Catalytic Activation of Carbon Monoxide - American Chemical Society

3 Heterobimetallic Carbon Monoxide Hydrogenation Hydrogen Transfer to Coordinated Acyls: The Molecular Structure of (C H ) Re[(C H )2ZrCH ](OCHCH ) Downloaded by EAST CAROLINA UNIV on March 27, 2016 | http://pubs.acs.org Publication Date: May 5, 1981 | doi: 10.1021/bk-1981-0152.ch003

5

5

2

5

5

3

3

J O H N A . M A R S E L L A , J O H N C . H U F F M A N , and K E N N E T H G . C A U L T O N Department of Chemistry and Molecular Structure Center, Indiana University, Bloomington, I N 47405

There is mounting evidence that the intramolecular transformation of a hydridocarbonyl, M(H)CO, into a ηformyl, MC(O)H, is not thermodynamically favorable (1). This has directed attention towards reactions which provide exceptional stability to the formyl species. The oxophilic character of the early transition metals may provide such stabilization in the form of dihapto binding (I). This unusual donor behavior was first 1

0097-6156/81 /0152-0035$05.00/0 © 1981 American Chemical Society Ford; Catalytic Activation of Carbon Monoxide ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

Downloaded by EAST CAROLINA UNIV on March 27, 2016 | http://pubs.acs.org Publication Date: May 5, 1981 | doi: 10.1021/bk-1981-0152.ch003

36

CATALYTIC ACTIVATION OF CARBON MONOXIDE

demonstrated c r y s t a l l o g r a p h i c a l l y by Floriani, et. al. (2,3) for homologous a c e t y l complexes of titanium and zirconium. One approach to promoting the k i n e t i c s of hydrogen transfer to bound carbon monoxide i s based on maximiz ing the difference i n p o l a r i t y of the carbon (eg. δ+) and hydrogen (eg. δ-) involved (4). This strategy leads n a t u r a l l y to a bimolecular approach, based upon MCO and Μ'Η. The a d d i t i o n a l degree of freedom which follows from employing two d i f f e r e n t t r a n s i t i o n metals i s noteworthy as an a l t e r n a t i v e to c l u s t e r a c t i v a t i o n or c a t a l y s i s . In view of the fact that early t r a n s i t i o n metal a l k y l s i n s e r t CO under very mild conditions (2,3), we chose to examine the reactions of e l e c t r o n - r i c h metal hydrides (5) with the resultant dihapto a c y l complexes. Such acyls obviously benefit from reduction of the CO bond order from three ( i n C=O) to two. More s i g n i f i cantly, the dihapto binding mode w i l l s i g n i f i c a n t l y enhance the e l e c t r o p h i l i c character of the a c y l carbon. In the course of t h i s work, we found that addition of Cp ReH (6) to Cp Zr[C(0)Me]Me (2) yielded a product whose spectroscopic properties were i n accord with the stoichiometry Cp Re[Cp ZrMe](OCHMe) (7). The presence of a c h i r a l carbon produced a s l i g h t Tnequivalence (0.0016 ppm) i n the cyclopentadienyl r i n g protons attached to zirconium. These r e s u l t s do not d i s t i n guish between structures IT and I I I , both being 2

2

2

2

H Me Cp Re—0,

Cp Re->c'

2

p

/C-ZrMeCpg H

0 — ZrMeCp,

Me

reasonable i n view of the high o x o p h i l i c i t y of rhenium and zirconium. Moreover, i n view of the f a c t that [ C p Z r C m E t ] C H C H exhibits a structure (IV) 2

3

2

2

2

CH Cp (AlCIEt )Zr 2

3

/

2

^Zr(AlClEt )Cp 3

2

Ford; Catalytic Activation of Carbon Monoxide ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

3.

MARSELLA ET AL.

Hydrogen Transfer to Coordinated Acyls

with remarkably acute ZrC^C^ angles ( 7 6 ° )

37

(8),

structure V, with a bridging acetaldehyde ligand, also

1

V · Downloaded by EAST CAROLINA UNIV on March 27, 2016 | http://pubs.acs.org Publication Date: May 5, 1981 | doi: 10.1021/bk-1981-0152.ch003

C

p

2

R

e

\ |

/

Z

r

M

e

C p

2

merits consideration. A structure of t h i s type may represent the t r a n s i t i o n state i n the f l u x i o n a l pro cess displayed by (Cp ZrCl) OCH (£). We now report a solution to t h i s s t r u c t u r a l problem by means of c r y s t a l l o g r a p h i c methods. 2

2

2

Experimental Synthesis. Crystals of Cp Re[Cp ZrMe](OCHMe) were grown from a toluene/hexane s o l u t i o n (ca. 2:1) i n the following manner. Equimolar amounts oF~Cp Zr[C(0)Me]Me and Cp ReH were dissolved i n a minimum of toluene. Within several hours, the s o l u t i o n had taken on the dark orange color of the dimeric product. Hexane was added and the r e s u l t i n g s o l u t i o n was allowed to stand f o r several days a t room temperature u n t i l bright orange c r y s t a l s formed. The compound i s s e n s i t i v e to both oxygen and moisture. 2

2

2

2

Crystallography. The c r y s t a l was transferred to the goniostat using i n e r t atmosphere techniques. C r y s t a l data and parameters of the data c o l l e c t i o n (at - 1 7 3 ° , 5° < 2Θ < 45°) are shown i n Table I. A data set c o l l e c t e d on a p a r a l l e l o p i p e d of dimensions 0.09 x 0.18 χ 0.35 mm y i e l d e d the molecular structure with l i t t l e d i f f i c u l t y using d i r e c t methods and Fourier techniques. F u l l matrix refinement using i s o t r o p i c thermal para meters converged to R = 0.17. Attempts to use aniso t r o p i c thermal parameters, both with and without an absorption c o r r e c t i o n , yielded n o n - p o s i t i v e - d e f i n i t e thermal parameters f o r over h a l f of the atoms and the r e s i d u a l remained a t ca. 0.15. Data was then c o l l e c t e d on a smaller c r y s t a l . The r e s i d u a l s improved, but several non-hydrogen aniso t r o p i c thermal parameters converged t o non-positived e f i n i t e values. There was no evidence f o r


38


Table I. C r y s t a l Data f o r ( C5H5) ZrCH (OCHCH3)Re(C5H5)2 2

3

F ο rmula

C 3 H 7 OZrRe

Color

yellow

C r y s t a l Dimensions (mm)

0.032 χ 0.019

2

2


χ 0.064 Ρ 2 /a

Space Group

x

C e l l Dimensions (at -173°C;

28 r e f l e c t i o n s ) 20.762(13) A

a

-

b

=

7.8^3(5)

c

=

12.724(8)

β

=

72.28(2)° k

Ζ (Molecules/cell)

1

1973.7 *

C e l l Volume Calculated Density (gm/cm )

2.009

Wavelength

O.7I069 A

Molecular Weight

596.89

Linear Absorption C o e f f i c i e n t

67.4

3

Min. Absorption

=

0.6k

Max. Absorption

=

0.79

T o t a l Number of Reflections c o l l e c t e d

3^9

Number of unique i n t e n s i t i e s

2598

Number with F > 0.0

2302

Number with F > σ (F)

21 kl

Number with F > 2.33 σ (F)

189^

F i n a l Residuals R(F) Rw(F) Goodness of f i t f o r the l a s t cycle Maximum Δ/σ f o r l a s t cycle

.087 .068 1.33 .05


3.

MARSELLA ET AL.


39

decomposition during the data c o l l e c t i o n (four standard r e f l e c t i o n s v a r i e d randomly within t 0.8 σ ) , nor was there evidence of disorder or solvent molecules i n the crystal lattice. Consequently, we report here the re s u l t s from t h i s second c r y s t a l but using i s o t r o p i c thermal parameters f o r a l l atoms except Zr and Re. These data are corrected f o r absorption. In the f i n a l l e a s t squares c y c l e s , a l l hydrogen atoms whose p o s i tions are f i x e d by assumed s p or s p h y b r i d i z a t i o n were included i n f i x e d positions with C-H = 0.95 A and Β = 3.0 Â ; methyl hydrogens were not included. The r e s u l t s of the X-ray study are contained i n Tables II-IV. Anisotropic B's and a table of observed and c a l c u l a t e d structure factors are a v a i l a b l e (10). The molecular structure i s shown i n Figures 1 and 2. The cyclopentadienyl r i n g carbons deviate by less than 0.6 σ from t h e i r respective least squares planes. The average C-C distances i n the four rings are iden t i c a l within experimental e r r o r . Metal-to-ring mid point l i n e s i n t e r s e c t the r i n g planes at angles of 87.h° and 8 7 . 7 ° (Re) and 86.8* and 8 8 . 3 ° ( Z r ) . The shortest intramolecular nonbonded contacts are from C(2k) to C(3), 2.75 A, and to C(9), 2.83 A. The shortest distances to oxygen are from C(3) and C(15) (both 2.95 A). A l l i n t e r - r i n g carbon-carbon distances exceed 3 A. Intermolecular C ··Η contacts (calculated with a l l C-H distances f i x e d a t 1.08 A)exceed 2.6 Â while intermolecular Η···Η contacts exceed 2.2 A. 2

3


2

e

Results and Discussion O v e r a l l Structure. The r e s u l t s i n d i c a t e that structure III i s correct and that the reaction i s a geminal a d d i t i o n of the Re-Η bond to the a c e t y l carbon. The cyclopentadienyl rings on the same metal center are i n the semi-staggered configuration t y p i c a l l y found f o r bent metallocene structures (11), while rings on d i f ferent metals assume a cog-liïcê arrangement (Figure 3a). The rings are arranged so that a l l four r i n g centroids f a l l approximately i n one plane; deviations of these centroids are t 0.1 Â from t h e i r least squares plane. The arrangement minimizes end-to-end i n t e r actions of cyclopentadienyl rings with both methyl groups, as can be seen i n Figure 3. These space f i l l i n g models c l e a r l y show that both methyl groups are located i n c a v i t i e s formed by the canted rings a t the opposite end of the molecule. This arrangement of cyclopentadienyl rings contrasts with that observed (12.) i n Cp W=C(H)0Zr(H)Cp*2 (Cp* = C Me ). In t h i s carbene complex, both the minimal s t e r i c requirements 2

5

5



40

Table I I . F r a c t i o n a l Coordinates f o r (Cp)2(Me)ZrOCHCH Re(Cp) > a

3

10 X 8828(0) 6469(1) 8125(12) 8250(13 8951(12) 9247(12) 8740(13) 9338(11) 8842(12) 9030(l2) 9643(12 9824(12) 6228(l4 6865(14) 6859(l4) 6202(13 5790(12) 5995(12) 5466(12) 5273(13) 5655(12) 6l32(l2) 7363(8) 7989(H) 7976(14) 6733(12)


4

10 Y 4288(1) 5769b) 2186(35) 1904(37) I6l6(33) 1792(33) 2144(34) 6862(30) 70lo(33) 5870(37) 5033(32) 56ol(4o) 8105 37 839l(39) 8829(37) 8735(35) 8322(34) 4293 39 5279(33) 4626(35) 3208(32) 2990(33) 5414(23) 5639(36) 5304(38) 44oi(39) 4

b

2

4

10 Z 6798(1) 8129(2) 6577(21 7565(23' 7306(21 6192(21 5679(21 6347(19; 7476(21 8156(20] 7519(20 6392(21 9564(23] 8943(24' 7892(23' 7856(21' 8913(21 6759(20] 7412(21 8482(21 8530(20] 7479(20 7083(l4 6329(19; 5104(24' 9566(21'

The i s o t r o p i c thermal parameter l i s t e d f o r those atoms refined a n i s o t r o p i c a l l y i s the i s o t r o p i c equivalent. ^Numbers i n parenthesis i n this and a l l following tables refer to the error i n the least s i g n i f i c a n t digits.


MARSELLA ET AL.

3.



Table I I I . Re Re

M(l) M(2)

Re Re Re Re Re

C(3) C(4) C(5) C(6] C(7)

Re Re Re Re Re Re

d

a

Bond Distances (Â)

Γ90 1.90

2.28(3) 2.28(3) 2.23(3) 2.18(3) 2.25(3) av. 2 . 2 Î W C(8) 2.27(2) C 9) 2.31 3 CflO) 2.27(3) Cfll) 2.23(2) C(12) 2.23(3) av. 2.26(3) C(24) 2.27(2)

Tr

M(3) M(4)

Zr

Zr Zr Zr Zr Zr

C(8) C8 C 9) c 10) C(ll)

a

b

2.21 2.24

c

av. Zr Zr Zr Zr Zr

c

C(l8' C 19* C(2o' C(2l' C(22' av.

Zr Zr

C(26) 0

C(24) 1.38(4) C(13) c( 1.43(3) C(13) C(J) 1.41(3) C(l4) C(,5 C( 1.37(3 C(15 C(!7) 1.43(3 ) C(l6) av. 1.40(3) 1.50(3) C(18) C(\9) 1.43(3 C(18 C(>12) CI 1.38(3) C(19) 1.44(3) C(20) CI'11 ) 1.44(3) C(21) CI[l2) av. 1.44(4) 6

C(24) c(25) c(i4; C(17 C(15 C(l6' C(17' av. C(19] C(22 C(20 C(2l' C(22' (

av.

M ( l ) and M(2) are the midpoints of the C H bound to Re. 5

b

2.53(3) 2.55(3) 2.52 3 2.44(3) 2.48 3 2.50(4) 2.53(3) 2.54(2) 2.55 3 2.57 2 2.50 3 2.5^(3) 2.32(3) 1.95 2 1.37(3) 1.59(4) 1.34(4) 1 .41(4) 1.38(4) 1.38(4 1.4o(4) 1.38(3) 1.39(3) 1.46 4 1.39 3 1.38(3) 1.41(3) 1.41 3

C(13 C 1Ί C(15] 0(16* C(l7*

0

C(3) C 3 φ C5 C(6)

41

5

rings

M(3) i s the midpoint of the r i n g C(13) thru C(l7).

c

Esd's on average values are calculated using the scatter formula a(av) = [Σ(ά -Έ) /(N-l)] where d. i s one of Ν i n d i v i d u a l values and d i s t h e i r 2

l/2

±

average.



42


Table IV. Re Re 0 0 Zr M(l ) Mm Ml) M(2) M(3) M(4)

M(3) M(4) C(4)

cm C(4

C(24) C(24) C(24) Zr 0 Re Zr Re Re Zr Zr Zr Zr C(3) C(4

C(5 C(3)

C(5 C 6 C(7)

C(9) C(8) C9) C(10) C(8)

C(8) C 9) C(10) C(ll ) C(12)

C(14)

Bond Angles (deg). 0 C(25) C 25) C(26) C(24) M(2) M 4) C(24) C(24) 0 0 C(26) C(26) C(7) C(5) C(6) C7 C(6) C(12) C(10) C(ll ) C(12) C(ll)

C 13) C(14) C 15 C(13)

C(13) C(14) C(15 C(l6) C(17)

C(17) C 15 C(l6) C(17) C(l6)

C(19) C(18 C(19 C(20) C(18)

C(18) C(19) C(20 C(21 ) C(22)

C(22) C(20) C(21 ) C(22) C(21)

113.31'2) 115.11^2) 111.71*2) 93.9 8 164.3)[2) 150.5 129.6 104.9 104.6 107.9 110.8 103.3 104.9 110.8(2) 106.3 2) 109.4(2) 109.4(2) 104.0(2) 108.0(3) 107.7(2) 108.0(2) 108.2 2) 109.8(2) 106.3(2) 108.0(1) 109.3(3) 108.4(3) 108.6(3) 107.6(2) 106.1 (2) 108.0(l) 106.5(2) 108.6(2) 109.9(2) 107.7(2) 107.2 2 I08.0 1

av.

av.

av.

av.




MARSELLA ET AL.

Figure 1. ORTEP drawing of Cp ReCH(Me)OZrMeCp showing atom labeling scheme; unlabeled ring carbons follow the numerical sequence determined by the atom labels given. 2

2

Figure 2. Stereo view of Cp ReCH(Me)OZrMeCp approximately perpendicular to the bridging group; the Rh fragment is at the top. 2

2


44


of the bridge l i n k i n g the metal atoms and the b u l k i e r nature of the C Me rings on zirconium d i c t a t e that the four rings arrange themselves so as to minimize r i n g r i n g repulsions; that i s , the plane containing the Cp centroids and the tungsten atom i s almost perpendicular to the plane containing the C Me centroids and the zirconium atom. The same staggered arrangement i s seen i n the s a l t [Cp W H +] [C10 ~], due to the short W-W (nonbonded) separation (13»). The compound [Cp* ZrN ]N (14) and complexes of the type [Cp MX] 0 (11,15,16,12, 1ST a l s o show staggering of Cp M units, but o r b i t a l overlap requirements are a major determining factor i n these complexes (1_9). 5

5

5

4

2

3

5

4

2

2

2

2

2


2

S t r u c t u r a l Features Around the Zr Atom. The arrangement of ligands around zirconium i s quite t y p i c a l of Cp MXY structures. The methyl carbon and oxygen atoms form an angle of 9 5 . 9 ( 8 ) ° at zirconium. The centers of the Cp rings average 2 . 2 3 Â from the z i r conium atom and the r i n g midpoints subtend an angle of 130° a t Zr. These values are a l l quite comparable to those i n C p Z r C l ( H ) . The zirconium-methyl carbon distance i s 2.32(3)~~£, i d e n t i c a l w i t h i n experimental error to that i n Cp ZrCH [C(0)CH ] ( 2 ) . The i n t e r e s t ing feature at the zirconium center Ts the Zr-0 bond. Table V shows a comparison of some parameters of t h i s bond with those found i n other oxygen-containing metallocene dimers. An examination of these parameters shows that the a l k o x i d e - l i k e ligand i n both Cp W=C(H)0ZrMeCp* and JEII are bound with m u l t i p l i c i t i e s approaching those i n oxo-bridged dimers. While s t e r i c e f f e c t s c e r t a i n l y contribute to the wide Zr-O-C angles i n the tungsten and rhenium compounds, the short Zr-0 bond distances imply multiple bonding due to P ^ d ^ 2

2

2

2

3

3

2

2

donation, as postulated e a r l i e r (20]. I t should be noted that zirconium-oxygen " s i n g l e bonds average 2 . 1 9 8 ( 9 ) A i n Z r ( a c a c ) (21J . Since dimer I I I contains a Zr-C bond of purely σ character, this bond length provides an i n t e r n a l standard f o r comparison of bond order. Thus, while the single bond radius of oxygen i s 0.11 A shorter than that of carbon, the Zr-0 bond i n III i s 0.37 A shorter than the Zr-CH bond; a s i g n i f i cant TT-component i s present i n t h i s Zr-OR bond. In Cp MXY complexes (M = T i , Zr, Hf), the ligands X and Y together donate a t o t a l of four electrons to the n e u t r a l fragment Cp M. When Y i s a ηοη-ττ-donor, as CH i n complex I I I , a l l π bonding i s provided by X(0R); t h i s leads to maximum contraction of the Zr-0 distance. It was noted previously (3) that the T i - C l distance i n 7

4

3

2

2

3



2

2

2

2

2

2

2

5

4

2

2

2

2

5

2

2

4

Cp W=C(H)OZr(Me)(C Me ) Cp ReC(H)(Me)0Zr(Me)Cp (Cp HfMe) 0 [(Cp NbCl) 0](BF ) UCpaTi(H 0)]0}(C10 )

2

(Cp ZrSPh) 0

2

(Cp ZrCl) 0

2

1.941(3) 1.88(1) 1.829(2)

1.95(2) 173.9(3) 109.3(8) 175.8(5)

164.3(17)

1J_ 11_ 18

t h i s work

16 ~~ 12

165.8(2) 166.4(7)

15

168.9(8)

Reference

1.94(1) 1.95(1) 1.964(3) 1.968(3) 1.973(10)

/Zr-O-C fdeg)

^M-O-M (deg)

d(M-0)(Â)

Selected S t r u c t u r a l Data on Dimeric Cyclopentadienyl Complexes

Compound

Table V.



46

Cp TiCl[Tl -C(0)Me], i s 0.13 Â longer than i n C p T i C l . Intramolecular competition f o r π-donation i n t h i s com plex i s dominated by the η -acetyl group, so that the T i - C l bond has nearly pure σ character. On the other hand, the Z r - a l k y l bond lengths i n III and i n Cp ZrCH [T] -C(0)CH ] (2) are i d e n t i c a l , as expected. A f i n a l example of t h i s competition exists i n C p T i ( p - n i t r o benzoate) (22). Here, the two compositionally iden t i c a l carboxyTate ligands do not perform i d e n t i c a l donor functions. Instead, one functions as a ττ-donor (Ti-0 = 1.94 Â a n d ^ T i - O - C = 157°) while the other serves as a σ-donor (Ti-0 = 2.04 A and Ti-O-C = 136°). 2

2

2

2

2

2

3

2

3

2


2

S t r u c t u r a l Features Around the Re Atom. This portion of the molecule consists of a carbon atom bound symmetrically between two t i l t e d Cp rings. None of the points Re, C(24), M ( l ) , M(2) deviates by more than 0.02 A from t h e i r least squares plane (M(i) i s the r i n g centroid). This i s the structure predicted f o r a d complex of Cp MX stoichiometry (19). The complexes C p V C l ( d ) (23), Cp Ti(2,6-ditertbutyl-4-methylphenyl) (2JL), Cp Ti(2,6-dimethylphenyl)(d ) (2£), and Cp V[ N ( S i M e ) j ( d ) (26) also have the symmetric structure exhibited by the Cp ReC fragment i n I I I . According to MO c a l c u l a t i o n s (19), the more electron r i c h the metal center i n a "bent^metallocene. the greater the M ( l ) M-M(2) angle. Indeed, the M(l)-Re-M(2) angle i n 111 i s I50°, while i t i s i n the range 136°-l4l° i n the compounds c i t e d above (19.,23,24_,2£,26J . The largest previously reported value Tor t h i s parameter f o r metalsubstituted metallocenes i s 149° for [Cp MoHLi] (27) (also formally d ) . Large angles have also been re ported for Cp MoD (148.2°) (28), Cp W=C(H)0Zr(H)Cp* (145.6°), [ C p W H ] (148.2°), [CpMoHCO] * (144.5°) (£9) and Cp MoH -ZnBr -DMF (143.5°) (50). When the metal-ring distance i s short, i t has been postulated that large M(l)-M-M(2) angles are a s t e r i c consequence of i n t e r - r i n g repulsions (27). An exami nation of Table III shows that the Re-C(Cp) distances are i n f a c t shorter than those to zirconium; they are a l s o shorter than the corresponding distances i n several Cp MX complexes of titanium and vanadium. How ever, the Re-C(Cp) distances i n [Cp ReBr lBF (IjJ comparably short (Re-C = 2.26, ReM = 1.924), but the CpReCp angle i n t h i s s a l t i s only 1 3 9 . 5 ° . C l e a r l y the increase i n CpReCp angle i s very strongly dependent on e l e c t r o n i c e f f e c t s and on the number of attached ligands, i n accord with previous calculations (19). Note that the great d i s p a r i t y (0.28 A) i n the distance from r i n g carbons to Zr vs. Re i n ΓΙΙ i s not r e f l e c t e d 4

2

2

2

2

1

2

2

1

2

3

2

2

2

4

4

2

2

2

+

2

2

2

2

2

4

3

2

2

a

2

2

4


r

e


3.

MARSELLA


ET AL.

47

90°

Figure 3. View of spacefillingmodels of Cp ReCH(Me)OZrMeCp : a, molecule oriented as in Figure 2; b, rotated 90° about a vertical axis from a; c, molecule oriented as in Figure 1; H indicates the hydrogen atom on the tertiary carbon, C(24) 2

2

H(Me) Λ

C

W

Re)

P ïï?ïï) < > (2.27Γ 2

1.3!

Ι.9?\

2.25 r> _*/^_ χ

Zr

C

lC

°(T55) (253l P2 P2

)

/Î137)

H(H+Me) Figure 4.

Structure parameters for Cp WC(H)OZrHCp *; corresponding atoms and parameters in compound III are shown in parentheses 2

2

American Chemical Society Library 1155 16th St. N. W.

Ford; Catalytic Activation of Carbon Monoxide ACS Symposium Series; Washington, American Chemical Washington, DC, 1981. D. Society: C. 20030


48

i n the metal a l k y l bond lengths: Zr-CH = 2.32(3) Â and Re-CH(Me)0 = 2.27(2) A. The rhenium-σ carbon bond distance of 2.27(2) A does not d i f f e r s t a t i s t i c a l l y from those observed i n CpReMeBr(ÇO) (2.32(M) A) (31) and CpRe(H -C H Me)Me (2.23(3) A) (32). The distance i s shorter (2.19(1) A) in Li (Re Me T(33). Structure determinations of secondary metal a l k y l complexes are r e l a t i v e l y rare, yet they provide an opportunity to assess interactions of the metal with the j8-atoms of the a l k y l . The angles (excluding hydrogen) about C(24) a l l exceed 1 0 9 ° , ranging from 1 1 1 . 7 ° to 1 1 5 . 1 ° . There i s no evidence f o r any Re---0 i n t e r a c t i o n (compare V), t h i s distance exceeding 3 A. Both the jS-carbon, C(25), and i t s attached hydrogens are over 3 A from rhenium. The hydrogen on the acarbon, C(2k), i s 2.76 A from rhenium. Figure 4 shows the remarkable s t r u c t u r a l s i m i l a r i t y between the b i m e t a l l i c carbene (12_) and alkoxy complexes formed from diverse paths: 1,2 addition of Zr-H to a carbonyl bound to tungsten (eq. 1) and 1,1 addition of Re-Η to a zirconium-bound a c e t y l (eq. 2). 3

4

2


2

2

5

Cp WC0 + ( C M e ) Z r H 5

5

2

>Cp W=C

2

2

Cp ReH + (C H ) Zr[C(0)Me]Me 2

2

8

0 2

5

5

5

2

H

^Zr(C Me )2 5

5

(1)

— > Me

Cp Re-CH(Me)0-Zr(C H ) 2

5

5

2

(2)

The major metric difference i s i n the WC (carbene) and ReC (alkyl) bonds, the former being shorter due to i t s multiple character. The s i m i l a r i t y i n CO distances implies n e g l i g i b l e 0 - C multiple bonding i n the W/Zr compound. This i s a consequence of 0 Zr tr donation i n both compounds (compare the Zr-0 bond lengths), which represents the dominant u t i l i z a t i o n of the oxygen lone p a i r s . Conclusion This structure determination affirms the spec troscopic i n d i c a t i o n that the product of the reaction of Cp Zr[C(0)Me]Me and Cp ReH involves geminal addition of the Re-Η bond to the e l e c t r o p h i l i c a c e t y l carbon. The unique Zr-0 bond i n Cp Zr[C(0)Me]Me i s retained i n 2

2

2


3.

MARSELLA ET AL.


49

t h i s reaction, suggesting that i t contributes to the d r i v i n g force f o r t h i s f a c i l e reduction of carbon monoxide. To our knowledge, t h i s i s the f i r s t d e f i n i t i v e example of an i n s e r t i o n of an a c e t y l carbon into an M-H bond and we are continuing our i n v e s t i g a t i o n of the importance of such insertions i n Fischer-Tropsch syntheses.


A cknowledgemen t This work was supported by NSF Grant No. CHE 7710059 and by the M. H. Wrubel Computer Center. G i f t s of chemicals from Climax Molybdenum Company are grate f u l l y acknowledged.

Literature Cited 1.

Collman, J . P . ; 1973, 95, 4089.

2.

Fachinetti, G . ; Fochi, G . ; Floriani, C. J. Chem. Soc., Dalt. Trans., 1977, 1946.

3.

Fachinetti, G . ; Floriani, C . ; Stoeckli-Evans, H. J . Chem. Soc., Dalt. Trans., 1977, 2297.

4.

Marsella, J . Α . ; Curtis, C. J.; Bercaw, J . E.; Caulton, K. G. J. Am. Chem. Soc., 1980, 102.

5.

Labinger, J . Α . ; Komadina, K. J. Organometa1. Chem., 1978, 155, C25.

6.

King, R. B . , "Organometallic Syntheses," Vol. 1, Academic Press, New York, 1965, p. 80.

7.

Marsella, J . Α . ; 1980, 102, 1747.

8.

Kaminsky, W.; Kopf, J.; Sinn, H . ; Vollmer, H . - J . Angew. Chem., Int. Ed. Engl., 1276, 15, 629.

9.

Fachinetti, G . ; Floriani, C . ; Roselli, Α . ; Pucci, S. J . Chem. Soc., Chem. Commun., 1978, 269.

10.

Winter, S. R. J . Amer. Chem. Soc.,

Caulton, K. G. J . Am. Chem. Soc.,

Huffman, J . C . , Indiana University Molecular Structure Center, Report No. 7944.




50 11.

Prout, K . ; Cameron, T. S.; Forder, R. Α . ; Critchley, S. R.; Denton, B . ; Rees, G. V. Acta Cryst. Sect. B, 1974, 30, 2290.

12.

Wolczanski, P. T . ; Threlkel, R. S.; Bercaw, J. E. J. Am. Chem. Soc., 1978, 101, 218.

13.

Klingler, R. J.; Huffman, J . C . ; Kochi, J . K. J. Am. Chem. Soc., 1980, 102, 208.

14.

Sanner, R. D.; Manriquez, J . M.; Marsh. R. E.; Bercaw, J . E. J . Am. Chem. Soc., 1976, 98, 8351.

15. Clarke, J. F.; Drew, M.G.B. Acta Cryst. Sect. B, 1974, 30, 2267. 16.

Petersen, J . L. J. Organometallic Chem., 1979, 166, 179.

17.

Fronczek, F. R.; Baker, E. C . ; Sharp, P. R.; Raymond, Κ. N . ; A l t , H. G . ; Rausch, M. D. Inorg. Chem., 1976, 15, 2284.

18.

Thewalt, U . ; Kebbel, B. J . Organometal. Chem., 1578, 150, 59.

19.

Lauher, J . W.; Hoffmann, R. J. Am. Chem. Soc., 1976, 98, 1729.

20.

Huffman, J . C . ; Moloy, K. G . ; Marsella, J . Α . ; Caulton, K. G. J . Am. Chem. Soc., 1980, 102, 3009.

21.

Silverton, J . V . ; 1963, 2, 243.

22.

Kuntsevich, T. S.; Gladkikh, E.; Lebedev, V. Α . ; Linevag, Α . ; Bolov, Ν. V. Sov. Phys.: Crystallogr., 1976, 21, 40.

23.

Fieselmann, B. F.; Stucky, G. D. J . Organometal. Chem., 1977, 137, 43.

24.

Cetinkaya, B.; Hitchcock, P. B.; Lappert, M. F.; Torroni, S.; Atwood, J . L.; Hunter, W. E.; Zaworotko, M. J. J. Organometal. Chem., 1980, 188, C31.

25.

Olthof, G. J.; Van Bolhuis, F. J . Organometal. Chem., 1276, 122, 47.

Hoard, J . L. Inorg. Chem.,



3. MARSELLA ET AL.


26.

Veith, M. Angew. Chem., Int. Ed. Engl., 1976, 15, 387.

27.

Forder, R. Α . ; Prout, K. Acta Cryst., Sect. B . , 1974, 30, 2318.

28.

Schultz, A. J.; Stearly, K. L.; Williams, J . M . ; Mink, R.; Stucky, G. D. Inorg. Chem., 1977, 16, 3303.

29.

Adams, Μ. Α . ; Folting, K . ; Huffman. J . C . ; Caulton, K. G. Inorg. Chem., 1979, 18, 3020.

30.

Crotty, D. E.; Corey, E. R.; Anderson, T. J.; Glick, M. D.; Oliver, J . P. Inorg. Chem., 1977, 16, 920.

31.

Aleksandrov, G. G . ; Struchkov, Yu. T.; Makarov, Yu. V. Zh. Strukt. Khim., 1975, 14, 98.

32.

Alcock, N. W. J. Chem. Soc. ( Α ) , 1967, 2001.

33.

Cotton, F. Α . ; Grange, L . D.; Mertis, K . ; Shive, L. W.; Wilkinson, G. J. Chem. Soc., Dalt. Trans., 1976, 98, 6922.

RECEIVED

December 8, 1980.


51

Catalytic Activation of Carbon Monoxide - American Chemical Society

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