Preparation and X-Ray Structure of a Hydrazine-Bridged Dinuclear

24 Preparation and X-Ray Structure of a Hydrazine-Bridged Dinuclear Molybdenum Complex [ M o ( S C N ( C H ) ) ( C O ) ] N H . 2

2

5

2

2

2

2

2

4

CH Cl

Downloaded by PURDUE UNIV on April 9, 2016 | http://pubs.acs.org Publication Date: June 1, 1977 | doi: 10.1021/ba-1977-0162.ch024

2

2

J. A. BROOMHEAD and J. BUDGE Department of Chemistry, Faculty of Science, Australian National University, Canberra A.C.T. 2600, Australia J. H. ENEMARK, R. D. FELTHAM, J. I. GELDER, and P. L. JOHNSON Department of Chemistry, University of Arizona, Tucson, AZ 85721

The reaction of hydrazine with bis(diethyldithiocarbamato) -dicarbonylmolybdenum, Mo(S CN(C H ) ) (CO) , results in formation of the dimeric complex [Mo(S CN(C H ) ) (CO) ] N H , (1). The H NMR spectrum of 1 in CDCl is consistent with the solid state composition. Determination of the structure of the CH Cl solvate of 1 by x-ray diffrac tion has shown that the two crystallographically independent molybdenum atoms are asymmetrically bridged by the hydrazine ligand (Mol-N5=2.36(1) and Mo2-N6=2.44(1) Å). Each molybdenum atom is seven-coordinate, but their stereochemistries are not identical. The bridging hydrazine ligand is disordered about two well resolved positions, and the N - N distance is 1.44(2) Å. 2

2

5

2

2

2

2

2

5

2

2

1

2

2

2

4

3

2

2

o o r d i n a t e d h y d r a z i n e has f r e q u e n t l y b e e n p r o p o s e d as a n i n t e r m e d i a t e ^ i n t h e r e d u c t i o n of c o o r d i n a t e d d i n i t r o g e n t o a m m o n i a . ( See for e x a m p l e R e f . 1 a n d references t h e r e i n . ) A l t h o u g h h y d r a z i n e is k n o w n to f o r m a v a r i e t y of t r a n s i t i o n m e t a l c o m p l e x e s ( 2 ) a n d has b e e n s h o w n t o react w i t h s e v e r a l m o l y b d e n u m c o m p l e x e s ( 3 , 4), there is l i t t l e d e t a i l e d s t r u c tural information about

discrete m e t a l c o m p l e x e s o f h y d r a z i n e . T w o

r e c e n t reports ( 5 , 6 ) d e s c r i b e t h e p r e p a r a t i o n a n d s t r u c t u r e d e t e r m i n a tions o f t w o m o l y b d e n u m c o m p l e x e s d e r i v e d f r o m s u b s t i t u t e d h y d r a z i n e s . 421

Raymond; Bioinorganic Chemistry—II Advances in Chemistry; American Chemical Society: Washington, DC, 1977.

422

BIOINORGANIC

T h i s c h a p t e r describes compound,

CHEMISTRY

t h e p r e p a r a t i o n a n d m o l e c u l a r s t r u c t u r e of

1, i n w h i c h h y d r a z i n e itself is c o o r d i n a t e d to t w o

II

a

molyb

d e n u m atoms. Experimental Preparation of [ M o ( S 2 C N ( C 2 H ) 2 ) 2 ( C O ) 2 ] 2 N 2 H 4 . Molybdenum h e x a c a r b o n y l ( 1 g, 3.79 m m o l ) w a s p l a c e d i n a 2 5 0 - m l t h r e e - n e c k e d flask fitted w i t h a m a g n e t i c stirrer. A n i t r o g e n s t r e a m w a s t h e n p a s s e d t h r o u g h t h e flask a n d w a s m a i n t a i n e d t h r o u g h o u t the p r e p a r a t i o n . A l l solvents u s e d i n the p r e p a r a t i o n w e r e t h o r o u g h l y d e o x y g e n a t e d . D i c h l o r o m e t h a n e ( 2 0 m l ) w a s a d d e d a n d the s u s p e n s i o n c o o l e d i n a n a c e t o n e - s o l i d C 0 b a t h . D i b r o m i n e (0.61 g, 3.79 m m o l ) i n d i c h l o r o m e t h a n e ( 2 m l ) w a s a d d e d d r o p w i s e to t h e s t i r r e d s u s p e n s i o n . U p o n w a r m i n g to r o o m t e m perature, carbon monoxide was evolved a n d dibromotetracarbonylmolybd e n u m ( I I ) f o r m e d . D i c h l o r o m e t h a n e w a s a l l o w e d to evaporate i n the n i t r o g e n s t r e a m b e f o r e a d d i n g m e t h a n o l ( 1 0 m l ) a n d t h e n a s o l u t i o n of s o d i u m d i e t h y l d i t h i o c a r b a m a t e - 3 - h y d r a t e ( 1.71 g, 7.58 m m o l ) i n m e t h a n o l ( 1 0 m l ). D i c h l o r o m e t h a n e ( ~ 15 m l ) w a s a d d e d to the p r e c i p i t a t e d m i x t u r e of d i - a n d t r i c a r b o n y l complexes ( 7 ) , a n d t h e s o l u t i o n w a s s t i r r e d for a b o u t 10 m i n . H y d r a z i n e - 1 - h y d r a t e 9 9 % w / w (0.15 g, 3 m m o l ) i n m e t h a n o l ( 1 m l ) w a s next a d d e d s l o w l y . I m m e d i a t e l y t h e solution became dark red, a n d a bright r e d crystalline product ( 1 ) was obtained. 5


2

T h e r e a c t i o n vessel w a s t r a n s f e r r e d to a g l o v e - b o x a n d the p r o d u c t r e m o v e d b y filtration u n d e r n i t r o g e n . T h e p r o d u c t w a s w a s h e d w i t h m e t h a n o l ( 3 X 10 m l ) a n d d i s s o l v e d i n d i c h l o r o m e t h a n e ( 10 m l ) to w h i c h a d r o p of h y d r a z i n e - 1 - h y d r a t e h a d b e e n a d d e d . T h e a d d i t i o n of m e t h a n o l ( 5 0 m l ) r e s u l t e d i n the f o r m a t i o n of crystals of 1. A f t e r w a s h i n g w i t h m e t h a n o l ( 3 X 10 m l ) a n d d r y i n g at 0° for 8 h r i n v a c u u m , t h e y i e l d w a s 0.98 g ( 5 6 % b a s e d o n M o ( C O ) ) . 6

Analytically calculated for C24H44M02N6O4S8 : C , 31.03; H , 4.78; N , 9.05; S, 27.61 C , 30.94 ; H , 4.92 ; N , 9.13; S, 27.83

Found :

T h e i n f r a r e d s p e c t r u m of c o m p o u n d at 3125 and

CS

(„ 2

N n

);

1 ( K B r discs)

1930(s) a n d 1845(s) cm" , 1

(vco).

showed

2

b a n d s w e r e also p r e s e n t at 1 5 0 0 ( s ) , 1 1 4 9 ( m ) , a n d

cm" . The Ή 1

N M R s p e c t r u m (100 m H z ) i n C D C 1

bands

The C ^ _ i N , N C ,

3

( F i g u r e 1)

1002(m) consists

of a t r i p l e t (8,1.26), q u a r t e t (8,3.71), a n d s i n g l e t (8,5.07) w i t h i n t e g r a t e d intensities of

6:4:1,

i n agreement

w i t h the stoichiometry

[Mo(S CN2

(C H )2)2(CO) ] N H . 2

5

2

2

2

4

C r y s t a l s s u i t a b l e for x - r a y s t r u c t u r e d e t e r m i n a t i o n w e r e g r o w n s l o w l y (~ 1 h r ) f r o m d i c h l o r o m e t h a n e b y t h e g r a d u a l a d d i t i o n of m e t h a n o l u n t i l i n c i p i e n t c r y s t a l l i z a t i o n . U n d e r these c o n d i t i o n s t h e crystals o b t a i n e d c o n t a i n e d one m o l e c u l e of d i c h l o r o m e t h a n e p e r m o l e c u l e of 1. T h e d i c h l o r o m e t h a n e of c r y s t a l l i z a t i o n w a s lost u p o n s t a n d i n g i n a i r or b y d r y i n g i n a v a c u u m ( v i d e s u p r a ) . T h e s o l v a t e d crystals of 1 w e r e


24.

Dinuclear

BROOMHEAD E T A L .

Molybdenum

423

Complex


π 8

7

5

6

4

3

2

6ppm

Figure 1.

The proton magnetic resonance spectrum of 1 in

CDCl

3

stable i n d e f i n i t e l y w h e n sealed i n a c a p i l l a r y u n d e r n i t r o g e n s a t u r a t e d w i t h dichloromethane vapor. Structure Determination.

A c r y s t a l of

1 w a s sealed i n a 0.3 m m

glass c a p i l l a r y i n n i t r o g e n a t m o s p h e r e s a t u r a t e d w i t h C H C 1 . 2

Prelim

2

i n a r y x - r a y d i f f r a c t i o n p i c t u r e s s h o w e d t h a t the c r y s t a l w a s t r i c l i n i c w i t h p r o b a b l e space g r o u p P I . T h e d a t a c r y s t a l also c o n t a i n e d one m o l e c u l e of C H C 1 2

2

p e r f o r m u l a u n i t of 1. T h e c e l l p a r a m e t e r s are s u m m a r i z e d i n

T a b l e I. A t o t a l of 7578 i n d e p e n d e n t reflections h a v i n g 20

3a(F

G

2

).

T h e positions of the t w o m o l y b d e n u m atoms w e r e

0

2

deter

m i n e d f r o m a P a t t e r s o n f u n c t i o n , a n d the r e m a i n i n g atoms w e r e l o c a t e d b y successive least-squares refinements a n d difference e l e c t r o n d e n s i t y maps.

These maps

r e v e a l e d that 1 w a s

dimeric and contained

the

M o - N - N - M o l i n k a g e . H o w e v e r , the t w o b r i d g i n g n i t r o g e n atoms w e r e statistically d i s o r d e r e d a m o n g f o u r positions. T h e s e positions w e r e c o m p a t i b l e w i t h m o d e l s l a a n d l b . I n o r d e r to a v o i d a p r e j u d i c i a l c h o i c e of either m o d e l a n d to m i n i m i z e c o m p u t i n g t i m e , a n u n c o n s t r a i n e d refine m e n t of the n i t r o g e n a t o m d i s o r d e r was c a r r i e d out. T h i s refinement i n d i c a t e d t h a t m o d e l l a w a s p r e f e r r e d a n d t h a t the r e l a t i v e o c c u p a n c i e s of the Ν a n d N ' positions w e r e 65:35. A final differ e n c e m a p f r o m this refinement also r e v e a l e d t h e presence of 31 of the 44

la

lb


424

BIOINORGANIC CHEMISTRY

Table I.

Crystal D a t a for [ M o ( C O ) ( S C N E t ) ] N H 2

2

2

2

2

β y Space group Ζ dobs

1.57

dcaicd

g

cm"

· CH Cl

4

13.872 (7) A 14.145(13)A 13.695 (9) Â 118.50(5)° 103.28(3)° 65.76 (4) ° PI 2 1.56(1) g e m '

a b c


2

II

2

2

3

3

p o s s i b l e h y d r o g e n atoms of t h e e t h y l g r o u p s . T h e h y d r o g e n atoms w e r e i n c l u d e d as fixed c o n t r i b u t i o n s i n the final least-squares refinement w h i c h gave R, 2 w F o

2]i/

= 2

_

(S||F |-|F ||)/S|F | = 0

0

0

8

5

)

C

f

o

r

t

h

6

1

2

9

d

a

t

a

0.058 a n d R = 2 ( 2) 2

0

e

w

i

t

h

F o

> 3 ( 7

F o

d e v i a t i o n of a n o b s e r v a t i o n of u n i t w e i g h t w a s 3.35. a t o m i c p a r a m e t e r s a n d a list of F

0

[2w(F -F )Vstandard 0

Preparation and X-Ray Structure of a Hydrazine-Bridged Dinuclear

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