Synthesis, molecular structure, and reactivity of neutral and cationic areneosmium(II) complexes with diarylcarbenes as ligands

DOI: 10.1021/om0207109

Source and publish data:

Organometallics p. 744 - 758 (2003)

Update date:2022-07-30

Topics:

Authors:

Weberndoerfer, Birgit

Henig, Gerhard

Hockless

Bennett, Martin A.

Werner, Helmut

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Article abstract of DOI:10.1021/om0207109

While the dinuclear compounds [(η⁶-mes)Os{κ¹-OC(O)CF₃} (μ-Cl)]₂ (2) and [(η⁶-mes)Os{κ¹-OS(O)₂ CF₃}(μ-Cl)]₂ (3), prepared from [(η⁶-mes)OsCl(η³-C₃H₅)] (1) and CF₃CO₂H or CF₃SO₃H by elimination of propene, are not suitable precursors for the synthesis of osmium carbenes, the bis(trifluoroacetato) derivatives [(η⁶-arene)Os{κ¹-OC(O)CF₃} (κ²-O₂CCF₃)] (4, 9, 10) are useful starting materials. They react with diaryldiazomethanes R₂CN₂ to give the half-sandwich-type complexes [(η⁶-arene)Os{κ-OC(O)CF₃}₂ (=CR₂)] (11-17) in good to excellent yields. The bis(tosylato)osmium(II)compounds [(η⁶-arene) Os{κ¹-OS(O)₂R} {κ²-O₂ S(O)R}] (20, 21; R = p-C₆H₄CH₃) behave differently and upon treatment with Ph₂CN₂ and PhCHN₂ afford tetraphenylethene and a mixture of (E)- and (Z)-stilbene. The reaction of 12-15 and 17 with either Me₃SiX or NH₄X (X = Cl, Br, I) leads to the replacement of the trifluoroacetato ligands and the formation of the corresponding carbene complexes [(η⁶-arene)OsX₂(=CR₂)] (22-31) in 67-91% yield. An exchange of trifluoroacetate for chloride or bromide by using HCl or HBr is also possible. Treatment of [(η⁶-mes)OsCl₂(=CPh₂)] (28) with M(acac-[F_n]) (M = Na, Tl; n = 0, 3, or 6) affords the chelate compounds [(η⁶-mes)OsCl(κ²-acac-[F_n])] (33-35) via elimination of the carbene ligand. Compounds 33-35 are also accessible from [(η⁶-mes)-OsCl₂]₂ (19) and Hacac/NEt₃ or Na(acac-[F_n]) (n = 3 or 6), respectively. While 14 (arene = mes; R = Ph) and 28 react with C₆H₅MgBr and CH₃MgI only by displacement of trifluoroacetate or chloride for bromide or iodide, the reaction of 14 with CH₂=CHMgBr gives the η³-allyl complex [(η⁶-mes)OsBr(η³-CH₂CHCPh₂)] (36). A C-C coupling also takes place upon treatment of 14 with CH₂=CHOEt, resulting in the formation of the metallacyclic compound [(η⁶-mes)Os{κ²(C,O)-Ph₂CCH=CHOEt} {κ¹-OC(O)CF₃}] (38). The bis(trifluoroacetato) derivatives 14, 15, and 17 react in acetone with water to afford the diaryl(carbonyl)-osmium(II) complexes [(η⁶-mes)OsR₂(CO)] (39-41). On the basis of a labeling experiment, a mechanism for this unusual C-C cleavage reaction is proposed. The reaction of the dichloro compounds 28 and 29 with PPh₃ in the presence of AgPF₆ gives the cationic carbene complexes [(η⁶-mes)OsCl(PPh₃)(=CR₂)]PF₆ (45, 46) in nearly quantitative yields. The molecular structures of 2, 15, 28, 35, and 46 were determined crystallographically.

Full text of DOI:10.1021/om0207109

744

Organometallics 2003, 22, 744-758

Syn th esis, Molecu la r Str u ctu r e, a n d Rea ctivity of

Neu tr a l a n d Ca tion ic Ar en eosm iu m (II) Com p lexes w ith

Dia r ylca r ben es a s Liga n d s^§

Birgit Weberndo¨rfer,^†Gerhard Henig,^†D. C. R. Hockless,^‡

Martin A. Bennett,^‡and Helmut Werner*^,†

Institut fu¨r Anorganische Chemie der Universita¨t Wu¨rzburg, Am Hubland,

D-97074 Wu¨rzburg, Germany, and the Research School of Chemistry,

Australian National University, Canberra ACT 0200, Australia

Received August 29, 2002

While the dinuclear compounds [(η⁶-mes)Os{κ¹-OC(O)CF₃}(µ-Cl)]₂(2) and [(η⁶-mes)Os{κ¹-

OS(O)₂CF₃}(µ-Cl)]₂(3), prepared from [(η⁶-mes)OsCl(η³-C₃H₅)] (1) and CF₃CO₂H or CF₃SO₃H

by elimination of propene, are not suitable precursors for the synthesis of osmium carbenes,

the bis(trifluoroacetato) derivatives [(η⁶-arene)Os{κ¹-OC(O)CF₃}(κ²-O₂CCF₃)] (4, 9, 10) are

useful starting materials. They react with diaryldiazomethanes R₂CN₂to give the half-

sandwich-type complexes [(η⁶-arene)Os{κ¹-OC(O)CF₃}₂(dCR₂)] (11-17) in good to excellent

yields. The bis(tosylato)osmium(II) compounds [(η⁶-arene)Os{κ¹-OS(O)₂R}{κ²-O₂S(O)R}] (20,

21; R ) p-C₆H₄CH₃) behave differently and upon treatment with Ph₂CN₂and PhCHN₂afford

tetraphenylethene and a mixture of (E)- and (Z)-stilbene. The reaction of 12-15 and 17

with either Me₃SiX or NH₄X (X ) Cl, Br, I) leads to the replacement of the trifluoroacetato

ligands and the formation of the corresponding carbene complexes [(η⁶-arene)OsX₂(dCR₂)]

(22-31) in 67-91% yield. An exchange of trifluoroacetate for chloride or bromide by using

HCl or HBr is also possible. Treatment of [(η⁶-mes)OsCl₂(dCPh₂)] (28) with M(acac-[F_n]) (M

) Na, Tl; n ) 0, 3, or 6) affords the chelate compounds [(η⁶-mes)OsCl(κ²-acac-[F_n])] (33-35)

via elimination of the carbene ligand. Compounds 33-35 are also accessible from [(η⁶-mes)-

OsCl₂]₂(19) and Hacac/NEt₃or Na(acac-[F_n]) (n ) 3 or 6), respectively. While 14 (arene )

mes; R ) Ph) and 28 react with C₆H₅MgBr and CH₃MgI only by displacement of

trifluoroacetate or chloride for bromide or iodide, the reaction of 14 with CH₂dCHMgBr

gives the η³-allyl complex [(η⁶-mes)OsBr(η³-CH₂CHCPh₂)] (36). A C-C coupling also takes

place upon treatment of 14 with CH₂dCHOEt, resulting in the formation of the metallacyclic

compound [(η⁶-mes)Os{κ²(C,O)-Ph₂CCHdCHOEt}{κ¹-OC(O)CF₃}] (38). The bis(trifluoro-

acetato) derivatives 14, 15, and 17 react in acetone with water to afford the diaryl(carbonyl)-

osmium(II) complexes [(η⁶-mes)OsR₂(CO)] (39-41). On the basis of a labeling experiment,

a mechanism for this unusual C-C cleavage reaction is proposed. The reaction of the dichloro

compounds 28 and 29 with PPh₃in the presence of AgPF₆gives the cationic carbene

complexes [(η⁶-mes)OsCl(PPh₃)(dCR₂)]PF₆(45, 46) in nearly quantitative yields. The

molecular structures of 2, 15, 28, 35, and 46 were determined crystallographically.

In tr od u ction

which upon treatment with [Et₃NH]Cl are converted to

the more stable chloro derivatives [(η⁵-C₅H₅)RuCl(d

CRR′)(PPh₃)]. As far as the reactivity of these complexes

is concerned, the most interesting facet is that they react

with Grignard reagents or organolithium compounds

not only by substitution of chloride but subsequently

also by C-C coupling of the carbene ligand with a

methyl, phenyl, or vinyl moiety to generate an olefin or

an allyl group coordinated to ruthenium(II).^1,2

In the course of our investigations on the reactivity

of carbenemetal complexes, in which a non-Fischer-type

carbene ligand is coordinated to an electron-rich metal

center, we recently reported that diarylcarbeneruthe-

nium(II) compounds of the general composition [(η⁵-

C₅H₅)RuX(dCRR′)(PPh₃)] (R ) R′ ) aryl; X ) Cl,

acetate) can easily be obtained from the acetato deriva-

tive [(η⁵-C₅H₅)Ru(κ²-O₂CCH₃)(PPh₃)] as the precursor.¹

This complex reacts with diaryldiazomethane in toluene

at room temperature via elimination of N₂to give the

compounds [(η⁵-C₅H₅)Ru{κ¹-OC(O)CH₃}(dCRR′)(PPh₃)],

By taking into consideration that earlier attempts to

prepare half-sandwich-type carbeneosmium(II) com-

plexes [(η⁶-arene)OsX₂(dCRR′)] (X ) Cl, I) from [(η⁶-

arene)OsX₂]_nand diaryldiazomethanes failed,³we de-

cided to use instead of the dichlorides or diiodides the

^§Dedicated to Professor Robert H. Grubbs on the occasion of his

60th birthday.

^†Institut fu¨r Anorganische Chemie der Universita¨t Wu¨rzburg.

^‡Australian National University.

(2) Braun, T.; Mu¨nch, G.; Windmu¨ller, B.; Laubender, M.; Werner,

H. Chem. Eur. J ., submitted for publication.

(3) Henig, G. Dissertation, Universita¨t Wu¨rzburg, 1997.

(1) Braun, T.; Gevert, O.; Werner, H. J . Am. Chem. Soc. 1995, 117,

7291-7292.

Publication on Web 01/22/2003

Areneosmium(II) Complexes

Sch em e 1

Organometallics, Vol. 22, No. 4, 2003 745

corresponding bis(trifluoroacetates) [(η⁶-arene)Os{κ¹-

OC(O)CF₃}{κ²-O₂CCF₃}] as the starting materials. We

found that this was the method of choice. In the present

paper we report the synthesis of a series of mononuclear

areneosmium(II) complexes with an osmium-carbene

bond and show that, although the reactivity of these

compounds is less pronounced than that of their ruthe-

nium counterparts, under particular conditions they

also undergo C-C coupling reactions. Moreover, we

illustrate that from the neutral compounds [(η⁶-arene)-

OsX₂(dCRR′)] related cationic species can be obtained

and that besides the bis(trifluoroacetates) also arene-

osmium(II) complexes with OsCl{κ¹-OC(O)CF₃}, OsCl-

{κ¹-OS(O)₂CF₃}, and OsCl{κ²-acac} as building blocks

are accessible. Some preliminary results of these studies

have already been communicated.⁴

F igu r e 1. Molecular diagram of compound 2. Selected

bond distances (Å) and angles (deg): Os1-Cl1 2.448(2),

Os1-Cl2 2.430(2), Os1-O1 2.120(7), Os1-C1 2.170(8),

Os1-C2 2.156(8), Os1-C3 2.174(8), Os1-C4 2.161(9),

Os1-C5 2.184(9); Os1-C6 2.161(8); Cl1-Os1-Cl2 80.40-

(8), Cl1-Os1-O1 82.1(2), Cl2-Os1-O1 81.6(2), Os1-Cl1-

Os2 99.1(1), Os1-Cl2-Os2 100.1(1).

Resu lts a n d Discu ssion

1. P r ep a r a tion of Neu tr a l Ha lf-Sa n d w ich -Typ e

Com p lexes [(η⁶-a r en e)Os{K¹-OC(O)CF ₃}₂(dCR ₂)].

On the basis of our experience with the synthesis of the

ruthenium compounds [(η⁵-C₅H₅)RuX(dCRR′)(PPh₃)],

we initially considered the mono(trifluoroacetato) and

mono(triflato) complexes 2 and 3 as suitable precursors

for the wanted osmium carbenes. Compounds 2 and 3

were prepared from the η³-allylosmium derivative 1,⁵

which reacts with equimolar amounts of CF₃CO₂H or

CF₃SO₃H by elimination of propene to give the products

in nearly quantitative yields (Scheme 1). The X-ray

crystal structure analysis of 2 reveals that in the crystal

the compound is a centrosymmetric dimer with a

pseudo-octahedral coordination sphere around each

metal center (Figure 1). The Os-C and Os-Cl bond

lengths as well as the Os-Cl-Os and Cl-Os-Cl bond

angles are quite similar to those of [(η⁶-cym)OsCl(µ-

Sch em e 2

Cl)]₂and thus deserve no further comment.

Quite surprisingly, the NMR spectra of the trifluoro-

acetato compound 2 indicate that the molecular struc-

ture found in the crystal is not maintained in solution.

The ¹H NMR spectrum of 2 (in CDCl₃) displays four sets

of signals for the CH and CH₃protons of the mesitylene

ring, which could be due to the presence of the three

equilibrating species shown in Scheme 2. Both the

observation of five resonances for the ¹⁹F nuclei of the

CF₃CO₂groups in the ¹⁹F NMR spectrum of 2 and the

conductivity Λ ) 63 cm²Ω^-1mol^-1(measured in CD₃-

NO₂) support this proposal. It should be mentioned that

one of us already reported the isolation of the ionic

ruthenium complex [(η⁶-C₆Me₆)₂Ru₂(µ-Cl)₂(µ-O₂CCF₃)]-

(CF₃CO₂), which seems to be preferred compared to the

neutral species [(η⁶-C₆Me₆)Ru{κ¹-OC(O)CF₃}(µ-Cl)]₂.⁷In

contrast to 2, the H and ¹⁹F NMR spectra of 3 are in

complete agreement with the existence of a nonionic

dimer in solution and give no hint for a similar dis-

sociation as depicted in Scheme 2 for the trifluoroacetato

derivative.

While attempts to use either 2 or 3 as precursor for

the preparation of carbeneosmium(II) compounds [(η⁶-

mes)OsCl(X)(dCRR′)] failed, the bis(trifluoroacetato)

complexes 4, 9, and 10 proved to be suitable starting

materials. In exploratory experiments it was first shown

that upon treatment of the mesitylene compound 4⁸with

(4) Weberndo¨rfer, B.; Henig, G.; Werner, H. Organometallics 2000,

19, 4687-4689.

(5) Stahl, S.; Werner, H. J . Am. Chem. Soc. 1991, 113, 2944-2947.

(6) Watkins, S. F.; Fronczek, F. R. Acta Crystallogr., Sect. B 1982,

38, 270-271.

(7) Tocher, D. A.; Goul, R. O.; Stephenson, T. A.; Bennett, M. A.;

Ennett, J . P.; Matheson, T. W.; Sawyer, L.; Shah, V. K. J . Chem. Soc.,

Dalton Trans. 1983, 1571-1581.

(8) Werner, H.; Stahl, S.; Kohlmann, W. J . Organomet. Chem. 1991,

409, 285-298.

746 Organometallics, Vol. 22, No. 4, 2003

Weberndo¨rfer et al.

Sch em e 3

Sch em e 4^a

F igu r e 2. Molecular diagram of compound 15. Selected

bond distances (Å) and angles (deg): Os-C1 1.957(7), Os-

O1 2.108(4), Os-O4 2.096(4), Os-C30 2.197(6), Os-C31

2.328(6), Os-C32 2.342(6), Os-C33 2.207(6), Os-C34

2.214(5), Os-C35 2.265(5); C1-Os-O1 85.0(2), C1-Os-

O4 95.1(2), O1-Os-O4 81.8(2), Os-C1-C10 121.6(5), Os-

C1-C20 123.9(5), C10-C1-C20 114.5(6).

temperature the rotation around the Os-C(carbene)

bond is not hindered on the NMR time scale.

10: arene ) p-cym.

The X-ray crystal structure analysis of 15 (Figure 2)

confirms the anticipated piano-stool configuration of the

molecule.⁴The Os-C1 distance of 1.957(7) Å is almost

identical to that in the five-coordinate osmium(0) com-

pound [OsCl(dCF₂)(NO)(PPh₃)₂] (1.967(4) Å)¹¹and in

the six-coordinate osmium(II) complexes [OsHCl(dCHR)-

(CO)(PiPr₃)₂] (R ) CO₂Et, 1.949(2) Å; R ) SiMe₃, 1.965-

(5) Å) and [OsCl₂(dCHR)(CO)(PR′₃)₂] (R ) Ph, R′ ) iPr,

1.95(2) Å; R ) 2-naphthyl, R′ ) Ph, 1.930(7) Å).^12,13The

Os-C1 distance is, however, slightly shorter than in the

above-mentioned half-sandwich-type molecule [(η⁶-mes)-

OsPh₂{dC(NHMe)Ph}] (1.992(5) Å) with a substituted

aminocarbene ligand.¹⁰The two bond angles C1-Os-

O1 and C1-Os-O4 of 15 differ by about 10°, which is

probably due to steric hindrance between one of the tolyl

moieties and the mesitylene unit. The sum of the bond

angles around C1 amounts to 359°, which is in agree-

ment with the sp²-hybridization of the carbene carbon

atom. There is no interaction between one of the oxygen

atoms of the CF₃CO₂groups with the carbon atom C1,

as found in a related η⁵-cyclopentadienyl ruthenium-

(II) complex.¹⁴The two rings containing the carbon

atoms C30 to C35 and C10 to C15 are nearly parallel

to each other, the dihedral angle between the two planes

being 10.5(2)°.

CNMe, CNtBu, or PPh₃, an opening of the Os-(κ²-O₂-

CCF₃) chelate ring takes place and the mononuclear

isocyanide and phosphine complexes 5-7 are formed in

88-95% yield (Scheme 3). The IR and ¹⁹F NMR spec-

troscopic data of 5-7 confirm that the CF₃CO₂ligands

are coordinated in a monodentate fashion and that from

a structural point of view 5-7 are near relatives of the

well-known dichloro derivatives [(η⁶-mes)OsCl₂(L)].⁹

The diarylcarbeneosmium(II) compounds 11-17 were

obtained under similar conditions as found for 5-7

(Scheme 4). Treatment of the starting materials 4, 9,

and 10 (of which 9 was formally unknown and prepared

from 8 and 4 equiv of CF₃CO₂Ag) in benzene with a

solution of the corresponding diaryldiazomethane in the

same solvent led to a rapid evolution of gas (N₂), and

after evaporation of the solvent the complexes 11-17

were isolated as olive-green or red-brown, only moder-

ately air-sensitive solids in good to excellent yields. Only

in the case of 17 was it necessary to work in CH₂Cl₂at

low temperature because otherwise the formation of the

carbene compound was accompanied by that of un-

known side products. The most characteristic spectro-

scopic feature of 11-17 is the resonance of the carbene

carbon atom in the ¹³C NMR spectra at δ 300-310,

which is considerably shifted to lower field compared

with the Fischer-type carbene complex [(η⁶-mes)OsPh₂-

{dC(NHMe)Ph}] (δ 220).^10aFor the ¹³C nuclei of the

C-bonded aryl groups of 11-17 only a single set of

signals is observed, indicating that at least at room

In contrast to [(η⁵-C₅H₅)Ru(κ²-O₂CCH₃)(PPh₃)], which

reacts not only with Ph₂CN₂but also with phenyldiazo-

(11) (a) Hill, A. F.; Roper, W. R.; Waters, J . M.; Wright, A. H. J .

Am. Chem. Soc. 1983, 105, 5939-5940. (b) Roper, W. R. J . Organomet.

Chem. 1986, 300, 167-190.

(12) Werner, H.; Stu¨er, W.; Wolf, J .; Laubender, M.; Weberndo¨rfer,

B.; Herbst-Irmer, C.; Lehmann, C. Eur. J . Inorg. Chem. 1999, 1889-

1897.

(9) Bennett, M. A.; Weerasuria, A. M. M. J . Organomet. Chem. 1990,

394, 481-513.

(10) (a) Werner, H.; Wecker, U.; Peters, K.; von Schnering, H. G. J .

Organomet. Chem. 1994, 469, 205-212. (b) Wecker, U.; Werner, H.;

Peters, K.; von Schnering, H. G. Chem. Ber. 1994, 127, 1021-1029.

(13) Baker, L.-J .; Clark, G. R.; Rickard, C. E. F.; Roper, W. R.;

Woodgate, S. D.; Wright, L. J . J . Organomet. Chem. 1998, 551, 247-

259.

(14) Daniel, T.; Mahr, N.; Braun, T.; Werner, H. Organometallics

1993, 12, 1475-1477.

Areneosmium(II) Complexes

Sch em e 5^a

Organometallics, Vol. 22, No. 4, 2003 747

Sch em e 6^a

R ) p-C₆H₄Me.

methane to give the corresponding carbene complex [(η⁵-

C₅H₅)Ru{κ¹-OC(O)CH₃}(dCHPh)(PPh₃)],²the reaction

of 4 with PhCHN₂affords besides N₂only (Z)-stilbene

as the product. Even at low temperatures, no other

osmium-containing species other than the starting

material 4 (of which ca. 90% was reisolated) could be

detected. Due to the selective formation of the cis isomer

of stilbene, we assume that initially an Os(dCHPh)

intermediate is generated, which presumably reacts

with a second molecule of PhCHN₂to give the olefin.

Taking into consideration that in half-sandwich-type

transition metal compounds the coordinating abilities

32: [(η⁶-mes)OsBr₂(dCPh₂)].

pounds22, 23, and 28-30 in 67-87% yield (Scheme 6).

On a similar route, the dibromo derivatives 24 and 25

are obtained from 12, 13, and Me₃SiBr and like the

dichloro counterparts isolated as brown, almost air-

stable solids in excellent yields. An alternative prepara-

tive route to 22, 24, 28, and 32 consists of the reaction

of the bis(trifluoroacetates) and HCl or HBr, respec-

tively, in this case benzene being the preferred solvent.

Regarding the spectroscopic data of 22-25, 28-30, and

32, a noteworthy aspect is that in the ¹³C NMR spectra

the carbene carbon resonance appears at δ ca. 300 and

thus at slightly higher field compared with the analo-

gous bis(trifluoroacetato) derivatives.

The synthesis of the diiodo complex 31 has been

achieved from 14 and Me₃SiI. For the preparation of

the related compounds 26 and 27 instead of Me₃SiI even

NH₄I could be used as an iodide source, the driving force

probably being the well-known strength of the Os-I

bond.¹⁵Attempts to substitute the CF₃CO₂ligands in

12 or 14 by fluoride failed, independent of whether NaF,

CsF, AgF, or [NBu₄]F was used as the substrate.

The molecular structure of the dichloro compound 28

is shown in Figure 3. It crystallizes in the chiral space

group C2, and since the single crystals were grown from

CH₂Cl₂/pentane, it contains one-half molecule of dichlo-

romethane in the asymmetric unit. Due to the presence

of H-Cl-H bridges between the chloro ligand Cl2 and

the hydrogen atoms of CH₂Cl₂and the hydrogen atom

H14 linked to the phenyl carbon atom C14 of a neigh-

bored molecule, a network between the half-sandwich-

type complex 28 and the solvent is built up in the crystal

lattice, which is illustrated in Figure 4. The structure

of each single molecule of 28 is similar to that of 15 (see

Figure 2), the bond length Os-C1 being nearly identical

in both compounds. The difference between the bond

angles C1-Os-Cl1 and C1-Os-Cl2 in 28 (ca. 6°) is less

than the difference between the bond angles C1-Os-

O1 and C1-Os-O2 in the bis(trifluoroacetato) analogue

15 (ca. 10°) probably due to the different size of the

anionic ligands.

of the CF₃CO₂and p-CH₃C₆H₄SO₃anions are quite

similar, we assumed that like the bis(trifluoroacetato)

complexes 4 and 10 also the bis(tosylato) counterparts

20 and 21 could be suitable precursors for the synthesis

of osmium(II) carbenes. The preparation of 20 and 21

proceeded analogously to that of 4 and 10 and gave, by

using 4 equiv of silver tosylate for 1 equiv of the dimers

18 or 19, the wanted products in good yields (Scheme

5). Both the elemental analyses and the ¹H NMR

spectra confirmed that the isolated solids contained

water molecules, which are probably necessary for the

formation of the crystal lattices. The H NMR spectra

of 20 and 21 display both at 295 and 243 K only one set

of signals for the C₆H₄and CH₃protons of the tosylate

units, indicating that a rapid change between the κ¹and

the κ²bonding mode of the anionic ligands occurs. In

contrast to 4 and 10, the tosylato analogues 20 and 21

do not react with Ph₂CN₂by generating a compound

with an OsdCPh₂bond but only gave tetraphenylethene.

Similarly, upon treatment of 20 or 21 with PhCHN₂a

1:1 mixture of (E)- and (Z)-stilbene is formed, indepen-

dent of whether the reactions are carried out at room

temperature or at -78 °C. In both cases, the starting

material could be reisolated nearly quantitatively.

2. Liga n d Rep la cem en t Rea ction s of th e Ca r -

ben e Com p lexes [(η⁶-a r en e)OsX₂(dCR₂)]. As was

already mentioned, the dichloro analogues of 12-15 are

not accessible from the corresponding dimers 18, 19, and

diphenyl- or di(p-tolyl)diazomethane.³However, treat-

ment of 12-15 and also of 17 with a 3-fold excess of

Me₃SiCl in dichloromethane at -78 °C affords, after

warming of the solution to room temperature, evapora-

tion of the solvent, and recrystallization of the residue

from toluene/hexane, the dichloroosmium(II) com-

(15) (a) Roder, K.; Werner, H. Chem. Ber. 1989, 122, 833-840. (b)

Stahl, S. Dissertation, Universita¨t Wu¨rzburg, 1990.

748 Organometallics, Vol. 22, No. 4, 2003

Weberndo¨rfer et al.

F igu r e 5. Molecular diagram of compound 35. Selected

bond distances (Å) and angles (deg): Os-Cl 2.405(2), Os-

O1 2.111(4), Os-O2 2.105(3), Os-C10 2.198(4), Os-C11

2.201(4), Os-C12 2.200(4), Os-C13 2.191(5), Os-C14

2.194(4), Os-C15 2.185(4); Cl-Os-O1 83.1(1), Cl-Os-O2

82.5(1), O1-Os-O2 86.8(1).

F igu r e 3. Molecular diagram of compound 28. Selected

bond distances (Å) and angles (deg): Os-C1 1.947(5), Os-

Cl1 2.399(2), Os-Cl2 2.387(1), Os-C30 2.222(9), Os-C31

2.221(6), Os-C32 2.346(5), Os-C33 2.321(6), Os-C34

2.202(7), Os-C35 2.274(7); C1-Os-Cl1 95.2(3), C1-Os-

Cl2 89.4(2), Cl1-Os-Cl2 83.61(7), Os-C1-C10 122.7(3),

Os-C1-C20 124.2(3), C10-C1-C20 113.1(4).

Sch em e 7

prepared by one of us from 19 and Tl(acac).¹⁶The Os-

(acac) complexes 33-35 are yellow or red, air-stable,

and thermally exceedingly stable solids, for which

correct elemental analyses were obtained.

The hexafluoroacetylacetonato complex 35 was also

characterized crystallographically. As shown in Figure

5, the coordination sphere around the metal is built up

by the six-membered ring, the chloride, and the chelat-

ing acac-[F₆] ligand, the bond angles Cl-Os-O1, Cl-

Os-O2, and O1-Os-O2 of the three-leg fragment lying

between 82.5° and 86.8°. The chelate ring consisting of

Os, O1, O2, C2, C3, and C4 is practically planar; the

dihedral angle between the two planes [O1,Os,O2] and

[O1,C1,C2,C3,C4,C5,O2] is 1,1(2)°.

While upon treatment of 28 with Tl(acac) or Na(acac-

[F_n]) one chloride and the carbene are displaced, the

reactions of 14 and 28 with C₆H₅MgBr and CH₃MgI lead

to the substitution of the two chloro or the two trifluo-

roacetato ligands by bromide or iodide (Scheme 8).

Under various conditions, we never succeeded in gen-

erating a product with an Os-C₆H₅or Os-CH₃bond.

This result is surprising insofar as the reactions of [(η⁶-

mes)OsCl₂(CNMe)] with either C₆H₅MgBr or RMgI (R

) CH₃, C₆H₅) led partly or completely to the replace-

ment of chloride by phenyl or methyl, respectively.¹⁷

F igu r e 4. Packing of the molecules of 28 and CH₂Cl₂in

the crystal (XP plot). The dotted lines indicate the bridging

bonds between the hydrogen atoms of the solvent molecule

and the chloro ligands of the osmium complex. Selected

distances (Å): Cl1B-H38A 2.75, Cl2B-H14C 2.60, Cl2B-

H40C 2.68.

The reactions of 28 with Tl(acac) and the trifluoro and

hexafluoro derivatives Na(acac-[F₃]) and Na(acac-[F₆])

took an unexpected course. While we had anticipated

that the chloro ligands of 28 would be substituted by

the chelating unit to afford the ionic complexes [(η⁶-

mes)Os(κ²-acac-[F_n])(dCPh₂)]Cl (n ) 0, 3, or 6), instead

of the two halides only one of them plus the carbene

group is replaced and the neutral compounds 33-35 are

formed in moderate to good yields. They can be obtained

more conveniently (and almost quantitatively) from the

dinuclear precursor 19 and Hacac/NEt₃or Na(acac-[F_n]),

respectively (see Scheme 7). Compound 33 was already

(16) Bennett, M. A.; Mitchell, T. R. B.; Stevens, M. R.; Willis, A. C.

Can. J . Chem. 2001, 79, 655-669.

(17) Werner, H.; Wecker, U.; Schulz, M.; Stahl, S. Organometallics

1991, 10, 3278-3282.

Areneosmium(II) Complexes

Organometallics, Vol. 22, No. 4, 2003 749

Sch em e 8^a

37: [(η⁶-mes)OsBr(κ²-O₂CCF₃)].

3. C-C Cou p lin g a n d C-C Clea va ge Rea ction s

of Ca r ben eosm iu m (II) Com p lexes. The vinyl Grig-

nard reagent CH₂dCHMgBr behaves differently com-

pared with C₆H₅MgBr. Treatment of a solution of 14 in

THF with a solution of CH₂dCHMgBr in the same

solvent at low temperature affords, after chromato-

graphic workup and recrystallization from hexane, the

(η³-allyl)osmium(II) complex 36 as a yellow, slightly air-

sensitive solid in 61% isolated yield (Scheme 8). We

assume that a carbene(η¹-vinyl) metal species is formed

as an intermediate, which by intramolecular C-C

coupling is transformed to the final product. An alterna-

tive pathway, addition of the C-nucleophile to the

carbene carbon atom followed by elimination of trifluo-

roacetate with concomitant η¹/η³allyl rearrangement,

could equally be considered. Although on the basis of

atoms appear in the ¹³C NMR spectrum of 38 at δ 148.1

and 142.8, while the signal for the metal-bonded CPh₂

carbon atom is observed at δ 61.7. Regarding the

mechanism of the formation of 38, it is conceivable that

in the initial step a substitution of one carboxylate

ligand by CH₂dCHOEt takes place followed by abstrac-

tion of a proton from the less electron-rich part of the

coordinated olefin with Na₂CO₃. The so-formed η¹- or

η²-bonded vinylic unit could then undergo an intramo-

lecular C-C coupling reaction with the CPh₂group

similar to what probably occurs during the formation

of 36. Although d⁶transition metal centers are not

particularly oxophilic, we assume that not only for steric

but also for electronic reasons the five-membered OsC₃O

ring is preferred compared to an OsC₃ring or an η³-

allylosmium species containing an OEt substituent. We

note that recently Caulton, Eisenstein, and co-workers

reported that the coordinatively unsaturated cation

[RuH(CO)(PR₃)₂]⁺(PR₃) PMetBu₂) reacts with methyl-

and ethyl(vinyl)ether to afford â-alkoxyethylruthenium-

(II) complexes with a Ru-O bond.¹⁸Treatment of the

osmium compound 38 with CF₃CO₂H leads to protolytic

cleavage of the Os-C bond and to the generation of the

substituted allyl(ethyl)ether Ph₂CdCHCH₂OEt (see

Scheme 8).

In the course of experiments aimed to replace one

trifluoroacetato ligand of 14, 15, or 17 by a solvent

molecule and thus to generate a reactive cationic species

[(η⁶-mes)Os{κ¹-OC(O)CF₃}(S)(dCR₂)]⁺(S ) solvent), we

discovered a C-C cleavage reaction for which, as far as

we know, there is no precedence. The bis(trifluoro-

acetato) complexes 14, 15, and 17 react with water in

acetone solution to give the diaryl(carbonyl)osmium(II)

compounds 39-41 (Scheme 9) in good to excellent

yields. The diphenyl derivative 39 was already known

and had previously been prepared in our laboratory

from [(η⁶-mes)OsCl₂(CO)] and C₆H₅Li.¹⁹Similarly to 39,

the H and ¹³C NMR data it cannot be decided whether

the η³-CH₂CHCPh₂ligand of 36 is linked in exo or endo

position to the (η⁶-mes)OsBr moiety, there is no doubt

that in contrast with the η⁵-cyclopentadienylruthenium

compounds [(η⁶-C₅H₅)Ru(η³-CH₂CHCR₂)(PPh₃)] (R )

p-C₆H₄X)¹only one isomer is present. In analogy with

the crystallographically characterized η³-2-methallyl

complex [(η⁶-mes)OsCl{η³-CH₂C(CH₃)CH₂}]^10bwe be-

lieve that the exo isomer is thermodynamically pre-

ferred. We note that the reaction of 36 with CF₃CO₂H

gives besides [(η⁶-mes)OsBr(κ²-O₂CCF₃)] (37) the trisub-

stituted ethene derivative Ph₂CdCHCH₃.

A C-C coupling involving the diphenylcarbene ligand

of 14 also occurs upon treatment of 14 with ethyl(vinyl)-

ether in the presence of Na₂CO₃. Stirring a mixture of

14 and Na₂CO₃in CH₂dCHOEt as the solvent at room

temperature causes a smooth change of color from dark

green to brown and finally gives the metallacyclic

product 38 as a pale brown solid in 78% yield. The H

NMR spectrum of 38 displays two doublets at δ 5.88

and 5.28 for the olefinic CH protons of the five-

membered ring, the H-H coupling constant of 7.4 Hz

being typical for a Z configuration of the -CHdCH-

unit. The resonances for the corresponding CH carbon

(18) Huang, D.; Ge´rard, H.; Clot, E.; Young, V.; Streib, W. E.;

Eisenstein, O.; Caulton, K. G. Organometallics 1999, 18, 5441-5443.

750 Organometallics, Vol. 22, No. 4, 2003

Weberndo¨rfer et al.

Sch em e 9

Sch em e 10

also the analogous complexes 40 and 41 are yellow

solids, which are only moderately air-sensitive and

soluble in all common organic solvents. The most typical

spectroscopic features are the strong ν(CO) absorption

in the IR spectrum at 1924 (40) and 1942 cm^-1(41) and

the resonance for the CO carbon atom in the ¹³C NMR

spectrum at δ 184.8 (40) and 179.1 (41), respectively.

A proposal for the mechanism of the unusual C-C

cleavage reaction (exemplified for R ) C₆H₅) is shown

in Scheme 10. We assume that in the initial step the

anticipated dissociation of one of the trifluoroacetate

ions occurs followed by an attack of the positively

charged metal center on the ipso-carbon atom of one

phenyl group. The subsequent C-C bond cleavage could

lead to a cationic [Os(C₆H₅)(tCC₆H₅)]⁺intermediate,

the carbyne carbon atom of which is presumably readily

attacked by a nucleophile such as water or a trifluoro-

acetate anion. Due to this attack, a hydroxocarbene

intermediate is generated in one or two steps and

rearranges, after cleavage of the Os-OC(O)CF₃bond

and abstraction of a proton, to a κ²-bonded benzoylos-

mium(II) species. Finally, migration of the phenyl group

from the PhC(O) carbon to osmium affords the isolated

product. Although the formation of a dicationic di-

nuclear intermediate cannot be excluded, we consider

the possibility of an intermolecular transfer of group R

from carbon to osmium as less likely. With regard to

the postulated cationic intermediate formed in the

initial step, we note that a metallacyclopropene struc-

ture has also been discussed in the context of the

reactivity of related half-sandwich-type rhodium and

molydenum systems.^20,21Moreover, Roper et al. re-

ported²²that the cationic carbyneruthenium complex

[RuCl(I)(tCPh)(CO)(PPh₃)₂]⁺reacts with water to give

the phenylruthenium(II) derivative [RuCl(C₆H₅)(CO)₂-

(PPh₃)₂], probably via an analogous series of steps as

proposed in Scheme 10.

Support for the argument that one of the trifluoro-

acetate ions is involved in the formation of the CO

ligand coordinated to osmium in 39-41 stems from a

labeling experiment. If the starting material 14 is

treated in unlabeled acetone with H₂¹⁸O and the reac-

tion mixture worked up as described for 39, the IR

spectrum (in CH₂Cl₂) of the residue displays two strong

ν(CO) bands at 1946 and 1904 cm^-1assigned to 39 and

39a , respectively. The intensity ratio is approximately

2:1. Since 39a is not formed exclusively, we assume

either that both H₂¹⁸O and unlabeled CF₃CO₂attack

the cationic carbyneosmium intermediate in parallel

steps or that initially in a fast equilibrium trifluoro-

acetate reacts with H₂¹⁸O to give ¹⁸O-labeled trifluoro-

acetate and H₂¹⁶O, the latter being the substrate to form

39 with unlabeled oxygen.

4. P r ep a r a tion of Ca tion ic Ca r ben eosm iu m (II)

Com p lexes. With the aim of further modifying the

coordination sphere of osmium(II) in the carbene com-

plexes with [(η⁶-arene)Os(dCR₂)] as the building block,

we also attempted to generate carbeneosmium(II) cat-

ions of the general composition [(η⁶-mes)Os{κ¹-OC(O)-

CF₃}(L)(dCR₂)]⁺from the bis(trifluoroacetato) deriva-

tives 14 and 15 and ligands L such as PPh₃, PiPr₃, and

AsiPr₃as the precursors. However, under various condi-

tions only decomposition of the osmium compounds

occurred. If the dichloro complex 28 is used as the

starting material, instead of the substitution of chloride

(19) Werner, H.; Stahl, S.; Schulz, M. Chem. Ber. 1991, 124, 707-

712.

(20) Werner, H.; Wolf, J .; Schubert, U.; Ackermann, K. J . Orga-

nomet. Chem. 1983, 243, C63-C70.

(21) Feher, F. J .; Green, M.; Rodrigues, R. A. J . Chem. Soc., Chem.

Commun. 1987, 1206-1208.

(22) Gallop, M. A.; Roper, W. R. Adv. Organomet. Chem. 1986, 25,

121-198.

Areneosmium(II) Complexes

Sch em e 11

Organometallics, Vol. 22, No. 4, 2003 751

Sch em e 12

F igu r e 6. Molecular diagram of compound 45. Selected

bond distances (Å) and angles (deg): Os-C1 1.93(1), Os-

Cl1 2.384(2), Os-P1 2.377(2), Os-C30 2.305(9), Os-C31

2.35(1), Os-C32 2.40(1), Os-C33 2.26(1), Os-C34 2.32-

(1), Os-C35 2.27(1); C1-Os-Cl1 98.1(4), C1-Os-P1 93.4-

(3), Cl1-Os-P1 81.54(9), Os-C1-C10 127.9(8), Os-C1-

C20 121.7(8), C10-C1-C20 110(1).

Con clu sion s

The results presented in this paper illustrate that the

bis(trifluoroacetato)osmium(II) compounds [(η⁶-arene)-

Os{κ¹-OC(O)CF₃}(κ²-O₂CCF₃)] (4, 9, 10) are useful

starting materials for the preparation of half-sandwich-

type complexes containing an OsdCR₂bond. An unex-

pected facet is that the related bis(tosylato) compounds

[(η⁶-arene)Os{κ¹-OS(O)₂R}{κ²-O₂S(O)R}] (20, 21) react

with Ph₂CN₂and PhCHN₂in a different fashion and

afford catalytically tetraphenylethene and a mixture of

(E)- and (Z)-stilbene, respectively. Since there is general

agreement that tosylate is a better leaving group than

trifluoroacetate, we assume that the reactions of 20 and

21 with Ph₂CN₂and PhCHN₂also give in the initial

step a corresponding carbene complex, which, however,

seems to be very labile and reacts with a second

molecule of the diazoalkane to yield the olefin.

The lability of the Os-OC(O)CF₃linkages in the bis-

(trifluoroacetato) derivatives [(η⁶-arene)Os{κ¹-OC(O)-

CF₃}₂(dCR₂)] opens the gate to prepare dichloro-,

dibromo-, and diiodoosmium(II) carbenes [(η⁶-arene)-

OsX₂(dCR₂)] via ligand exchange using either Me₃SiX

or NH₄X (X ) Cl, Br, I) and, in some cases, even HCl or

HBr as substrates. A remarkable difference has been

observed in the reactivity of the η⁶-mesitylene com-

plexes [(η⁶-mes)OsX₂(dCPh₂)] (X ) CF₃CO₂, Cl) toward

Grignard reagents. While these compounds react with

C₆H₅MgBr and CH₃MgI by replacement of trifluoro-

acetate or chloride for bromide or iodide, treatment of

[(η⁶-mes)Os{κ¹-OC(O)CF₃}₂(dCPh₂)] (14) with CH₂d

CHMgBr yields the η³-allyl complex [(η⁶-mes)OsBr(η³-

CH₂CHCPh₂)]. Taking previous results from our labo-

ratory into consideration,¹we assume that the formation

of the η³-allyl ligand occurs stepwise via an Os(CHd

CH₂)(dCPh₂) species as an intermediate. An unusual

C-C coupling reaction also takes place upon treat-

ment of 14 with the vinyl ether CH₂dCHOEt, which

affords the metallacyclic compound [(η⁶-mes)Os{κ²(C,O)-

Ph₂CCHdCHOEt}{κ¹-OC(O)CF₃}] in high yield. It is

conceivable that equally in this case a carbene(vinyl)-

osmium(II) intermediate is involved which after C-C

coupling generates an ethoxy-substituted allyl unit that

preferentially binds via C and O to the metal.

by EiPr₃(E ) P, As, Sb), the replacement of the carbene

by the P-, As-, or Sb-donor takes place (Scheme 11). The

so-formed half-sandwich-type osmium(II) compounds

42-44 are known and have recently been prepared on

a straightforward route from the dimer 19 and EiPr₃.²³

Stable PF₆^-salts of [(η⁶-mes)OsCl(L)(dCR₂)]⁺cations

with L ) PPh₃and R ) phenyl or p-tolyl were obtained

upon teatment of a solution of 28 or 29 in THF with

PPh₃in the presence of AgPF₆at -78 °C (see Scheme

12). After separation of AgCl, evaporation of the solvent

and recrystallization of the residue from CH₂Cl₂/hexane

dark green solids analyzing as 45 and 46 were isolated

in nearly quantitative yields. Conductivity measure-

ments are in agreement with the proposed composition.

The ¹³C NMR spectra of 45 and 46 display a doublet

for the carbene carbon atom at δ 292.3 and 291.2,

respectively, the signal being shifted ca. 10 ppm upfield

compared with the precursors 28 and 29. It should be

mentioned that attempts to prepare the complexes 45

and 46 by an alternative method from [(η⁶-mes)-

OsCl₂(PPh₃)], Ph₂CN₂, and AgPF₆remained unsuccess-

ful.

The molecular structure of the cation of 46 is shown

in Figure 6. The X-ray structure analysis of 46 revealed⁴

that in the grown single crystal only one enantiomer of

the racemate possessing the R-configuration at the

metal center is present. The cation has the expected

piano-stool arrangement with distances between os-

mium and the carbon atoms of the six-membered ring

that are somewhat longer than in the neutral complex

17. The Os-C(carbene) bond length in both compounds

17 and 46 is nearly identical. Two of the bond angles of

the three-legged OsL¹L²L³fragment, C1-Os-P1 (93.4-

(8)°) and C1-Os-Cl1 (98.1(4)°), are considerably larger

than the third one, P1-Os-Cl1 (81.54(9)°), which we

assume is due to the steric demand of the carbene

ligand.

(23) Weberndo¨rfer, B.; Werner, H. J . Chem. Soc., Dalton Trans.

2002, 1479-1486.

752 Organometallics, Vol. 22, No. 4, 2003

Weberndo¨rfer et al.

vacuo, the remaining pale yellow solid was washed three times

with 5 mL portions of ether and dried: yield 191 mg (88%);

mp 202 °C. IR (CH₂Cl₂): ν(OSO) and ν(CF) 1382, 1160, 1156,

However, the diarylcarbeneosmium compounds un-

dergo not only C-C coupling but also C-C cleavage

reactions. Thus, upon treatment of the bis(trifluoro-

acetates) [(η⁶-mes)Os{κ¹-OC(O)CF₃}₂(dCR₂)] (R ) C₆H₄X)

with water in acetone the C-R bonds are split and the

diaryl(carbonyl) complexes [(η⁶-mes)OsR₂(CO)] are formed

in good to excellent yields. A carbyneosmium cation is

possibly involved as an intermediate, which reacts with

water and/or trifluoroacetate to generate the carbonyl

ligand. A labeling experiment supports this proposal.

We finally note that although various osmium(0) and

osmium(II) compounds with an OsdCR₂linkage were

already reported,^10-13,24,25to the best of our knowledge

the complexes 11-17, 22-32, and 45, 46 are the first

half-sandwich-type osmium derivatives with a non-

Fischer-type carbene ligand.

1032 cm^-1. H NMR (CDCl₃, 200 MHz): δ 6.04 (s, 3 H, CH of

mes), 2.32 (s, 9 H, CH₃of mes). ¹³C NMR (CDCl₃, 50.3 MHz):

δ 118.2 [q, J (F,C) ) 297.3 Hz, CF₃SO₃], 92.0 (s, CCH₃of mes),

67.3 (s, CH of mes), 19.2 (s, CCH₃of mes). ¹⁹F NMR (CD₂Cl₂,

188.3 MHz): δ -76.4 (s). Anal. Calcd for C₂₀H₂₄Cl₂F₆O₆Os₂S₂

(989.8): C, 24.27; H, 2.44; S, 6.48. Found: C, 24.63; H, 2.69;

S, 6.52.

P r ep a r a tion of [(η⁶-m es)Os{K¹-OC(O)CF ₃}₂(CNMe)] (5).

A solution of 4 (102 mg, 0.19 mmol) in 5 mL of CH₂Cl₂was

treated with methylisocyanide (10 mg, 0.25 mmol) and stirred

for 10 min at room temperature. The solvent was evaporated

in vacuo, and the remaining light yellow residue was washed

three times with 5 mL portions of hexane and dried: yield 97

mg (88%); mp 117 °C dec. IR (KBr): ν(CN) 2204, ν(OCO) 1697

cm^-1. H NMR (CDCl₃, 200 MHz): δ 5.47 (s, 3 H, CH of mes),

3.70 (s, 3 H, CNCH₃), 2.23 (s, 9 H, CH₃of mes). ¹³C NMR

(CDCl₃, 50.3 MHz): δ 162.8 [q, J (F,C) ) 36.9 Hz, CF₃CO₂],

139.3 (s, CNCH₃), 113.6 [q, J (F,C) ) 290.0 Hz, CF₃CO₂], 100.8

(s, CCH₃of mes), 71.7 (s, CH of mes), 58.9 (s, CNCH₃), 18.5 (s,

CCH₃of mes). ¹⁹F NMR (CD₂Cl₂, 188.3 MHz): δ -74.6 (s).

Anal. Calcd for C₁₅H₁₅F₆NO₄Os (577.5): C, 31.20; H, 2.62; N,

2.43. Found: C, 31.58; H, 2.44; N, 2.48.

Exp er im en ta l Section

All reactions were carried out under an atmosphere of argon

by Schlenk techniques. Solvents were dried by known proce-

dures and distilled before use. The starting materials 1,⁵4,⁸

8,²⁶10,²⁷18,²⁸and 19^5,9were prepared as described in the

literature. NMR spectra were recorded on Bruker AC 200,

Bruker DRX 300, and Bruker AMX 400 instruments. Chemical

shifts are expressed in ppm downfield from TMS (¹H and ¹³C-

{¹H}), 85% H₃PO₄(³¹P{¹H}), or CFCl₃(¹⁹F{¹H}). IR spectra

were recorded on a Bruker IFS 25 FT-IR and mass spectra on

a Finnigan MAT 90 or on a Hewlett-Packard G 1800 GCD

instrument. The conductivity Λ was measured in nitromethane

with a Schott Konduktometer CG 851 instrument, and melting

and decomposition points were determined by DTA.

P r epar ation of [(η⁶-m es)Os{K¹-OC(O)CF ₃}₂(CNtBu )] (6).

This compound was prepared as described for 5, from 4 (107

mg, 0.20 mmol) and CNtBu (21 mg, 0.25 mmol). Pale yellow

solid: yield 117 mg (95%); mp 121 °C dec. IR (KBr): ν(CN)

2187, ν(OCO) 1705, 1691 cm^-1. H NMR (C₆D₆, 200 MHz): δ

4.56 (s, 3 H, CH of mes), 1.67 (s, 9 H, CH₃of mes), 1.09 [s, 9

H, C(CH₃)₃]. ¹³C NMR (CDCl₃, 100.6 MHz): δ 162.7 [q, J (F,C)

) 36.2 Hz, CF₃CO₂], 121.8 (s, CNCCH₃), 113.8 [q, J (F,C) )

289.7 Hz, CF₃CO₂], 100.5 (s, CCH₃of mes), 71.5 (s, CH of mes),

58.4 (s, CNCCH₃), 30.2 (s, CNCCH₃), 18.7 (s, CCH₃of mes).

¹⁹F NMR (C₆D₆, 188.3 MHz): δ -73.9 (s). Anal. Calcd for

P r ep a r a tion of [(η⁶-m es)Os{K¹-OC(O)CF ₃}(µ-Cl)]₂(2). A

solution of 1 (62 mg, 0.16 mmol) in 10 mL of benzene was

treated with CF₃CO₂H (18 mg, 0.16 mmol) and stirred for 1 h

at room temperature. After the solvent was evaporated in

vacuo, the residue was dissolved in 1 mL of CH₂Cl₂and the

solution was layered with 10 mL of hexane. Pale yellow

crystals precipitated, which were separated from the mother

liquor, washed twice with 5 mL portions of hexane, and

₁₈H₂₁F₆NO₄Os (619.6): C, 34.90; H, 3.42; N, 2.26. Found: C,

34.61; H, 3.43; N, 2.18.

P r ep a r a tion of [(η⁶-m es)Os{K¹-OC(O)CF ₃}₂(P P h ₃)] (7).

A solution of 4 (134 mg, 0.25 mmol) in 10 mL of CH₂Cl₂was

treated with PPh₃(79 mg, 0.30 mmol) and stirred for 15 min

at room temperature. After the solution was concentrated to

ca. 0.5 mL in vacuo, it was layered with 10 mL of hexane. A

pale yellow solid precipitated, which was filtered, washed three

times with 5 mL portions of hexane, and dried: yield 182 mg

dried: yield 68 mg (93%); mp 221 °C dec; Λ 63 cm²Ω^-1mol^-1

MS (70 eV): m/z 883 (M⁺- Cl), 805 (M⁺- CF₃CO₂), 460 (M⁺/

2). IR (KBr): ν(OCO) 1713, 1702, 1700, 1694 cm^-1. H NMR

(91%); mp 138 °C dec. IR (KBr): ν(OCO) 1717, 1712 cm^-1. H

(CDCl₃, 200 MHz): δ 5.87, 5.76, 5.75, 5.62 (all s, CH of mes),

2.15, 2.14, 2.13, 2.08 (all s, CH₃of mes). ¹³C NMR (CDCl₃, 100.6

MHz): δ 162.3 [q, J (F,C) ) 33.7 Hz, CF₃CO₂], 115.4 [q, J (F,C)

) 289.3 Hz, CF₃CO₂], 92.4 (s, CCH₃of mes), 66.4 (s, CH of

mes), 19.2 (s, CCH₃of mes). ¹⁹F NMR (CD₂Cl₂, 188.3 MHz): δ

-78.7, -76.1, -75.8, -74.4, -74.1 (all s). Anal. Calcd for

₂₂H₂₄Cl₂F₆O₄Os₂(917.7): C, 28.79; H, 2.64. Found: C, 28.70;

H, 2.32.

P r ep a r a tion of [(η⁶-m es)Os{K¹-OS(O)₂CF ₃}(µ-Cl)]₂(3).

NMR (C₆D₆, 200 MHz): δ 7.62, 7.57, 7.03 (all m, 15 H, C₆H₅),

5.26 (s, 3 H, CH of mes), 1.68 (s, 9 H, CH₃of mes). ¹³C NMR

(CDCl₃, 100.6 MHz): δ 163.2 [q, J (F,C) ) 34.2 Hz, CF₃CO₂],

134.8 [d, J (P,C) ) 43.3 Hz, ipso-C of PC₆H₅], 132.7 [d, J (P,C)

) 10.1 Hz, meta-C of PC₆H₅], 131.0 [d, J (P,C) ) 2.0 Hz, para-C

of PC₆H₅), 128.6 [d, J (P,C) ) 13.1 Hz, ortho-C of PC₆H₅], 114.1

[q, J (F,C) ) 290.7 Hz, CF₃CO₂], 95.0 (s, CCH₃of mes), 76.1 (s,

CH of mes), 19.0 (s, CCH₃of mes). ¹⁹F NMR (CD₂Cl₂, 188.3

MHz): δ -74.3 (s). ³¹P NMR (C₆D₆, 81.0 MHz): δ 7.4 (s). Anal.

Calcd for C₃₁H₂₇F₆O₄OsP: C, 46.62; H, 3.41. Found: C, 46.23;

H, 3.12.

A solution of 1 (170 mg, 0.44 mmol) in 10 mL of THF was

treated with CF₃SO₃H (66 mg, 0.44 mmol) and stirred for 2 h

at room temperature. After the solvent was evaporated in

P r ep a r a tion of [(η⁶-tol)Os{K¹-OC(O)CF ₃}(K²-O₂CCF ₃)]

(9). A suspension of 8 (430 mg, 0.61 mmol) in 10 mL of benzene

was treated with a solution of CF₃CO₂Ag (511 mg, 2.30 mmol)

in 2 mL of benzene and stirred for 30 min at room temperature.

The reaction mixture was filtered with Celite, and the residue

was washed with 5 mL of benzene. After the filtrate was

brought to dryness in vacuo, a yellow oil was obtained, which

did not crystallize even after being stored for 24 h at 0 °C.

The analysis of the oil revealed that the monohydrate of the

product was isolated: yield 273 mg (88%). IR (CH₂Cl₂): ν(OCO)

(24) Brothers, P. J .; Roper, W. R. Chem. Rev. 1988, 88, 1293-1326.

(25) Werner, H.; Weber, B.; Nu¨rnberg, O.; Wolf, J . Angew. Chem.

1992, 104, 1105-1107; Angew. Chem., Int. Ed. Engl. 1992, 31, 1025-

1026. Esteruelas, M. A.; Lahoz, F. J .; Onate, E.; Oro, L. A.; Zeier, B.

Organometallics 1994, 13, 4258-4265. Esteruelas, M. A.; Lahoz, F.

J .; Onate, E.; Oro, L. A.; Valero, C.; Zeier, B. J . Am. Chem. Soc. 1995,

117, 7935-7942. Werner, H.; Flu¨gel, R.; Windmu¨ller, B.; Michenfelder,

A.; Wolf, J . Organometallics 1995, 14, 612-618.

(26) Lewis, J .; Li, C.-K., Morewood, C. A.; Ramirez de Arellano, M.

C.; Raithby, P. R.; Wong, W. T. J . Chem. Soc., Dalton Trans. 1994,

2159-2165. Bell, A. G.; Kozminski, W.; Linden, A.; von Philipsborn,

W. Organometallics 1996, 15, 3124-3135.

1675, 1651, 1442, 1405 cm^-1. H NMR (CDCl₃, 400 MHz): δ

(27) Cabeza, J . A.; Mann, B. E.; Maitlis, P. M.; Brevard, C. J . Chem.

Soc., Dalton Trans. 1988, 629-634.

(28) Werner, H.; Zenkert, K. J . Organomet. Chem. 1988, 345, 151-

166.

6.52 (m, 2 H, meta-H of C₆H₅CH₃), 6.24 (m, 1 H, para-H of

C₆H₅CH₃), 6.12 (m, 2 H, ortho-H of C₆H₅CH₃), 2.21 (s, 3 H,

C₆H₅CH₃). ¹³C NMR (CDCl₃, 100.6 MHz): δ 165.9 [q, J (F,C)

Areneosmium(II) Complexes

Organometallics, Vol. 22, No. 4, 2003 753

) 38.8 Hz, CF₃CO₂), 115.0 [q, J (F,C) ) 289.9 Hz, CF₃CO₂],

89.6 (s, ipso-C of C₆H₅CH₃), 74.6 (s, para-C of C₆H₅CH₃), 67.0,

64.2 (both s, ortho- and meta-C of C₆H₅CH₃), 18.8 (s, C₆H₅CH₃).

¹⁹F NMR (CDCl₃, 376.5 MHz): δ -75.2 (s). Anal. Calcd for

₁₁H₁₀F₆O₅Os₂(526.4): C, 25.10; H, 1.91. Found: C, 24.77; H,

2.06.

P r ep a r a tion of [(η⁶-tol)Os{K¹-OC(O)CF ₃}₂{dC(p-C₆H₄-

156.4 (s, ipso-C of C₆H₄CH₃), 144.9 (s, para-C of C₆H₄CH₃),

132.2, 128.9 (both s, ortho- and meta-C of C₆H₄CH₃), 120.6,

98.1 [both s, ipso- and para-C of CH₃C₆H₄CH(CH₃)₂], 114.5 [q,

J (F,C) ) 291.1 Hz, CF₃CO₂], 88.4, 75.3 [both s, ortho- and

meta-C of CH₃C₆H₄CH(CH₃)₂], 32.2 [s, CH₃C₆H₄CH(CH₃)₂],

22.4, 22.1 [both s, C₆H₄CH₃and CH₃C₆H₄CH(CH₃)₂], 17.3 [s,

CH₃C₆H₄CH(CH₃)₂]. ¹⁹F NMR (CD₂Cl₂, 376.5 MHz): δ -74.5

(s). Anal. Calcd for C₂₉H₂₈F₆O₄Os: C, 46.77; H, 3.79. Found:

C, 46.88; H, 4.26.

Me)₂}] (11). A solution of 9 (107 mg, 0.21 mmol) in 2 mL of

benzene was treated dropwise with a solution of (p-C₆H₄-

Me)₂CN₂(38 mg, 0.17 mmol) in 0.5 mL of benzene and stirred

for ca. 1 min at room temperature. Both an evolution of gas

(N₂) and a change of color from yellow to olive-green occurred.

The solvent was evaporated in vacuo, the oily residue was

dissolved in 1 mL of toluene, and the solution was layered with

10 mL of hexane. After the mixture was irrradiated for ca. 3

min in an ultrasound bath, olive-green crystals precipitated,

which were separated from the mother liquor, washed twice

with 5 mL portions of hexane, and dried: yield 131 mg (89%);

P r ep a r a tion of [(η⁶-m es)Os{K¹-OC(O)CF₃}₂{dC(C₆H₅)₂}]

(14). This compound was prepared as described for 11, from

4 (150 mg, 0.28 mmol) and (p-C₆H₄Me)₂CN₂(38 mg, 0.17 mmol)

in 2 mL of benzene. An olive-green solid was obtained without

using the irradiation in an ultrasound bath: yield 179 mg

(91%); mp 89 °C dec. IR (KBr): ν(OCO) 1709, 1674, 1664, 1439

cm^-1. H NMR (CD₂Cl₂, 200 MHz): δ 7.60, 7.42, 7.29 (all m,

10 H, C₆H₅), 5.37 (s, 3 H, CH of mes), 2.29 [s, 9 H, CH₃of

mes). ¹³C NMR (CD₂Cl₂, 50.3 MHz): δ 310.3 (s, OsdC), 161.7

[q, J (F,C) ) 36.9 Hz, CF₃CO₂], 158.9 (s, ipso-C of C₆H₅), 132.6

(s, para-C of C₆H₅), 130.6, 127.5 (both s, ortho- and meta-C of

C₆H₅), 114.3 [q, J (F,C) ) 290.7 Hz, CF₃CO₂], 106.9 (s, CCH₃

of mes), 79.8 (s, CH of mes), 18.1 (s, CCH₃of mes). ¹⁹F NMR

(CD₂Cl₂, 188.3 MHz): δ -73.4 (s). Anal. Calcd for C₂₆H₂₂F₆O₄-

Os (702.6): C, 44.44; H, 3.16. Found: C, 44.16; H, 3.29.

P r ep a r a tion of [(η⁶-m es)Os{K¹-OC(O)CF ₃}₂{dC(p-C₆H₄-

Me)₂}] (15). This compound was prepared as described for 11,

from 4 (91 mg, 0.17 mmol) and (p-C₆H₄Me)₂CN₂(38 mg, 0.17

mmol) in 2 mL of benzene. Olive-green solid: yield 88 mg

(71%); mp 107 °C dec. MS (70 eV): m/z (I_r) 731 (M⁺), 611 (M⁺

- mes). IR (CH₂Cl₂): ν(OCO) 1702, 1684, 1407 cm^-1. ¹H NMR

(CD₂Cl₂, 400 MHz): δ 7.21, 7.16 [both d, J (H,H) ) 8.2 Hz, 4

H each, C₆H₄CH₃], 5.33 (s, 3 H, CH of mes), 2.39 (s, 6 H,

C₆H₄CH₃), 2.26 (s, 9 H, CH₃of mes). ¹³C NMR (CD₂Cl₂, 100.6

MHz): δ 307.9 (s, OsdC), 161.9 [q, J (F,C) ) 36.9 Hz, CF₃CO₂],

156.4 (s, ipso-C of C₆H₄CH₃), 144.6 (s, para-C of C₆H₄CH₃),

131.6, 128.4 (both s, ortho- and meta-C of C₆H₄CH₃), 114.6 [q,

J (F,C) ) 291.1 Hz, CF₃CO₂], 105.6 (s, CCH₃of mes), 79.3 (s,

CH of mes], 21.8 (s, C₆H₄CH₃), 18.3 (s, CCH₃of mes). ¹⁹F NMR

(376.5 MHz, CD₂Cl₂): δ -75.3 (s). Anal. Calcd for C₂₈H₂₆F₆O₄-

Os (730.7): C, 46.02; H, 3.59; Os, 26.03. Found: C, 46.21; H,

3.24; Os, 25.71.

P r ep a r a tion of [(η⁶-m es)Os{K¹-OC(O)CF ₃}₂{dC(p-C₆H₄-

Cl)₂}] (16). This compound was prepared as described for 11,

from 4 (123 mg, 0.23 mmol) and (p-C₆H₄Cl)₂CN₂(61 mg, 0.23

mmol) in 2 mL of benzene. Olive-green solid: yield 103 mg

(58%); mp 118 °C dec. IR (CH₂Cl₂): ν(OCO) 1665, 1662, 1434

cm^-1. ¹H NMR (CD₂Cl₂,400 MHz): δ 7.40, 7.20 [both d, J (H,H)

) 8.8 Hz, 4 H each, C₆H₄Cl], 5.37 (s, 3 H, CH of mes), 2.29 (s,

9 H, CH₃of mes). ¹³C NMR (CD₂Cl₂, 100.6 MHz): δ 305.9 (s,

OsdC), 162.1 [q, J (F,C) ) 37.2 Hz, CF₃CO₂], 157.4 (s, ipso-C

of C₆H₄Cl), 139.6 (s, para-C of C₆H₄Cl), 131.9, 128.4 (both s,

ortho- and meta-C of C₆H₄Cl), 114.5 [q, J (F,C) ) 290.7 Hz, CF₃-

CO₂], 108.2 (s, CCH₃of mes), 80.2 (s, CH of mes), 18.5 (s, CCH₃

of mes). ¹⁹F NMR (CD₂Cl₂, 376.5 MHz): δ -75.2 (s). Anal.

Calcd for C₂₆H₂₀Cl₂F₆O₄Os (771.6): C, 40.47; H, 2.61. Found:

C, 40.33; H, 2.63.

mp 123 °C dec. IR (KBr): ν(OCO) 1686, 1669, 1408 cm^-1. H

NMR (C₆D₆, 400 MHz): δ 7.12, 6.88 (both m, 4 H each, C₆H₄-

CH₃], 5.22 (m, 2 H, meta-H of C₆H₅CH₃), 5.10 (m, 1 H, para-H

of C₆H₅CH₃), 4.70 (m, 2 H, ortho-H of C₆H₅CH₃), 2.04 (s, 6 H,

C₆H₄CH₃), 1.70 (s, 3 H, C₆H₅CH₃). ¹³C NMR (C₆D₆, 100.6

MHz): δ 307.0 (s, OsdC), 163.2 [q, J (F,C) ) 38.1 Hz, CF₃CO₂],

156.1 (s, ipso-C of C₆H₄CH₃), 144.5 (s, para-C of C₆H₄CH₃),

131.2, 128.3 (both s, ortho- and meta-C of C₆H₄CH₃), 114.8 [q,

J (F,C) ) 290.0 Hz, CF₃CO₂], 102.3 (s, ipso-C of C₆H₅CH₃), 86.7,

82.7 (both s, ortho- and meta-C of C₆H₅CH₃), 74.7 (s, para-C

of C₆H₅CH₃), 21.3 (s, C₆H₄CH₃), 17.3 (s, C₆H₅CH₃). ¹⁹F NMR

(C₆D₆, 376.5 MHz): δ -74.2 (s). Anal. Calcd for C₂₆H₂₂F₆O₄Os

(702.7): C, 44.44; H, 3.16. Found: C, 43.94; H, 3.66.

P r epar ation of [(η⁶-cym )Os{K¹-OC(O)CF₃}₂{dC(C₆H₅)₂}]

(12). (a) This compound was prepared as described for 11, from

10 (66 mg, 0.12 mmol) and CPh₂N₂(23 mg, 0.12 mmol) in 2

mL of benzene: olive-green solid; yield 92 mg (79%). (b) An

alternative procedure is as follows: A solution of 18 (88 mg,

0.11 mmol) in 10 mL of benzene was treated with a solution

of CF₃CO₂Ag (88 mg, 0.40 mmol) in 5 mL of benzene and

stirred for 30 min at room temperature. The yellow solution

was separated from the precipitate (AgCl), concentrated to ca.

1 mL in vacuo, and treated with CPh₂N₂(78 mg, 0.40 mmol).

The reaction mixture was then worked up as described for

11: yield 122 mg (85%); mp 138 °C dec. IR (KBr): ν(OCO)

1697, 1439, 1408 cm^-1. H NMR (CD₂Cl₂, 400 MHz): δ 7.58,

7.40, 7.20 (all m, 10 H, C₆H₅), 6.33, 5.36 [both d, J (H,H) ) 6.2

Hz, 2 H each, CH₃C₆H₄CH(CH₃)₂], 2.83 [sept, J (H,H) ) 7.0

Hz, 1 H, CH₃C₆H₄CH(CH₃)₂], 1.89 [s, 3 H, CH₃C₆H₄CH(CH₃)₂],

1.24 [d, J (H,H) ) 7.0 Hz, 6 H, CH₃C₆H₄CH(CH₃)₂]. ¹³C NMR

(CD₂Cl₂, 100.6 MHz): δ 306.1 (s, OsdC), 162.9 [q, J (F,C) )

38.1 Hz, CF₃CO₂], 159.0 (s, ipso-C of C₆H₅), 132.8 (s, para-C

of C₆H₅), 131.7, 127.9 (both s, ortho- and meta-C of C₆H₅),

121.8, 99.3 (both s, ipso- and para-C of C₆H₄), 114.2 [q, J (F,C)

) 291.1 Hz, CF₃CO₂], 89.0, 76.0 (both s, ortho- and meta-C of

C₆H₄), 32.0 [s, CH(CH₃)₂], 22.0 [s, CH(CH₃)₂], 17.0 (s, CH₃C₆H₄).

¹⁹F NMR (CD₂Cl₂, 376.5 MHz): δ -75.3 (s). Anal. Calcd for

C₂₇H₂₄F₆O₄Os (716.7): C, 45.25; H, 3.38. Found: C, 45.38; H,

3.87.

P r ep a r a tion of [(η⁶-m es)Os{K¹-OC(O)CF ₃}₂{dC(p-C₆H₄-

OMe)₂}] (17). A solution of 4 (86 mg, 0.16 mmol) in 2 mL of

CH₂Cl₂was treated at -78 °C with a solution of (p-C₆H₄-

OMe)₂CN₂(41 mg, 0.16 mmol) in 0.5 mL of CH₂Cl₂and then

slowly warmed to room temperature. Both an evolution of gas

(N₂) and a change of color from yellow to brown occurred. The

solvent was evaporated in vacuo and the residue worked up

as described for 11. Red-brown solid: yield 79 mg (65%); mp

P r ep a r a tion of [(η⁶-cym )Os{K¹-OC(O)CF ₃}₂{dC(p-C₆H₄-

Me)₂}] (13). This compound was prepared as described for 11,

either from 10 (66 mg, 0.12 mmol) and (p-C₆H₄Me)₂CN₂(27

mg, 0.12 mmol) or from 18 (103 mg, 0.13 mmol), CF₃CO₂Ag

(106 mg, 0.48 mmol), and (p-C₆H₄Me)₂CN₂(107 mg, 0.48

mmol). Olive-green solid: yield 66 mg (74%) (route a) and 120

mg (67%) (route b); mp 102 °C dec. IR (KBr): ν(OCO) 1695,

1410, 1393 cm^-1

¹H NMR (CD₂Cl₂, 400 MHz): δ 7.21, 7.11

120 °C dec. IR (CH₂Cl₂): ν(OCO) 1685, 1670, 1407 cm^-^{1 1}H

[both d, J (H,H) ) 8.2 Hz, 4 H each, C₆H₄CH₃], 6.29, 5.33 [both

d, J (H,H) ) 6.2 Hz, 2 H each, CH₃C₆H₄CH(CH₃)₂], 2.82 [sept,

J (H,H) ) 6.7 Hz, 1 H, CH₃C₆H₄CH(CH₃)₂], 2.39 (s, 6 H,

C₆H₄CH₃), 1.87 [s, 3 H, CH₃C₆H₄CH(CH₃)₂], 1.23 [d, J (H,H) )

6.7 Hz, 6 H, CH₃C₆H₄CH(CH₃)₂]. ¹³C NMR (CD₂Cl₂,100.6

MHz): δ 304.5 (s, OsdC), 163.3 [q, J (F,C) ) 36.8 Hz, CF₃CO₂],

NMR (C₆D₆, 400 MHz): δ 7.30, 6.68 [both d, J (H,H) ) 8.8 Hz,

4 H each, C₆H₄OCH₃], 4.83 (s, 3 H, CH of mes), 3.30 (s, 6 H,

OCH₃), 1.90 (s, 9 H, CH₃of mes). ¹³C NMR (C₆D₆, 100.6

MHz): δ 300.1 (s, OsdC), 164.4 (s, ipso-C of C₆H₄OCH₃), 162.4

[q, J (F,C) ) 36.2 Hz, CF₃CO₂], 152.0 (s, para-C of C₆H₄OCH₃),

134.8 (s, ortho-C of C₆H₄OCH₃), 115.5 [q, J (F,C) ) 290.7 Hz,

754 Organometallics, Vol. 22, No. 4, 2003

Weberndo¨rfer et al.

CF₃CO₂], 113.3 (s, meta-C of C₆H₄OCH₃), 102.8 (s, CCH₃of

mes), 79.2 (s, CH of mes), 55.2 (s, OCH₃), 18.0 (s, CCH₃of mes).

¹⁹F NMR (C₆D₆, 376.5 MHz): δ -74.2 (s). Anal. Calcd for

₂₈H₂₆F₆O₆Os (762.7): C, 44.09; H, 3.44. Found: C, 44.60; H,

3.26.

P r ep a r a t ion of [(η⁶-cym )Os{K¹-OS(O)₂C₆H ₄Me-p }(K²-

mL of CH₂Cl₂. After the reaction mixture was warmed to room

temperature, it was concentrated to ca. 5 mL in vacuo and

then filtered with Celite. The filtrate was brought to dryness

in vacuo, and the greenish oil was dissolved in 0.5 mL of

toluene. After the solution was layered with 10 mL of hexane,

an olive-green solid precipitated, which was separated from

the mother liquor, washed twice with 5 mL portions of hexane,

and dried: yield 45 mg (67%). (b) An alternative procedure is

as follows: A solution of 12 (107 mg, 0.15 mmol) in 5 mL of

benzene was treated with a 1.3 M solution of HCl in benzene

(0.35 mL, 0.45 mmol) and stirred for 15 min at room temper-

ature. The solvent was evaporated in vacuo and the oily

residue worked up as described for (a). Olive-green solid: yield

O₂S(O)C₆H₄Me-p)] (20). A solution of 18 (184 mg, 0.23 mmol)

in 10 mL of benzene was treated with silver tosylate (246 mg,

0.88 mmol) and stirred for 24 h at room temperature. The

reaction mixture was filtered with Celite, and the residue was

washed with 5 mL of benzene. The filtrate was brought to

dryness in vacuo, and the residue was recrystallized from

benzene/hexane (1:10). A yellow hygroscopic solid was ob-

tained, which was separated from the mother liquor, washed

with small portions of hexane, and dried (the analytical data

are for the trishydrate of the product): yield 197 mg (67%);

77 mg (92%); mp 132 °C dec. H NMR (CD₂Cl₂, 400 MHz): δ

7.57, 7.39 (both m, 10 H, C₆H₅), 5.79, 5.08 [both d, J (H,H) )

6.2 Hz, 2 H each, CH₃C₆H₄CH(CH₃)₂], 2.89 [sept, J (H,H) )

7.0 Hz, 1 H, CH₃C₆H₄CH(CH₃)₂], 1.98 [s, 3 H, CH₃C₆H₄CH-

(CH₃)₂], 1.25 [d, J (H,H) ) 7.0 Hz, 6 H, CH₃C₆H₄CH(CH₃)₂].

¹³C NMR (CD₂Cl₂, 100.6 MHz): δ 300.7 (s, OsdC), 163.0 (s,

ipso-C of C₆H₅), 132.0 (s, para-C of C₆H₅), 130.0, 127.3 (both

s, ortho- and meta-C of C₆H₅), 119.9, 102.8 [both s, ipso- and

para-C of CH₃C₆H₄CH(CH₃)₂], 90.9, 80.7 [both s, ortho- and

meta-C of CH₃C₆H₄CH(CH₃)₂], 31.1 [s, CH₃C₆H₄CH(CH₃)₂],

22.2 [s, CH₃C₆H₄CH(CH₃)₂], 17.3 [s, CH₃C₆H₄CH(CH₃)₂]. Anal.

Calcd for C₂₃H₂₄Cl₂Os (561.6): C, 49.19; H, 4.31. Found: C,

48.87; H, 4.28.

P r ep a r a tion of [(η⁶-cym )OsCl₂{dC(p-C₆H₄Me)₂}] (23).

This compound was prepared as described for 22, from 13 (93

mg, 0.12 mmol) and Me₃SiCl (51 µL, 0.40 mmol). Olive-green

solid: yield 54 mg (76%); mp 144 °C dec. ¹H NMR (CD₂Cl₂,

400 MHz): δ 7.32, 7.18 [both d, J (H,H) ) 8.2 Hz, 4 H each,

C₆H₄CH₃], 5.77, 5.03 [both d, J (H,H) ) 6.2 Hz, 2 H each,

CH₃C₆H₄CH(CH₃)₂], 2.90 [sept, J (H,H) ) 7.0 Hz, 1 H,

CH₃C₆H₄CH(CH₃)₂], 2.37 [s, 3 H, CH₃C₆H₄CH(CH₃)₂], 1.93 (s,

6 H, C₆H₄CH₃), 1.25 [d, J (H,H) ) 7.0 Hz, 6 H, CH₃C₆H₄CH-

(CH₃)₂]. ¹³C NMR (CD₂Cl₂, 100.6 MHz): δ 299.3 (s, OsdC),

159.9 (s, ipso-C of C₆H₄CH₃), 143.4 (s, para-C of C₆H₄CH₃),

131.0, 127.9 (both s, ortho- and meta-C of C₆H₄CH₃), 118.7,

101.2 [both s, ipso- and para-C of CH₃C₆H₄CH(CH₃)₂], 90.0,

79.0 [both s, ortho- and meta-C of CH₃C₆H₄CH(CH₃)₂], 30.9

[s, CH₃C₆H₄CH(CH₃)₂], 22.1, 21.6 [boths s, C₆H₄CH₃and

CH₃C₆H₄CH(CH₃)₂], 17.0 [s, CH₃C₆H₄CH(CH₃)₂]. Anal. Calcd

for C₂₅H₂₈Cl₂Os (589.6): C, 50.93; H, 4.77. Found: C, 50.91;

H, 4.45.

mp 72 °C. IR (KBr): ν(OSO) 1209, 1204, ν(SdO) ) 1127 cm^-1

¹H NMR (CDCl₃, 400 MHz): δ 7.61, 7.06 [both d, J (H,H) )

7.3 Hz, 4 H each, C₆H₄CH₃], 6.59, 6.39 [both d, J (H,H) ) 4.7

Hz, 2 H each, CH₃C₆H₄CH(CH₃)₂], 2.71 [sept, J (H,H) ) 6.7

Hz, 1 H, CH₃C₆H₄CH(CH₃)₂], 2.31 (s, 6 H, C₆H₄CH₃), 2.14 [s,

3 H, CH₃C₆H₄CH(CH₃)₂], 1.22 [d, J (H,H) ) 6.7 Hz, 6 H,

CH₃C₆H₄CH(CH₃)₂]. ¹³C NMR (CDCl₃, 100.6 MHz): δ 141.5,

139.0 (both s, ipso- and para-C of C₆H₄CH₃), 128.9, 126.4 (both

s, ortho- and meta-C of C₆H₄CH₃), 90.0, 85.4 [both s, ipso- and

para-C of CH₃C₆H₄CH(CH₃)₂], 69.8, 68.4 [both s, ortho- and

meta-C of CH₃C₆H₄CH(CH₃)₂], 31.6 [s, CH₃C₆H₄CH(CH₃)₂],

22.2, 21.4 [both s, CH₃C₆H₄CH(CH₃)₂and C₆H₄CH₃], 18.8 [s,

CH₃C₆H₄CH(CH₃)₂]. Anal. Calcd for C₂₄H₂₈O₆OsS₂‚3H₂O: C,

39.99; H, 4.75; S, 8.90. Found: C, 40.12; H, 4.75; S, 8.72.

P r ep a r a t ion of [(η⁶-m es)Os{K¹-OS(O)₂C₆H ₄Me-p }(K²-

O₂S(O)C₆H₄Me-p)] (21). This compound was prepared as

described for 20, from 19 (198 mg, 0.26 mmol) and silver

tosylate (279 mg, 1.00 mmol). A pale yellow solid was isolated

which proved to be the monohydrate of the product: yield 295

mg (88%); mp 152 °C. IR (C₆H₆): ν(OSO) ) 1268, 1141, ν(Sd

O) 1102 cm^-1. ¹H NMR (C₆D₆, 200 MHz): δ 8.00, 6.76 [both d,

J (H,H) ) 7.8 Hz, 4 H each, C₆H₄CH₃], 6.74 (br s, 2 H, H₂O),

4.40 (s, 3 H, CH of mes), 2.03 (s, 6 H, C₆H₄CH₃), 1.92 (s, 9 H,

CH₃of mes). ¹³C NMR (CDCl₃, 50.3 MHz): δ 140.8, 139.4 (both

s, ipso- and para-C of C₆H₄CH₃), 128.4, 126.3 (both s, ortho-

and meta-C of C₆H₄CH₃), 91.0 (s, CCH₃of mes), 86.8 (s, CH of

mes), 21.1 (s, C₆H₄CH₃), 19.3 (s, CCH₃of mes). Anal. Calcd

for C₂₃H₂₆O₆OsS₂‚H₂O (670.8): C, 41.18; H, 4.21; S, 9.56.

Found: C, 40.99; H, 4.48; S, 9.15.

P r ep a r a tion of [(η⁶-cym )OsBr ₂(dCP h ₂)] (24). This com-

pound was prepared as described for 22, either from 12 (72

mg, 0.10 mmol) and Me₃SiBr (53 µL, 0.40 mmol) or from 12

(72 mg, 0.10 mmol) and a 0.7 M solution of HBr in benzene

(0.36 mL, 0.25 mmol). Brown solid: yield 56 mg (86%) (route

Rea ction of Com p ou n d 21 w ith P h CHN₂. A solution of

21 (67 mg, 0.10 mmol) in 2 mL of benzene was treated

dropwise with a 1.25 M solution of PhCHN₂in hexane (80 µL,

0.10 mmol) and stirred for 5 min at room temperature. An

evolution of gas (N₂) occurred. The solvent was evaporated in

vacuo, the oily residue was dissolved in CH₂Cl₂, and the

solution was chromatographed on Al₂O₃(basic, activity grade

III). With hexane a colorless fraction was eluted, which was

brought to dryness in vacuo. The white residue was identified

a) and 48 mg (74%) (route b); mp 132 °C dec. H NMR (C₆D₆,

400 MHz): δ 7.46, 7.05 (both m, 10 H, C₆H₅), 5.44, 4.45 [both

d, J (H,H) ) 5.6 Hz, 2 H each, CH₃C₆H₄CH(CH₃)₂], 2.98 [sept,

J (H,H) ) 6.8 Hz, 1 H, CH₃C₆H₄CH(CH₃)₂], 1.36 [s, 3 H,

CH₃C₆H₄CH(CH₃)₂], 1.02 [d, J (H,H) ) 6.8 Hz, 6 H, CH₃C₆H₄-

CH(CH₃)₂]. ¹³C NMR (C₆D₆, 100.6 MHz): δ 299.9 (s, OsdC),

165.4 (s, ipso-C of C₆H₅), 131.3 (s, para-C of C₆H₅), 129.4, 126.7

(both s, ortho- and meta-C of C₆H₅), 120.2, 102.1 (both s, ipso-

and para-C of C₆H₄), 91.4, 79.7 (both s, ortho- and meta-C of

C₆H₄), 30.1 [s, CH(CH₃)₂], 22.4 [s, CH(CH₃)₂], 17.0 (s, CH₃C₆H₄).

by GC/MS and H NMR data as a 1:1 mixture of cis- and trans-

stilbene.²⁹The same result was obtained by using 20 as the

starting material.

Rea ction of Com p ou n d 21 w ith P h ₂CN₂. A solution of

21 (67 mg, 0.10 mmol) in 3 mL of benzene was treated

dropwise with a solution of Ph₂CN₂(19 mg, 0.10 mmol) in 2

mL of benzene. While the reaction mixture was stirred for 5

min at room temperature, an evolution of gas (N₂) occurred.

The solvent was evaporated in vacuo and the remaining

residue identified by ¹H NMR spectroscopy and GC/MS as a

mixture of 21 and Ph₂CdCPh₂.

P r ep a r a tion of [(η⁶-cym )OsCl₂(dCP h ₂)] (22). (a) A solu-

tion of 12 (88 mg, 0.12 mmol) in 15 mL of CH₂Cl₂was treated

at -78 °C with a solution of Me₃SiCl (47 µL, 0.37 mmol) in 5

Anal. Calcd for

C₂₃H₂₄Br₂Os (650.5): C, 42.47; H, 3.72.

Found: C, 42.15; H, 3.35.

P r ep a r a tion of [(η⁶-cym )OsBr ₂{dC(p-C₆H₄Me)₂}] (25).

This compound was prepared as described for 22, from 13 (62

mg, 0.08 mmol) and Me₃SiBr (53 µL, 0.40 mmol). Brown

solid: yield 39 mg (72%), mp 147 °C dec. ¹H NMR (CD₂Cl₂,

400 MHz): δ 7.35, 7.20 [both d, J (H,H) ) 8.2 Hz, 4 H each,

C₆H₄CH₃], 5.95, 5.17 [both d, J (H,H) ) 6.2 Hz, 2 H each,

CH₃C₆H₄CH(CH₃)₂], 3.05 [sept, J (H,H) ) 7.0 Hz, 1 H,

CH₃C₆H₄CH(CH₃)₂], 2.39 (s, 6 H, C₆H₄CH₃), 1.95 [s, 3 H,

CH₃C₆H₄CH(CH₃)₂], 1.29 [d, J (H,H) ) 7.0 Hz, 6 H, CH₃C₆H₄-

CH(CH₃)₂]. ¹³C NMR (CD₂Cl₂, 100.6 MHz): δ 299.4 (s, Osd

(29) Hesse, M.; Meier, H.; Zeeh, B. Spektroskopische Methoden in

der Organischen Chemie, 4th ed.; Thieme: Stuttgart, 1991.

Areneosmium(II) Complexes

Organometallics, Vol. 22, No. 4, 2003 755

C), 161.9 (s, ipso-C of C₆H₄CH₃), 143.5 (s, para-C of C₆H₄CH₃),

130.9, 128.0 (both s, ortho- and meta-C of C₆H₄CH₃), 119.5,

102.4 [both s, ipso- and para-C of CH₃C₆H₄CH(CH₃)₂], 90.5,

78.8 [both s, ortho- and meta-C of CH₃C₆H₄CH(CH₃)₂], 31.3

[s, CH₃C₆H₄CH(CH₃)₂], 22.5, 21.8 [both s, C₆H₄CH₃and

CH₃C₆H₄CH(CH₃)₂], 17.4 [s, CH₃C₆H₄CH(CH₃)₂]. Anal. Calcd

for C₂₅H₂₈Br₂Os (678.5): C, 44.25; H, 4.16. Found: C, 44.33;

H, 4.00.

P r ep a r a tion of [(η⁶-m es)OsCl₂{dC(p-C₆H₄OMe)₂}] (30).

This compound was prepared as described for 22, from 17 (92

mg, 0.12 mmol) and Me₃SiCl (48 µL, 0.36 mmol). Red-brown

solid: yield 60 mg (82%); mp 137 °C dec. H NMR (C₆D₆, 400

MHz): δ 7.59, 6.66 [both d, J (H,H) ) 8.8 Hz, 4 H each, C₆H₄-

OCH₃], 4.37 (s, 3 H, CH of mes), 3.27 (s, 6 H, OCH₃), 1.94 (s,

9 H, CH₃of mes). ¹³C NMR (C₆D₆, 100.6 MHz): δ 163.5 (s,

ipso-C of C₆H₄OCH₃), 156.4 (s, para-C of C₆H₄OCH₃), 132.4

(s, ortho-C of C₆H₄OCH₃), 112.6 (s, meta-C of C₆H₄OCH₃), 105.2

(s, CCH₃of mes), 80.2 (s, CH of mes), 54.8 (s, OCH₃), 18.9 (s,

CCH₃of mes), signal for OsdC carbon atom not exactly located.

Anal. Calcd for C₂₄H₂₆Cl₂O₂Os (607.6): C, 47.44; H, 4.31.

Found: C, 47.77; H, 4.04.

P r ep a r a tion of [(η⁶-m es)OsI₂(dCP h ₂)] (31). A solution

of 14 (105 mg, 0.15 mmol) in 5 mL of benzene was treated

with Me₃SiI (60 mg, 0.30 mmol) and stirred for 5 min at room

temperature. A change of color from dark green to red

occurred. The reaction mixture was filtered with Celite, and

the filtrate was brought to dryness in vacuo. The residue was

dissolved in 1 mL of CH₂Cl₂, and the solution was layered with

10 mL of hexane. Red crystals precipitated, which were

separated from the mother liquor, washed twice with 5 mL

portions of ether, and dried: yield 79 mg (72%); mp 98 °C dec.

¹H NMR (C₆D₆, 200 MHz): δ 7.38, 7.34, 6.97 (all m, 10 H,

C₆H₅), 4.48 (s, 3 H, CH of mes), 2.03 (s, 9 H, CH₃of mes). ¹³C

NMR (CD₂Cl₂, 50.3 MHz): δ 296.8 (s, OsdC), 169.6 (s, ipso-C

of C₆H₅), 131.0 (s, para-C of C₆H₅), 127.9, 127.1 (both s, ortho-

and meta-C of C₆H₅), 106.4 (s, CCH₃of mes), 85.9 (s, CH of

mes), 20.3 (s, CCH₃of mes). Anal. Calcd for C₂₂H₂₂I₂Os

(730.4): C, 36.18; H, 3.04. Found: C, 35.83; H, 2.94.

P r ep a r a tion of [(η⁶-cym )OsI₂(dCP h ₂)] (26). A solution

of 10 (95 mg, 0.13 mmol) in 40 mL of CH₂Cl₂was treated with

NH₄I (188 mg, 1.30 mmol) and stirred for 8 h at room

temperature. The reaction mixture was filtered with Celite,

and the filtrate was concentrated to ca. 1 mL in vacuo. After

the solution was layered with 10 mL of hexane, a red-brown

solid precipitated, which was separated from the mother

liquor, washed twice with 5 mL portions of hexane, and

dried: yield 66 mg (68%); mp 132 °C dec. ¹H NMR (CD₂Cl₂,

400 MHz): δ 7.55, 7.31 (both m, 10 H, C₆H₅), 6.11, 5.41 [both

d, J (H,H) ) 5.8 Hz, 2 H each, CH₃C₆H₄CH(CH₃)₂], 3.12 [sept,

J (H,H) ) 6.9 Hz, 1 H, CH₃C₆H₄CH(CH₃)₂], 2.00 [s, 3 H,

CH₃C₆H₄CH(CH₃)₂], 1.24 [d, J (H,H) ) 6.9 Hz, 6 H, CH₃C₆H₄-

CH(CH₃)₂]. ¹³C NMR (CD₂Cl₂, 100.6 MHz): δ 297.3 (s, Osd

C), 168.5 (s, ipso-C of C₆H₅), 131.2 (s, para-C of C₆H₅), 128.4,

127.2 (both s, ortho- and meta-C of C₆H₅), 121.5, 106.5 (both

s, ipso- and para-C of C₆H₄), 90.9, 82.0 [both s, ortho- and

meta-C of C₆H₄), 31.9 [s, CH(CH₃)₂], 22.7 [s, CH(CH₃)₂], 18.0

(s, CH₃C₆H₄). Anal. Calcd for C₂₃H₂₄I₂Os (744.5): C, 37.11; H,

3.25. Found: C, 36.76; H, 3.10.

P r ep a r a t ion of [(η⁶-cym )OsI₂{dC(p -C₆H ₄Me)₂}] (27).

This compound was prepared as described for 26, from 13 (60

mg, 0.08 mmol) and NH₄I (116 mg, 0.80 mmol). Red-brown

solid: yield 56 mg (91%), mp 134 °C dec. ¹H NMR (CD₂Cl₂,

400 MHz): δ 7.23, 7.10 [both d, J (H,H) ) 7.9 Hz, 4 H each,

C₆H₄CH₃], 6.09, 5.34 [both d, J (H,H) ) 6.2 Hz, 2 H each,

CH₃C₆H₄CH(CH₃)₂], 3.14 [sept, J (H,H) ) 7.0 Hz, 1 H,

CH₃C₆H₄CH(CH₃)₂], 2.32 (s, 6 H, C₆H₄CH₃), 1.94 [s, 3 H,

CH₃C₆H₄CH(CH₃)₂], 1.24 [d, J (H,H) ) 7.0 Hz, 6 H, CH₃C₆H₄-

CH(CH₃)₂]. ¹³C NMR (CD₂Cl₂, 100.6 MHz): δ 297.3 (s, Osd

C), 165.4 (s, ipso-C of C₆H₄CH₃), 142.8 (s, para-C of C₆H₄CH₃),

130.0, 127.8 (both s, ortho- and meta-C of C₆H₄CH₃), 120.2,

104.8 [both s, ipso- and para-C of CH₃C₆H₄CH(CH₃)₂], 90.2,

80.4 [both s, ortho- and meta-C of CH₃C₆H₄CH(CH₃)₂], 31.9

[s, CH₃C₆H₄CH(CH₃)₂], 22.8, 21.8 [both s, C₆H₄CH₃and

CH₃C₆H₄CH(CH₃)₂], 17.8 [s, CH₃C₆H₄CH(CH₃)₂]. Anal. Calcd

for C₂₅H₂₈I₂Os (772.5): C, 38.87; H, 3.65. Found: C, 38.51; H,

3.17.

P r ep a r a tion of [(η⁶-m es)OsBr ₂(dCP h ₂)] (32). A solution

of 14 (100 mg, 0.14 mmol) in 5 mL of benzene was treated

with a 0.7 M solution of HBr in benzene (0.31 mL, 0.40 mmol)

and stirred for 15 min at room temperature. The solvent was

evaporated in vacuo, and the oily residue was dissolved in 0.5

mL of CH₂Cl₂. Addition of 10 mL of hexane led to the

precipitation of a brown solid, which was separated from the

mother liquor, washed twice with 3 mL portions of hexane,

and dried: yield 62 mg (70%); mp 138 °C dec. H NMR (C₆D₆,

200 MHz): δ 7.56, 7.39, 7.04 (all m, 10 H, C₆H₅), 4.31 (s, 3 H,

CH of mes), 1.92 (s, 9 H, CH₃of mes). Anal. Calcd for C₂₂H₂₂

Br₂Os (636.4): C, 41.52; H, 3.48. Found: C, 41.96; H, 3.35.

P r ep a r a tion of [(η⁶-m es)OsCl(K²-a ca c)] (33). (a) A solu-

tion of 28 (55 mg, 0.10 mmol) in 10 mL of benzene was treated

with Tl(acac) (30 mg, 0.10 mmol) and stirred for 2 h at room

temperature. After the reaction mixture was concentrated in

vacuo to ca. 0.5 mL, it was chromatographed on Al₂O₃(basic,

activity grade III). With benzene a yellow fraction was eluted,

which was concentrated in vacuo to ca. 0.5 mL. Addition of

hexane (20 mL) led to the precipitation of yellow crystals,

which were separated from the mother liquor, washed twice

with 5 mL portions of hexane, and dried: yield 28 mg (64%).

(b) A suspension of 19 (53 mg, 0.07 mmol) in 20 mL of benzene

was treated with both acetylacetone (72 µL, 0.70 mmol) and

NEt₃(50 µL, 0.36 mmol) and stirred for 30 min at 80 °C. The

reaction mixture was filtered with Celite and the residue

washed twice with 5 mL portions of benzene. The combined

filtrates were brought to dryness in vacuo, the remaining

yellow solid was washed twice with 5 mL portions of hexane

and dried: yield 58 mg (93%); mp 156 °C. The product was

identified by comparison of the IR and ¹H NMR data with

those reported in the literature.^{16 13}C NMR (CDCl₃, 100.6

MHz): δ 186.3 (s, CCH₃of acac), 100.9 (s, CH of acac), 93.7 (s,

CCH₃of mes), 65.4 (s, CH of mes), 27.8 (s, CH₃of acac), 18.5

(s, CCH₃of mes).

P r ep a r a tion of [(η⁶-m es)OsCl₂(dCP h ₂)] (28). This com-

pound was prepared as described for 22, either from 14 (136

mg, 0.19 mmol) and Me₃SiCl (72 µL, 0.57 mmol) or from 14

(136 mg, 0.19 mmol) and a 1.3 M solution of HCl in benzene

(0.38 mL, 0.50 mmol). Olive-green solid: yield 82 mg (79%)

(route a) and 90 mg (87%) (route b); mp 126 °C dec. H NMR

(CD₂Cl₂, 400 MHz): δ 7.58, 7.38, 7.37 (all m, 10 H, C₆H₅), 4.97

(s, 3 H, CH of mes), 2.27 (s, 9 H, CH₃of mes). ¹³C NMR (CD₂-

Cl₂, 100.6 MHz): δ 299.2 (s, OsdC), 163.8 (s, ipso-C of C₆H₅),

131.9 (s, para-C of C₆H₅), 130.1, 127.6 (both s, ortho- and

meta-C of C₆H₅), 108.7 (s, CCH₃of mes), 82.6 (s, CH of mes),

18.2 (s, CCH₃of mes). Anal. Calcd for C₂₂H₂₂Cl₂Os (547.5): C,

48.26; H, 4.05. Found: C, 48.66; H, 4.17.

P r ep a r a tion of [(η⁶-m es)OsCl₂{dC(p-C₆H₄Me)₂}] (29).

This compound was prepared as described for 22, from 15 (88

mg, 0.12 mmol) and Me₃SiCl (70 µL, 0.55 mmol). Olive-green

solid: yield 60 mg (87%); mp 153 °C dec. ¹H NMR (CD₂Cl₂,

200 MHz): δ 7.38, 6.98 [both d, J (H,H) ) 8.0 Hz, 4 H each,

C₆H₄CH₃], 4.78 (s, 3 H, CH of mes), 2.09 (s, 6 H, C₆H₄CH₃),

2.00 (s, 9 H, CH₃of mes). ¹³C NMR (CD₂Cl₂, 50.3 MHz): δ

302.8 (s, OsdC), 158.1 (s, ipso-C of C₆H₄CH₃), 143.9 (s, para-C

of C₆H₄CH₃), 131.0, 128.3 (both s, ortho- and meta-C of C₆H₄-

CH₃), 106.6 (s, CCH₃of mes), 80.3 (s, CH of mes), 21.7 (s,

C₆H₄CH₃), 18.3 (s, CCH₃of mes). Anal. Calcd for C₂₄H₂₆Cl₂Os

(575.6): C, 50.08; H, 4.55. Found: C, 50.37; H, 4.25.

P r ep a r a tion of [(η⁶-m es)OsCl(K²-a ca c-[F ₃])] (34). This

compound was prepared as described for 33, either from 28

(82 mg, 0.15 mmol) and Na(acac-[F₃]) (26 mg, 0.15 mmol) in

10 mL of benzene or from 19 (76 mg, 0.10 mmol) and Na(acac-

[F₃]) (53 mg, 0.30 mmol) in 10 mL of MeOH. Red-brown solid:

yield 28 mg (38%) (route a) and 93 mg (93%) (route b); mp

756 Organometallics, Vol. 22, No. 4, 2003

Weberndo¨rfer et al.

218 °C dec. IR (KBr): ν(CO) 1616 cm^-1. H NMR (CDCl₃, 200

CF₃CO₂H (15 mg, 0.13 mmol) and stirred for 30 min at room

temperature. After the solvent was evaporated in vacuo, the

residue was extracted with 10 mL of hexane. The extract was

concentrated to ca. 1 mL, and the solution was chromato-

graphed on Al₂O₃(basic, activity grade III). With benzene a

colorless fraction was eluted, which after removal of the solvent

gave a white solid, identified by comparison of the NMR

spectroscopic data with those of an authentic sample³⁰as

Ph₂CdCHMe: yield 21 mg (84%). The ¹H and ¹⁹F NMR

spectroscopic data of the solid residue (from which the olefin

was extracted) indicate the presence of a mixture of products

containing [(η⁶-mes)OsBr(κ²-O₂CCF₃)] (37) as the major com-

ponent. Data for 37: ¹H NMR (C₆D₆, 200 MHz): δ 4.70 (s, 3

H, CH of mes), 1.30 (s, 9 H, CH₃of mes). ¹⁹F NMR (C₆D₆, 188.3

MHz): δ -74.9 (s).

MHz): δ 5.67 (s, 3 H, CH of mes), 5.51 (s, 1 H, CH of acac-

[F₃]), 2.14 (s, 9 H, CH₃of mes), 2.06 (s, 3 H, CH₃of acac-[F₃]).

¹³C NMR (CDCl₃, 50.3 MHz): δ 192.9 (s, CCH₃of acac-[F₃]),

166.2 (q, J (F,C) ) 34.2 Hz, CCF₃of acac-[F₃]), 117.6 [q, J (F,C)

) 282.9 Hz, CF₃], 96.3 (br s, CH of acac-[F₃]), 93.8 (s, CCH₃of

mes), 65.1 (s, CH of mes), 28.6 (s, CCH₃of acac-[F₃]), 17.9 (s,

CH₃of mes). ¹⁹F NMR (CDCl₃, 188.3 MHz): δ -74.9 (s). Anal.

Calcd for C₁₄H₁₆ClF₃O₂Os (499.0): C, 33.70; H, 3.23. Found:

C, 33.44; H, 2.98.

P r ep a r a tion of [(η⁶-m es)OsCl(K²-a ca c-[F ₆])] (35). This

compound was prepared as described for 33, either from 28

(93 mg, 0.17 mmol) and Na(acac-[F₆]) (39 mg, 0.17 mmol) in

10 mL of benzene or from 19 (61 mg, 0.08 mmol) and Na(acac-

[F₆]) (55 mg, 0.24 mmol) in 10 mL of MeOH. Red solid: yield

40 mg (43%) (route a) and 80 mg (90%) (route b); mp 229 °C

P r ep a r a tion of [(η⁶-m es)Os{K²(C,O)-P h ₂CCHdCHOEt}-

{K¹-OC(O)CF ₃}] (38). A solution of 14 (115 mg, 0.16 mmol)

in 5 mL of ethyl(vinyl)ether was treated with Na₂CO₃(200 mg,

1.89 mmol) and stirred for 3.5 h at room temperature. A slow

change of color from dark green to brown occurred. After the

solvent was evaporated in vacuo, the residue was extracted

with 20 mL of benzene/hexane (1:1), and then the extract was

brought to dryness in vacuo. A pale brown solid was obtained,

which was washed twice with 5 mL portions of hexane (0 °C)

and dried: yield 84 mg (78%); mp 104 °C dec. IR (KBr):

dec. IR (KBr): ν(CO) 1623 cm^-1. H NMR (CDCl₃, 200 MHz):

δ 6.02 (s, 1 H, CH of acac-[F₆]), 5.63 (s, 3 H, CH of mes), 2.19

(s, 9 H, CH₃of mes). ¹³C NMR (CDCl₃, 50.3 MHz): δ 172.7 [q,

J (F,C) ) 36.0 Hz, CCF₃], 116.9 [q, J (F,C) ) 283.8 Hz, CF₃],

95.0 (s, CCH₃of mes), 92.4 (br s, CH of acac-[F₆]), 65.9 (s, CH

of mes), 18.0 (s, CCH₃of mes). ¹⁹F NMR (CDCl₃, 188.3 MHz):

δ -75.6 (s). Anal. Calcd for C₁₄H₁₃ClF₆O₂Os (552.9): C, 30.41;

H, 2.37. Found: C, 30.25; H, 2.25.

Rea ction of Com p ou n d 28 w ith C₆H₅MgBr . A solution

of 28 (71 mg, 0.13 mmol) in 5 mL of THF was treated at -78

°C with a 1.62 M solution of C₆H₅MgBr in THF (0.34 mL, 0.54

mmol). After the reaction mixture was stirred for 15 min, it

was slowly warmed to room temperature, and then the solvent

was evaporated in vacuo. The residue was recrystallized from

CH₂Cl₂/hexane to give 32 as the sole product: yield 49 mg

(59%). A similar result was obtained by using compound 14

as the starting material; yield 64%.

ν(OCO) 1691, ν(CdC) 1596 cm^-1. H NMR (C₆D₆, 400 MHz):

δ 7.39, 7.13, 7.00, 6.88 (all m, 10 H, C₆H₅), 5.88 [d, J (H,H) )

7.4 Hz, 1 H, OCHdCHR], 5.28 [d, J (H,H) ) 7.4 Hz, 1 H, OCHd

CHR], 4.84 (s, 3 H, CH of mes), 3.86, 3.47 [both dq, ²J (H,H) )

10.0, ³J (H,H) ) 7.2 Hz, 1 H each, OCH₂CH₃], 1.51 (s, 9 H,

CH₃of mes), 1.12 [t, J (H,H) ) 7.2 Hz, 3 H, OCH₂CH₃]. ¹³C

NMR (C₆D₆, 50.3 MHz): δ 163.0 [q, J (C,F) ) 36.0 Hz, CF₃CO₂],

148.1 (s, OCHdCHR), 142.8 (s, OCHdCHR), 132.6, 128.3,

128.2, 127.4, 126.1, 125.0, 108.3 (all s, C₆H₅), 114.6 [q, J (C,F)

) 290.9 Hz, CF₃CO₂], 93.1 (s, CCH₃of mes), 81.6 (s, CH of

mes), 68.2 (s, OCH₂CH₃), 61.7 (s, OsCPh₂), 17.2 (s, CCH₃of

mes), 15.1 (s, OCH₂CH₃). ¹⁹F NMR (CD₂Cl₂, 188.3 MHz): δ

-74.7 (s). Anal. Calcd for C₂₈H₂₉F₃O₃Os (660.7): C, 50.90; H,

4.42. Found: C, 50.62; H, 4.08.

Rea ction of Com p ou n d 28 w ith CH₃MgI. A solution of

28 (66 mg, 0.12 mmol) in 5 mL of THF was treated at -78 °C

with a 1.88 M solution of CH₃MgI in THF (0.26 mL, 0.50

mmol). After the reaction mixture was stirred for 15 min, it

was slowly warmed to room temperature. The solvent was

evaporated in vacuo, and the residue was extracted with 5 mL

of toluene. The extract was concentrated to ca. 0.5 mL in vacuo,

and the solution was layered with 10 mL of pentane. A red

Rea ction of Com p ou n d 38 w ith CF ₃CO₂H. A solution of

38 (92 mg, 0.14 mmol) in 5 mL of benzene was treated with

CF₃CO₂H (16 mg, 0.14 mmol) and stirred for 30 min at room

temperature. After the solvent was evaporated in vacuo, the

residue was extracted with 10 mL of hexane. The extract was

concentrated to ca. 1 mL, and the solution was chromato-

graphed on Al₂O₃(basic, activity grade III). With benzene a

colorless fraction was eluted, which after removal of the solvent

gave a white solid, identified by comparison of the NMR

spectroscopic data with those of an authentic sample³¹as

solid precipitated, which was shown by H NMR spectroscopy

to be 32: yield 45 mg (51%). A similar result was obtained by

using compound 14 as the starting material; yield 66%.

P r ep a r a tion of [(η⁶-m es)OsBr (η³-CH₂CHCP h ₂)] (36). A

solution of 11 (84 mg, 0.12 mmol) in 5 mL of THF was treated

at -78 °C with a 1.88 M solution of CH₃MgI in THF (0.50 mL,

0.25 mmol). While the reaction mixture was stirred for 30 min,

it was slowly warmed to room temperature and then filtered

with Celite. The filtrate was brought to dryness in vacuo, and

the residue was dissolved in 2 mL of benzene. The solution

was chromatographed on Al₂O₃(basic, activity grade III). With

benzene/hexane (1:1) a yellow fraction was eluted, from which

the solvent was evaporated in vacuo. The oily residue was

dissolved in 1 mL of hexane and the solution stored at -78

°C. A pale yellow solid precipitated, which was separated from

the mother liquor, washed with small quantities of pentane

(-20 °C), and dried: yield 43 mg (61%); mp 94 °C dec. ¹H NMR

(C₆D₆, 400 MHz): δ 7.69, 7.34, 7.11, 7.01 (all m, 10 H, C₆H₅),

5.00 [dd, J (H¹,H³) ) 8.8, J (H¹,H²) ) 6.7 Hz, 1 H, CH₂CH¹CPh₂],

4.51 (s, 3 H, CH of mes), 2.75 [dd, J (H¹,H²) ) 6.7, J (H²,H³) )

1.5 Hz, 1 H, H²of CH₂cis to H¹], 2.42 [dd, J (H¹,H³) ) 8.8,

J (H²,H³) ) 1.5 Hz, 1 H, H³of CH₂trans to H¹], 1.59 (s, 9 H,

CH₃of mes). ¹³C NMR (C₆D₆, 100.6 MHz): δ 160.1 (s, ipso-C

of C₆H₅), 138.8, 136.4, 129.8, 129.7, 129.1, 128.7, 128.3 (all s,

C₆H₅), 93.2 (s, CCH₃of mes), 76.7 (s, CH of mes), 74.5(s,

CH₂CHCPh₂), 66.1 (s, CC₆H₅), 33.8 (s, CH₂CHCPh₂), 18.4 (s,

CCH₃of mes). Anal. Calcd for C₂₄H₂₅BrOs (583.6): C, 49.40;

H, 4.32. Found: C, 49.82; H, 4.58.

Ph₂CdCHCH₂OEt: yield 24 mg (72%). The H and ¹⁹F NMR

spectroscopic data of the solid residue (from which the olefin

was extracted) indicate the presence of a mixture of products

containing 4 as the major component.

P r ep a r a tion of [(η⁶-m es)Os(C₆H₅)₂(CO)] (39). A solution

of 14 (142 mg, 0.20 mmol) in 3 mL of acetone was treated with

water (100 µL, 5.45 mmol) and stirred for 5 h at room

temperature. A slow change of color from green to yellow

occurred. After the solvent was evaporated in vacuo, the

residue was dissolved in 2 mL of hexane/CH₂Cl₂(1:1) and the

solution chromatographed on Al₂O₃(basic, activity grade III).

With hexane/CH₂Cl₂(1:1) a yellow fraction was eluted, which

was brought to dryness in vacuo. The remaining yellow solid

was washed twice with 5 mL portions of hexane and dried:

yield 89 mg (89%). It was identified by comparison of the IR

and ¹H NMR spectroscopic data with those of an authentic

sample as 39.¹⁹Formerly unpublished data for 39: ¹³C NMR

(30) Kitamura, T.; Kobayashi, S.; Taniguchi, H. J . Am. Chem. Soc.

1986, 108, 2641-2645.

Rea ction of Com p ou n d 36 w ith CF ₃CO₂H. A solution of

36 (76 mg, 0.13 mmol) in 5 mL of benzene was treated with

(31) Eisch, J . J .; Merkley, J . H. J . Am. Chem. Soc. 1979, 101, 1148-

1155.

Areneosmium(II) Complexes

Organometallics, Vol. 22, No. 4, 2003 757

Ta ble 1. Cr ysta llogr a p h ic Da ta for 2, 28, a n d 35

formula

₂₂H₂₄Cl₂F₆O₄Os₂

C₂₂H₂₂Cl₂Os + 1/2CH₂Cl₂

589.96

C₁₄H₁₃ClF₆O₂Os

552.89

917.73

cryst size,mm

cryst syst

0.24 × 0.18 × 0.16

0.3 × 0.2 × 0.2

0.22 × 0.20 × 0.18

monoclinic

triclinic

space group

cell dimens determn

a, Å

C2/c (No. 15)

25 rflns, 49.5° < θ < 50.0°

10.066(2)

C2 (No. 5)

25 rflns, 10° < θ < 15°

18.282(1)

P1h (No. 2)

5000 rflns, 2.57° < θ < 25.03°

8.719(8)

b, Å

12.935(2)

7.710(1)

8.774(5)

c, Å

20.197(2)

15.709(1)

12.132(8)

R, deg

â, deg

γ, deg

V, Å³

94.54(1)

2621.5(5)

2.325

89.12(8)

76.50(9)

65.23(9)

816(1)

105.05(2)

2138.3(3)

_calcd, g cm^-1

1.833

2.251

temp, K

296(2)

20.585

ω-2/θ

59.94

273(2)

6.343

ω/θ

52.02

173(2)

8.046

50.06

6253

µ, mm^-1

scan method

2θ(max), deg

total no. of rflns

2186

7562

no. of unique rflns

no. of obsd rflns

1951 (R(int) ) 0.08528)

1860 (I > 2σ(I))

1951

3808 (R(int) ) 0.0311)

3479 (I > 2σ(I))

3808

2716 (R(int) ) 0.0256)

2444 (I > 2σ(I))

2716

no. of rflns used for refinement

no. of params refined

final R indices (I > 2σ(I))

R indices (all data)

resid electron density, e Å^-3

165

243

224

R₁) 0.0369, wR₂) 0.0567^a

R₁) 0.0381, wR₂) 0.0569^a

1.41/-1.30

R₁) 0.0206, wR₂) 0.0443^a

R₁) 0.0263, wR₂) 0.0481^a

0.696/-0.947

R₁) 0.0186, wR₂) 0.0418^a

R₁) 0.0225, wR₂) 0.0427^a

0.860/-0.948

w^-1) [σ²F_o+ (0.00022P)²+ 0.0000P] (2), w^-1) [σ²F_o+ (0.0321P)²+ 0.0321P] (28), w^-1) [σ²F_o+ (0.0256P)²+ 0.0000P] (35),

where P ) (F_o+ 2F_c²)/3.

(C₆D₆, 100.6 MHz): δ 185.1 (s, CO), 142.9 (s, ipso-C of C₆H₅),

128.3, 127.7, 122.7 (all s, C₆H₅), 112.4 (s, CCH₃of mes), 86.9

(s, CH of mes), 18.7 (s, CCH₃of mes).

was eluted, which was brought to dryness in vacuo. The yellow

solid (L ) PiPr₃, AsiPr₃) or light brown solid (L ) SbiPr₃) was

washed twice with 5 mL portions of hexane and dried: yield

46% for 42, 49% for 43, and 54% for 44. The products were

identified by comparing the NMR spectroscopic data with those

of authentic samples.^9,23

P r ep a r a tion of [(η⁶-m es)Os(C₆H₅)₂(C¹⁸O)] (39a ). This

compound was prepared as described for 39, from 14 (171 mg,

0.24 mmol) and H₂¹⁸O (100 µL, 4.75 mmol) in 5 mL of acetone.

After the solvent was removed, the residue was characterized

spectroscopically. The IR spectrum (in CH₂Cl₂) displayed two

strong absorptions at 1946 and 1904 cm^-1in the approximate

ratio of 2:1 assigned to 39 and 39a , respectively.

P r ep a r a tion of [(η⁶-m es)OsCl(dCP h ₂)(P P h ₃)]P F ₆(45).

A solution of 28 (88 mg, 0.12 mmol) and PPh₃(66 mg, 0.25

mmol) in 15 mL of THF was treated at -78 °C with a solution

of AgPF₆(61 mg, 0.24 mmol) in 5 mL of THF. After the reaction

mixture was warmed to room temperature, it was filtered to

remove the precipitate of AgCl. The filtrate was brought to

dryness in vacuo, and the greenish oil was dissolved in 1.0

mL of CH₂Cl₂. The solution was filtered with Celite and then

concentrated in vacuo to ca. 2 mL. After the solution was

layered with 15 mL of hexane, a dark green solid precipitated.

The formation of the product was facilitated by irradiation of

the mixture in an ultrasonic bath. The green solid was

separated from the mother liquor, washed twice with 5 mL

portions of hexane, and dried: yield 212 mg (96%); mp 136 °C

dec; Λ 67 cm²Ω^-1mol^-1. MS (FAB): m/z 775 (M⁺+ 1). ¹H

NMR (CD₂Cl₂, 300 MHz): δ 7.52-7.41 (m, 15 H, C-C₆H₅,

P-C₆H₅), 7.09-7.03 (m, 10 H, C-C₆H₅, P-C₆H₅), 5.44 (s, 3

H, CH of mes), 2.07 (s, 9 H, CH₃of mes). ¹³C NMR (CD₂Cl₂,

75.5 MHz): δ 292.3 [d, J (P,C) ) 11.3 Hz, OsdC], 165.3 (s,

ipso-C of C-C₆H₅), 134.2 [d, J (P,C) ) 37.0 Hz, ipso-C of

P-C₆H₅], 132.7 (s, para-C of C-C₆H₅), 131.4 [d, J (P,C) ) 15.3

Hz, ortho-C of P-C₆H₅], 130.2, 127.4 (both s, ortho- and meta-C

of C-C₆H₅), 129.6 (br s, para-C of P-C₆H₅), 128.8 [d, J (P,C)

) 10.6 Hz, meta-C of P-C₆H₅], 121.6 [d, J (P,C) ) 2.8 Hz, CCH₃

of mes], 87.3 [d, J (P,C) ) 3.2 Hz, CH of mes], 18.5 (s, CCH₃of

mes). ³¹P NMR (CD₂Cl₂, 81.0 MHz): δ 0.4 (s, PPh₃), -144.1

[sept, J (P,F) ) 712.6 Hz, PF₆^-]. Anal. Calcd for C₄₀H₃₇ClF₆-

OsP₂(919.3): C, 52.26; H, 4.06. Found: C, 52.19; H, 4.23.

P r ep a r a tion of [(η⁶-m es)OsCl{dC(p-C₆H₄Me)₂}(P P h ₃)]-

P F ₆(46). This compound was prepared as described for 45,

from 29 (63 mg, 0.11 mmol), PPh₃(31 mg, 0.12 mmol), and

AgPF₆(28 mg, 0.11 mmol). Green solid: yield 97 mg (93%),

P r ep a r a tion of [(η⁶-m es)Os(p-C₆H₄Me)₂(CO)] (40). This

compound was prepared as described for 39, from 15 (63 mg,

0.09 mmol) and water (50 µL, 2.77 mmol). Yellow solid: yield

29 mg (61%); mp 116 °C dec. IR (KBr): ν(CO) 1924 cm^-1. H

NMR (CDCl₃, 200 MHz): δ 7.40, 6.71 [both d, J (H,H) ) 8.0

Hz, 4 H each, C₆H₄], 5.22 (s, 3 H, CH of mes), 2.19 (s, 6 H,

C₆H₄CH₃), 2.04 (s, 9 H, CH₃of mes). ¹³C NMR (CDCl₃, 50.3

MHz): δ 184.8 (s, CO), 142.0 (s, ipso-C of C₆H₄), 134.3 (s,

para-C of C₆H₄), 130.8, 128.3 (both s, ortho- and meta-C of

C₆H₄), 112.7 (s, CCH₃of mes), 86.9 (s, CH of mes), 20.7 (s,

C₆H₄CH₃), 19.1 (s, CCH₃of mes). Anal. Calcd for C₂₄H₂₆OOs

(520.7): C, 55.36; H, 5.03. Found: C, 55.21; H, 4.92.

P r ep a r a t ion of [(η⁶-m es)Os(p -C₆H ₄OMe)₂(CO)] (41).

This compound was prepared as described for 39, from 17 (84

mg, 0.11 mmol) and water (50 µL, 2.77 mmol). Yellow solid:

yield 44 mg (72%); mp 121 °C dec. IR (KBr): ν(CO) 1942 cm^-1

¹H NMR (CDCl₃, 200 MHz): δ 7.33, 6.88 [both d, J (H,H) )

8.0 Hz, 4 H each, C₆H₄], 4.64 (s, 3 H, CH of mes), 3.83 (s, 6 H,

OCH₃), 2.13 (s, 9 H, CH₃of mes). ¹³C NMR (CDCl₃, 50.3

MHz): δ 179.1 (s, CO), 157.7 (s, para-C of C₆H₄), 139.8 (s,

ipso-C of C₆H₄), 131.1 (s, ortho-C of C₆H₄), 113.1 (s, meta-C of

C₆H₄), 97.4 (s, CCH₃of mes), 74.8 (s, CH of mes), 55.3 (s,

OCH₃), 19.8 (s, CCH₃of mes). Anal. Calcd for C₂₄H₂₆O₃Os

(552.7): C, 52.16; H, 4.74. Found: C, 52.07; H, 4.58.

Rea ction s of Com p ou n d 28 w ith P iP r ₃, AsiP r ₃, a n d

SbiP r ₃. A solution of 28 (49 mg, 0.09 mmol) in 10 mL of

benzene was treated with a 2-fold excess of PiPr₃, AsiPr₃, or

SbiPr₃and stirred for 3 h at 80 °C. The solvent was evaporated

in vacuo, the remaining residue was dissolved in 2 mL of CH₂-

Cl₂, and the solution was chromatographed on Al₂O₃(basic,

activity grade III). With CH₂Cl₂/hexane (5:1) a yellow fraction

mp 151 °C dec; Λ 71 cm²Ω^-1mol^{-1 1}H NMR (CD₂Cl₂, 200

MHz): δ 7.62-6.81 (m, 23 H, C₆H₅and C₆H₄), 5.38 (s, 3 H,

CH of mes), 2.23 (s, 6 H, C₆H₄CH₃), 2.04 (s, 9 H, CH₃of mes).

758 Organometallics, Vol. 22, No. 4, 2003

Weberndo¨rfer et al.

¹³C NMR (CD₂Cl₂, 50.3 MHz): δ 291.2 [d, J (P,C) ) 11.4 Hz,

OsdC], 162.2 (br s, ipso-C of C₆H₄), 144.4 (s, para-C of C₆H₄),

134.6 [d, J (P,C) ) 41.2 Hz, ipso-C of C₆H₅], 133.9 [d, J (P,C) )

15.3 Hz, ortho-C of C₆H₅], 131.3 (br s, para-C of C₆H₅), 131.0,

128.1 (both s, ortho- and meta-C of C₆H₄), 129.5 [d, J (P,C) )

8.3 Hz, meta-C of C₆H₅], 120.2 [d, J (P,C) ) 2.1 Hz, CCH₃of

mes], 86.1 [d, J (P,C) ) 3.8 Hz, CH of mes], 21.7 (s, C₆H₄CH₃),

18.4 (s, CCH₃of mes). ³¹P NMR (CD₂Cl₂, 81.0 MHz): δ 0.1 (s,

PPh₃), -143.8 [sept, J (P,F) ) 712.1 Hz, PF₆^-]. Anal. Calcd for

and anisotropic displacement parameters were refined by full

matrix least-squares against F_o(SHELXL-97).³³The asym-

metric unit of 28‚1/2CH₂Cl₂contains half a molecule of CH₂-

Cl₂, the carbon atom of which (C40) lies on a special position.

The second half of the CH₂Cl₂molecule was generated with

the symmetry operation -x+1, y, -z+1. The methyne hydro-

gen atom H3 of the acetylacetonato ligand of 35 was found in

a differential Fourier synthesis and refined isotropically. The

positions of all other hydrogen atoms were calculated according

to ideal geometry and refined using the riding method.

₄₂H₄₁ClF₆OsP₂(947.4): C, 53.25; H, 4.36. Found: C, 53.21;

H, 4.62.

X-r a y Str u ctu r a l Deter m in a tion of Com p ou n d s 2, 28‚

Ack n ow led gm en t . We thank the Deutsche For-

schungsgemeinschaft (Grant SFB 347) and the Alex-

ander-von-Humboldt-Stiftung (Max-Planck-Forschungs-

preis) for financial support. Moreover, we gratefully

acknowledge support by Mrs. R. Schedl and Mr. C. P.

Kneis (elemental analyses and DTA), Mrs. M.-L. Scha¨fer

and Dr. W. Buchner (NMR measurements), Dr. G.

Lange and Mr. F. Dadrich (mass spectra), and Mr. S.

Stellwag for practical assistance.

1/2CH₂Cl₂, a n d 35. Single crystals of these compounds were

grown by slow diffusion of pentane or hexane into a solution

of 2, 28‚1/2CH₂Cl₂, or 35 in CH₂Cl₂at room temperature. The

data were collected for 2 on a Rigaku AFC6R diffractometer,

for 28‚1/2CH₂Cl₂on a Enraf-Nonius CAD 4 diffractometer, and

for 35 on a Stoe IPDS diffractometer using monochromated

Mo KR radiation (λ ) 0.71073 Å). Crystal data collection

parameters are summarized in Table 1. The corresponding

data for 15 and 45 have already been reported.⁴Intensity data

were corrected by Lorentz and polarization effects, and empiri-

cal absorption corrections were applied. The structures were

solved by direct methods (SHELXS-97).³²Atomic coordinates

Su p p or tin g In for m a tion Ava ila ble: Tables of crystal

data and refinement parameters, bond lengths and angles, and

positional and thermal parameters for 2, 28‚1/2CH₂Cl₂, and

35. This material is available free of charge via the Internet

at http://pubs.acs.org.

(32) Sheldrick, G. M. Acta Crystallogr., Sect. A 1990, 46, 467-473.

(33) Sheldrick, G. M. SHELXL-97; University of Go¨ttingen: Go¨t-

tingen, Germany, 1997.

OM0207109

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