'AD-AO92 211 BOSTON COLL CHESTNUT HILL MASS DEPT OF CHEMISTRY F/S 7/2CARBON DIOXIDE ACTIVATIONI FORMATION OF TRANS- (PH3P) 2RH(CO) (--(TC(U)NOV s0 S F HOSSAIN. K M NICHOLAS, C L TEAS NOCOX4-78-C-0558

UNCLASSIFIED TR-2

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OFFICE OF A VAL RESEARCHAL :-;z ....

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Task No. NR 053-683/~TechnicalRep ;t'No. 2

0 )Carbon'Dioxide Activation;/Formation of trans-(Ph3P)zRh(CO)(OCO2H) in/the Reaction of CO2 with IRh(CO)(PPh3)3/CO-

by

S. FazleylHossainj Kenneth M.jNicholas ,

Carol L.jTeas Raymond E.j Davis

Prepared for Publication -

inFTiChemical Communications till

ABoston College

Departm~ent of Chemistry

Chestnut Hill, Massachusetts 02167

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4. TITLE (and Subtitle) S. TYPE OF PEPORT & PERIOD COVEREO

Carbon Dioxide Activation; Formation oftrans-(Ph 3P)2Rh(Co) (OCO2H) in the .PROMNOG EOTNUVEReaction of CO 2 with HRh(CO)(PPh3)3 /CO __________

7. AUTHOR(s) 8. CONTRACT OR GRANT NUMUEP.)

S.F. Hossain, K.M. Nicholas*, C.L. Teas,and R.E. Davis N 0001478-C0558

9. PERFORMING ORC-ANIZATiON NAME AND ADDRESS 10. PROGPAIM ELEuENT. PR.;JCT. TASK

Department of Chemistry 7 RA&WN(UI UbR

Boston College NR 053-683Chestnut Hill, MA 02167

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Office of Naval Research1 nDepartment of the Navy 1*) NUMBER OF PAGES

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unclassified15&. DECL ASSIFICATIOti!OW-AGRADING

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Prepared for publication in Chemical Communications.

1S. SUPPLEMENTARY NOTES

It. KEY WORDS (Continue on revere., side it neessary and idsntffI' by block number)

Activation of C02, hydrido rhodium complexes, bicarbonate complex,

reversible CO2 fixation.

20. AS ACT (Continue on reverse side It neessary and Identify by block number)

Teintermediate produced from the interaction ofHRh(CO)(PPh) with CO reacts with Cc~)to yield a novel bicarbonatecomplex, trans-(PPh3)2Rh(CO)(OCO2H) - whose structure has beenestablishW-YFray cry stallographically. The bicarbonate complex

4 undergoes reversible loss Of C02 . Results from the reaction ofDRh(CO) (PPh,) s/CO with C02 are consistent with a mechansim forformation of I involvinj rhodium-promoted C02 diaproportionation

D 9 JOA*7 1473 loo-71w of, I Nlov 65 is 08501 StE

Carbon Dioxide Activation; Formation of trans-(Ph3P)2Rh(CO)(OCO 2H) in

the Reaction of CO, with HRh(CO)(PPh ) /CO.

By S. Fazley Hossain, Kenneth M. Nicholas*, (Department of Chemistry,

Boston College, Chestnut Hill, Massachusetts, U.S.A. 0210,7)

Carol L. Teas, and Raymond E. Davis*(Department of Chemistry, University

of Texas, Austin, Texas, U.S.A. 78712)

Summary. The intermediate produced from the interaction of ERh(CO)-

(PPh3)3 with CO reacts with carbon dioxide to yield a novel bicarbonate

complex, trans-(PPh3)2Rh(CO)(OCO2H)(I), whose structure has been

established X-ray crystallographically; I undergoes reversible loss of

CO2.

The search for alternative fuels and chemical feedstocks has stimulated

considerable interest in the activation of carbon oxides by transition

metals. While there exists a long-standing and rich chemistry of

coordinated carbon monoxide, the coordination chemistry

1of carbon dioxide is largely unknown. We report herein a novel

bicarbonate complex, (Ph3P)2Rh(CO)(OCO 211)(1), produced via a previously

unrecognized pathway from the reaction of CO 2 with HRh(cn)(PPh 3)3 /Co.

When a yellow benzene solution of HRh(CO (PPh3)2 and Rh2(CO)4(I'Ph3)4

(formed by pretreatment of HRh(CO)(PPh3 )3 with CO 2) was stirred for

ca. 36 hr under an atmosphere of pure CO2 at 50C, the solution slowly2- - -

A.Vailaliity CodesAnaji and/or "

U1 t Special

-2-

turned red then yellow again with formation of a yellow precipitate of I

(70%. yield, eq. 1).

flRh(CO) 2(P" 3

+ CO2Co2HRh(CO)(PPh :01 Rh 2 (CO) 4('h) 0_ (1)

33 benzene 2_ 1

(yellow) (yellJow) (orvd 'yel~low)

Compound I had the composition Rh(PPh 3)2 C2 H04 9 produced CO and CO 2 (ca. 1:1)

upon pyrolysis, and exhibited the following spectroscopic properties: 3

IR(K3r): 1970(s), 1600(m), 1500(m), 1350(m); NMR(CD 2 C122,5:7.25(bm).

The structure of I was established by an X-ray study 3 of single

crystals grown at -100 from CO 2 saute CH 2C12.

Crystal data: (I.) C 3 8 H31 0 4 P2Rh2 CH 2 C12, j! 886.4

triclinic, space group P1I, a - 12.702(2), b -14.736(2), c 11l.582(2)R,

o- 99.46(l), a - 107.56(l), y - 98.258(1), U = 1995.2 X All

X-ray measurements were carried out on a Syntex P2 1 autodIffractometer

(MoKaz radiation, graphite monochrotnator), where the crystal was

maintained at -1000C in a dry N2 stream. Thie unit cell contains two

molecules of CH Cl2 of solvation. Using 6473 reflectioins with I > 3.O0a2- 2-0i _

the structure was solved by conventional heavy-atom methods and refined

to final R and wR values of 0.040 and 0.043, respectively. Refinement

included treatment of phenyl rings as rigid groups, but independent

refinement of all other parameters, including those of the solvent

hydrogen atoms.t

t Atomic coordinates for this work are available on request from theDirector of the Cambridge Crystallograpic Centre, University Chemical

Laboratory, Lensfield Road, Cambridge CBIIEW. Any request should beaccompanied by the full literature citation for this communication.

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The molecular structure (Figure) consists of a square planar

arrangement of trans-triphenylphosphines, CO, and bicarbonate ligands

about Rh; the five atoms Rh, P1, P2, Cl, 02 are coplanar to within

0.01R. The bicarbonate plane, (also ±O.01) makes an angle of 85.20

with the metal coordination plane compared with 730 in (blcarbonati)-

methyl-trans-bis(triethylphosphine)palladium(II).4 Pairs of molecules

are hydrogen bonded through the bicarbonate Jigands across crystallo-

graphic inversion centers, in a manner similar to the afore-mentioned

Pd(II) complex, except that in I the C-O distances (Figure) are

significantly different, the bicarbonato hydrogen being attached to

the oxygen with the longest C-0 bond.+

Regarding the mechanism leading to 1, especially the origin of

the bicarbonate ligand, the major pathway leading to I apparently does

not involve adventitious moisture as demonstrated by the following

observations: 1) neither intentional addition of H2 0 to the reaction

medium nor scrupulous drying of all materials and glassware had any

significant effect on the yield or rate of formation of I; 2) starting

with DRh(CO)(PPh3 )3 (ca. 66 atom Z), product I was obtained, substan-

tially deuterium-enriched (ca. 33 atom %, calculated from H20/D 20 ratio

produced on pyrolysis). § These results are consistent with a mechanism

The formation of (PhSP)2 Rh(CO)(OCO2H) from (Ph3P)2 Rh(CO)OH and CO2

has been mentioned in two earlier reports. The IR spectrum of ourauthentic I is identical to the compound prepared by Otsuka andIbers,$ but at variance with Vasks's product,' the formulation ofwhich has been questioned. s

I No D/H exchange was observed between DRh(CO)(PPh 3)3 and H20 in benzeneat 200 over a few hours.

-4-

involving initial rhodium-promoted reductive disproportionation of

CO 2 78followed by H-transfer from Rh to 0 of coordinated carbonate

(Scheme I). Our preliminary attempts to isolate the red suspected

precursor to I (possibly a hydrido-CO 2or hydrido-carbonate species)

have resulted in rapid conversion, even in the solid state, to I.

Whlesouios fI n O atrae CH Cl 2are stable at 00

for several hours, under an atmosphere of argon I is rapidly converted

with loss of CO PhadH OM? to a new material II (IR: 1970(s),C2 * P~ 3 2

1502(s), 1190(m) cm 1 ; Ph P/Rh ca. 1.5). Interestingly, pyrolysis of

II still produced CO 2 (1 C0 2/2 Rli/3 PPh 3 ) and 11 was reconverted to I in

the presence of C02 , PPh 3, and H 2O0 (eq. 2). Based on these results we

tentatively formulate 11 as a binuclear carbonate complex, (PPh )3 C)

Rh(1i-C0 3)Rh(CO) (PPh3)

2 (I'llIP) Rh(CO) (0CO2 1 (phP 3 (Co) 2Rh2 j(j-Co3 +CH2 2

1 I (2)

CO 2 +- PPh 3 + H 200)

Support from the Office of Naval Research and Alfred P. Sloan

Foundation (K.M.N.) and the Robert A. Welch Foundntion (R.E.D.) Is

acknowledged. The Texas group is also grateful to the National Science

§A similar decomposition mode has been postulated for the corres-ponding (R3P)2Rh(CO)OCO2H complexes (R cyclohexyl, i-propyl). 5

The related perphosphinated derivative, Rh2(PPhi3)5(V-CO3), isknowne (V c0 1485, 1465 cm').

Foundation for the purchase of the Syntex P2 diffractometer and an NSF

Undergraduate Research Participation award (C.L.T.).

-6-

Review: M.E. Volpin and L.S. Kolmnikov, 'Organometallic Reactions',

1975, 5,313; see also references in V.D. Bianco, S. Doronzo, andN. Gallo, Inorg. Nucl. Chem. Lett., 1979, 15, 187.

D. Evans, G. Yagupsky, and G. Wilkinson, J. Chem. Soc. A, 1968, 2660.

Details of the X-ray structure determination method are essentiallyas previously described: P.E. Riley and R.E. Davis, Acta Crystallogr.,1976, B32, 381.

R.J. Crutchley, J. Powell, R. Faggiani, and C.J.L. lock, Inorg. Chim.Acta, 1977, 24, L 15.

T. Yoshida, D.L. Thorn, T. Okano, J.A. Ibers, and S. Otsuka, J. Am.Chem. Soc., 1979, 101, 4212.

6 B.R. Flynn and L. Vaska, J. Am. Chem. Soc., 1973, 95, 5081.

7T. Herskovitz, J. Am. Chem. Soc., 1977, 99, 2391; J. Chatt, M. Kubota,G. Leigh, F.C. March, R. Mason, and D.J. Yarrow, J. Chem. Soc. Chem.Commun., 1974, 1033; G. Fachinetti, C. Floriani, A. Chiesi-Villa,and C. Guastini, J. Am. Chem. Soc., 1979, 101, 1767; G.O. Evans,W.F. Walter, D.R. Mills, and C.A. Streit, J. Organometal. Chem., 1978,144, C 34; K.M. Nicholas, ibid, 1980, 188, C 10.

8S. Krogsrud, S. Komiya, T. Ito, J.A. Ibers, and A. Yamamoto, Inorg.Chem., 1976, 15, 2798.

-7-

Scheme I

H =O C2 H 0RhC=o +C

Rh-H +C0 2 Rh 0Noo0,

Figure Caption:

A view of the structure of 1. PrincipA bond lengths (R:Rh-Cl =1.798(4),

Rh-Pl - 2.333(l), Rh-P2 = 2.332(l), Rh-02 = 2.075(2), 02-C2 = 1.283(4),

C2-03 - 1.243(4), C2-04 - 1.336(4). Principal bond angles (0:Cl-Rh-Pl

89.1(1), C1-Rh-P2 = 91.8(1), 02-Rh-PI = 90.4(1), 02-Rh-P2 =88.7(l),

Rh-02-C2 - 118.6(2), 02-C2-03 =124.8(3), o2-C2-04 113.2(3),

03-C2-04 - 122.0(3).

F 01

Cl

0 Ri

E 0C

72 0