C3}–

{C4–C3–C21} = −1.8^◦, where cnt is the centroid of the (Me)Cp

ring) (Fig. 2, right side). Such an orientation of the carbene

ligand was predicted by Hoffman and co-workers²⁰and Kostic

and Fenske²¹on the basis of MO calculations. It corresponds

to a conﬁguration for which the overlap between the HOMO

of the metal fragment and the LUMO of the carbene moiety

is maximized (Scheme 4). This sort of consideration allows one

to predict with a high degree of conﬁdence the orientation of

1

2

wide variety of ligands L (g -carbene, g -alkene, g -alkyne, g -

ketene. . .) attached to a Cp(CO)₂Mn fragment,²²including, as

2

we shall see later, g -allene complexes.

5

=

Structure of (g -MeC₅H₄)(CO)₂Mn C(Tol)C≡CPh (3c).

Single crystals of 3c suitable for an X-ray structure determina-

tion were obtained from a hexane solution in the cold. ORTEP

drawings of 3c are shown in Fig. 2. Relevant crystallographic

data are set out in Tables 1 and 5. The structure is naturally

=

very similar to that of Cp(CO)₂Mn C(Tol)C≡CPh, recently dis-

closed by Casey et al.^15bAt 1.905(2) A, the Mn–C3 double bond

is the longest ever observed for a non-heteroatom-substituted

Mn–carbene complex. Examination of the CCDC data base

˚

Scheme 4

=

indeed reveals an average of ꢁMn Cꢂ bond distances within

Reactivity of the alkynyl carbene complexes (g⁵-MeC₅H₄)(CO)₂-

˚

Mn–(non-heteroatom-substituted)carbenes of 1.876 A, with a

ꢀ

=

Mn C(R)C≡CR (3) toward triphenylphosphine

˚

minimum of 1.853(6) A associated with Cp(CO)₂Mn[10,11-

dihydro-5H-bibenzo(a,d)cyclohepten-5 ylidene]^17aand a maxi-

Synthesis and spectroscopic characterisation of the r-allen-

5

˚

= =

mum of 1.896(4) A associated with (g -MeC₅H₄)(CO)₂Mn[1,2-

ylphosphonium complexes (g -MeC₅H₄)(CO)₂MnC(R) C

diphenylcyclopropen-3-ylidene].^17bAs a matter of fact, the Mn–

C(PPh₃)R^ꢀ(5). The alkynyl carbene complexes (g -MeC₅H₄)-

(CO)₂Mn C(R)C≡CR (3) react instantaneously with

5

ꢀ

=

C3 bond distance compares well with Mn C bonds found

1 6 2 2

D a l t o n T r a n s . , 2 0 0 5 , 1 6 2 0 – 1 6 3 6

View Article Online

triphenylphosphine in hexane solution to produce zwitterionic

In other words, the NMR data shows that complexes 5 derive

from 3 by a nucleophilic attack of the phosphine on the remote

alkynyl carbon atom.

5

r-allenylphosphonium complexes of the type (g -MeC₅H₄)-

ꢀ

= =

(CO)₂MnC(R) C C(PPh₃)R (5; 5a: R = R = Ph; 5b: R =

Ph, R^ꢀ= Tol; 5c: R = Tol, R^ꢀ= Ph) (Scheme 5).

Dynamic behaviour of 5a in solution. Incidentally, NMR

studies revealed that complexes 5 experience a dynamic process

in solution. This was examined in detail in the case of 5a.

Since the four substituents attached to the allene backbone are

different, complexes 5 are chiral. Consequently, the CO ligands

5

and the CH groups of the g -MeC₅H₄ligand should exhibit

diastereotopic character. At 193 K, the ¹H spectrum of 5a does

show three signals for the CH groups at d 4.10 (H¹), 3.92 (H²)

and 3.86 (H³and H⁴) ppm, in a 1 : 1 : 2 ratio, while the ¹³C

NMR spectrum does show two singlets for the CO ligands at d

239.5 and 238.9 ppm and four sharp signals for the CH groups

5

Scheme 5

of the g -MeC₅H₄ligand at d 87.5, 84.5, 81.3 and 79.5 ppm.

Fig. 4 shows the changes in the ¹H NMR spectra, depending on

the temperature. Upon warming, the signal attributed to H³and

H⁴sharpens, while the signals attributed to H¹and H²slowly

coalesce [coalescence temperature of 263 K] giving ultimately

a single signal at 293 K. In the same temperature range, on

Complexes 5 were isolated as orange precipitates and charac-

terised by the usual spectroscopic techniques, complemented for

5b by an X-ray diffraction structure determination.

The IR spectra (CH₂Cl₂soln.) of 5 show three absorption

bands in the 1600–2100 cm⁻¹domain: two strong bands at

ca. 1890 cm⁻¹and ca. 1814 cm⁻¹attributed to the m_COof the

carbonyl ligands, and a third one, of medium intensity, at ca.

1

the ¹³C{ H} spectra, the signals due to the CO ligands also

coalesce to give one sharp signal, while the four CH signals

5

of the g -MeC₅H₄ligand coalesce in pairs culminating in two

sharp signals at d 84.6, 81.3 ppm. Clearly, it appears that

the complex executes a fast [NMR time-scale] racemisation in

solution. Analysis of coalescence behaviour of the H¹and H²

led to an activation energy barrier of ca. 12 kcal mol⁻¹for the

process.²⁴

1839 cm⁻¹attributed to the m_C₌

of the allenyl ligand. The

=

C

strong bathochromic shift observed for the m_COabsorption bands

in 5 relative to those of the parent species 3 reﬂects a negative

1

charge at Mn. At room temperature, the ¹³C{ H} NMR spectra

of 5 show three doublets at d 163–186 ppm with a J_CP≈ 11 Hz,

at d 115–119 ppm with a J_CP≈ 12 Hz, and at d 55–66 ppm with

a J_CP≈ 110 Hz. Considering the chemical shifts and the values

of the J_PCcoupling constants, these signals were attributed to

the carbon atoms C_b, C_a(attached to Mn) and C_cresonances,

respectively. The J_CPof 110 Hz for the resonances at d 55–

66 ppm, in particular, is indeed the signature of a carbon atom

attached to the phosphorus atom of a phosphonium group

(C_c).²³For 5b and 5c, the position of the tolyl group relative

to the phosphonium group has been determined by a series of

NMR experiments (¹H, ¹³C, HMQC and HMQC-LR). Fig. 3

shows a key HMQC-LR spectrum for 5c. It shows that the

1

H_orthoof the tolyl group that appears at 7.12 ppm in the H

dimension correlates with two signals in the ¹³C dimension: a

ﬁrst signal at 135.5 ppm corresponding to the C_paraof the tolyl

group, and a second one at 114.8 ppm corresponding to C_a.

This unambiguously demonstrates that the tolyl group in 5c is

attached to C_a. The same type of analysis was conducted on 5b

and showed that, conversely, the tolyl group was attached to C_c.

Fig. 4 Selected section of the ¹H NMR spectrum of complex

5

=

(g -MeC₅H₄)(CO)₂MnC(Tol)

C C(PPh₃)Ph (5a) (400 MHz, CD₂Cl₂).

As the addition of PPh₃on the remote alkynyl car-

bon atom of the parent Re–alkynyl carbene complex

11

=

Cp(CO)₂Re C(Tol)C≡CPh had been shown to be reversible,

we ﬁrst considered that the racemisation we were observing by

NMR was the consequence of a similar equilibrium that could

be fast [NMR time-scale] in the present Mn complexes.

However, upon addition of an excess of MePPh₂, a more basic

and more nucleophilic phosphine than PPh₃, to a solution of

5

5a in dichloromethane, no trace of the exchange product (g -

= =

MeC₅H₄)(CO)₂MnC(Ph) C C(Ph)PPh₂Me (10a, vide infra)

could be detected, even after 18 h of reaction (Scheme 6). This

suggests that complex 5a is not prone to dissociate in solution

under these reaction conditions.

Fig. 3 Selected section of the HMQC-LR NMR spectrum of com-

5

1

=

plex (g -MeC₅H₄)(CO)₂MnC(Tol)

C C(PPh₃)Ph (5c) (400 MHz ( H),

CD₂Cl₂, 298 K).

D a l t o n T r a n s . , 2 0 0 5 , 1 6 2 0 – 1 6 3 6

1 6 2 3

View Article Online

First of all, the solid-state structure of 5b corroborates the

NMR analyses. The triphenylphosphine and tolyl fragments are

indeed in an adjacent position on the carbon atom C5 of the

allene ligand moiety, this being the consequence of a nucleophilic

attack of the phosphine on the remote alkynyl carbon atom.

The allene backbone shows a structure in agreement with a

sp²/sp/sp²hybridisation of the carbon atoms in the chain,

the atoms C3, C4 and C5 being virtually aligned (C3–C4–

C5 177.2(2)^◦) and the torsion angle {Mn1–C3–C5–P1} being

relatively close to 90^◦({Mn1–C3–C5–P1} = 104.9^◦). The

Scheme 6

Actually, we suggest that the dynamic process that allows the

racemisation of the molecule consists simply of a fast [NMR

time-scale] rotation of the PhCPPh₃group relative to the (g -

MeC₅H₄)(CO)₂MnCPh fragment around the axis of the allene.

(Scheme 7). The activation barrier for the rotation we estimated,

12 kcal mol⁻¹, is considerably lower than in a typical allene

(45 kcal mol⁻¹).²⁵Yet, a decrease of the bond order within one

˚

Mn1–C3 bond (2.066(2) A) is signiﬁcantly longer than the

5

corresponding bond in its precursor 3b and appears to be in

the range of a typical Mn–C single bond.²⁶

An interesting comparison has to be made between the

structure of 5a and that of the r-allenylphosphonium com-

= =

plex Cp(CO)₂MnC(PPh₃) C CPh₂, obtained by Kolobova

=

the C C bond of that peculiar allene could lower the rotation

barrier. Metrical features in the solid-state structure of 5b suggest

=

et al. upon reaction of the allenylidene complex Cp(CO)₂MnC

27

=

C CPh₂with triphenylphosphine (Scheme 8). The two com-

that it is indeed the case.

plexes differ in the relative position of the formally charged

substituents and, likely as a consequence, in the absolute and

relative C_a–C_band C_b–C_cbond lengths. Given that the formally

charged substituents of the allene in Kolobova’s complex are

adjacent, they are expected to have little or no inﬂuence on

the carbon–carbon bond distances within the allene backbone.

Effectively, such bond distances are equal within the experimen-

tal error and are in the normal expected range for an allenic

C C bond (1.307 A). By contrast, in complex 5b, where the

formally charged substituents are on each end of the allene

backbone, the C3–C4 (1.275(3) A) and C4–C5 (1.347(3) A)

bonds become signiﬁcantly different one from the other, the

19

˚

=

˚

Scheme 7

latter being signiﬁcantly elongated as compared to the regular

5

19

= =

Structure of (g -MeC₅H₄)(CO)₂MnC(Ph) C C(PPh₃)Tol,

=

allenic C C bond value. Such a reduction in the bond order

5b. Single crystals of 5b suitable for an X-ray structure analysis

were obtained from a dichloromethane–hexane solution in the

cold. An ORTEP drawing of the complex is shown in Fig. 5.

Relevant crystallographic data are set out in Tables 2 and 5.

of the C4–C5 linkage may account for the relative ease of the

allene rotation observed in solution.

Scheme 8

In summary, this ﬁrst reaction clearly reﬂects the ability of the

alkynyl carbene complexes 3 to act as Michael acceptors. Such

a reactivity pattern parallels both that of the parent group 6

heteroatom-substituted alkynyl carbene complexes^10a,band that

of their rhenium analogues.¹¹However, whereas the conjugate

addition of triphenylphosphine to carbene complexes is often

reversible, the zwitterionic r-allenylphosphonium adducts 5

appear to be stable in solution.

5

Fig.

(Ph)

5

=

A

=

perspective view of complex (g -MeC₅H₄)(CO)₂MnC-

Reactivity of the alkynyl carbene complexes

C C(PPh₃)Tol (5b). Thermal ellipsoids are shown at the 50%

5

ꢀ

=

probability level.

Table 2 Bond lengths (A) and angles ( ) for complex 5b

(g -MeC₅H₄)(CO)₂Mn C(R)C≡CR (3) toward

trimethylphosphine and diphenylmethylphosphine

◦

˚

Reaction of 3a–c with PMe₃and spectroscopic characterisation

of the resulting complexes. In solution in hexane, the alkynyl

C(3)–C(4)

C(3)–C(21)

C(3)–Mn(1)

C(4)–C(5)

C(5)–C(31)

1.275(3)

1.484(3)

2.066(2)

1.347(3)

1.489(3)

C(5)–P(1)

C(41)–P(1)

C(51)–P(1)

C(61)–P(1)

1.767(2)

1.797(2)

1.810(2)

1.804(2)

5

ꢀ

=

carbene complexes (g -MeC₅H₄)(CO)₂Mn C(R)C≡CR (3) re-

act instantaneously with trimethylphosphine to afford red

precipitates. The IR spectrum (CH₂Cl₂soln.) of these pre-

cipitates shows two bands of equal intensity at ca. 1880

5

and 1804 cm⁻¹characteristic of the m_COvibrations in a [(g -

C(4)–C(3)–C(21)

C(4)–C(3)–Mn(1)

C(21)–C(3)–Mn(1)

C(3)–C(4)–C(5)

C(4)–C(5)–C(31)

C(4)–C(5)–P(1)

C(31)–C(5)–P(1)

C(5)–P(1)–C(41)

124.5(2)

C(5)–P(1)–C(61)

C(41)–P(1)–C(61)

C(5)–P(1)–C(51)

C(41)–P(1)–C(51)

C(61)–P(1)–C(51)

C(2)–Mn(1)–C(1)

C(2)–Mn(1)–C(3)

C(1)–Mn(1)–C(3)

111.50(11)

104.85(10)

108.12(10)

111.24(10)

110.21(11)

87.01(10)

99.31(10)

91.51(10)

MeC₅H₄)(CO)₂MnX]⁻fragment, and a weak band at ca.

2177 cm⁻¹attributable to the m_C≡Cof an alkyne substituent. This

is consistent with the formation of the r-propargylphosphonium

118.59(17)

116.85(15)

177.2(2)

5

complexes (g -MeC₅H₄)(CO)₂MnC(R)(PMe₃)C≡CR^ꢀ(6a: R,

123.9(2)

115.66(16)

120.36(15)

110.94(10)

R^ꢀ= Ph; 6b: R = Ph, R^ꢀ= Tol; 6c: R = Tol, R^ꢀ= Ph) (Scheme 9).

Attempts to fully characterise 6 by NMR were unsuccess-

ful due to the formation of paramagnetic impurities upon

1 6 2 4

D a l t o n T r a n s . , 2 0 0 5 , 1 6 2 0 – 1 6 3 6

View Article Online

Scheme 9

dissolution, even at low temperature. Actually, these complexes

appeared to be extremely unstable in solution, evolving within

minutes at 25 ^◦C to give new complexes whose IR spectra

correspond to r-allenylphosphonium species (7a–c, Scheme 9).

IR monitoring reveals the disappearance of the weak m_C≡Cband

at ca. 2177 cm⁻¹, the appearance of a new band of medium

intensity at ca. 1857 cm⁻¹, and a slight hypsochromic shift of

the two m_CObands. Complex 7a has been further characterised

C_d) are adjacent to a phosphonium-type ³¹P nucleus. Since 8a

possesses a stereogenic centre, C_c, the carbonyl ligands are

diastereotopic and give two singlets at d 238.2 and 237.2 ppm.

The four CH groups of the g -MeC₅H₄ligands are magnetically

inequivalent and give rise to four signals which are observed at

d 85.1, 84.9, 81.7 and 81.1 ppm.

The reactivity of complexes 3 toward trimethylphosphine

seemed to keep paralleling that of Casey^ꢀs Re complexes since

upon standing at room temperature, the Re–r-allenyl com-

5

1

by NMR. The ¹³C{ H} NMR spectrum shows in particular a

= =

singlet at 165.4 ppm and two doublets at 115.1 ppm (J_CP

=

plex Cp(CO)₂ReC(Tol) C C(Ph)PPh₂Me, for instance, had

15 Hz) and 59.1 ppm (J_CP= 105 Hz), respectively, attributable

to the carbon atoms C_a, C_band C_cof the allene backbone.

Casey et al. have recently reported that the analogous Re–

previously been shown to give the Re–r-dihydrophospholium

ꢀ

11

=

complex Cp(CO)₂MnC C(R )PMe₂CH₂CH(R) (Scheme 10).

The cyclisation reaction was rationalised in terms of an acido–

basic process, which is probably also operative for the present

7 → 8 transformation.

=

alkynyl complex Cp(CO)₂Re C(Tol)C≡CPh (A) reacts with

diphenylmethylphosphine to afford either the “kinetic” Re–

r-propargyl complex Cp(CO)₂Re–C(PPh₂Me)(Tol)C≡CPh), or

the “thermodynamic” Re–r-allenyl complex Cp(CO)₂Re–

In the context of an evaluation of the reactivity of complexes

3 toward nucleophiles, it was of importance to determine the

position of the phenyl and/or tolyl group within the dihy-

drophospholinium ring in 8b and/or 8c. This was achieved by

a series of 2D NMR experiments. The NOESY NMR spectrum

of 8b shown in Fig. 6 clearly indicates that the H_cproton, which

appears at 5.18 ppm, correlates with the H_orthoof the tolyl group,

which appear at 7.14 ppm, and with these aromatic hydrogen

nuclei only. This implies that the tolyl group is attached to C_c.

The NMR data thus indicate that the trimethylphosphine which

has attacked the carbene carbon atom in the antecedent species

3b to give 6b remains attached to the same carbon atom in 8b,

as shown in Scheme 9. This implies that the isomerisation of the

Mn–r-propargyl complexes 6 to the Mn–r-allenyl complexes 7

does not proceed through the displacement of the phosphine but

= =

C(Tol) C C(Ph)PPh₂Me, depending on the reaction condi-

tions (Scheme 10).¹¹With these observations in mind, we

originally considered that the isomerisation of 6 into 7 might

take place via a parallel mechanism, ie. by displacement of

the phosphine. Yet, additional experiments revealed a different

picture.

5

through a 1,3 migration of the (g -MeC₅H₄)(CO)₂Mn fragment.

Scheme 10

Indeed, during attempts to characterise further complexes

7a–c by NMR, we observed their clean conversion into new

well-deﬁned complexes. Later on, such transformations were

performed upon heating 7 in reﬂuxing CH₂Cl₂solution for

5

2 hours, giving the Mn–r-dihydrophospholium complexes (g -

ꢀ

=

MeC₅H₄)(CO)₂MnC C(R )PMe₂CH₂CH(R) (8a: R, R = Ph;

8b: R = Ph, R^ꢀ= Tol; 8c: R = Tol, R^ꢀ= Ph) (Scheme 9).

Complexes 8 were characterised by usual spectroscopic methods.

The IR spectra show two m_CObands of equal intensity at ca.

1880 and 1805 cm⁻¹, in a region typical for the m_COvibrations

in [(g -MeC₅H₄)(CO)₂MnX]⁻fragments. The ¹³C{ H} NMR

5

1

spectra are particularly informative. For 8a, for instance, a

singlet at d 253.5 ppm and three doublets at d 120.0 (J_CP

=

60 Hz), 68.5 (J_CP= 17 Hz) and 32.6 (J_CP= 62 Hz) ppm are

observed. Considering the chemical shifts and the values of

the J_PCcoupling constants, these signals are attributed to C_b,

C_a, C_cand C_dof the dihydrophospholinium ring, respectively

(see Scheme 9). The two strong J_CPcoupling constants of

60 Hz and 62 Hz for the d 120.0 ppm and d 32.6 ppm signals,

respectively, indeed indicate these two carbon atoms (C_aand

Fig. 6 Selected section of the NOESY NMR spectrum of com-

5

=

plex (g -MeC₅H₄)(CO)₂MnC C(Ph)PMe₂CH₂CH(Tol) (8b) (400 MHz,

CD₂Cl₂, 298 K).

The literature gives a few examples of 1,3 migration of the

metallic fragment within r-propargyl complexes to give r-allenyl

D a l t o n T r a n s . , 2 0 0 5 , 1 6 2 0 – 1 6 3 6

1 6 2 5

View Article Online

stretch in the solid-state IR spectra of the precipitate resulting

from the reaction of PPh₂Me with complexes 3 is certainly

5

due to an overlap with the rightmost m_COband of the (g -

MeC₅H₄)Mn(CO)₂fragments. Upon dissolution in CH₂Cl₂, 9b

would isomerise to give 10b^ꢀ, while 10b would remain as is.

Complex 3c led also to a 1 : 1 mixture of complexes 10b and

10b^ꢀ. In this case, however, 10b^ꢀwould result from the nucle-

ophilic attack of the phosphine on the remote alkynyl carbon

atom in 3c, whereas 10b would arise from the isomerisation of

9c (R = Tol, R^ꢀ= Ph).

Upon heating under reﬂux in CH₂Cl₂for a few hours, 10a was

converted into the corresponding Mn–r-dihydrophospholinium

complex 11a. Hence, the 1 : 1 mixture of 10b and 10b^ꢀ,

Scheme 11

complexes.²⁸It has been proposed such an isomerisation could

proceed through the formation of a transient metallacyclobutene

species (Scheme 11).²⁹the driving force for the isomerisation

being the release of the steric hindrance around the sp³carbon

atom in the r-propargyl species.

obtained from either 3b or 3c, leads to a 1 : 1 mixture

5

=

of (g -MeC₅H₄)(CO)₂MnC C(Ph)PMe₂CH₂CH(Tol) (11b) and

5

ꢀ

=

(g -MeC₅H₄)(CO)₂MnC C(Tol)PMe₂CH₂CH(Ph) (11b ). The

latter complexes were characterised by the usual spectroscopic

methods.

In summary, in the presence of a basic and nucleophilic

phosphine such as trimethylphosphine, the Mn–alkynyl car-

bene complexes 3 behave as typical Fischer carbenes as

they undergo a nucleophilic attack on the carbene car-

bon atom³⁰to give Mn–r-propargylphosphonium zwitterionic

complexes. The latter species readily isomerise into Mn–r-

allenylphosphonium zwitterionic complexes through a 1,3 shift

Reaction of 3a–c with PPh₂Me and spectroscopic characteriza-

tion of the resulting complexes. All three complexes 3a–c react

similarly with diphenylmethylphosphine in hexane solution to

afford a pyrophoric red precipitate. The IR spectrum of the

precipitate in dispersion in KBr shows two strong bands at

ca. 1880 and 1804 cm⁻¹for the m_COand a very weak band at

2180 cm⁻¹attributable to a m_C≡Cstretch. Upon dissolution in

dichloromethane, new species form instantaneously as indicated

by the disappearance of the band at 2180 cm⁻¹, the occurrence of

a new band of medium intensity at ca. 1838 cm⁻¹. These obser-

vations suggest that, just like in the reaction with trimethylphos-

phine, the incipient Mn–r-propargylphosphonium complex,

which can be intercepted in the solid state, rapidly iso-

merises to a Mn–r-allenylphosphonium species upon dis-

solution in dichloromethane. NMR analyses of the unique

complex isolated from the reaction of 3a and diphenylmeth-

5

of the (g -MeC₅H₄)Mn(CO)₂fragment, and ultimately into

Mn–r-dihydrophospholinium complexes through a cyclisation

process. The reaction of 3 with the less basic and more

sterically demanding diphenylmethylphosphine is not selective.

The nucleophilic attack of the phosphine occurs on both the

carbene carbon atom and the remote alkynyl carbon atom to

afford a mixture of Mn–r-propargylphosphonium complexes

and Mn–r-allenylphosphonium complexes. The mixture then

evolves to give Mn–r-dihydrophospholinium complexes as a

mixture of two regioisomers.

5

ylphosphine indicates the formation of (g -MeC₅H₄)(CO)₂-

= =

MnC(Ph) C C(Ph)PPh₂Me (10a) (Scheme 12). When 3b is

used as starting material, the NMR analyses showed the forma-

Reactivity of the propynylidene complexes 3a–c with secondary

phosphines

tion of two isomers of Mn–r-allenylphosphonium complexes, in

a ca. 1 : 1 ratio. The NMR data are consistent with the formation

of (g -MeC₅H₄)(CO)₂MnC(Ph) C C(Tol)PPh₂Me (10b) and

Reactions of 3a–c with HPPh₂and HPCy₂and spectro-

5

= =

scopic characterisation of the resulting complexes. In con-

5

ꢀ

5

ꢀ

= =

=

trast to the reactions of (g -MeC₅H₄)(CO)₂Mn C(R)C≡CR

(g -MeC₅H₄)(CO)₂MnC(Tol) C C(Ph)PPh₂Me (10b ). This

suggests that the precipitates formed upon addition of the

phosphine consist in fact of a mixture of the Mn–r-propargyl

complexes 9b (R = Ph, R^ꢀ= Tol) resulting from the nucleophilic

attack of the phosphine on the carbene carbon atom in 3, and

of the Mn–r-allenyphosphonium complexes 10b resulting from

a nucleophilic attack of the phosphine on the terminal alkynyl

(3) with tertiary phosphines, which give isolable zwitteri-

onic species from hexane, adducts from the secondary phos-

phines HPR¹(R¹= Ph, Cy) appeared to be extremely

2

unstable and could not be isolated. When the reactions

were run in CH₂Cl₂an intricate mixture of complexes was

obtained. Upon chromatographic workup, two new species

2

carbon atom (Scheme 12). The absence of a clearly visible m_C₌

were isolated, namely, g -allene complexes of general formula

=

C

Scheme 12

1 6 2 6

D a l t o n T r a n s . , 2 0 0 5 , 1 6 2 0 – 1 6 3 6

View Article Online

Scheme 13

Table 3 Reactions of 3a–c with PPh₂H and PPh₂Cy

Reactants

Products; yield (%)

1

2

3

4

5

6

3a/HPPh₂

3b/HPPh₂

3c/HPPh₂

3a/HPCy₂

3b/HPCy₂

3c/HPCy₂

12a (R = R^ꢀ= R¹= Ph); 73

13a (R = R^ꢀ= R¹= Ph); 4

12b (R = Ph, R^ꢀ= Tol, R¹= Ph); 52

12c (R = Tol, R^ꢀ= Ph, R¹= Ph); 53

12d (R = R^ꢀ= Ph, R¹= Cy); 6

13b + 13b^ꢀ(R = Tol, R^ꢀ= Ph, R¹= Ph), 1 : 1 mixture; 14 (total)

13c (= 13b^ꢀ) + 13c^ꢀ(= 13b) (R = Tol, R^ꢀ= Ph, R¹= Ph), 1 : 1 mixture; 8 (total)

13d (R = R^ꢀ= Ph, R¹= Cy); 55

12e (R = Ph, R^ꢀ= Tol, R¹= Cy); 16

12f (R = Tol, R^ꢀ= Ph, R¹= Cy); 14

13e + 13e^ꢀ(R = Ph, R^ꢀ= Tol, R¹= Cy), 1 : 5 mixture; 51 (total)

13f (= 13e^ꢀ) + 13f^ꢀ(= 13e) (R = Tol, R^ꢀ= Ph, R¹= Cy) 1 : 5 mixture; 48 (total)

5

2

1

ꢀ

= =

formed at 298 K showed that two of the CH-type protons of the

(g -MeC₅H₄) ligand (those appearing at d 3.17 and 3.91 ppm)

(g -MeC₅H₄)(CO)₂Mn[g -{R PC(R) C C(R )H}] (12) and

2

5

4

g -vinylketene complexes, the latter complexes being ob-

tained as a mixture of two inseparable regioisomers (g -

5

correlate with one of the H_ortho(d 7.66 ppm) of the phenyl ring

attached to C_a, whereas the other two CH-type protons (those

appearing at d 4.49 and 4.53 ppm) correlate with the H_ortho

protons of the tolyl group (d 7.81 ppm) (Fig. 7). This indicates

that the phenyl ring and the tolyl group attached to each end of

4

1

ꢀ

=

= =

MeC₅H₄)(CO)Mn[g -{R PC(R ) CHC(R) C O}] (13) and

2

5

4

1

ꢀ

(g -MeC₅H₄)(CO)Mn[g -{R PC(R) CHC(R ) C O}] (13^ꢀ)

=

= =

2

for R = R^ꢀ(Scheme 13).

2

As shown in Table 3, the g -allene complexes 12 are the major

5

the allene ligand remains in a relatively close proximity to the (g -

reaction products when HPPh₂is used as the incoming substrate

(entries 1–3), whereas the g -vinylketene complexes 13 form

predominantly in the case of HPCy₂(entries 4–6). In fact, for a

given phosphine, 3b and 3c yield a mixture of the same isomeric

4

MeC₅H₄) ligand. This suggests that the coordinated allene does

not experience a propeller rotation on the NMR time-scale in

the 233–313 K range, and that the conﬁguration of the molecule

in solution is the same than the solid state (vide infra).

4

g -vinylketene complexes (entries 2 and 3 and 5 and 6). In the

case of HPPh₂, the ratio between the two isomers is close to 1,

whatever is the starting complex (entries 2 and 3). By contrast,

in the case of HPCy₂, the corresponding ratio reverses from 1 : 5

to 5 : 1 depending on whether 3b or 3c is used as the starting

complex (entries 5 and 6).

Complexes 12 and 13 were characterised by the usual spec-

troscopic techniques and, for 12b and 13d, by X-ray diffraction

structure analyses.

1

³¹P{ H} NMR spectra of complexes 12 exhibit one singlet in

a d 19–43 ppm zone, thus clearly indicating that the phosphorus

1

atom is not coordinated to the Mn center.³¹The ¹³C{ H} NMR

spectra show two doublets at d 35–37 ppm (J_CP= 25 Hz) and

at d 165–167 ppm (J_CP≈ 7 Hz) attributable to the coordinated

C_aand C_bcarbon atoms of the allene chain, respectively (see

Scheme 12). A series of NMR experiments (¹H, ¹³C{ H},

1

31

¹³C{ H}{ P}, HMQC, HMQC-LR) allowed us to determine

unambiguously the chemical shift of C_ccarbon atom, which

appears at d 122–126 ppm, depending on the complex (see

experimental). The vinylic proton appears at ca. d 8.5 ppm. In

addition, for 12b–c and 12e–f, the NMR experiments allowed

us to determine the relative position of the tolyl and phosphido

Fig. 7 NMR correlation scheme for complex 12b.

The second species resulting from reaction of the alkynyl

carbene complexes 3 with the secondary phosphine are the vinyl

ketene complexes 13/13^ꢀ. The IR signature of these complexes

is a single strong m_COband at ca. 1960 cm⁻¹for the carbonyl

ligand and a broad m_COband at ca. 1712 cm⁻¹, much weaker,

for the carbonyl group of the coordinated vinyl ketene ligand.

2

groups on the g -allene moiety. In each case, we were able to

establish that the phosphido group is attached to the carbon

atom that bears the group R, as shown in Scheme 13.

1

The ³¹P{ H} NMR spectra of complexes 13 and/or 13^ꢀshow

Lentz et al. have reported that the energy barriers for the

propeller rotation of the coordinated allene in parent manganese

complexes are in the 8.9–12.8 kcal mol⁻¹range.³²We have

attempted to determine the corresponding energy barrier for 12b

but no signiﬁcant changes were observed in the NMR spectra

singlet(s) in a 17–40 ppm zone that clearly indicate that the

phosphorus atom in these complexes is not coordinated to Mn.

1

The H NMR spectra show in particular a distinctive signal

at ca. 6.0 ppm (J_HP= 12 Hz) attributable to the vinyl proton.

Complexes 13/13^ꢀpossess several stereogenic centres, yet the

solution NMR spectra of 13a and 13d show that they form as

1

(400 MHz for H) between 233 K, the lowest temperature we

1

were able to reach considering the relatively poor solubility of

the compound, and 313 K. Above 313 K, a transformation of

12b was observed in the NMR tube, giving rise to a mixture

of compounds.³³ROESY-type 2D-¹H NMR experiments per-

a single diastereoisomer. The ¹³C{ H} NMR spectra of 13a, for

instance, show one singlet at d 237.3 ppm attributable to the

carbonyl of the ketene moiety, one singlet at d 232.4 ppm for the

carbon atom of the carbonyl ligand, then three doublets at d 85.4

D a l t o n T r a n s . , 2 0 0 5 , 1 6 2 0 – 1 6 3 6

1 6 2 7

View Article Online

◦

˚

(J_CP= 46 Hz), 73.9 (J_CP= 38 Hz) and 29.9 ppm (J_CP= 11 Hz)

Table 4 Bond lengths (A) and angles ( ) for complexes 12b and 13d

assignable to C_b, C_c, C_a, respectively (see Scheme 13). The CH

5

12b

13d

groups of the (g -MeC₅H₄) ligand give four signals that appear

at d 89.8, 88.3 (J_CP= 4 Hz), 86.3 (J_CP= 7 Hz) and 85.8 ppm. A

complete set of NMR experiments (¹H, ¹³C{ H}, ¹³C{ H}{ P},

HMQC and HMQC-LR) on samples of 13b/13b^ꢀand 13e/13e^ꢀ

gave the chemical shifts and correlations represented in Fig. 8.

This clearly shows that in both cases, the two inseparable isomers

are not diastereoisomers but regioisomers that differ in the

relative position of the phenyl and tolyl substituents on the

vinyl ketene ligand. In addition, for the mixture of complexes

13e/13e^ꢀarising from the reaction of 3b with HPCy₂, we were

able to establish that the major regioisomer is the one in which

the dicyclohexylphosphido and the tolyl substituents are in an

adjacent position, 13e^ꢀ. Conversely, the NMR spectra revealed

that the latter complex is in fact the minor regioisomer in the

reaction of 3c with HPCy₂.

1

31

Mn(1)–C(1)

Mn(1)–C(2)

Mn(1)–C(4)

Mn(1)–C(3)

Mn(1)–C(5)

P(1)–C(5)

P(1)–C(51)

P(1)–C(41)

P(1)–C(3)

1.7733(18)

1.7992(19)

2.0265(16)

2.2013(16)

2.249(2)

—

1.8287(17)

1.8353(16)

1.8582(16)

—

1.155(2)

1.149(2)

1.407(2)

1.503(2)

1.327(2)

1.480(2)

1.784(2)

1.9370(17)

2.0679(19)

2.1180(19)

—

1.8687(17)

1.873(2)

1.8611(19)

P(1)–C(5)

1.8687(17)

1.146(2)

1.199(2)

1.427(2)

1.478(3)

1.420(3)

1.502(2)

O(1)–C(1)

O(2)–C(2)

C(3)–C(4)

C(3)–C(21)

C(4)–C(5)

C(5)–C(31)

C(1)–Mn(1)–C(2)

C(1)–Mn(1)–C(4)

C(2)–Mn(1)–C(4)

C(1)–Mn(1)–C(3)

C(2)–Mn(1)–C(3)

C(51)–P(1)–C(41)

C(51)–P(1)–C(3)

C(51)–P(1)–C(5)

C(41)–P(1)–C(3)

C(41)–P(1)–C(5)

O(1)–C(1)–Mn(1)

O(2)–C(2)–Mn(1)

C(4)–C(3)–C(21)

C(4)–C(3)–P(1)

C(21)–C(3)–P(1)

C(21)–C(3)–Mn(1)

P(1)–C(3)–Mn(1)

C(5)–C(4)–C(3)

C(5)–C(4)–Mn(1)

C(3)–C(4)–Mn(1)

C(4)–C(5)–C(31)

C(4)–C(5)–P(1)

89.04(8)

88.27(7)

116.75(7)

105.36(7)

82.36(7)

99.26(8)

105.70(8)

—

74.37(8)

114.64(8)

75.93(8)

108.92(7)

41.53(8)

100.88(9)

—

103.17(8)

—

108.28(8)

174.41(16)

145.92(15)

121.22(17)

—

101.98(7)

—

173.37(14)

176.34(15)

121.29(14)

122.78(12)

110.81(11)

110.38(10)

118.61(7)

142.34(14)

139.42(12)

77.44(9)

128.06(14)

—

131.72(13)

—

122.86(17)

77.91(11)

72.00(11)

117.87(14)

110.56(13)

119.45(13)

114.75(8)

Fig. 8 NMR correlation scheme for complexes 13b/13b^ꢀand 13e and

13e^ꢀ.

C(31)–C(5)–P(1)

P(1)–C(5)–Mn(1)

—

5

2

= =

Structure of (g -MeC₅H₄)(CO)₂Mn[g -{Ph₂PC(Ph) C C-

(Tol)H}] (12b). Single crystals of 12b suitable for an X-

ray structure determination were obtained from a hex-

ane/dichloromethane solution in the cold. An ORTEP drawing

of the complex appears as Fig. 9. Relevant crystallographic data

are set out in Tables 4 and 5. The allene moiety is bonded

The phosphorus atom remains away from the manganese

atom as clearly indicated by the non-bonding distance

˚

Mn1 · · · P1 of 3.495(1) A. Trends in the metrical features are

similar to those found in other manganese allene complexes.³⁴

In particular, the manganese-to-central carbon atom distance

5

to the manganese atom of the (g -MeC₅H₄)(CO)₂Mn fragment

through C3 and C4. Attached to C3 are a phenyl group and a

diphenylphosphido group, while a tolyl group and an hydrogen

atom are attached to the non-coordinated carbon atom C5,

the tolyl group being in a cisoid position relative to the (g -

MeC₅H₄)(CO)₂Mn fragment.

˚

(Mn–C4 2.027(2) A) is signiﬁcantly shorter than the manganese-

˚

to-terminal carbon atom (Mn–C3 2.201(2) A). The non-

˚

=

coordinated C C double bond (C4–C5 1.327(2) A) com-

5

pares reasonably well with those of the free allene molecules

(1.307 A), in contrast to the coordinated one which is

signiﬁcantly elongated (1.407(2) A). Also, due to coordination

20

˚

to the metal, the allene appears to be strongly bent (C3–C4–C5

142.3(2)^◦).

It is worth noting that the coordination plane of the

allene ligand is almost orthogonal to the mirror plane of

5

the (g -MeC₅H₄)(CO)₂Mn fragment ({cent1–Mn–cent2–C3} =

108.60^◦, where cnt1 is the centroid of the (Me)Cp ligand and cnt2

the centroid of the C3–C4 bond). As already pointed out, such an

orientation can be rationalized in terms of a maximum overlap

between the HOMO of the metal fragment and the LUMO, here

a p*-type orbital, of the allene ligand (Scheme 14).²⁰Among the

5

2

Fig. 9 A perspective view of complex (g -MeC₅H₄)(CO)₂Mn[g -

=

C

=

C(Tol)H}] (12b). Thermal ellipsoids are shown at the

{Ph₂PC(R)

Scheme 14

50% probability level.

1 6 2 8

D a l t o n T r a n s . , 2 0 0 5 , 1 6 2 0 – 1 6 3 6

View Article Online

two rotamers that would satisfy such a maximum overlap, the

one we observed in solid state is certainly thermodynamically

favoured, the bulky diphenylphosphido group being away from

5

the g -MeC₅H₄ligand.

5

4

=

Structure of (g -MeC₅H₄)(CO)Mn[g -{Cy₂PC(Ph) CHC-

= =

(Ph) C O}], 13d. Single crystals of 13d suitable for an X-

ray structure determination were obtained from a hexane–

dichloromethane solution in the cold. An ORTEP drawing of

the complex is given in Fig. 10. Relevant crystallographic data

are set out in Tables 4 and 5. The vinyl ketene ligand backbone

is constituted by the O2, C2 and C3 atoms for the ketene part,

and the C4 and C5 carbon atoms for the vinyl part. The vinyl

ketene bears a phenyl ring attached to C3, a hydrogen atom

attached to C4, and a phenyl ring and a dicyclohexylphosphido

group attached to C5, the latter substituent being in a cisoid

position relative to the hydrogen atom attached to C4. The

phosphorus atom P1 is clearly located at a non-bonding distance

Scheme 15

that the phosphido group in 12 is in an adjacent position relative

to the substituent R. Hence, these complexes likely result from

an initial nucleophilic attack of the secondary phosphine onto

the carbene carbon atom, C_a. Such an attack would lead to

the r-propargylphosphonium complex A. A hydrogen migration

onto the Mn atom would then afford the r-propargyl hydride

species B and subsequent addition of the Mn–H bond across

˚

from Mn1 (Mn1 · · · P1 3.474(1) A). Metrical features within 13d

4

are very similar to those of the parent complexes Cp(CO)Mn[g -

{PhC(H) CPhC(Ph) C O}].³⁵In particular, amongst the four

Mn–C bonds of the vinyl ketene linkage, the bond between the

carbonyl carbon atom C2 and the manganese centre, and the

bond between the terminal vinylic carbon atom C5 and the metal

are respectively, the shortest and the longest (C2–Mn1 1.937(2)

=

= =

the C≡C bond²⁹would give the ﬁnal product 12. The g -

4

vinylketene complexes 13 and 13^ꢀare minor products in this

reaction. The NMR studies show that the two complexes are

regioisomers that differ in the relative position of the R and R^ꢀ

substituents. In the ﬁrst isomer, 13, the phosphido group is in an

adjacent position relative to R. Logically, this complex should

also arise from an initial nucleophilic attack of the phosphine

onto the carbene carbon atom. We propose that a fraction of

intermediate A could undergo a 1,3-[Mn] shift, similar to the

6 → 7 isomerisation we have evidenced (Scheme 9), to give

the r-allenylphosphonium complex C. Then, just like for their

group 6 cousins (Scheme 15), a fast rearrangement by hydrogen

migration would give the alkenyl carbene complex D. From D, a

˚

A; C5–Mn1 2.252(2) A vs. C3–Mn1 2.119(2) A and C4–Mn1

˚

2.068(8) A). Within the vinyl ketene ligand, the C–C bonds are

in the order C2–C3 > C3–C4 = C4–C5. Finally, because of its

linkage to the metal, the ketene part of the vinylketene ligand is

strongly bent (C3–C2–O2 137.1(2)^◦).

=

CO insertion into the Mn C bond would lead to 13. The other

regioisomer, 13^ꢀ, would arise from a direct nucleophilic attack

of the phosphine on the remote alkynyl carbon atom to give

intermediate C^ꢀ. From C^ꢀ, the same kind of rearrangement as for

C would lead to 13^ꢀ. The last step is probably the most debatable

step in that mechanism. Indeed, although this speciﬁc reaction

has precedent in the chemistry of iron carbene complexes,³⁶

manganese carbene complexes–whether they be heteroatom-

substituted or not–are not considered to be particularly prone to

undergo carbonylation.³⁷We suggest that the CO insertion might

be possibly be assisted by a reversible inter- or intramolecular

coordination of the phosphine moiety.

Finally, upon reaction of 3 with dicyclohexylphosphine, the

4

g -vinylketene species 13^ꢀbecomes the main product of the

reaction. This observation supports and justiﬁes the above

suggestions. Indeed, the dicyclohexylphosphine, being bulkier

than diphenylphosphine, is expected to attack predominantly

on C_c, thus favouring the formation of intermediate C^ꢀin the

direction of 13^ꢀ, at the expense of intermediate A that leads to

12 and 13.

5

4

Fig. 10 A perspective view of complex (g -MeC₅H₄)(CO)Mn[g -

=

= =

O}] (13d). Thermal ellipsoids are shown

{Cy₂PC(Ph) CHC(Ph)

C

at the 50% probability level.

Mechanistic considerations. Prior to this work, the only

alkynyl carbene complexes for which the reactivity toward

secondary phosphine had been investigated were the group 6

Conclusions

The non-heteroatom-substituted manganese alkynyl carbene

5

ꢀ

=

alkynyl carbene complexes (CO)₅M C(OEt)C≡CPh (M = Cr,

complexes (g -MeC₅H₄)(CO)₂Mn C(R)C≡CR (3) (R = R =

Ph; R = Ph, R^ꢀ= Tol; R = Tol, R^ꢀ= Ph) have been

synthesised in high yields upon treatment of the corresponding

W). From these complexes, Aumann et al. have obtained alkenyl

carbene species resulting formally from an 1,2-addition of the

P–H bond across the C≡C triple bond (Scheme 15).^10b

5

carbyne complexes [(g -MeC₅H₄)(CO)₂Mn≡CR][BPh₄] with the

Surprisingly, the corresponding 1,2-addition products were

never observed in the reactions of the Mn–alkynyl carbene

complexes 3 with the secondary phosphines we have considered.

appropriate alkynyllithium reagents LiC≡CR^ꢀ(R^ꢀ= Ph, Tol).

The use of tetraphenylborate as counter anion associated with

the cationic carbyne complexes has been decisive. Incidentally,

this study revealed that, contrary to the generally accepted

idea, cationic carbyne complexes are not intrinsically thermally

unstable. Indeed, the tetraphenylborate salts can be manipulated

at room temperature, even in the presence of air. In solution in

an inert solvent, they naturally remain extremely reactive, and

2

4

Instead, g -allene complexes and g -vinylketene complexes have

been isolated. A mechanism that may account for the formation

2

of these species is shown in Scheme 16. The g -allene complexes

12 are obtained predominantly in the reaction of 3 with

diphenylphosphine. Both the X-ray and NMR analyses show

D a l t o n T r a n s . , 2 0 0 5 , 1 6 2 0 – 1 6 3 6

1 6 2 9

View Article Online

Scheme 16

this suggests that the reactivity of manganese carbyne complexes

merits reinvestigation under unusual reaction conditions, i.e. at

room temperature or above.

phosphine on the carbene carbon atom, whereas we propose

that the third species evolve from a nucleophilic attack on the

remote alkynyl carbon atom.

When studied with the beneﬁt of phosphorus probes, com-

plexes 3 revealed subtle reactivity patterns. In the presence

of PPh₃, as their parent group 6 heteroatom-substituted

alkynyl carbene complexes and their rhenium analogues,

they act as a Michael acceptor and undergo a nucle-

ophilic attack on the remote alkynyl carbon atom, C_c, thus

Experimental

General

Tetrahydrofuran and diethyl ether used for the synthesis were

distilled under nitrogen from sodium benzophenone ketyl

just before use. Other solvents were puriﬁed following stan-

dard procedure, and stored under nitrogen. The following

reagent grade chemicals NaBPh₄, PhC≡CLi (1 M solution in

5

affording zwitterionic r-allenylphosphonium complexes (g -

ꢀ

= =

MeC₅H₄)(CO)₂MnC(R) C C(PPh₃)R (5). In the presence

of PMe₃, a more basic and more nucleophilic phosphine,

complexes 3 behave as typical Fischer carbene complexes

and experience a nucleophilic attack on the carbene carbon,

C_a, atom to give zwitterionic r-propargylphosphonium com-

n

THF), BuLi (1.6 M solution in hexane), TolC≡CH, PPh₂H,

PCy₂H, PPh₂Me, PMe₃(1 M solution in THF) were ob-

5

tained from Aldrich and used without further puriﬁcation. (g -

plexes (g -MeC₅H₄)(CO)₂MnC(R)(PMe₃)C≡CR^ꢀ(6). Although

5

=

MeC₅H₄)(CO)₂Mn C(OEt)R (R = Ph, Tol) was prepared by

they are stable in the solid state, the latter complexes read-

ily isomerise in solution to give r-allenylphosphonium com-

plexes 7. Surprisingly enough, the determination of the struc-

slight modiﬁcation of literature procedures.³⁸All synthetic ma-

nipulations were carried out using standard Schlenk techniques

under an atmosphere of dry nitrogen atmosphere. A liquid

N₂/isopropanol slush bath was used to maintain samples at

the desired low temperature. Chromatographic separation of

the complexes was performed on alumina (neutral, activity III

(Aldrich)). Solution IR spectra were recorded on a Perkin-Elmer

983G spectrophotometers with0.1 mm cells equippedwith CaF₂

windows. ¹H, ¹³C and ³¹P NMR spectra were obtained on Bruker

WM250, DPX300, AMX400 spectrometers and were referenced

to the residual signals of the deuterated solvent. NMR spectra

were recorded at room temperature otherwise speciﬁed. Mass

spectra were recorded on AEI-MS9, or Nermag R10–10 mass

spectrometers (EI). Microanalyses of C and H elements were

performed on a Perkin-Elmer 2400 CHN analyser.

5

ture in solution of the r-dihydrophospholium complexes (g -

MeC₅H₄)(CO)₂MnC C(R )PMe₂CH₂CH(R) (8) derived from

subsequent thermal cyclisation of complexes 7, revealed that

ꢀ

=

5

the 6 → 7 isomerisation proceeds through a 1,3 shift of the [(g -

MeC₅H₄)(CO)₂Mn] fragment, rather than phosphine migration.

This reactivity pattern is unprecedented for both group 6 alkynyl

carbene and non-heteroatom-substituted rhenium alkynyl car-

bene complexes. In the presence of PPh₂Me, an intermediate

phosphine in terms of both size and basicity, complexes 3

undergo a nucleophilic attack on both C_aand Cc.

The reactivity of complexes 3 toward secondary phosphines

revealed a totally new reactivity pattern for alkynyl carbene.

Indeed, whereas group 6 [heteroatom-substituted] alkynyl

carbene complexes react with secondary phosphines to afford

stable alkenyl carbenes resulting from typical 1,2 addition on

Synthesis of the carbyne complexes

[(g⁵-MeC₅H₄)(CO)₂Mn≡CR][BPh₄] (2); [2a][BPh₄]: R = Ph;

2

the alkynyl moiety, complexes 3 afford mixtures of the g -allene

[2b][BPh₄]: R = Tol)

5

2

1

ꢀ

= =

complexes (g -MeC₅H₄)(CO)₂Mn[g -{R PC(R) C C(R )H}]

2

4

5

(12) and regioisomeric g -vinylketene complexes (g -

Typical procedure as illustrated for [2a][BPh₄]. Complex

4

1

ꢀ

5

=

= =

=

MeC₅H₄)(CO)Mn[g -{R PC(R) CHC(R ) C O}] (13) and

(g -MeC₅H₄)(CO)₂Mn C(OEt)Ph (1a, 7.45 g, 23 mmol) was

2

dissolved in hexane (150 mL), the solution was cooled to −50 ^◦C

then BCl₃(51 mL of a 1 M solution in hexane, 51 mmol) was

added rapidly under vigorous stirring. This caused the formation

5

4

1

ꢀ

=

= =

(g -MeC₅H₄)(CO)Mn[g -{R PC(R ) CHC(R) C O}] (13 ).

2

The formation of the ﬁrst two complex can be rationalized

in terms of an initial nucleophilic attack of the secondary

1 6 3 0

D a l t o n T r a n s . , 2 0 0 5 , 1 6 2 0 – 1 6 3 6

View Article Online

of an abundant pale yellow precipitate. After the addition of BCl₃

was complete and while the ﬂask was maintained at −50 ^◦C,

the supernatant was removed by means of cannula tipped with

a ﬁlter paper. The ﬂask was then cooled to −80 ^◦C and the

precipitate was dissolved in THF (50 mL). To this was added

[Na][BPh₄] (8.10 g, 23 mmol) and the heterogeneous mixture

was vigorously stirred for 2 h. Hexane (50 mL) was then added,

and the mixture was stirred for an additional 15 min. While the

ﬂask was maintained at −80 ^◦C, the supernatant was removed by

means of canula tipped with a ﬁlter paper. The cooling bath was

then removed and while the ﬂask was warming up, the remaining

yellow precipitate was thoroughly dried under high vacuum

until it showed constant weight (see CAUTION note below).

After the precipitate was thoroughly dried the rubber septum

obstructing the ﬂask was removed and while maintaining the

stock precipitate under a slow ﬂow of nitrogen, it was dropped

portion-wise in a beaker containing distilled water (200 mL)

chilled at 2 ^◦C, under vigorous stirring. The yellow suspension

of [2a][BPh₄] in water was ﬁltered off over a Bu¨chner funnel and

washed with distilled water until the ﬁltrate shows a neutral

pH. The yellow powder of [2a][BPh₄] was dried under high

vacuum until it showed constant weight (11.83 g, 19.8 mmol,

86% yield).

3a: ¹H NMR (300.1 MHz, CD₂Cl₂) d 8.1–7.5 (m, 10H,

C₆H₅), 5.22–5.13 (m, 4H, g -MeC₅H₄), 2.06 (s, 3H, g -MeC₅H₄).

5

13

1

=

C{ H} NMR (75.5 MHz, CD₂Cl₂) d 300.9 (Mn C), 234.6

(CO), 156.3–125.7 (C₆H₅), 125.5, 106.1 (C≡C), 108.6, 95.2,

5

94.2 (g -MeC₅H₄), 13.8 (g -MeC₅H₄). IR (CH₂Cl₂): 2124 (m_C≡C),

1969, 1905 (m_CO). Anal. Calc. for C₂₃H₁₇MnO₂: C, 72.64; H, 4.51.

Found: C, 72.55; H, 4.49%.

3b: ¹H NMR (250.1 MHz, C₆D₆) d 8.3–6.7 (m, 9H, C₆H₅and

5

MeC₆H₄), 4.72–4.58 (m, 4H, g -MeC₅H₄), 1.99 (s, 3H, MeC₆H₄),

1.55 (s, 3H, g -MeC₅H₄). ¹³C{ H} NMR (100.0 MHz, C₆D₆)

5

1

=

d 301.5 (Mn C), 234.5 (CO), 153.2–125.4 (C₆H₅, MeC₆H₄),

5

113.2, 102.9 (C≡C), 107.5, 94.5, 93.2 (g -MeC₅H₄), 21.2

5

(MeC₆H₄), 12.9 (g -MeC₅H₄). IR (CH₂Cl₂): 2121 (m_C≡C), 1970,

1907 (m_CO). Anal. Calc. for C₂₄H₁₉MnO₂: C, 73.08; H, 4.86.

Found: C, 72.84; H, 4.58%.

3c: ¹H NMR (250.1 MHz, CD₂Cl₂) d 8.1–7.3 (m, 9H,

5

C₆H₅and MeC₆H₄), 5.2–5.1 (m, 4H, g -MeC₅H₄), 2.4 (s, 3H,

5

1

MeC₆H₄), 1.7 (s, 3H, g -MeC₅H₄). ¹³C{ H} NMR (62.9 MHz,

=

CD₂Cl₂) d 299.5 (Mn C), 234.9 (CO), 153.2–131.3 (C₆H₅and

5

MeC₆H₄), 125.5, 105.5 (C≡C), 108.4, 95.3, 94.1 (g -MeC₅H₄),

5

21.7 (MeC₆H₄), 13.8 (g -MeC₅H₄). IR (CH₂Cl₂): 2126 (m_C≡C),

1970, 1907 (m_CO). Anal. Calc. for C₂₄H₁₉MnO₂: C, 73.08; H, 4.86.

Found: C, 72.98; H, 4.59%.

CAUTION: the organic solvents must have been thoroughly

removed before proceeding to the next step; if not, the precipitate

reacts in a very exothermic manner upon exposure to air and even

though this never happened to us, we suspect it could even ignite.

Synthesis of the r-allenylphosphonium complexes

5

ꢀ

= =

(g -MeC₅H₄)(CO)₂MnC(R) C C(PPh₃)R (5; 5a: R = R =

Ph; 5b: R = Ph, R^ꢀ= Tol; 5c: R = Tol, R^ꢀ= Ph)

1

[2a][BPh₄]: H NMR (300.1 MHz, CD₂Cl₂, 223 K) d 7.9–

5

6.9 (m, 25H, C₆H₅), 4.99 (m, 4H, g -MeC₅H₄, 1.96 (s, 3H,

Typical procedure as illustrated for (g⁵-MeC₅H₄)(CO)₂MnC-

5

1

g -MeC₅H₄). ¹³C{ H} NMR (75.5 MHz, CD₂Cl₂, 223 K) d

(Ph) C C(PPh₃)Ph (5a). Triphenylphosphine (0.26 g,

= =

5

356.1 (Mn≡C), 214.0 (CO), 164.5–122.1 (C₆H₅), 115.1, 91.8,

1.0 mmol) was added to

a

solution of (g -MeC₅H₄)-

5

=

91.7 (g -MeC₅H₄), 13.9 (g -MeC₅H₄). IR (CH₂Cl₂): 2084, 2047

(m_CO). IR (KBr): 2064, 2027 (m_CO). IR (THF): 1994, 1930

(m_CO). MS (electrospray, positive mode, CH₂Cl₂–CH₃CN) m/z

(CO)₂Mn C(Ph)C≡CPh (3a, 0.38 g, 1.0 mmol) in hexane

(15 mL) at room temperature. An abundant red precipitate

formed. Hexane was removed by means of canula tipped with

a ﬁlter paper. The precipitate was washed with hexane (3 ×

5 mL) then dried under high vacuum. This yielded complex

279.1 [(g -MeC₅H₄)(CO)₂Mn≡CPh]⁺. MS (electrospray, nega-

5

tive mode, CH₂Cl₂–CH₃CN) m/z 319.0 [BPh₄]⁻. Anal. Calc. for

C₃₉H₃₂BMnO₂: C, 78.24; H, 5.39. Found: C, 77.06; H, 5.46%.

[2b][BPh₄]: IR (CH₂Cl₂): 2081, 2042 (m_CO). IR (THF): 1994,

1929 (m_CO). Anal. Calc. for C₄₀H₃₄BMnO₂: C, 78.41; H, 5.60.

Found: C, 77.60; H, 5.71%.

5

= =

(g -MeC₅H₄)(CO)₂MnC(Ph) C C(PPh₃)Ph (5a) as

a red

powder (0.59 g, 0.9 mmol, 92% yield).

The complexes (g -MeC₅H₄)(CO)₂MnC(Ph) C C(PPh₃)Tol

(5b), (g -MeC₅H₄)(CO)₂MnC(Tol) C C(PPh₃)Ph (5c) were

5

= =

5

= =

synthesised using the same protocol from complexes 3b and

3c and they were isolated in 82 and 84% yield, respectively.

5a: ¹H NMR (300.1 MHz, CD₂Cl₂, 293 K) d 7.8–6.9 (m, 25H,

Synthesis of the alkynyl carbene complexes

C₆H₅), 4.0 (m, 4H, g -MeC₅H₄), 1.7 (s, 3H, g -MeC₅H₄). ¹³C{ H}

NMR (75.5 MHz, CD₂Cl₂, 293 K) d 238.7 (CO), 163.7 (d, C_b,

²J_CP= 11 Hz), 143.3–123.0 (C₆H₅), 115.8 (d, C_a, ³J_CP= 12 Hz),

5

1

5

ꢀ

=

(g -MeC₅H₄)(CO)₂Mn C(R)C≡CR (3; 3a: R = R = Ph; 3b:

R = Ph, R^ꢀ= Tol; 3c: R = Tol, R^ꢀ= Ph)

Typical procedure as illustrated for (g⁵-MeC₅H₄)(CO)₂-

97.8, 84.6, 81.3 (g -MeC₅H₄), 55.8 (d, C_c, ¹J_CP= 110 Hz), 14.2

5

Mn C(Ph)C≡CPh (3a). Lithium phenylacetylide (2.0 mL of

(g -MeC₅H₄). ¹H NMR (300.1 MHz, CD₂Cl₂, 193 K): d 7.8–6.8

=

5

a 1 M solution in THF, 2 mmol) was added dropwise to a solu-

(m, 25H, C₆H₅), 4.10, 3.92, 3.86 (m, 4H, g -MeC₅H₄), 1.66 (s, 3H,

5

tion of [(g -MeC₅H₄)(CO)₂Mn≡CPh][BPh₄] ([2a][BPh₄], 1.21 g,

g -MeC₅H₄). NMR ¹³C (75.5 MHz, CD₂Cl₂, CD₂Cl₂, 193 K):

◦

2

2.02 mmol) in CH₂Cl₂(15 mL) cooled at −80 C. The yellow

d 239.5, 238.9 (CO), 168.4 (C_b, J_CP= 11 Hz), 142.8–122.1

5

solution turned rapidly dark red. The cold solution was ﬁltered

on a short column of alumina. The solvents were removed

under high vacuum and the oily black residue was puriﬁed by

chromatography on alumina. An initial elution with a 1 : 20

diethyl ether–pentane mixture gave a yellow band containing

(C₆H₅), 115.9 (C_a, ³J_CP= 12 Hz), 98.3, 87.5, 84.5, 81.3, 79.5 (g -

MeC₅H₄), 56.1 (C_c, J_CP= 109 Hz), 14.7 (g -MeC₅H₄). ³¹P{ H}

5

1

NMR (121.5 MHz, CD₂Cl₂, 293 K): d 22.5. IR (CH₂Cl₂): 1835

(sh, m_C₌_C), 1891, 1814 (m_CO). Anal. Calc. for C₄₁H₃₂MnO₂P: C,

=

C

76.62; H, 5.02 Found: C, 76.93; H, 5.07.

5

trace amount of (g -MeC₅H₄)Mn(CO)₃. A second elution with

5b: ¹H NMR (300.1 MHz, CD₂Cl₂, 293 K) d 7.8–6.9 (m, 24H,

5

a 1 : 5 diethyl ether–pentane mixture afforded a dark red band

C₆H₅and MeC₆H₄), 3.98 (m, 4H, g -MeC₅H₄), 2.26 (MeC₆H₄),

5

1

containing complex (g -MeC₅H₄)(CO)₂Mn C(Ph)C≡CPh (3a),

1.73 (g -MeC₅H₄). ¹³C{ H} NMR (75.5 MHz, CD₂Cl₂, 293 K)

=

2

which was isolated as a dark red oil after removal of the solvent

under high vacuum (0.63 g, 82% yield).

d 238.8 (CO), 167.8 (C_b, J_CP= 11 Hz), 143.5–123.1 (C₆H₅

3

5

and MeC₆H₄), 116.3 (C_a, J_CP= 12 Hz), 97.5, 84.4, 81.2 (g -

1

5

Final elution with a 1 : 1 diethyl ether–pentane mixture

in the chromatographic workup eventually affords a pink

MeC₅H₄), 56.2 (C_c, J_CP= 109 Hz), 21.0 (MeC₆H₄), 14.3 (g -

MeC₅H₄). ³¹P{ H} NMR (121.5 MHz, CD₂Cl₂, 293 K): d 24.8.

1

5

band containing trace amount of [(g -MeC₅H₄)(CO)₂Mn]₂[l-

¹H NMR (300.1 MHz, CD₂Cl₂, 193 K): d 7.8–6.8 (m, 24H,

4

5

=

g -PhC≡CC(Ph) C(Ph)C≡CPh] (4).

C₆H₅and MeC₆H₄), 3.93, 3.85, 3.81, 3.71 (m, 4H, g -MeC₅H₄),

5

1

The complexes (g -MeC₅H₄)(CO)₂Mn C(Ph)C≡CTol (3b)

2.15 (s, 3H, MeC₆H₄), 1.66 (s, 3H, g -MeC₅H₄). ¹³C{ H} NMR

(75.5 MHz, CD₂Cl₂, 193 K) d 239.5, 238.9 (CO), 168.4 (C_b,

²J_CP= 11 Hz), 142.8–122.1 (C₆H₅and MeC₆H₄), 115.9 (C_a,

=

5

=

and (g -MeC₅H₄)(CO)₂Mn C(Tol)C≡CPh (3c) were obtained

in 85 and 85%, respectively, following the above procedure and

using the appropriate combination of cationic carbyne complex

and alkynyllithium reagent.

5

³J_CP= 12 Hz), 98.3, 87.5, 84.5, 81.3, 79.5 (g -MeC₅H₄), 56.1 (C_c,

5

³J_CP= 109 Hz), 21.3 (MeC₆H₄), 14.7 (g -MeC₅H₄). IR (CH₂Cl₂):

D a l t o n T r a n s . , 2 0 0 5 , 1 6 2 0 – 1 6 3 6

1 6 3 1

View Article Online

1839 (sh, m_C₌_C), 1898, 1814(m_CO). Anal. Calc. for C₄₂H₃₄MnO₂P:

(CH₂Cl₂): 1857 (sh, m_C₌_C), 1882, 1808 (m_CO). Anal. Calc. for

=

C

C, 76.81; H, 5.22. Found: C, 76.87; H, 4.88%.

C₂₆H₂₆MnO₂P: C, 68.41; H, 5.75. Found: C, 68.55; H, 5.71%.

Complexes 7b and 7c were generated in situ following the

above procedure starting from complexes 6a and 6b, respectively,

but they have not been isolated. The crude solution of 7b and 7c

thus prepared have been used to synthesise complexes 8b and 8c

(vide infra).

5c: ¹H NMR (400.1 MHz, CD₂Cl₂) d 7.9–7.0 (m, 24H, C₆H₅

5

and MeC₆H₄), 4.08 (m, 4H, g -MeC₅H₄), 2.28 (s, 3H, MeC₆H₄),

5

1

1.82 (s, 3H, g -MeC₅H₄). ¹³C{ H} NMR (100.6 MHz, CD₂Cl₂)

2

d 238.8 (CO), 165.1 (C_b, J_CP= 11 Hz), 139.9–122.9 (C₆H₅

3

5

and MeC₆H₄), 115.2 (C_a, J_CP= 12 Hz), 98.0, 84.8, 81.3 (g -

1

5

MeC₅H₄), 55.6 (C_c, J_CP= 110 Hz), 21.3 (MeC₆H₄), 14.4 (g -

7b: IR (CH₂Cl₂): 1854 (sh, m_C₌_C), 1885, 1805 (m_CO).

=

C

MeC₅H₄). ³¹P{ H} NMR (162.0 MHz, CD₂Cl₂): d 24.7. ¹H

7c: IR (CH₂Cl₂): 1857 (sh, m_C₌_C), 1886, 1806 (m_CO).

1

=

C

NMR (400.1 MHz, 233 K, CD₂Cl₂): d 7.8–6.8 (m, 24H, C₆H₅

5

and MeC₆H₄), 4.08, 4.06, 3.91, 3.89 (s, 4H, g -MeC₅H₄), 2.28

Synthesis of the dihydrophospholinium complexes

5

1

(s, 3H, MeC₆H₄), 1.72 (s, 3H, g -MeC₅H₄). ¹³C{ H} NMR

(100.6 MHz, CD₂Cl₂, 233 K) d 239.3, 238.9 (CO), 165.7 (C_b,

²J_CP= 11 Hz), 139.1–122.2 (C₆H₅and MeC₆H₄), 114.8 (C_a,

5

ꢀ

=

(g -MeC₅H₄)(CO)₂MnC C(R)PMe₂CH₂CH(R ) (8; 8a: R =

R^ꢀ= Ph; 8b: R = Ph, R^ꢀ= Tol; 8c: R = Tol, R^ꢀ= Ph)

³J_CP= 12 Hz), 98.3, 86.5, 84.7, 81.1, 80.1 (g -MeC₅H₄), 54.9

Typical procedure as illustrated for (g⁵-MeC₅H₄)(CO)₂-

5

1

5

(C_c, ¹J_CP= 110 Hz), 21.5 (MeC₆H₄), 14.6 (g -MeC₅H₄). ³¹P{ H}

MnC C(Ph)PMe₂CH₂CH(Ph) (8a). Complex (g -MeC₅H₄-

=

NMR (162.0 MHz, CD₂Cl₂, 233 K): d 24.5. IR (CH₂Cl₂): 1841

)(CO)₂MnC(Me₃P)(Ph)C≡CPh (6a) (0.360 g, 0.8 mmol) was

dissolved in dichloromethane and the solution was heated

under reﬂux for 2 h, under stirring. After removal of the

dichloromethane solvent under vacuum, the oily residue was

puriﬁed by chromatography on an alumina column. An initial

elution with a 1 : 10 diethyl ether–pentane mixture gave a

(sh, m_C₌_C), 1891, 1814 (m_CO). Anal. Calc. for C₄₂H₃₄MnO₂P: C,

=

C

76.81; H, 5.22. Found: C, 76.93; H, 5.08%.

Synthesis of the r-propargylphosphonium complexes

(g⁵-MeC₅H₄)(CO)₂MnC(Me₃P)(R)C≡CR^ꢀ(6; 6a: R = R^ꢀ= Ph;

6b: R = Ph, R^ꢀ= Tol; 6c: R = Tol, R^ꢀ= Ph)

5

yellow band containing trace amount of (g -MeC₅H₄)Mn(CO)₃.

Typical procedure as illustrated for (g⁵-MeC₅H₄)(CO)₂MnC-

A second elution with a 1 : 1 diethyl ether–pentane mix-

5

(Me₃P)(Ph)C≡CPh (6a). Trimethylphosphine (0.105 mL;

ture afforded a yellow band containing the complex (g -

5

=

1.0 mmol) was added to

a

solution of (g -MeC₅H₄)-

MeC₅H₄)(CO)₂MnC C(Ph)PMe₂CH₂CH(Ph) (8a), which was

=

(CO)₂Mn C(Ph)C≡CPh (3a, 0.38 g, 1.0 mmol) in hexane

(15 mL) at room temperature. An abundant red precipitate

formed. Hexane was removed by means of canula tipped with

a ﬁlter paper. The precipitate was washed with hexane (3 ×

subsequently isolated as a yellow solid after removal of the

solvents under high vacuum (0.28 g, 0.49 mmol, 61% yield).

5

=

The complexes (g -MeC₅H₄)(CO)₂MnC C(Ph)PMe₂CH₂-

5

=

CH(Tol) (8b) and (g -MeC₅H₄)(CO)₂MnC C(Tol)PMe₂CH₂-

5

5 mL) then dried under high vacuum. This yielded complex (g -

CH(Ph) (8c) were synthesised using the same protocol from

complexes 4b and 4c as starting material and they were isolated

in 58 and 69% yield, respectively.

= =

MeC₅H₄)(CO)₂MnC(Ph) C C(PPh₃)Ph (6a) as a red powder

(0.38 g, 0.84 mmol, 84% yield).

5

The complexes (g -MeC₅H₄)(CO)₂MnC(Ph)(Me₃P)C≡CTol

Alternatively, complexes 8a–c can be obtained in similar yield

upon addition of trimethylphosphine to solutions of complexes

3a–c in dichloromethane at 25 ^◦C, followed by a heating under

reﬂux for 2 h.

5

(6b), (g -MeC₅H₄)(CO)₂MnC(Tol)(Me₃P)C≡CPh (6c) were syn-

thesised using the same protocol from complexes 3b and 3c as

starting material and they were isolated in 76 and 84% yield,

respectively.

1

8a: H NMR (300.1 MHz, CD₂Cl₂, 293 K): d 8.1–6.9 (m,

5

6a: IR (CH₂Cl₂): 2177 (m_C≡C), 1880, 1804 (m_CO). Anal. Calc. for

C₂₆H₂₆MnO₂P: C, 68.41; H, 5.75. Found: C, 68.63; H, 5.41%.

6b: IR (CH₂Cl₂): 2177 (m_C≡C), 1880, 1804 (m_CO). Anal. Calc. for

C₂₇H₂₈MnO₂P: C, 68.92; H, 6.00. Found: C, 68.97; H, 5.93%.

6c: IR (CH₂Cl₂): 2177 (m_C≡C), 1879, 1803 (m_CO). Anal. Calc. for

C₂₇H₂₈MnO₂P: C, 68.92; H, 6.00. Found: C, 69.27; H, 6.23%.

10H, C₆H₅), 5.25 (m, 1H, CHPh), 3.55, 3.52, 3.45, (m, 4H, g -

2

MeC₅H₄), 2.85, 2.35 (m, 2H, CH₂), 1.67 (d, 3H, PMe₂, J_HP

=

2

5

13 Hz), 1.56 (d, 3H, PMe₂, J_HP= 13 Hz), 1.52 (s, 3H, g -

MeC₅H₄). ¹³C{ H} NMR (75.5 MHz, CD₂Cl₂, 293 K): d 253.5

1

(C_b), 238.2, 237.2 (CO), 147.4–125.0 (C₆H₅), 120.0 (C_a, J_CP

=

5

60 Hz), 97.2, 85.1, 85.1, 81.7, 81.1 (g -MeC₅H₄), 68.5 (C_c,

²J_CP= 17 Hz), 32.6 (C_d, ¹J_CP= 62 Hz), 14.0 (g -MeC₅H₄), 13.4

5

Synthesis of the r-allenylphosphonium complexes

(PMe₂, J_CP= 69 Hz). ³¹P{ H} NMR (121.5 MHz, CD₂Cl₂,

293 K): d 32.7. IR (CH₂Cl₂): 1882, 1808 (m_CO). Anal. Calc. for

C₂₆H₂₆MnO₂P: C, 68.41; H, 5.75. Found: C, 68.55; H, 5.71%.

1

5

ꢀ

= =

(g -MeC₅H₄)(CO)₂Mn[C(R ) C C(PMe₃)R] (7; 7a: R = R’ =

Ph; 7b: R = Ph, R’ = Tol; 7c: R = Tol, R’ = Ph)

Typical procedure as illustrated for (g⁵-MeC₅H₄)(CO)₂-

8b: H NMR (400.1 MHz, CD₂Cl₂, 293 K): d 7.6–7.0 (m,

1

5

= =

MnC(Ph) C C(PMe₃)Ph (7a). Complex (g -MeC₅H₄)-

9H, C₆H₅and MeC₆H₄), 5.18 (m, 1H, CHTol), 3.49, 3.46, 3.42,

5

(CO)₂MnC(Me₃P)(Ph)C≡CPh (6a) (0.38 g, 0.84 mmol) was

dissolved in dichloromethane and the solution was stirred for

15 min at 25 ^◦C. IR monitoring showed the disappearance

of the band 2177 cm⁻¹band of 6a, and the appearance of

3.41 (m, 4H, g -MeC₅H₄), 2.83, 2.30 (m, 2H, CH₂), 2.38 (s,

2

3H, MeC₆H₄), 1.65 (d, 3H, PMe₂, J_HP= 13 Hz), 1.55 (d, 6H,

5

1

PMe₂, ²J_HP= 13 Hz), 1.50 (s, 3H, g -MeC₅H₄). ¹³C{ H} NMR

(100.6 MHz, CD₂Cl₂, 293 K): d 252.7 (C_b), 238.4, 237.3 (CO),

144.4–126.4 (C₆H₅and MeC₆H₄), 120.1 (C_a, ¹J_CP= 60 Hz), 96.9,

a shoulder at 1857 cm⁻¹due the m_C₌

of the newly formed

=

C

5

complex 7a. The solution was concentrated under vacuum

to a volume of ca. 2 mL then hexane (10 mL) was added

under vigorous stirring to induce the precipitation of 7a. The

supernatant was removed by means of canula tipped with a

ﬁlter paper. The remaining red precipitate was washed with

85.4, 85.4, 83.0, 81.0 (g -MeC₅H₄), 68.0 (C_c, ²J_CP= 17 Hz), 32.5

5

(C_d, ¹J_CP= 62 Hz), 21.3 (MeC₆H₄), 14.1 (g -MeC₅H₄), 13.9, 12.9

1

(PMe₂, J_CP= 44 Hz). ³¹P{ H} NMR (162.0 MHz, CD₂Cl₂) d

•

32.3. IR (CH₂Cl₂): 1881, 1806 (m_CO). MS (EI) m/z 470 [M]⁺, 414

•

[M − 2CO]⁺, 280 [M − (g -MeC₅H₄(CO)₂Mn)]⁺. Anal. Calc. for

5

hexane (3 × 5 mL) then dried under high vacuum. This yielded

C₂₇H₂₈MnO₂P: C, 68.92; H, 6.00. Found: C, 68.27; H, 5.46%.

5

1

= =

complex (g -MeC₅H₄)(CO)₂MnC(Ph) C C(PMe₃)Ph (7a) as

8c: H NMR (300.1 MHz, CD₂Cl₂) d 7.5–7.1 (m, 9H, C₆H₅

a red powder (0.38 g, 0.71 mmol, 84% yield).

and MeC₆H₄), 5.22 (dd, 1H, HCPh, ³J_HH= 9 Hz, ³J_HP= 10 Hz),

7a: ¹H NMR (300.1 MHz, CD₂Cl₂, 293 K) d 7.6–7.0 (m, 10H,

3.54, 3.54, 3.45, 3.42 (m, 4H, g -MeC₅H₄, 2.84 (ddd, 1H, CH₂,

5

C₆H₅), 4.28, 4.21 (m, 4H, g -MeC₅H₄), 1.90 (d, 9H, PMe₃, ²J_CP

=

²J_HH= 15 Hz, ³J_HH= 9 Hz, ²J_HP= 10 Hz), 2.33 (dd, 1H, CH₂,

5

12 Hz), 1.80 (s, 3H, g -MeC₅H₄). ¹³C{ H} NMR (75.5 MHz,

²J_HH= 15 Hz, J_HP= 10 Hz), 2.46 (s, 3H, MeC₆H₄), 1.64 (d,

5

1

2

CD₂Cl₂, 293 K) d 239.0 (CO), 165.4 (C_b), 143.6–125.0 (C₆H₅),

3H, PMe₂, J_HP= 13 Hz), 1.55 (d, 3H, PMe₂, J_HP= 13 Hz),

3

5

1

115.1 (C_a, J_CP= 15 Hz), 99.1, 83.7, 82.3 (g -MeC₅H₄), 59.1

1.51 (s, 3H, g -MeC₅H₄). ¹³C{ H} NMR (75.5 MHz, CD₂Cl₂) d

1

5

1

(C_c, J_CP= 105 Hz), 14.1 (g -MeC₅H₄), 13.8 (PMe₃, J_CP

=

251.6 (C_b), 238.7 (CO), 147.5–126.4 (C₆H₅and MeC₆H₄), 120.2

1

5

69 Hz). ³¹P{ H} NMR (121.5 MHz, CD₂Cl₂, 293 K) d 19.1. IR

(C_a, J_CP= 60 Hz), 96.9, 85.3, 84.9, 81.7, 81.1 (g -MeC₅H₄),

1 6 3 2

D a l t o n T r a n s . , 2 0 0 5 , 1 6 2 0 – 1 6 3 6

View Article Online

5

68.8 (C_c, ²J_CP= 17 Hz), 32.5 (C_d, ¹J_CP= 63 Hz), 21.4 (MeC₆H₄),

band containing trace amount of (g -MeC₅H₄)Mn(CO)₃.

second elution with diethyl ether–pentane

mixture afforded a yellow band containing the complex

5

1

13.9 (g -MeC₅H₄), 13.8, 12.9 (PMe₂, J_CP= 45 Hz). ³¹P{ H}

A

a 1 : 1

NMR (121.5 MHz, CD₂Cl₂) d 32.0. IR (CH₂Cl₂): 1881, 1807

5

(m_CO). MS (EI) m/z 470 [M]⁺, 414 [M − 2CO]⁺, 280 [M − (g -

(g -MeC₅H₄)(CO)₂MnC C(Ph)PMe₂CH₂CH(Ph) (11a), which

=

MeC₅H₄(CO)₂Mn)]⁺. Anal. Calc. for C₂₇H₂₈MnO₂P: C, 68.92;

H, 6.00. Found: C, 68.35; H, 5.64%.

was subsequently isolated as a yellow solid after removal of the

solvents under high vacuum (0.25 g, 0.43 mmol, 61% yield).

A similar treatment of a 1 : 1 mixture of complexes

mixture of complexes

(g -MeC₅H₄)(CO)₂MnC C(Ph)PMe₂CH₂CH(Tol) (11b) and

Synthesis of the r-allenylphosphonium complexes

10b and 10b^ꢀyielded

a

1

:

1

5

ꢀ

5

= =

=

(g -MeC₅H₄)(CO)₂MnC(R ) C C(PMePh₂)R (10; 10a: R =

R^ꢀ= Ph; 10b/10b^ꢀ: R = Ph/Tol, R^ꢀ= Tol/Ph)

(g -MeC₅H₄)(CO)₂MnC C(Tol)PMe₂CH₂CH(Ph) (11b ) (58%

yield).

5

ꢀ

=

Typical procedure as illustrated for (g⁵-MeC₅H₄)(CO)₂-

11a: ¹H NMR (300.1 MHz, CD₂Cl₂) d 8.1–7.0 (m, 20H, C₆H₅),

= =

MnC(Ph) C C(PMePh₂)Ph

(10a). Methyldiphenylphos-

5

5.51 (m, CHPh), 3.76, 3.73, 3.52, 3.48 (g -MeC₅H₄), 3.27, 3.05

phine (0.20 g, 1.0 mmol) was added to a solution of

(m, 2H, H_c), 1.61 (g -MeC₅H₄). ¹³C{ H} NMR (75.5 MHz,

5

1

5

=

(g -MeC₅H₄)(CO)₂Mn C(Ph)C≡CPh (3a, 0.38 g, 1.0 mmol)

CD₂Cl₂) d 260.3 (C_b), 238.1, 237.1 (CO), 147.5–126.4 (C₆H₅),

in hexane (15 mL) at room temperature. An abundant red

precipitate formed. Hexane was removed by means of canula

tipped with a ﬁlter paper. The precipitate was washed with

hexane (3 × 5 mL) then dried under high vacuum. IR analysis

of the solid gave indication of the presence of a r-propargyl

complex (m_C≡Cat 2177 cm⁻¹). The precipitate was dissolved

in dichloromethane (2 mL) then hexane (10 mL) was added

under vigorous stirring to induce the precipitation of an

orange powder. The supernatant was removed by means

of canula tipped with a ﬁlter paper and the remaining

orange precipitate was washed with hexane (3 × 5 mL)

116.4 (C_a, ¹J_CP= 60 Hz), 97.0, 85.3, 85.2, 81.9, 81.4 (g -MeC₅H₄),

5

2

1

5

68.7 (C_c, J_HP= 15 Hz), 35.2 (C_d, J_CP= 68 Hz), 14.1 (g -

MeC₅H₄). ³¹P{ H} NMR (121.5 MHz, CD₂Cl₂) d 34.7. IR

1

(CH₂Cl₂): 1880, 1807 (m_CO). Anal. Calc. for C₃₆H₃₀MnO₂P: C,

74.47; H, 5.21. Found: C, 74.61; H, 5.39%.

11b + 11b^ꢀ: H NMR (300.1 MHz, CD₂Cl₂) d 7.7–7.0 (m,

1

5

C₆H₅and MeC₆H₄), 5.45 (m, CHPh/CHTol), 3.59–3.42 (m, g -

MeC₅H₄), 3.23, 2.99 (m, 2H, CH₂), 2.38, 2.38 (MeC₆H₄), 1.58,

1.57 (g -MeC₅H₄). ¹³C{ H} NMR (75.5 MHz, CD₂Cl₂) d 260.6,

259.9 (C_b), 238.1, 237.1 (CO), 147.4–126.4 (C₆H₅and MeC₆H₄),

116.2 (C_a, ¹J_CP= 53 Hz), 96.9, 85.5, 85.3, 85.2, 84.9, 81.8, 81.7,

5

1

5

then dried under high vacuum. This yielded complex (g -

5

3

81.4, 81.3 (g -MeC₅H₄), 68.6, 68.3 (C_c, J_HP= 17 Hz), 35.2,

= =

MeC₅H₄)(CO)₂MnC(Ph) C C(PMePh₂)Ph (10a) as a red

35.0 (C_d, ¹J_CP= 63 Hz), 21.4, 21.2 (MeC₆H₄), 14.1 (g -MeC₅H₄).

5

powder (0.41 g, 0.71 mmol, 71% yield).

³¹P{ H} NMR (121.5 MHz, CD₂Cl₂) d 34.4, 34.2. IR (CH₂Cl₂):

1

5

=

Similar treatment of complexes (g -MeC₅H₄)(CO)₂Mn

•

1881, 1806 (m_CO). MS (EI) m/z 594 [M]⁺, 538 [M − 2CO]⁺. Anal.

5

=

C(Ph)C≡CTol (3b) or (g -MeC₅H₄)(CO)₂Mn C(Tol)C≡CPh

Calc. for C₃₇H₃₂MnO₂P: C, 74.73; H, 5.43. Found: C, 74.82; H,

5.49%.

(3c) by methylphenylphosphine (one molar equivalent)

5

yielded 1 : 1 mixtures of complexes (g -MeC₅H₄)(CO)₂-

5

=

MnC C(Ph)PPh₂CH₂CH(Tol) (10b) and (g -MeC₅H₄-

)(CO)₂MnC C(Tol)PPh₂CH₂CH(Ph) (10b ) (84% yield from

Synthesis of the g²-allene complexes (g⁵-MeC₅H₄)(CO)₂Mn-

ꢀ

=

2

1

4

= =

3b, 82% yield from 3c).

10a: H NMR (300.1 MHz, CD₂Cl₂, 293 K): d 7.9–6.9 (m,

[g -{R PC(R) C C(R’)H}] (12) and of the g -vinylketene

2

1

5

4

1

=

complexes (g -MeC₅H₄)(CO)Mn[g -{R PC(R) CHC(R’)

2

5

4

1

=

20H, C₆H₅), 4.29, 4.25 (m, 4H, g -MeC₅H₄), 2.41 (d, 6H,

C O}] (13) and (g -MeC₅H₄)(CO)Mn[g {R PC(R’)

2

PMe₂, ²J_CP= 13 Hz), 1.87 (s, 3H, g -MeC₅H₄). ¹³C{ H} NMR

CHC(R) C O}] (13 )

5

1

ꢀ

= =

2

(75.5 MHz, CD₂Cl₂, 293 K): d 239.0 (CO), 166.4 (C_b, J_CP

=

Typical procedure as illustrated for (g⁵-MeC₅H₄)(CO)₂Mn[g²-

7 Hz), 143.2–123.3 (C₆H₅), 116.1 (C_a, ³J_CP= 15 Hz), 98.9, 84.3,

{Ph₂C(Ph) C C(Tol)H}] (12b), (g⁵-MeC₅H₄)(CO)Mn[g⁴-

= =

5

81.4 (g -MeC₅H₄), 56.8 (C_c, ¹J_CP= 106 Hz), 14.4 (g -MeC₅H₄),

{Ph₂C(Ph) CHC(Tol) C O}] (13b) and (g⁵-MeC₅H₄)-

=

= =

13.3 (PMe₂, ¹J_CP= 68 Hz). ³¹P{ H} NMR (121.5 MHz, CD₂Cl₂,

1

4

=

= =

(CO)Mn[g -{Ph₂C(Tol) CHC(Ph) C O}] (13b’). Diphenyl-

293 K) d 23.0. IR (CH₂Cl₂): 1838 (sh, m_C₌_C), 1889, 1811 (m_CO).

=

C

phosphine (0.220 mL; 1.2 mmol) was added to a solution of

Anal. Calc. for C₃₆H₃₀MnO₂P: C, 74.47; H, 5.21. Found: C,

74.50; H, 4.99%.

5

=

(g -MeC₅H₄)(CO)₂Mn C(Ph)C≡CTol (3b, 0.47 g, 1.2 mmol)

in CH₂Cl₂(10 mL) at −40 ^◦C, under stirring. The cooling

bath was removed and once reaction ﬂask had reached room

temperature (ca. 30 min) the solvent was removed under high

vacuum. The oily residue was puriﬁed by chromatography.

An initial elution with a 1 : 100 diethyl ether–pentane

mixture gave a yellow band containing trace amount of

10b + 10b^ꢀ: ¹H NMR (250.1 MHz, CD₂Cl₂): d 7.9–6.9 (C₆H₅

5

2

and MeC₆H₄), 4.3–4.1 (g -MeC₅H₄), 2.34 (d, PMe₂, J_CP

=

2

13 Hz), 2.29 (d, PMe₂, J_CP= 13 Hz), 2.35 (MeC₆H₅), 1.79,

1.78 (g -MeC₅H₄). ¹³C{ H} NMR (75.5 MHz, CD₂Cl₂, 293 K):

d 239.0 (CO), 166.4, 166.1 (C_b, ²J_CP= 7 Hz), 143.2–123.3 (C₆H₅

and MeC₆H₄), 116.1, 115.8 (C_a, ³J_CP= 15 Hz), 98.9, 98.5, 84.3,

5

1

5

(g -MeC₅H₄)Mn(CO)₃. A second elution with a 1 : 5 diethyl

ether–pentane mixture afforded a yellow band containing the

complex (g -MeC₅H₄)(CO)₂Mn[g -{Ph₂PC(Ph) C C(Tol)H}]

(12b), which was subsequently isolated as a yellow solid after

removal of the solvents under high vacuum (0.38 g, 52% yield). A

third elution with a 1 : 1 diethyl ether–pentane mixture afforded

83.9, 81.7, 81.4 (g -MeC₅H₄), 56.8, 55.7 (C_c, ¹J_CP= 106 Hz), 21.5,

5

1

21.3 (MeC₆H₄), 14.4 (g -MeC₅H₄), 13.3, 13.1, (PMe₂, J_CP

=

5

2

= =

68 Hz). ³¹P{ H} NMR (101.0 MHz, CD₂Cl₂) d 21.6, 21.5. IR

1

(CH₂Cl₂): 1845 (sh, m_C₌_C), 1888, 1810 (mCO). Anal. Calc. for

=

C

C₃₇H₃₂MnO₂P: C, 74.73; H, 5.43. Found: C, 74.52; H, 4.78%.

5

a brown band containing a 1 : 1 mixture of complexes (g -

Synthesis of the dihydrophospholinium complexes

4

=

= =

MeC₅H₄)(CO)Mn[g -{Ph₂PC(Ph) CHC(Tol) C O}] (13b)

5

ꢀ

=

(g -MeC₅H₄)(CO)₂MnC C(R)PPh₂CH₂CH(R ) (11; 11a: R =

5

4

=

= =

and (g -MeC₅H₄)(CO)Mn[g -{Ph₂PC(Tol) CHC(Ph) C O}]

(13b^ꢀ), which was subsequently isolated as a brown powder

(0.14 g; 14% yield).

R^ꢀ= Ph; 11b/11b^ꢀ: R = Ph/Tol, R^ꢀ= Tol/Ph)

Typical procedure as illustrated for (g⁵-MeC₅H₄)(CO)₂-

5

2

=

= =

(g -MeC₅H₄)(CO)₂Mn[g -{Ph₂PC(Ph) C C-

MnC C(Ph)PMe₂CH₂CH(Ph)

(11a).

A

solution

of

Complexes

(Ph)H}] (12a) and (g -MeC₅H₄)(CO)Mn[g -{Ph₂PC(Ph)

5

4

= =

=

the r-allenyl complex (g -MeC₅H₄)(CO)₂MnC(Ph) C C-

(PPh₂Me)Ph (10a, 0.41 g, 0.71 mmol) was dissolved in dichloro-

methane (15 mL) and the solution was heated under reﬂux

overnight, under stirring. After removal of the dichloromethane

solvent under vacuum, the oily residue was puriﬁed by

chromatography on an alumina column. An initial elution

with a 1 : 10 diethyl ether–pentane mixture gave a yellow

5

2

= =

CHC(Ph) C O}] (13a), (g -MeC₅H₄)(CO)₂Mn[g -{Cy₂PC-

5

4

= =

(Ph) C C(Ph)H}] (12d) and (g -MeC₅H₄)(CO)Mn[g -

5

=

= =

{Cy₂PC(Ph) CHC(Ph) C O}] (13d), and (g -MeC₅H₄)-

2

5

= =

(CO)₂Mn[g -{Cy₂PC(Ph) C C(Tol)H}] (12e), (g -MeC₅H₄)

4

5

=

= =

(CO)Mn[g -{Cy₂PC(Ph) CHC(Tol) C O}] (13e) and (g -

4

=

= =

MeC₅H₄)(CO)Mn[g -{Cy₂PC(Tol) CHC(Ph) C O}] (13e’)

D a l t o n T r a n s . , 2 0 0 5 , 1 6 2 0 – 1 6 3 6

1 6 3 3

View Article Online

5

1

11 Hz), 13.0 (g -MeC₅H₄). ³¹P{ H} NMR (101.0 MHz, CD₂Cl₂)

were prepared using the same protocol as above, using the

proper combination of alkynyl carbene complex and secondary

phosphine. The yields of the reaction products are gathered in

Table 4.

•

d 17.3. MS (EI) m/z 566 [M]⁺, 538 [M − CO]⁺. IR (CH₂Cl₂):

1961, 1724 (m_CO).

1

13b + 13b^ꢀ: H NMR (400.1 MHz, 233 K, CD₂Cl₂) d 8.00–

12a: ¹H NMR (300.1 MHz, C₆D₆) d 8.68 (s, 1H, H_c), 8.0–6.8

6.28 (m, C₆H₅and MeC₆H₄), 6.24 (d, 1H, H_b, ³J_HP= 9 Hz), 6.19

5

(d, 1H, H_b, ³J_HP= 8 Hz), 4.65, 4.62, 4.37, 4.23, 3.93, 3.91, 3.62,

(m, 20H, C₆H₅), 4.41, 4.10, 3.99, 3.01 (m, 4H, g -MeC₅H₄), 1.52

5

1

(s, 3H, g -MeC₅H₄). ¹³C{ H} NMR (75.5 MHz, C₆D₆) d 236.2

5

3.49 (m, 8H, g -MeC₅H₄), 2.41 (s, 3H, MeC₆H₄), 2.10 (s, 3H,

5

(broad), 228.7 (CO), 166.6 (C_b), 147.5, 140.6–124.8 (C₆H₅),

MeC₆H₄), 1.88 (s, 3H, g -MeC₅H₄), 1.86 (s, 3H, g -MeC₅H₄).

5

¹³C{ H} NMR (100.6 MHz, 233 K, CD₂Cl₂) d 237.4, 237.3

1

129.9 (C_c), 102.2, 93.3, 92.2, 90.2, 82.7 (g -MeC₅H₄), 36.7 (d, C_a,

¹J_CP= 25 Hz), 13.0 (g -MeC₅H₄). ³¹P{ H} NMR (101.2 MHz,

C₆D₆) d 18.6. IR (CH₂Cl₂): 1978, 1924 (m_CO). Anal. Calc. for

C₃₅H₂₈MnO₂P: C, 74.19; H, 4.98. Found: C, 73.37; H, 5.01%.

12b: ¹H NMR (400.1 MHz, CD₂Cl₂) d 8.72 (s, 1H, H_c), 8.8–

6.9 (m, 19H, C₆H₅and MeC₆H₄), 4.53, 4.49, 3.91, 3.17 (m, 4H,

5

1

(CO), 232.0, 231.9 (CO), 142.9–124.8 (C₆H₅and MeC₆H₄),

101.3, 101.1, 89.7, 89.4, 88.5 (J_CP= 2 Hz), 86.6 (J_CP= 2 Hz),

5

86.4 (J_CP= 2 Hz), 86.1 (J_CP= 2 Hz), 85.2, 85.2 (g -MeC₅H₄),

3

83.3 (C_b, J_CP= 33 Hz), 82.4 (C_b, J_CP= 33 Hz), 73.9 (C_c,

²J_CP= 32 Hz), 72.3 (C_c, ²J_CP= 32 Hz), 29.1 (C_a, ³J_CP= 8 Hz),

5

1

g -MeC₅H₄), 2.58 (s, 3H, MeC₆H₄), 1.98 (s, 3H, g -MeC₅H₄).

28.6 (C_a, J_CP= 6 Hz), 21.7 (MeC₆H₄), 21.4 (MeC₆H₄), 13.6

¹³C{ H} NMR (100.6 MHz, CD₂Cl₂) d 236.5 (d, CO, J_CP

=

1

(g -MeC₅H₄), 13.5 (g -MeC₅H₄). ³¹P{ H} NMR (162.0 MHz,

5

1

2

233 K, CD₂Cl₂) d 18.4, 15.4. MS (EI) m/z 580 [M]⁺, 552 [M −

16 Hz), 228.9 (s, CO), 164.4 (C_b, J_CP= 7 Hz), 147.4, 140.7–

124.5 (C₆H₅and MeC₆H₄), 126.3 (C_c), 103.0, 95.5, 92.7, 89.9,

•

CO]⁺, 524 [M − 2CO]. IR (CH₂Cl₂): 1961, 1724 (m_CO). Anal.

81.9 (g -MeC₅H₄), 35.6 (C_a, ¹J_CP= 25 Hz), 21.8 (MeC₆H₄), 13.7

5

Calc. for C₃₆H₃₀MnO₂P: C, 74.47; H, 5.21. Found: C, 74.32; H,

5.24%.

(g -MeC₅H₄). ³¹P{ H} NMR (162.0 MHz, CD₂Cl₂) d 18.9. MS

5

1

•

(EI) m/z 580 [M]⁺, 524 [M − 2CO]⁺, 390 [M − Cp^ꢀ(CO)₂Mn]⁺.

1

13d: H NMR (300.1 MHz, CD₂Cl₂) d 7.82–6.8 (m, C₆H₅),

3

5

IR (CH₂Cl₂): 1977, 1924 (m_CO). Anal. Calc. for C₃₆H₃₀MnO₂P:

C, 74.47; H, 5.21. Found: C, 74.09; H, 5.05%.

6.0 (d, 1H, H_b, J_HP= 12 Hz), 4.95, 4.49, 4.24, 4.21 (m, g -

MeC₅H₄), 2.9–0.9 (Cy₂P), 1.83 (s, g -MeC₅H₄). ¹³C{ H} NMR

(75.5 MHz, CD₂Cl₂) d 235.1 (CO), 232.4 (CO), 144.1–126.1

(C₆H₅), 101.7, 88.8, 88.1(J_CP= 4 Hz), 86.3(J_CP= 7 Hz), 86.1

5

1

12c: ¹H NMR (400.1 MHz, CD₂Cl₂) d 8.72 (s, 1H, H_c), 8.8–

6.9 (m, 19H, C₆H₅and MeC₆H₄), 4.52, 4.46, 3.96, 3.17 (m, 4H,

5

(g -MeC₅H₄), 89.4 (C_b, ²J_CP= 41 Hz), 73.9 (C_c, ¹J_CP= 44 Hz),

5

g -MeC₅H₄), 2.45 (s, 3H, MeC₆H₄), 1.96 (s, 3H, g -MeC₅H₄).

¹³C{ H} NMR (100.6 MHz, CD₂Cl₂) d 236.5 (d, ³J_CP= 16 Hz),

1

3

5

30.9 (C_a, J_CP= 11 Hz), 38.4–26.9 (Cy₂P), 13.0 (g -MeC₅H₄).

2

³¹P{ H} NMR (121.5 MHz, CD₂Cl₂) d 39.3. MS (EI) m/z 578

1

228.9 (CO), 165.1 (C_b, J_CP= 7 Hz), 147.0–124.5 (C₆H₅and

•

5

[M]⁺, 550 [M − CO]⁺, 522 [M −2CO]. IR (CH₂Cl₂): 1950, 1710

(m_CO). Anal. Calc. for C₃₅H₄₀MnO₂P: C, 72.64; H, 6.97. Found:

C, 72.99; H, 7.20%.

MeC₆H₄), 126.2 (C_c), 103.0, 95.4, 92.3, 89.9, 82.1 (g -MeC₅H₄),

1

5

35.3 (C_a, J_CP= 24 Hz), 21.6 (MeC₆H₄), 13.7 (g -MeC₅H₄).

³¹P{ H} NMR (121.5 MHz, C₆D₆) d 21.5. MS (EI) m/z 580

1

•

[M]⁺, 524 [M − 2CO]⁺, 390 [M − Cp^ꢀ(CO)₂Mn]⁺. IR (CH₂Cl₂):

1977, 1922 (m_CO). Anal. Calc. for C₃₆H₃₀MnO₂P: C, 74.47; H,

5.21. Found: C, 74.66; H, 4.98%.

13e + 13e^ꢀ(1 : 5 mixture obtained from 3b and HPCy₂): H

1

NMR (400.1 MHz, 233 K, CD₂Cl₂) d 7.8–6.2 (m, C₆H₅and

3

MeC₆H₄), 5.92 (minor, d, H_b, J_HP= 13 Hz), 5.90 (major, d,

1

3

5

12d: H NMR (300.1 MHz, CD₂Cl₂) d 8.6–6.9 (m, C₆H₅),

H_b, J_HP= 13 Hz), 5.0–4.2 (m, g -MeC₅H₄), 2.9–0.8 (Cy₂P),

2.40 (minor, s, MeC₆H₄), 2.20 (major, s, MeC₆H₄), 1.74 (s,

5

8.19 (s, 1H, H_c), 4.44, 4.33, 3.56, 3.19 (g -MeC₅H₄), 1.91 (s,

g -MeC₅H₄), 2.3–0.9 (m, Cy₂P). ¹³C{ H} NMR (75.5 MHz,

5

1

g -MeC₅H₄). ¹³C{ H} NMR (100.6 MHz, 233 K, CD₂Cl₂) d

237.2 (minor, CO), 236.9 (major, CO), 232.8 (minor, CO), 232.7

(major, CO), 144.4–125.1 (C₆H₅and MeC₆H₄), 102.5 (major),

5

1

2

CD₂Cl₂) d 235.5, 232.8 (CO), 167.1 (C_b, J_CP= 0 Hz), 148.0–

5

124.1 (C₆H₅), 125.5 (C_c), 102.5, 94.0, 92.9, 90.5, 82.6 (g -

1

2

MeC₅H₄), 37.4 (C_a, J_CP= 32 Hz), 43.3–26.7 (Cy₂P), 13.4

102.5 (minor), 89.8 (major, C_b, J_CP= 43 Hz), 89.7 (minor,

(g -MeC₅H₄). ³¹P{ H} NMR (121.5 MHz, CD₂Cl₂) d 42.5. IR

(CH₂Cl₂): 1972, 1916 (mCO). Anal. Calc. for C₃₅H₄₀MnO₂P: C,

72.64; H, 6.97. Found: C, 72.75; H, 7.20%.

5

1

2

C_b, J_CP= 43 Hz), 88.6 (major), 88.6 (minor), 88.4 (minor,

J_CP= 5 Hz), 88.2 (major, J_CP= 6 Hz), 86.5 (major, J_CP

=

5

6 Hz), 86.5 (J_CP= 5 Hz, minor), 86.1 (g -MeC₅H₄), 73.0 (major,

¹J_CP= 40 Hz, C_c), 71.9 (minor, ¹J_CP= 41 Hz, C_c), 31.8 (minor,

12e: ¹H NMR (300.1 MHz, CD₂Cl₂) d 8.6–6.9 (m, 9H, C₆H₅

5

3

and MeC₆H₄), 8.14 (s, 1H, H_c), 4.48, 4.37, 3.52, 3.15 (g -

C_a, J_CP= 15 Hz), 31.7 (major, C_a, J_CP= 15 Hz), 38.0–26.9

5

MeC₅H₄), 2.47 (s, 3H, MeC₆H₄), 1.93 (s, 3H, g -MeC₅H₄), 2.5–

(Cy₂P), 21.7 (minor, MeC₆H₄), 21.4 (major, MeC₆H₄), 13.3 (g -

0.9 (m, 22H, Cy₂P). ¹³C{ H} NMR (75.5 MHz, CD₂Cl₂) d 235.6,

1

MeC₅H₄). ³¹P{ H} NMR (162.0 MHz, 233 K, CD₂Cl₂) d 36.6

(major), 36.2 (minor). MS (EI) m/z 592 [M]⁺, 564 [M − CO]⁺,

536 [M − 2CO]⁺. IR (CH₂Cl₂): 1950, 1710 (m_CO). Anal. Calc. for

C₃₆H₄₂MnO₂P: C, 72.94; H, 7.15. Found: C, 72.89; H, 7.00%.

232.8 (CO), 165.9 (C_b), 148.0–123.6 (C₆H₅and MeC₆H₄), 124.4

(C_c), 102.4, 94.1, 92.8, 90.4, 82.6 (g -MeC₅H₄), 37.4 (C_a, ¹J_CP

=

5

30 Hz), 21.4 (MeC₆H₄), 43.0–26.8 (Cy₂P), 13.4 (g -MeC₅H₄).

³¹P{ H} NMR (121.5 MHz, CD₂Cl₂) d 42.4. MS (EI) m/z 592

1

•

[M]⁺, 564 [M − CO]⁺, 536 [M − 2CO]⁺. IR (CH₂Cl₂): 1972,

1916 (m_CO). Anal. Calc. for C₃₆H₄₂MnO₂P: C, 72.94; H, 7.15.

Found: C, 73.01; H, 6.99%.

X-Ray diffraction studies

Crystals of [2b][BPh₄], 3c, 5b, 12b and 13d suitable for X-

ray diffraction were obtained through re-crystallization from

pentane or dichloromethane–pentane solutions in the cold.

Data were collected at 160 K for [2b][BPh₄], 5b, 12b and

13d, and at 293 K for 3c, on a Stoe IPDS diffractometer.

All calculations were performed on a PC-compatible computer

using the WinGX system.³⁹Full crystallographic data are given

in Table 5. The structures were solved by using the SIR92

program,⁴⁰which revealed in each instance the position of most

of the non-hydrogen atoms. All remaining non-hydrogen atoms

were located by the usual combination of full matrix least-

squares reﬁnement and difference electron density syntheses by

using the SHELXL97 program.⁴¹Atomic scattering factors were

taken from the usual tabulations. Anomalous dispersion terms

for Mn and P atoms were included in F_c. All non-hydrogen atoms

were allowed to vibrate anisotropically. All the hydrogen atoms

12f: ¹H NMR (300.1 MHz, CD₂Cl₂) d 8.6–6.9 (m, 9H, C₆H₅

5

and MeC₆H₄), 8.16 (s, 1H, H_c), 4.45, 4.35, 3.56, 3.17 (g -

5

MeC₅H₄), 2.25 (s, 3H, MeC₆H₄), 1.91 (s, 3H, g -MeC₅H₄), 2.5–

0.9 (m, 22H, Cy₂P). ¹³C{ H} NMR (75.5 MHz, CD₂Cl₂) d 235.6,

1

232.8 (CO), 165.9 (C_b), 148.2–123.8 (C₆H₅, MeC₆H₄), 124.9 (C_c),

102.4, 94.3, 92.8, 90.1, 82.5 (g -MeC₅H₄), 37.8 (C_a, ¹J_CP= 30 Hz),

5

21.0 (MeC₆H₄), 39.9.4–26.9 (Cy₂P), 13.4 (g -MeC₅H₄). ³¹P{ H}

NMR (121.5 MHz, CD₂Cl₂) d 44.4. IR (CH₂Cl₂): 1972, 1916

(m_CO). Anal. Calc. for C₃₆H₄₂MnO₂P: C, 72.94; H, 7.15. Found:

C, 73.32; H, 6.95%.

5

1

13a: ¹H NMR (250.1 MHz, CD₂Cl₂) d 8.00–6.40 (m, C₆H₅),

3

6.32 (d, 1H, H_b, J_HP= 9 Hz), 4.63, 4.35, 3.92, 3.51 (m, 4H,

g -MeC₅H₄), 1.57 (s, 3H, g -MeC₅H₄). ¹³C{ H} NMR (63 MHz,

5

1

=

CD₂Cl₂) d 237.3 (C O), 232.4 (CO), 143.1–125.1 (C₆H₅), 101.7,

5

89.8, 88.3 (J_CP= 4 Hz), 86.3 (J_CP= 7 Hz), 85.8 (g -MeC₅H₄),

85.4 (C_b, ²J_CP= 33 Hz), 73.9 (C_c, ¹J_CP= 32 Hz), 29.9 (C_a, ³J_CP

=

were set in idealised position (R₃CH, C–H = 0.96 A; R₂CH₂,

˚

1 6 3 4

D a l t o n T r a n s . , 2 0 0 5 , 1 6 2 0 – 1 6 3 6

View Article Online

Table 5 Crystal data and structure reﬁnements for complexes [2b][BPh₄], 3c, 5b, 12b and 13d

Complex

[2b][BPh₄]

3c

5b

12b

13d

Empirical formula

C₄₀H₃₄BMnO₂

612.42

160

C₂₄H₁₉MnO₂

394.33

293

C₄₂H₃₄MnO₂P

656.60

160

C₃₆H₃₀MnO₂P

580.51

160

C₃₅H₄₀MnO₂P

578.58

160

M_r

T/K

˚

k/A

0.71069

Triclinic

0.71069

Triclinic

Crystal system

Monoclinic

P2₁/n (14)

8.9056(7)

27.574(2)

13.2761(11)

Monoclinic

P2₁/c (14)

12.2313(8)

14.3158(12)

19.2117(14)

Monoclinic

P2₁/c (14)

9.625(2)

20.583(9)

14.798(3)

¯

Space group (no.)

P1 (2)

˚

a/A

9.2496(12)

9.6772(12)

10.7107(14)

90.284(15)

104.051(15)

91.083(15)

929.8(2)

2

10.749(5)

11.050(5)

13.349(5)

74.299(5)

83.501(5)

71.477(5)

1446.7(11)

2

˚

b/A

˚

c/A

a/^◦

b/^◦

c /^◦

100.188(10).

104.369(8)

95.87(3)

3

˚

V/A

3208.7(4)

4

1.268

3258.8(4)

4

1.336

2916.3(16)

4

1.322

Z

D_c/g cm⁻³

1.408

0.725

1.328

0.542

l/mm⁻¹

0.445

0.491

0.539

F(000)

1280

25.95

408

24.20

1368

26.03

1208

26.04

612

25.95

◦

h_max

/

Completeness to h_max(%)

Index ranges, hkl

99

92.3

96.4

92.1

92.2

−10 to 10, −33 to

33, −16 to 16

22846

6181

6181/0/399

1.028

−10 to 10, −12 to

12, −12 to 12

7518

2763

2763/0/246

1.067

−15 to 14, −17 to

17, −23 to 23

24217

6196

6196/0/417

0.923

−10 to 11, −25 to

25, −17 to 18

22133

5301

5301/0/363

0.979

−13 to 13, −13 to

13, −16 to 16

14273

5221

5221/0/356

0.940

Reﬂections collected

Independent reﬂections

Data/restraints/parameters

GOF

R [I > 2r(I)]

0.0471

0.1167

0.0732

0.1298

0.0348

0.0940

0.0363

0.0991

0.0381

0.0797

0.0686

0.0892

0.0307

0.0794

0.0354

0.0828

0.0304

0.0658

0.0469

0.0700

R_w[I > 2r(I)]

R (all data)

R_w(all data)

−3

˚

Dq_max/min/e A

0.582/−0.369

0.286/−0.310

0.395/−0.326

0.231/−0.253

0.403/−0.223

2

˚

G. L. Geoffroy, B. S. Haggerty and A. L. Rheingold, Organometallics,

1993, 12, 3607; (c) C. P. Casey, S. Kraft and D. R. Powell, J. Am. Chem.

Soc., 2000, 122, 3771.

C–H = 0.97 A; RCH₃, C–H = 0.98 A; C(sp )–H = 0.93 A; U_iso

1.2 or 1.5 times greater than the U_eqof the carbon atom to which

the hydrogen atom is attached) and their position were reﬁned

as “riding” atoms.

4 (a) A. Rabier, N. Lugan, R. Mathieu and G. L. Geoffroy,

Organometallics, 1994, 13, 4676; (b) C. Gimenez, N. Lugan, R.

Mathieu and G. L. Geoffroy, J. Organomet. Chem., 1996, 517, 133.;

(c) C. Mongin, N. Lugan and R. Mathieu, Organometallics, 1997,

16, 3873; (d) C. Mongin, Y. Ortin, N. Lugan and R. Mathieu,

Eur. J. Inorg. Chem., 1999, 739; (e) C. Mongin, K. Gruet, N. Lugan

and R. Mathieu, Tetrahedron Lett., 2000, 41, 7341; (f) A. Rabier, N.

Lugan and R. Mathieu, J. Organomet. Chem., 2001, 617–618, 681.

5 (a) H. Fischer, P. Hofmann, F. R. Kreissl, R. R. Schrock, U. Schubert

and K. Weiss, Carbyne Complexes, VCH, Weinheim–New York,

1988; (b) E. O. Fischer, E. W. Meineke and F. R. Kreissl, Chem.

Ber., 1977, 110, 1140.

6 (a) E. O. Fischer, R. L. Clough, G. Besl and F. R. Kreissl, Angew.

Chem., Int. Ed. Engl., 1976, 15, 543; (b) E. O. Fischer and G.

Besl, Z. Naturforsch., Teil B, 1979, 34, 1186; (c) E. O. Fischer, W.

Schambeck and F. R. Kreissl, J.Organomet. Chem., 1979, 169, C27;

(d) E. O. Fischer and W. Schambeck, J. Organomet. Chem., 1980,

201, 311.

CCDC reference numbers 261452–261456.

See http://www.rsc.org/suppdata/dt/b5/b501008j/ for cry-

stallographic data in CIF or other electronic format.

Acknowledgements

We thank the Ministe`re de l^ꢀEducation Nationale, de

l^ꢀEnseignement Supe´rieur et de la Recherche for a fellow-

ship to Y. O. and Ethyl Corporation (USA) for a gener-

ous gift of (g -MeC₅H₄)Mn(CO)₃. We are in debt to Prof.

Michael J. McGlinchey for editing the manuscript.

5

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D a l t o n T r a n s . , 2 0 0 5 , 1 6 2 0 – 1 6 3 6

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=

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1

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phosphine end of the ligand. Indeed, the ³¹P{ H} spectra showed

the appearance of a signal at ca. d 101 ppm, typical for a phosphine

5

coordinated to a (g -MeC₅H₄)(CO)₂Mn fragment,³¹whereas the ¹³

C

NMR spectra shows concomitant appearance of a peak at d 210 ppm

that would be suitable for the sp carbon atom of a pendant allene

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=

37 Cp(CO)₂Mn CPh₂has been shown to undergo carbonylation

2

to yield the corresponding g -ketene complex Cp(CO)₂Mn(g -

=

C

=

O

CPh₂) under very high pressure, 650 atm (!): W. A.

Herrmann and J. Plank, Angew. Chem., Int. Ed. Engl., 1978,

17, 525. However, we have been able to obtain

ketene complex, namely (g -MeC₅H₄)(CO)₂Mn[g -O

g -C≡CPh)Co₂(CO)₆)], from the alkynyl carbene complex 3a upon

with Co₂(CO)₈at room temperature and under normal pressure [ref.

9(b)].

2

a

g -

5

2

=

C C(Ph)((l-

2

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1 6 3 6

D a l t o n T r a n s . , 2 0 0 5 , 1 6 2 0 – 1 6 3 6

Article Doi

Subtle reactivity patterns of non-heteroatom-substituted manganese alkynyl carbene complexes in the presence of phosphorus probes

DOI: 10.1039/b501008j

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