Preparation, Structure, and Reactions of Rh - ACS Publications

7 Preparation, Structure, and Reactions of Rh H (P(isopropyl)3)4 2

4

D A V I D L. T H O R N and J A M E S A. IBERS

Downloaded by CORNELL UNIV on August 29, 2016 | http://pubs.acs.org Publication Date: June 1, 1982 | doi: 10.1021/ba-1982-0196.ch007

Department of Chemistry, Northwestern University, Εvanston, I L 60201

new hydrido-bridged

A

rhodium

Pr) ) , has been prepared 3

with sodium reacting

hydride

hydrogen

(P(iso-Pr) ) . 3 2

in tetrahydrofuran

with a THF solution

The compound

units and approximately at -150°C

Rh H4(P(iso2

(THF) and by of

crystallizes

C52h-P21/n of the monoclinic dimensions

dimer,

by reacting RhClH2(P(isoPr)3)2

4

system

Rh(η3-C H )3

in space

with four

0.6 THF molecules

5

group formula

in a cell of

of a = 11.463(10) Å, b = 16.288(15)

Å, c = 23.891(23) Å, β = 93.88(6)°. The structure

has been

refined to an R index on Fo2 of 0.153, based on 207 varia ble

parameters

-150°C.

and 4997 Fo2 values

The compound

RhP units with a Rh-Rh

separation

2

interplanar

dihedral

angle

were used to establish dride. have

Possible been

positions

rhodium tions

drogenation tion of

A

hydrido

ligands

electron-density

and angles around the

mixed-valence

held together

such the compound

means

atoms. The most probable

a Rh(III)-Rh(I)

RhHP2-RhP2,

Åand an

was a tetrahy-

residual

bond distances

and phosphorus

yield

of 2.618(3)

for the four from

at

nonequivalent

of 72.6°. Chemical

that the material

established

peaks and from

obtained

consists of two

posi-

compound,

by three hydrido

bridges. As

may be an intermediate

in the hy-

of RhH(P(iso-Pr)3)2,3 and the

dehydrogena-

RhH (P(iso-Pr) ) . 3

3 2

s a continuation o f studies o f the reactivities o f r h o d i u m c o m plexes containing b u l k y phosphine ligands (1-6),

we have been

investigating alternative routes for synthesizing halogen-free

hydrido

r h o d i u m complexes w i t h these b u l k y phosphine ligands. In this con text we h a p p e n e d to react R h C l H ( P ( i s o - P r ) ) w i t h solid N a H ( 7 ) a n d 2

obtained

an unexpected

3

2

d i m eric product, R h H ( P ( i s o - P r ) ) 4 . 2

4

3

0065-2393/82/0196-0117$05.00/0 © 1982 American Chemical Society

Alyea and Meek; Catalytic Aspects of Metal Phosphine Complexes Advances in Chemistry; American Chemical Society: Washington, DC, 1982.

This

METAL PHOSPHINE COMPLEXES

118

c o m p l e x c r y s t a l l i z e d as s m a l l b l a c k p o l y h e d r a t h a t r e s e m b l e d t h e e a r lier reported c o m p o u n d RhH(P(f-Bu) ) 3

2

(2, 4 ) b o t h i n a p p e a r a n c e a n d

i n the I R s p e c t r u m , a n d w e i n i t i a l l y tentatively f o r m u l a t e d this n e w compound

as

[ R h H ( P ( i s o - P r ) ) ] j . (x = 1 or 2). A 3

low-temperature,

2

single-crystal X - r a y structure d e t e r m i n a t i o n r e v e a l e d the d i m e r i c na ture o f the c o m p l e x a n d also s t r u c t u r a l details that suggested the pres ence of a greater n u m b e r of h y d r i d o ligands. I n this p u b l i c a t i o n w e report the low-temperature

crystal structure of R h H ( P ( i s o - P r ) ) 2

4

3

4

and

its r e a c t i o n s w i t h d i n i t r o g e n a n d h e x e n e .


Experimental A l l manipulations were c a r r i e d out u n d e r an inert atmosphere (argon or nitrogen). Solvents were d r i e d b y refluxing over sodium/benzophenone under nitrogen a n d were degassed further b y v a c u u m transfer or f r e e z e - p u m p - t h a w cycles before use. I R spectra w e r e recorded on a P e r k i n - E l m e r 283 spec trometer; P-31 a n d H - l N M R spectra were recorded on a J E O L F X 9 0 Q spec trometer. Proton c h e m i c a l shifts are reported i n parts per m i l l i o n d o w n f i e l d from tetramethylsilane(TMS). D r y crystalline s o d i u m h y d r i d e a n d P(iso-Pr) were obtained from A l p h a Products a n d from Strem C h e m i c a l C o . , respec tively. Gas chromatographic ( G C ) analyses were performed on a H e w l e t t P a c k a r d 5750 chromatograph instrument e q u i p p e d w i t h a flame ionization detector a n d a 6-ft, i - i n . diameter c o l u m n p a c k e d w i t h 0 . 1 % S u p e l c o S P 1 0 0 on 80/100 carbopack C . R h C l H 2 ( P ( i s o - P r ) 3 ) , (5, 8). ( R h C l ( C H ) ) ( 9 ) (0.69 g, 1.92 m m o l rho d i u m ) a n d P(iso-Pr) (0.81 g, 5.06 m m o l ) were a d d e d to 10 m L T H F u n d e r nitro gen. T h e r e s u l t i n g p u r p l e - b r o w n solution was stirred overnight at room tem perature u n d e r a hydrogen atmosphere. T h e solution then was d r i e d i n v a c u u m a n d the residue was recrystallized from hexane to y i e l d y e l l o w crystals (0.435 g, 0.94 m m o l , 49%); IR (Nujol) 2140 c m " . H - l N M R (THF-c/ ): δ-22.8 (d oft, / H - R H 27 Η Ζ , / Η - Ρ 13 H z ) ; δ 1.26 ( < / , / H - H + H - P 7 H z ) ; δ 2.32 m ; carbon a n d h y d r o g e n analysis. R h 2 H ( P ( i s o - P r ) 3 ) 4 : M e t h o d A . R h C l H a i P U s o - P r ) ^ (0.21 g, 0.45 m m o l ) a n d s o d i u m h y d r i d e (~0.1 g) were a d d e d to one chamber of a two-chambered flask c o n t a i n i n g a glass w o o l p l u g b e t w e e n the two chambers. A b o u t 8 m L of T H F were d i s t i l l e d into the reaction chamber. T h e mixture then was put under 1 atm of argon a n d stirred at room temperature. After 2 d the resulting dark mixture was filtered through the glass w o o l into the second chamber, concentrated i n v a c u u m to ca. 1 m L , a n d c o o l e d to - 2 0 ° C . B l a c k crystals began to form after ~ 2 4 h . After 3 weeks the crystals were c o l l e c t e d a n d d r i e d briefly i n v a c u u m . Y i e l d : 0.04 g, 0.047 m m o l d i m e r , 2 1 % . R h H ( P ( i s o - P r ) 3 ) 4 : M e t h o d B . A m e t h o d analogous to that u s e d b y Sivak a n d Muetterties (10) for m a k i n g a l l y l r h o d i u m bisphosphite complexes was used to prepare R h ( 7 7 - C H ) ( P ( i s o - P r ) ) . H - l N M R ( C D ) of Rh(r> C H )(P(iso-Pr) )2: δ 1.19 (d of dJ 7 Η Ζ , / Η - Ρ 11 H z ) ; δ 2.05 m ; δ 3.10 (d J y n - H 7 H z ) ; δ 4.75 m ; carbon a n d hydrogen analysis. B u b b l i n g h y d r o g e n gas through a T H F solution of Rh( T7 -C H5)(P(iso-Pr) ) for 1 h at r o o m tem perature resulted i n its complete conversion to R h H 4 ( P ( i s o - P r ) ) , as j u d g e d b y N M R spectrum of the solution. X - R a y D a t a C o l l e c t i o n . For p r e l i m i n a r y room-temperature X-ray photo graphic examination, a w e l l - f o r m e d p o l y h e d r a l single crystal of R h H ( P ( i s o 3

2

8

1 4

2

2

3

1

8

4

2

4

3

3

5

3

3

5

3

2

e

3

e

H H

H S

3

3

3

2

2

3

4

2


4

7.

119

Rh H (P(isopropyl) )4

T H O R N A N D IB ERS

2

3

4

P r ) ) was sealed i n a glass c a p i l l a r y under an argon atmosphere. Weissenberg a n d precession photographs revealed m o n o c l i n i c symmetry a n d systematic absences consistent w i t h the space group C - P 2 i / n . T h e density c a l c u l a t e d from the room-temperature u n i t - c e l l constants is 1.22 g/cm for 4 molecules of R h H ( P ( i s o - P r ) ) 4 i n the c e l l , w h i c h agrees w i t h the density of 1.17(2) g/cm m e a s u r e d b y flotation i n aqueous Z n C l . For data c o l l e c t i o n this same crystal was r e m o v e d from its c a p i l l a r y a n d m o u n t e d d i r e c t l y on a computer-controlled, four-circle P i c k e r diffractometer, w h e r e it was bathed c o n t i n u o u s l y i n a stream o f c o l d (~- 150°C) dry nitrogen gas. (The diffractometer was r u n u n d e r the disk-oriented V a n d e r b i l t system (JJ) a n d the design of the low-temperature apparatus is that o f Huffman (12).) A t this temperature the c e l l constants, d e r i v e d from the setting angles of 15 hand-centered reflections i n the range 22.2° < 20 < 27.0°, (13), are a = 11.463(10), b = 16.288(15), c = 23.891(23) Α, β= 93.88(6)°, a n d V = 4450 À . O w i n g to the h i g h mosaicity of the crystal (typical peaks were 0.8° to 1.0° w i d e , half-height to half-height i n ω) data were c o l l e c t e d i n an omega step scan mode. E a c h peak was scanned i n 41 steps, c o u n t i n g for 1 s at each step, across a total w i d t h i n ω o f 3.0°. B a c k g r o u n d counts were c o l l e c t e d for 4 s at the low- a n d high-angle extremes. Weak reflections ( F ^ 3σ(¥ )) were rescanned a n d b a c k g r o u n d counts w e r e c o l l e c t e d for a total of 14 s at the l o w a n d high-angle extremes. A total of 5371 data were c o l l e c t e d i n the range 3.0 < 20 < 42.5°, o f w h i c h the 4997 u n i q u e data were u s e d i n the refinement. T h e intensities of six standard reflections were remeasured every 100 reflec tions, a n d they d i d not vary significantly d u r i n g the course of data collection. Information about the crystal a n d data collection is s u m m a r i z e d i n Table I. S o l u t i o n and Refinement of the Structure. Scattering factors for the hy drogen (14) a n d nonhydrogen (15) atoms are those u s e d p r e v i o u s l y . A n o m a lous dispersion terms (16) w e r e i n c l u d e d i n F for r h o d i u m a n d phosphorus atoms. For the processing o f the data a n d solution a n d refinement o f the structure procedures a n d computer programs standard i n this laboratory were used. (See, e.g., Ref. 17).) T r i a l absorption corrections c a l c u l a t e d for a random selection o f reflections gave transmission factors i n the range 0.71 to 0.73; therefore a f u l l absorption correction was considered to be unnecessary. T h e locations of the r h o d i u m atoms were obtained u s i n g direct methods, a n d a l l r e m a i n i n g nonhydrogen atoms (except for solvent atoms, v i d e infra) w e r e located u n a m b i g u o u s l y i n a subsequent F o u r i e r map. After two cycles of isotropic refinement a difference F o u r i e r map r e v e a l e d locations of many of the a l k y l h y d r o g e n atoms a n d also some peaks c l u s t e r e d about the inversion center (0, i, i) w h i c h strongly suggested a disordered solvent m o l e c u l e ( T H F ) o f partial occupancy. T h e isopropyl hydrogen atoms w e r e p l a c e d i n i d e a l i z e d locations ( C - H : 0.95 À, tetrahedral angles), assigned isotropic thermal param eters 1.0 A greater than those o f their respective attached carbon atoms, a n d kept fixed i n a l l subsequent refinement. T h e peaks a r o u n d (0, i , i) w e r e m o d e l e d b y a T H F m o l e c u l e w h i c h was refined subsequently as a r i g i d group (18) w i t h a single isotropic thermal parameter a n d a single, refined occupancy number. I n the final cycles the r h o d i u m and phosphorus atoms w e r e refined anisotropically and a l l o f the carbon atoms and the r i g i d solvent m o l e c u l e were refined isotropically for a total of 207 variables. F i n a l refinement was on F w i t h a l l o f the u n i q u e data i n c l u d e d . T h e refinement converged to values of R a n d Rw on F o f 0.153 a n d 0.172 a n d to an error i n an observation o f u n i t w e i g h t o f 1.12 electrons . T h e refined occupancy n u m b e r o f the T H F m o l ecule is 0.60(4) molecules per u n i t c e l l . A final difference F o u r i e r map re v e a l e d no peaks above 0.8 e/Â except for peaks a r o u n d the R h centers, some 3

4

2h

3

2

4

3

3


2

3

0

2

2

0

c

2

2

2

2

3


120


T a b l e I.

S u m m a r y o f C r y s t a l D a t a a n d I n t e n s i t y C o l l e c t i o n for Rh H (P(iso-Pr) )4 2

4

3

Compound Formula Temperature Formula weight Space group a b c

Rh H (P(iso-Pr) )4 C eH 8eP Rh -150°C 850.81 a m u 2

3

4

2

11.463(10) Â 16.288(15) Â 23.891(23) Â 93.88(6)° 4450 À 4 1.266 g / c m ( - 1 5 0 ° C ) 1.17(2) g / c m ( 2 0 ° C ) 0.052 m m Μ ο Κ α (λ(ΜοΚα,) = 0.709300 Â ) from monochromator 8.93 c m " 0.71 to 0.73 3.9° ω-step s c a n 3.0° i n ω i n 4 1 s t e p s 1 s/step (41 s t o s c a n r e f l e c t i o n ) 4 s for F > 3a(F ), 14 s for F,,* < 3 σ ( Ρ ) 3.0° < 2Θ < 4 2 . 5 207 5371

β V


4

3

3

Ζ

Density (calculated) Density (observed) Crystal volume Radiation

3

3

3

L i n e a r absorption coefficient T r a n s m i s s i o n factors Take-off angle Scan method Scan range Scan speed

1

2

2

0

B a c k g r o u n d at e a c h e n d

0

20 limits F i n a l no. o f variables Total data collected U n i q u e d a t a u s e d i n final refinement U n i q u e data, F > 3σ(Ρ ) R ( o n F ) for F > 3a(F ) Rw ( o n F ) for F > 3σ(Ρ ) R (on F ) , a l l d a t a Rw ( o n F ) , a l l d a t a " Error i n observation of unit w "e This i g h t includes reflections with F . 0

2

0

2

0

0

0

0

2

2

2

0

2

0

2

a

0

2

4997 2508 0.070 0.070 0.153 0.172

0

0

0

2

1.12 e l e c t r o n s 2

2

< 0.

o f w h i c h may b e h y d r i d o hydrogen atoms (vide infra). Table I I contains the final positional a n d thermal parameters o f the nonhydrogen atoms, e x c l u d i n g the solvent; Table I I I contains parameters for the r i g i d l y refined (18) T H F solvent m o l e c u l e . (A table o f 10 | F 1 vs. 10 | F | for the reflections u s e d i n the refinement a n d a table o f a l k y l h y d r o g e n atom positions has b e e n de p o s i t e d as N A P S D o c u m e n t N o . 03802 w i t h N A P S , c/o M i c r o f i c h e P u b l i c a tions, P.O. B o x 3513, G r a n d C e n t r a l Station, N e w York, N.Y. 10017.) 0

c


7.

T H O R N A N D IBERS

Results and

121

Rh H (P(isopropyl) ) 2

4

3 4

Discussion

Synthesis a n d Spectra o f R h H ( P ( i s o - P r ) 3 ) 4 . 2

This complex was

4

the totally u n e x p e c t e d p r o d u c t o f the reaction o f

RhClH (P(iso-Pr) ) 2

3

w i t h solid s o d i u m h y d r i d e i n T H F under a n argon atmosphere.

2

Once

w h e n the reaction was performed under a hydrogen atmosphere a yel l o w s o l i d w a s o b t a i n e d , b e l i e v e d t o b e R h H ( P ( i s o - P r ) ) (4 ); r e p e a t i n g 3

this

reaction

resulted

Rh H (P(iso-Pr) ) 2

4

3

either

in

the

3

formation

2

of

the

or o f n o tractable p r o d u c t s . T h e alternative

4

thetic method, reacting Rh(

T ? 3

-C H )(P(iso-Pr) ) 3

5

3

gives the d i m e r i c product R h H ( P ( i s o - P r ) ) 2

4

3

2

dimer syn

w i t h h y d r o g e n (10),

i n excellent yield a n d

4


r e a s o n a b l y free f r o m b y - p r o d u c t s . I n b o t h reactions w e s u s p e c t t h e formation

o f the d i m e r R h H ( P ( i s o - P r ) ) 2

4

3

proceeds

4

v i a the initial

f o r m a t i o n o f R h H ( P ( i s o - P r ) ) , w i t h s u b s e q u e n t loss o f h y d r o g e n a n d 3

3

2

d i m e r i z a t i o n . (Loss o f h y d r o g e n f r o m a d i m e r i c i n t e r m e d i a t e is r e l a t e d c l o s e l y t o t h e b i m o l e c u l a r loss o f h y d r o g e n p r o p o s e d b y N o r t o n (19).)

T h e IR spectrum of Rh H (P(iso-Pr) ) 2

4

3

4

i n t h e s o l i d state

(Nujol

m u l l ) s h o w s o n l y a w e a k t e r m i n a l R h - H s t r e t c h i n g b a n d at 2 0 4 0 c m " . 1

B r i d g i n g R h - H absorption bands have not been

observed.

T h e h y d r i d o - h y d r o g e n region o f the room-temperature H - l N M R spectrum o f R h H ( P ( i s o - P r ) ) (in T H F - d ) shows only t w o very broad 2

a n d featureless

4

3

4

8

p e a k s at δ — 1 3 . 3 a n d δ - 1 1 . 6 p p m . N o s i g n i f i c a n t

change w a s observed i n the spectrum w h e n the sample w a s c o o l e d to -20°C;

p r e c i p i t a t i o n o c c u r r e d at l o w e r

temperatures.

The alkyl-

h y d r o g e n r e g i o n o f t h e H - l N M R s p e c t r u m is a l s o u n i n f o r m a t i v e , c o n s i s t i n g o f b r o a d m u l t i p l e t s at δ 1.3 a n d δ 2.0 p p m . A t r o o m t e m p e r a t u r e t h e P - 3 1 { H - 1 } N M R s p e c t r u m ( T H F - d ) is c o m p l i c a t e d . T h e m o s t 8

p r o m i n e n t peaks are a d o u b l e t o f d o u b l e t s ; / - R h 108.5 ΗΖ,/Ρ-RH' 3.2 P

H z , a n d a s e c o n d d o u b l e t (/p^ first,

152.6 H z ) 19.3 p p m u p f i e l d f r o m t h e

Rh

a l l o f a p p r o x i m a t e l y e q u a l i n t e n s i t y . T h i s p a t t e r n is c o n s i s t e n t

w i t h a s t r u c t u r e i n w h i c h e a c h r h o d i u m c e n t e r is b o u n d t o t w o m u t u ally e q u i v a l e n t p h o s p h i n e ligands, y e t the t w o r h o d i u m centers re m a i n n o n e q u i v a l e n t (vide infra). T h e r e are n u m e r o u s a d d i t i o n a l peaks i n t h e P - 3 1 { H - 1 } N M R s p e c t r u m t h a t a r e less i n t e n s e i n c l u d i n g o n e that is a s s i g n a b l e to free p h o s p h i n e ; this m a y r e s u l t f r o m p a r t i a l frag m e n t a t i o n o f the d i m e r (vide infra). F l u x i o n a l processes analogous to t h o s e d i s c o v e r e d for R h H ( P ( 0 - i s o - P r ) ) (JO, 2 0 ) m a y b e o c c u r r i n g i n 2

4

3

4

t h e p r e s e n t s y s t e m as w e l l . Reactions o f Rh H (P(iso-Pr) ) . 2

4

3

4

A s might b e expected from pre

v i o u s w o r k (4), t h i s c o m p l e x r a p i d l y r e a c t s w i t h n i t r o g e n . T h e I R s p e c t r u m o f a N u j o l m u l l o f the s o l i d , p r e p a r e d u n d e r argon, s h o w s o n l y the R h - H s t r e t c h i n g b a n d at 2 0 4 0 c m " . A f t e r b r i e f e x p o s u r e o f t h e m u l l t o 1

n i t r o g e n a s e c o n d w e a k b a n d at 2 1 4 0 c m

- 1

m a y b e d i s c e r n e d w h i c h is

a s s i g n a b l e to t h e N - N s t r e t c h o f R h H ( N ) ( P ( i s o - P r ) ) 2

3

2

(4). B u b b l i n g



Rh(2) P(D P(2) P(3) P(4) C(ll) C(12) C(13) C(14) C(15) C(16) C(17) C(18) C(19) C(21) C(22) C(23) C(24) C(25) C(26) C(27)

mi)

Atom

0.1238(13) -0.0600(13) -0.0223(12) -0.0316(14) 0.1630(14) 0.2018(13)

0.287908(76) 0.343030(78) 0.34986(28) 0.20285(27) 0.27882(26) 0.39596(27) 0.32324(96) 0.3454(10) 0.46455(97) 0.3855(10) 0.2398(11) 0.2570(10) 0.3925(10) 0.4800(11) 0.5067(11) 0.20471(93) 0.2103(10) 0.09059(96) 0.28392(93) 0.1311(10) 0.2990(10) 0.1540(11)

0.106579(52) 0.207304(53) 0.05535(18) 0.04866(17) 0.27552(17) 0.24405(19) -0.01865(64) 0.09446(64) 0.05100(65) -0.05545(68) -0.02361(70) 0.10945(67) 0.06990(67) 0.02260(71) 0.10778(71) -0.02824(59) 0.06386(64) 0.06533(64) -0.05461(59) -0.06358(68) 0.05682(66) 0.03274(65)

BII 2

187.(10) 153.2(99) 260.(34) 280.(34) 235.(33) 240.(35) 2.39(33) 2.66(34) 2.44(34) 2.77(36) 3.48(40) 2.83(36) 2.91(37) 3.43(39) 3.41(39) 1.92(30) 2.64(34) 2.26(33) 1.81(30) 2.99(38) 2.93(36) 2.94(35)

or B , A

b

2

4

B33

BJ2 B13

B23

7.7(36) 2 5 . 0 ( 6 8 ) 14.1(40) 161.1(54) 92.2(27) 3.5(36) 5.7(67) 4.7(41) 99.8(27) 184.1(58) 60.(23) 24.(12) 0.(14) 208.(20) 120.4(98) 28.(23) -10.(12) 26.(14) 93.0(90) 229.(20) 5.(22) 1.(11) -4.(14) 84.7(88) 196.(19) -23.(22) -8.(12) -6.(15) 150.(10) 181.(20)

B22

P o s i t i o n a l a n d T h e r m a l P a r a m e t e r s for t h e N o n g r o u p A t o m s o f R h H ( P ( i s o - P r ) 3 ) 4

0.126289(98) -0.065488(99) -0.27302(34) -0.03761(34) -0.17199(33) 0.10592(34) -0.3179(13) -0.4095(13) -0.2508(13) -0.3843(14) -0.3769(15) -0.4441(14) -0.5181(14) -0.1404(15) -0.2500(15) -0.0660(12)

Table II.


Μ Χ Μ

Γ

Ό

s

ο Ο

w Ό Χ ζ m

> r •β a ο

Η

m

to to


-0.1886(14 -0.0135(14 -0.1823(12; -0.3328(12 -0.1349(12 -0.0581(13; -0.2427(13; -0.3584(14 -0.4153(14; -0.1732(13 -0.1657(14 0.2261(13; 0.1012(15; 0.1737(15; 0.2535(15 0.1988(14; 0.0317(17 0.2175(18 0.2983(19; 0.0990(16

4

3

0.06823(98) 0.0682(10) 0.16410(95) 0.30433(86) 0.29866(94) 0.12690(96) 0.13427(93) 0.3966(10) 0.26453(97) 0.23435(94) 0.3849(10) 0.31950(93) 0.4522(11) 0.4615(11) 0.2696(11) 0.2668(11) 0.5316(13) 0.4762(13) 0.4968(13) 0.5328(12)

0.05439(66) 0.12417(66) 0.27080(60) 0.26123(57) 0.35178(60) 0.27855(64) 0.21718(62) 0.25560(66) 0.30072(67) 0.39388(63) 0.36863(68) 0.26212(63) 0.30971(71) 0.19317(70) 0.21056(72) 0.31049(70) 0.30529(81) 0.34360(86) 0.20701(87) 0.16973(76)

b

2

2.64(35) 2.80(36) 1.86(31) 1.30(29) 2.01(31) 2.52(35) 2.19(33) 2.86(36) 2.90(36) 2.36(34) 2.98(37) 2.25(33) 3.57(40) 3.35(39) 3.71(41) 3.33(39) 4.90(48) 5.61(52) 5.89(54) 4.33(44)

or B , A

BJI

2

B22

2

B33

BJ2

Bi3

P o s i t i o n a l a n d T h e r m a l P a r a m e t e r s for the N o n g r o u p A t o m s o f R h 2 H ( P ( i s o - P r ) ) 4 B23

5

2

' Estimated standard deviations in the least significant figure(s) are given in parentheses in this and all subsequent tables. » The form of the anisotropic thermal ellipsoid is: exp[-(B 1 1 H + B 2 2 K + B 3 3 L + 2 B 1 2 H K + 2 B 1 3 H L + 2 B 2 3 K L )]. The quantities given in the table are the thermal coefficients x 10 .

Atom

T a b l e II.



C

c

0.4804(49)

Yc

Β,Α

c

x

b

-3.121(62)

S

-0.032(10) -0.0565(91)

Parameters

C(3) C(4)

Atom

0.5087(33)

Z

Group

6.4(18) 6.4(18) 6.4(18)

Rigid

0.4849(38) 0.4643(39) 0.5064(50)

ζ

c

°X , Yc, and Z are the fractional coordinates of the origin of the rigid group. The rigid group orientation angles δ, €, and 17 (radians) have been defined previously (18).

fe

Group

a

y 2

4

y

3

4

ζ

2

η

6.4(18) 6.4(18)

Β,Α

-2.138(62)

0.5509(40) 0.5371(39)

-2.667(58)

e

0.4409(68) 0.5312(64)

2

D e r i v e d P a r a m e t e r s for t h e R i g i d G r o u p A t o m s o f R h H ( P ( i s o - P r ) )

0.5480(50) 0.4751(63) 0.4066(50)

0.0022(76)

O(l) C(l) C(2)

THF

0.0002(89) 0.0596(89) 0.039(10)

X

x

Atom

Table III.


7.

125



2

3

4

nitrogen through a toluene solution of R h H ( P ( i s o - P r ) ) 4 , followed 2

4

3

evaporation of the t o l u e n e a n d recrystallization o f the residue

from

hexane

under

nitrogen,

[ R h H ( P ( i s o - P r ) ) ] ( / x - N ) (4).

results

i n the

of

were

i d e n t i f i e d p o s i t i v e l y b y t h e i r m e a s u r e d d e n s i t y (1.24(1) g / c m ;

com

p a r e d w i t h 1.260 g / c m

from

2

2

2

the

formation

latter p r o d u c t

3

Crystals of

by

yellow-orange

3

3

(4))

a n d the lattice constants o b t a i n e d

X - r a y film d a t a . T h e observed reactivity towards nitrogen indicates a possible dis sociation of the d i m e r i c m o l e c u l e into m o n o m e r i c fragments, w i t h one


c o n c e i v a b l e f r a g m e n t a t i o n m o d e i n d i c a t e d i n E q u a t i o n 1. Rh H (P(iso-Pr) ) 2

However,

4

3

^

4

RhH(P(iso-Pr) ) 3

+ RhH (P(iso-Pr) )

2

3

3

(1)

2

f r a g m e n t a t i o n is n o t o c c u r r i n g fast e n o u g h to a v e r a g e t h e

signals i n the P-31 N M R s p e c t r u m . B o t h o f the m o n o m e r i c r e s u l t i n g f r o m t h i s f r a g m e n t a t i o n m o d e (see

complexes

E q u a t i o n 1) a r e k n o w n

to r e a c t r a p i d l y w i t h n i t r o g e n t o g i v e R h H ( N ) ( P ( i s o - P r ) ) , w h i c h 2

3

t h e n d i m e r i z e s to g i v e [ R h H ( P ( i s o - P r ) ) ] ( μ - Ν ) 3

2

2

2

(4).

p e a r s t o r e a c t o n l y s l o w l y or n o t at a l l w i t h R h H ( P ( i s o - P r ) ) 2

2

Hydrogen

4

3

t e m p e r a t u r e . W e h a v e not o b s e r v e d a t h e r m a l loss o f h y d r o g e n room-temperature

ap

at r o o m

4

from

s o l u t i o n s o f t h e d i m e r a n d t h e s o l i d a p p e a r s to b e

v e r y s t a b l e u n d e r a r g o n at r o o m t e m p e r a t u r e . Room-temperature

solutions of Rh H (P(iso-Pr) ) 2

4

3

i n deuteroben-

4

z e n e u n d e r g o r a p i d H - D e x c h a n g e w i t h t h e s o l v e n t , as i n d i c a t e d b y the H - l N M R s p e c t r u m ; the s i g n a l o f C H D _ e

n

e

n

r a p i d l y gains intensity

a n d t h e h y d r i d o s i g n a l s d i s a p p e a r . T h e r e a c t i o n is c o m p l i c a t e d b y a n apparent concurrent H - D exchange w i t h the m e t h y l h y d r o g e n

atoms

o f t h e t r i i s o p r o p y l p h o s p h i n e l i g a n d s . T h e a c t i v e s p e c i e s for t h e

ex

c h a n g e reaction(s) m i g h t b e the d i m e r or m o n o m e r i c c o m p l e x e s

de

rived

from

its

fragmentation.

phine)rhodium complexes

are

Mononuclear active

bis(triisopropylphos-

c a t a l y s t s for

H - D

exchange

r e a c t i o n s (21 ). None

o f t h e e x p e r i m e n t s or s p e c t r a l d a t a p r e s e n t e d a b o v e p r o

v i d e s g o o d e v i d e n c e for o u r f o r m u l a t i o n o f t h e d i m e r as a t e t r a h y d r i d e . I n fact w e

i n i t i a l l y h a d b e l i e v e d t h e c o m p o u n d to b e a d i h y d r i d e ,

Rh H (P(iso-Pr) ) , 2

2

3

RhH(P(iso-Pr) ) 3

or

4

2

possibly

a

monomeric

monohydride,

(2, 4 ). T h e d i m e r i c n a t u r e is p r o v e d b y t h e c r y s t a l

s t r u c t u r e . W e b e g a n to s u s p e c t t h e p r e s e n c e o f m o r e h y d r i d o l i g a n d s after

completing

the

isopropylphosphite

structure a n d l e a r n i n g o f the

complexes

studied

by

Sivak

analogous

and

tri-

Muetterties

(10, 2 0 ) . O u r p r e s e n t e v i d e n c e for t h e t e t r a h y d r i d e is d e r i v e d f r o m a n e x p e r i m e n t i n w h i c h a large excess o f t r i m e t h y l p h o s p h i t e w a s v a c u u m transferred into a degassed, frozen solution of a k n o w n amount o f the



1 2 6

d i m e r i c complex. T h e solution was w a r m e d to r o o m temperature a n d s t i r r e d for 1 h , d u r i n g w h i c h t i m e the c o l o r c h a n g e d from d a r k green to red and

finally

t o y e l l o w , a n d h y d r o g e n gas w a s e v o l v e d . T h e s o l u

t i o n w a s t h e n r e f r o z e n a n d t h e a m o u n t o f gas p r e s e n t w a s

measured

w i t h a T o e p l e r p u m p . O n e m o l o f h y d r o g e n gas w a s e v o l v e d p e r m o l e o f d i m e r . T h e final s o l u t i o n w a s d r i e d i n v a c u u m a n d t h e r e s i d u e c o n sisted entirely o f R h H ( P ( O M e ) ) 3

( H - l N M R a n a l y s i s (10)). T h i s s e

4

q u e n c e o f r e a c t i o n s , s u m m a r i z e d i n S c h e m e I, is c o n s i s t e n t o n l y w i t h a f o r m u l a t i o n o f t h e d i m e r as a t e t r a h y d r i d e .


Scheme 1. Rh H (P(iso-Pr) ) 2

4

3

excess P(OMe)

2

8

% [RhH (P(OMe) )*]„

4

2

3

( r e d ; see R e f . J O ) excess P ( O M e )

(dark green)

3

2RhH(P(OMe) ) (yellow) 3

+ H

4

2

F u r t h e r e v i d e n c e for a tetrahydride comes from the reaction o f a k n o w n a m o u n t o f the d i m e r w i t h a n excess o f 1-hexene. A f t e r s e v e r a l h o u r s t h e a m o u n t o f h e x a n e p r o d u c e d w a s 1.4 ± 0 . 2 m m o l o f h e x a n e p e r m i l l i m o l e o f d i m e r (gas c h r o m a t o g r a p h y suggests

( G C ) analysis).

This

a rather c o m p l i c a t e d reaction b u t requires more t h a n o n e

h y d r i d o l i g a n d per r h o d i u m center. T h e nature o f the reaction a n d t h e resulting residual compound(s) are still under investigation. Description of the Structure.

T h e m o l e c u l a r structure o f the

present c o m p l e x c l o s e l y resembles that o f the P(£-Bu) ) ] 2

2

between

+

[Pt H^(t-Bu)2P(CH )r 2

2

cation (22). A formal electronic analogy c a n b e

the t w o complexes;

Pt H3(PR3)4 2

is i s o e l e c t r o n i c

+

made with a

h y p o t h e t i c a l c o m p o u n d R t ^ H ^ P R ^ " w h i c h c a n b e p r o t o n a t e d (con ceptually)

to give

the complex

Rh H (PR ) . 2

4

3

4

T h e structural re

semblance u n d o u b t e d l y results from this close electronic similarity. Another

species

to w h i c h

the present

complex

is r e l a t e d ,

both

b y s t r u c t u r a l s i m i l a r i t y a n d e l e c t r o n i c a n a l o g y , is [ I r H ( P P h ) ] (23, 2

5

3

4

+

24). D e p r o t o n a t i o n o f a h y p o t h e t i c a l r h o d i u m d i m e r o f this formula tion, R h H ( P R ) 2

5

3

4

+

, w o u l d give the present complex.

A d r a w i n g o f t h e p r e s e n t m o l e c u l e i s p r e s e n t e d i n F i g u r e 1. E a c h r h o d i u m c e n t e r is c o o r d i n a t e d b y t w o t r i i s o p r o p y l p h o s p h i n e l i g a n d s , the other r h o d i u m atom, a n d several h y d r i d o h y d r o g e n ligands (vide infra). A t o m Rh(2) lies 0.46 À a b o v e t h e p l a n e d e f i n e d b y atoms P ( l ) , P(2), a n d R h ( l ) ; a t o m R h ( l ) l i e s 0 . 9 4 À a b o v e t h e p l a n e d e f i n e d b y atoms Rh(2), P(3), a n d P(4). T h e d i h e d r a l angle b e t w e e n the planes d e f i n e d b y R h ( l ) , P ( l ) , P ( 2 ) , a n d R h ( 2 ) , P ( 3 ) , P ( 4 ) is 72.6°. ( H y d r i d o bridged, transition-metal dimers o f the formula M H 2

X

L

4

exhibit a



7.



2

127

3

4

r a n g e o f d i h e d r a l a n g l e s t h a t h a s b e e n p r o b e d t h e o r e t i c a l l y (25).) S e l e c t e d b o n d distances a n d angles are l i s t e d i n T a b l e IV. T h e

Rh-Rh

s e p a r a t i o n o f 2 . 6 1 8 ( 3 ) Â is s l i g h t l y s h o r t e r t h a n t h e d i s t a n c e o f 2.650( 1) À i n ( R h H ( P ( 0 - i s o - P r ) ) ) 2 a n d c o n s i d e r a b l y shorter t h a n the R h - R h 3

2

s e p a r a t i o n s r e p o r t e d for ( R h H ( P ( O M e ) ) ) 3 (the a v e r a g e is 2 . 8 1 À ) (20, 3

26, 27). T h e

2

s e p a r a t i o n is p e r h a p s b e l o w

the range

f o r m a l R h - R h s i n g l e b o n d , e.g., 2.88(2) À i n R h ( P F ) 2

3

expected 8

for a

(28), b u t n e e d

n o t b e c o n s t r u e d as i n d i c a t i n g a f o r m a l s i n g l e or m u l t i p l e b o n d i n t h e p r e s e n t c a s e (20, 2 3 , 2 4 , 2 9 , 3 0 ,

31).

T h e u n i t - c e l l p a c k i n g is i l l u s t r a t e d i n F i g u r e 2. P a c k i n g o f t h e d i m e r i c m o l e c u l e s a p p e a r s to b e d e t e r m i n e d b y i n t e r m o l e c u l a r v a n der Waals a n d steric interactions a m o n g the a l k y l h y d r o g e n

atoms.

T h e c l o s e s t i n t e r m o l e c u l a r Η · · · H c o n t a c t is 2 . 3 1 Â b e t w e e n a t o m H(2) o n C(25) a n d atom H ( l )

on C(37).

T h e t w o r h o d i u m centers are d i s t i n c t l y n o n e q u i v a l e n t i n the s o l i d state. T h e R h ( l ) - P ( l ) a n d R h ( l ) - P ( 2 ) b o n d l e n g t h s (see T a b l e I V )

are

i n s i g n i f i c a n t l y different a n d are b o t h shorter t h a n the R h ( 2 ) - P ( 3 ) a n d Rh(2)-P(4) bond

lengths.

The

Rh(l)-P

bond

lengths

(averaging

2.250(6) Â ) are t h e s h o r t e s t e v e r o b s e r v e d i n a t r i i s o p r o p y l p h o s p h i n e r h o d i u m structure. Values found previously i n low-temperature


struc-

M E T A L PHOSPHINE C O M P L E X E S

128

T a b l e IV.

S e l e c t e d B o n d D i s t a n c e s (À) a n d A n g l e s (Degrees) for R h H ( P ( i s o - P r ) )


2

4

Rh(l)-Rh(2) Rh(l)-P(l) Rh(l)-P(2) Rh(2)-P(3) Rh(2)-P(4)

2.618(3) 2.251(5) 2.249(5) 2.347(4) 2.267(5)

P(l)-Rh(l)-P(2) P(3)-Rh(2)-P(4) P(l)-Rh(l)-Rh(2) P(2)-Rh(l)-Rh(2) P(3)-Rh(2)-Rh(l) P(4)-Rh(2)-Rh(l) P(D-C(11) P(D-C(12) P(D-C(13) P(2)-C(21) P(2)-C(22) P(2)-C(23) P(3)-C(31) P(3)-C(32) P(3)-C(33) P(4)-C(41) P(4)-C(42) P(4)-C(43) C(ll)-C(14) C(ll)-C(15) C(12)-C(16) C(12)-C(17) C(13)-C(18) C(13)-C(19) C(21)-C(24) C(21)-C(25) C(22)-C(26) C(22)-C(27) C(23)-C(28) C(23)-C(29) C(31)-C(34) C(31)-C(35) C(32)-C(36) C(32)-C(37) C(33)-C(38) C(33)-C(39) C(41)-C(44) C(41)-C(45) C(42)-C(46) C(42)-C(47) C(43)-C(48) C(43)-C(49)

107.1(2) 112.2(2) 119.2(1) 132.3(1) 111.5(1) 131.0(1) 1.86(2) 1.88(2) 1.89(2) 1.84(2) 1.87(2) 1.89(2) 1.88(2) 1.90(1) 1.87(1) 1.89(2) 1.82(2) 1.83(2) 1.51(2) 1.52(2) 1.54(2) 1.54(2) 1.50(2) 1.52(2) 1.53(2) 1.53(2) 1.53(2) 1.51(2) 1.52(2) 1.51(2) 1.55(2) 1.50(2) 1.54(2) 1.52(2) 1.54(2) 1.51(2) 1.53(2) 1.49(2) 1.52(2) 1.57(2) 1.55(2) 1.53(2)

a

3

4

a

Rh(l) - P ( D - C ( l l ) Rh(l) - P ( D -C(12) Rh(l) - P ( D -C(13) Rh(l) -P(2) -C(21) Rh(l) -P(2) -C(22) Rh(l) -P(2) -C(23) Rh(2) - P ( 3 ) - C ( 3 1 ) Rh(2) - P ( 3 ) - C ( 3 2 ) Rh(2) - P ( 3 ) - C ( 3 3 ) Rh(2) - P ( 4 ) - C ( 4 1 ) Rh(2) - P ( 4 ) - C ( 4 2 ) Rh(2) - P ( 4 ) - C ( 4 3 ) C ( l l ) - P ( D -C(12) C ( l l ) - P ( D -C(13) C(12) - P ( D - C ( 1 3 ) C(21) - P ( 2 ) - C ( 2 2 ) C(21) - P ( 2 ) - C ( 2 3 ) C(22) - P ( 2 ) - C ( 2 3 ) C(31) - P ( 3 ) - C ( 3 2 ) C(31) - P ( 3 ) - C ( 3 3 ) C(32) - P ( 3 ) - C ( 3 3 ) C(41) - P ( 4 ) - C ( 4 2 ) C(41) - P ( 4 ) - C ( 4 3 ) C(42) -P(4) - C ( 4 3 )

124.1(5) 109.2(5) 112.0(5) 123.1(5) 108.9(5) 113.1(5) 115.8(5) 108.8(5) 120.3(5) 116.0(5) 116.7(6) 111.1(6) 106.2(7) 102.0(7) 100.7(7) 107.4(7) 102.0(7) 99.7(7) 98.7(6) 103.9(7) 106.9(6) 101.5(7) 101.6(7) 108.5(8)

The numbering scheme for carbon atoms is identical with that used in Ref. 4.



7.


129


4

3 4

t u r e d e t e r m i n a t i o n s a r e 2.273(3) À (ave) (4), 2.348(1) À (32, 3 3 ) i n R h ( I ) - d i n i t r o g e n c o m p l e x e s , 2.31(1) Â (ave) i n a R h ( I I I ) - b i c a r b o n a t o c o m p l e x ( 3 ) , a n d 2.294(3) (ave) a n d 2.330(1) À i n R h H ( P ( i s o - P r ) ) (6). T h e P ( l ) - R h - P ( 2 ) b o n d a n g l e , 107.1(2)°, is t h e s m a l l e s t s u c h a n g l e t h u s far f o u n d for t r i i s o p r o p y l p h o s p h i n e l i g a n d s b o n d e d t o r h o d i u m , s m a l l e r e v e n t h a n t h e a n g l e 109.2(8)° f o u n d b e t w e e n c i s - p h o s p h i n e ligands i n RhH(P(iso-Pr) ) (6). A s i n RhH(P(iso-Pr) ) the small P - R h - P angle causes significant distortions w i t h i n t h e triisopropyl p h o s p h i n e l i g a n d s (see T a b l e I V ) (6). T h e s m a l l a n g l e a n d a c c o m p a n y i n g steric strain p r o b a b l y w o u l d not prevail i n the present m o l e c u l e u n l e s s t h e r e w e r e o t h e r l i g a n d s ( h y d r i d o h y d r o g e n a t o m s , v i d e infra) a r o u n d the r h o d i u m centers. 3

3

3

3

3

3

P o s s i b l e H y d r i d o H y d r o g e n A t o m L o c a t i o n s . I t is p o s s i b l e t o obtain reasonably u n a m b i g u o u s h y d r i d o hydrogen atom positions f r o m l o w - o r e v e n r o o m - t e m p e r a t u r e X - r a y d i f f r a c t i o n d a t a (34), b u t i n the present structure t h e h i g h m o s a i c i t y o f the c r y s t a l — p o s s i b l y a re sult o f partial solvent l o s s — w i t h resulting d i m i n u t i o n i n the quality a n d q u a n t i t y o f the diffraction data has p r e v e n t e d this. H o w e v e r , b a s e d o n the angles a n d b o n d distances a r o u n d the r h o d i u m a n d p h o s p h o r u s a t o m s , a n d t h e l o c a t i o n s o f r e s i d u a l e l e c t r o n - d e n s i t y p e a k s i n t h e final d i f f e r e n c e F o u r i e r m a p , r e a s o n a b l e sites o f s o m e o f t h e h y d r i d o h y d r o gen atoms c a n b e postulated. A r o u n d the Rh(2) center the most l i k e l y s i t e o f a h y d r o g e n a t o m is t r a n s t o a t o m P ( 3 ) (see D i a g r a m I b e l o w ) , suggested b y the large R h ( l ) - R h ( 2 ) - P ( 4 ) angle a n d the l o n g R h ( 2 ) -


130



Rh(l)

Rh(2)

131.0(1)° I P(3) b o n d d i s t a n c e . T h e largest r e s i d u a l e l e c t r o n - d e n s i t y p e a k i n t h e final

différence F o u r i e r m a p is at t h a t p o s i t i o n a n d a h y d r o g e n a t o m

H ( l ) c a n b e p l a c e d there w i t h some confidence. T h e p l a c e m e n t o f h y d r o g e n a t o m s a b o u t t h e R h ( l ) c e n t e r i s less c e r t a i n . A n g l e s a n d R h ( l ) - P d i s t a n c e s (see D i a g r a m II b e l o w ) s u g g e s t

119.2(1)

~

132.3(1)

II


7.


131


4

3 4

the possible presence of two h y d r i d o h y d r o g e n atoms, H(2) a n d H(3), i n or a p p r o x i m a t e l y i n the l o c a l c o o r d i n a t i o n p l a n e . A g a i n there are re s i d u a l e l e c t r o n - d e n s i t y p e a k s at a b o u t t h e s e l o c a t i o n s . T h e s e three h y d r o g e n atoms, H ( l ) , H(2), a n d H(3), are p r o p e r l y c o n s i d e r e d to b e b r i d g i n g h y d r i d o l i g a n d s . T h e p o s i t i o n o f t h e f o u r t h h y d r i d o h y d r o g e n a t o m is n o t at a l l a p p a r e n t f r o m t h e s t r u c t u r a l d a t a . F r o m t h e I R s p e c t r u m i t is r e a s o n a b l e t o a s s u m e at l e a s t o n e t e r m i n a l h y d r i d o l i g a n d , b u t w h e t h e r i t is b o n d e d to a t o m R h ( l )

or Rh(2)

u n c e r t a i n . O n e l i k e l y l o c a t i o n is o n a t o m R h ( l ) , a b o v e t h e R h ( l ) ,

is

P(l),

P(2) p l a n e , a p p r o x i m a t e l y t r a n s to t h e b r i d g i n g a t o m H ( l ) . T h e r e s u l t


i n g s t r u c t u r e is s k e t c h e d b e l o w i n D i a g r a m I I I . It is t h e s t r u c t u r e S i v a k and

Muetterties

(10)

have

p o s t u l a t e d for t h e a n a l o g o u s

R h H ( P ( 0 - i s o - P r ) ) 4 , based on their N M R 2

4

3

complex

evidence.

Ilia

Illb

A n a t t r a c t i v e f e a t u r e o f t h i s s t r u c t u r e is t h a t i f i t is d r a w n as i n D i a g r a m I l l b i t c a n b e e n v i s i o n e d as a R h ( I I I ) - R h ( I )

mixed-valence

c o m p o u n d h e l d together b y h y d r i d o bridges. I n this p i c t u r e the

Rh(l)

c e n t e r is i n t h e + 3 o x i d a t i o n state, a n d w o u l d b e e x p e c t e d to h a v e a s m a l l e r covalent radius a n d shorter R h - P b o n d lengths t h a n those o f t h e R h ( 2 ) c e n t e r , w h i c h is o s t e n s i b l y i n t h e + 1 o x i d a t i o n state. It is p o s s i b l e , h o w e v e r , to e n v i s i o n a t e r m i n a l h y d r i d o h y d r o g e n

ligand

b o n d e d to R h ( 2 ) . T h e r e a r e , i n fact, s e v e r a l r e s i d u a l e l e c t r o n - d e n s i t y peaks a r o u n d the Rh(2) center w h i c h are p r o b a b l y noise b u t w h i c h m i g h t b e a s c r i b a b l e to a t e r m i n a l l y b o u n d h y d r i d o h y d r o g e n l i g a n d . Summary and

Conclusions

T h e p r e s e n t c o m p l e x , R h H ( P ( i s o - P r ) 3 ) 4 , is y e t a n o t h e r m e m b e r o f 2

the large family of R h H P x

pared and studied (I-6,

y

10).

4

c o m p l e x e s that r e c e n t l y h a v e b e e n

pre

It c a n b e v i e w e d c o n c e p t u a l l y a n d p e r

h a p s c h e m i c a l l y as w e l l as a c o m b i n a t i o n o f R h H ( P ( i s o - P r ) ) 3

with

2

R h H ( P ( i s o - P r ) ) , a n d it m a y b e a n i n t e r m e d i a t e i n the hydrogénation 3

3

2

o f R h H ( P ( i s o - P r ) ) , 3 a n d t h e d e h y d r o g e n a t i o n o f R h H ( P ( i s o - P r ) ) (4 ). 3

2

Its c h e m i s t r y h a s o n l y b e g u n

3

to b e

explored;

3

2

however it—or


the

132

M E T A L PHOSPHINE C O M P L E X E S

s p e c i e s r e s u l t i n g f r o m its f r a g m e n t a t i o n — i s c a p a b l e o f u n d e r g o i n g H - D exchange with C D e

e

a n d may be catalytically active i n numerous

other reactions.

Acknowledgments


W e t h a n k J o h n s o n M a t t h e y , I n c . , M a l v e r n , P e n n s y l v a n i a for t h e l o a n o f r h o d i u m u s e d i n this study. W e w i s h to t h a n k E . L . M u e t t e r t i e s for h e l p f u l s u g g e s t i o n s a n d for c o m m u n i c a t i n g r e s u l t s p r i o r t o p u b l i c a tion. T h i s work was supported b y the U . S . National Science F o u n d a tion ( C H E 76-10335). Literature

Cited

1. Hoffmann, P. R.; Yoshida, T.; Okano, T.; Otsuka, S.; Ibers, J. A. Inorg. Chem. 1976, 15, 2462-2466. 2. Yoshida, T.; Okano, T.; Otsuka, S. J. Chem. Soc. Chem. Commun. 1978, 855-856. 3. Yoshida, T.; Thorn, D. L.; Okano, T.; Ibers, J. Α.; Otsuka, S. J. Am. Chem. Soc. 1979, 101, 4212-4221. 4. Yoshida, T.; Okano, T.; Thorn, D. L.; Tulip, T. H.; Otsuka, S.; Ibers, J. A. J. Organometal. Chem. 1979, 181, 183-201. 5. Yoshida, T.; Otsuka, S.; Matsumoto, M.; Nakatsu, K. Inorg. Chim. Acta 1978, 29, L257-L259. 6. Yoshida, T.; Thorn, D. L.; Okano, T.; Otsuka, S.; Ibers, J. A. J. Am. Chem. Soc. 1980, 102, 6451-6957. 7. Werner, H.; Feser, R.; Buchner, W. Chem. Ber. 1979, 112, 834-843. 8. Van Gaal, H . L. M., Ph.D. Thesis, Katholieke Universiteit te Nijmegen, 1977. 9. van der Ent, Α.; Onderdelinden, A. L.; Inorg. Synth. 1973, 14, 92-93. 10. Sivak, A. J.; Muetterties, E . L. J. Am. Chem. Soc. 1979, 101, 4878-4887. 11. Lenhert, P. G. J. Appl. Crystallogr. 1975, 8, 568-570. 12. Huffman, J. C., Ph.D. Thesis, Indiana Univ., 1974. 13. Corfield, P. W. R.; Doedens, R. J.; Ibers, J. A. Inorg. Chem. 1967, 6, 197204. 14. Stewart, R. F.; Davidson, E . R.; Simpson, W. T. J. Chem. Phys. 1965, 42, 3175-3187. 15. Cromer, D. T.; Waber, J. T. "International Tables for X-ray Crystallog raphy"; Kynoch: Birmingham, England, 1974; Vol. 4, Table 2.2A. 16. Cromer, D. T. "International Tables for X-ray Crystallography;" Kynoch: Birmingham, England, 1974; Vol. 4, Table 2.3.1. 17. Waters, J. M.; Ibers, J. A. Inorg. Chem. 1977, 16, 3273-3277. 18. L a Placa, S. J.; Ibers. J. A. Acta Crystallogr. 1965, 18, 511-519. 19. Norton, J. R. Acc. Chem. Res. 1979, 12, 139-145. 20. Brown, R. K.; Williams, J. M.; Fredrich, M. F.; Day, V. W.; Sivak, A. J.; Muetterties, E . L. Proc. Natl. Acad. Sci. USA 1979, 76, 2099-2102. 21. Yoshida, T.; Okano, T.; Saito, K.; Otsuka, S. Inorg. Chim. Acta 1980, 44, L135-L136. 22. Tulip, T. H.; Yamagata, T.; Yoshida, T.; Wilson, R. D.; Ibers, J. Α.; Otsuka, S. Inorg. Chem. 1979, 18, 2239-2250. 23. Crabtree, R. H.; Felkin, H.; Morris, G. E . ; King, T. J.; Richards, J. A. J. Organometal. Chem. 1976, 113, C 7 - C 9 . 24. Crabtree, R. H.; Felkin, H.; Morris, G. E. J. Organometal. Chem. 1977, 141, 205-215.



7.

THORN AND IBERS


4

3 4

133

25. Barnett, B. L.; Krüger, C.; Tsay, Y.-H.; Summerville, R. H.; Hoffmann, R. Chem. Ber. 1977, 110, 3900-3909. 26. Day, V. W.; Fredrich, M. F.; Reddy, G. S.; Sivak, A. J . ; Pretzer, W. R.; Muetterties, E . L. J. Am. Chem. Soc. 1977, 99, 8091-8093. 27. Brown, R. K.; Williams, J. M.; Sivak, A. J.; Muetterties, E . L. Inorg. Chem. 1980, 19, 370—374. 28. Bennett, Μ. Α.; Johnson, R. N.; Turney, T. W. Inorg. Chem. 1976, 15, 2938-2941. 29. Bau, R.; Teller, R. G.; Kirtley, S. W.; Koetzle, T. F. Acc. Chem. Res. 1979, 12, 176-183. 30. Dedieu, Α.; Albright, Τ. Α.; Hoffmann, R. J. Am. Chem. Soc. 1979, 101, 3141-3151. 31. Summerville, R. H.; Hoffmann, R. J. Am. Chem. Soc. 1979, 101, 38213831. 32. Thorn, D. L.; Tulip, T. H.; Ibers, J. A. J. Chem. Soc. Dalton 1979, 20222025. 33. Busetto, C.; D'Alfonso, Α.; Maspero, F.; Perego, G.; Zazzetta, A. J. Chem. Soc. Dalton 1977, 1828-1834. 34. Ibers, J. A. In "Transition Metal Hydrides," Adv. Chem. Ser. 1978, 167, 26-35. RECEIVED July 10, 1980.


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