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AreneЦMetal Clusters; Metal Atom-Bis(arene) Metal Solution Phase Chemistry.

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Dieses Manuskript ist
zu zitieren als
Angew. Chem. Suppl.
1982,381-392
This manuscript is
to be cited as
Angew. Chem. Suppl.
7982, 381 -392
0 Verlag Chemie GrnbH, D-6940 Weinheim, 1982
0721 422718210303 0381802.5010
- 381
-
-
383
-
W@nmtaliic 1iqiil.d palyren or a ‘mi/Y, b1-M and t r h e t a l l i c
type
/Yhave
mtal &tons
recn:tly been synthesJ.7ed at 250°K by rcactirg transiticn
w l th ~ l y - ( m t ~ ~ l p . ~ r ~ l - ~ ~ t(!X
~ l510)
s i lInOa ~ e )
m t a l vapor rota7 mactor or r i d d matrix e q i e r h n t . Subseqwnt experii;ents led to tte ri:scovery of liquid plymr stabilized uii- an5
biirrtalllc ciusterv or a low nirclcarily type /2,W. ,mis vioric has sir.ce
been ex’knecd t c o:.lp?Clicr reactlcn media /5/.
mtal atan Iri-
duccd, Uqiiid phese polyrerl7atlm c r o l i m r s and cross-llnidng
or
polylm%. t.ypically vla bis(arene) =tal cmpiex f o m t l c n . yieids media with vlsrwity C!amc’.et*istics
trollcd m t a l c:uster
end t m i n g s i t e s siiitablc for ccn-
fomstlor. at, c r close to, rcuc t e w r a t w /6.7/.
Uv-visible absorptia:, esr, mr, 13. namn
n-84 S N /9/ and EXAFAJ/
spectmcoples have pmvlded insl@,t into the mchanism of m t a l clusXZLE I
ter ~ m c l i .cluster i5cntity and mock of cluster stabll.17atlm. Current
t?iou@ts a~ l l l u t r a t e d acxmatlc~11yin h’igure
I where t:?e bis-
( m n e ) mtnl c q l c m s are vlewd as nt?L¶l nucleation s i t e s f a r the
pmductia; of cluslers. elther msolvalrd (Figme 1. 111) o r solvatnd
by tine et’ier oqtyns or thc plymr backbone (Fi@re; .I). .Ctemative:v,
clustew n a y x.uc&:+lcar
?w,vol&
t o be stibilizeed by wygen
olLliy:e
?.i solvat-
within ttx? o~pw.m-.a; polynr-r coi:.s. In t!iis view cluJte-?s
am ioolnled by c w i eLlier a n d / c cryp:aid-llk@ Jnte?actiw,s (Figure
1,II) wilthout t:?e r;lrt:cipatlon
of ttz ptlery: substituents.
3eently we m?orteb a =t?J
teedniquc /u,E/ which p d t 3 k
vdp?
n l c m s o h l . 1 ~ ~s 1: ~ o t ; ? o s ~ u i c
s mdtor:fig
~
of thc f a k
or
mta: aLam dcpsltcd Into flulQ cryopnlc soliticm. aqd t:welefoole a
meam
or qwtlfyirs.
tte d m i c a l cvenLr that
CCC~L-
in a rac.ms=le
metal vapor mta-y 8olJtLm syntlws:.~. mesc r3cxe.oluLla;. experiments
-
382
-
-
384
-
the parent bis(a1cne) chraniun and vanadiun ccaplexes
/2-7/, me can
evaluate the o u t c m of t h e s o l u t i o n phase reactions'sham in Schem 11.
Fi-s
2A and 3A show t y p i c a l o p t i c a l spectia of approximately
M t h i n film of (I) and (11) in MUi at 140-160 K. These s p c t r a
are i d e n t i c a l t o t h w e of t h e CC 510 supported bis(arene1 ccplplexes
/1-4/. m e microsolution sampling technique has been described previously /8,12/.
A t no t i m during these experiments d i d the cryosolu-
xa
250
Pigwe 3:
t i o n s show any evidence of free arene (absorbing i n the range 200-300
350
at 140 K followed by the addition
m e absorption s p e c t r a of purified sanples of ( I ) and (11) (synthe-
respectively. In addi-
t i o n both conpounds absorb very weakly at 445 and 385 nm, respectively.
In Figure ZB it is apparent t h a t when vanadim atoms a r e deposited
i n t o a 140°K MCH solution of ( I ) a n e w species absohing at 453 run and
i d e n t i f i e d as t h e divanadim canpound
-
'3,6,7/
grows i n
at the expense
Of
(6)
- (F) 7 - 95 ilg
of c h m n i m a t m ; and in a separate e x p r i w n t ( C ) 35 ug
s i z e d both by Fi'schercHaf'ner /12/ and metal atm /14/ methods) show
MI,
"
bis(to1uene) chmmim in methylcyclohexane s o l u t i o n
nm).
very intense MLCT t r a n s i t i o n s a t 324 and 318
450
403
Microsolution o p t i c a l s p e c t r a of ( A ) 60 ul
of vanadim atans.
fig^
3 represents the o p t i c a l spectroscopic r e s u l t s of a s e r i e s of
s i m i l a r experiments in which Cr and V a t m were reacted with (11).
With i n c r e a s i n g a n w m t s of added c h m n i m the dimr absorption at
405 nm develops at the expense of (II), p a r a l l e l i n g t h e observations
F u r t h e m r e , when a MCH s o l u t i o n of (11)
mde for Cr/X 510 /3,6/.
- 387 -
385 -
r e a c t s with V atcms a CrV species is generated, absor4ing at 420 run,
i d e n t i c a l in p o s i t i o n t o that of t h e CrV species produced when ( I ) w a s
reacted with C r a t a n s described above.
Since we have found no evidence f o r free arene o r metal displacerent
reactions or reduced products /15/ in our experink?nts, t h e mt l i k e l y
metal dimer forming p m c e s s appears t o be d i r e c t addition of a depcs i t e d diffusing m t a atan t o t h e metal centre of t h e (areneI2M, yielding conpounds 111-v:
453 nm
(arene)2V2
I11
420 nm
(arene),CrV
IV, IV'
405 nm
(arene)2Cr2
V
Species I V and IV' c m t a i n i n g WV, both absorbing at 420 nm, are probably the same colpound. This inference is consistent with a syrmetric a l d i s t r i b u t i o n of the arene rinp,s with respect t o t h e dimr moiety as
I
. . . . .
,
.
m m u a U I D d m
Figure 2: MicmSolutlorr o p t i c a l s p e c t r a of ( A ) 60 ill of
M
bis(ben2ene) vanadiun in m t h y l c y c l o k x a n e s o l u t i o n a t
140 K followed by the addition of (B)
-
(F) 7
- 75 ug
of vanadium a t m ; and in a separate e x p e r i m n t (G) 30
ug of chmmiun
system, t h a t is a sextuple, twelve e l e c t r o n c h m n i u m c h m n i m intetaction with t h r e e n-electmns per mne ring contributing t o each Cr
atm.
of ( I ) . When a Wd s o l u t i o n of (I) is reacted with C r a t m a new abs o r p t i o n is detected at 420 nm.
Such a s t m c t m f o r M = C r i s fonnally an 24 e l e c t r o n closed s h e l l
me latter
occurs at the
Sam
energy
earlier a t t r i b u t e d t o CrV pmduced by t h e simultaneous o r sequential
deposition of a t a n l c Cr and V i n t o 250 K M: 510 /3,6,7/.
atan /16/.
It is i n t e r e s t i n g t o note t h a t in the known molecule, tetra-
a l l y l d i c h r a n i m /l7/,four
a l l y 1 ligands f o n a d i s t o r t e d tetrahedron
around t h e two chraniun a t m which are d i r e c t l y coupled over a distance of 1.97 A. This s h o r t C r - C r bond should be conpared t o t h a t of
1.85-2.54 A found in o t h e r m l t i p l y bonded chmnium dimers /18/.
- 386 -
- 388 -
P r e i i m i n a r y H W S /iO/ r e s u l t s for t h e DC 510 supported C r 2 analog show
6.
G . A . Ozin and C.G.
a C r - C r bond length in the range of 2 A strongly supporting o w view o f
7.
G.A.
b
hip;hly iiultiply bonded clrister moiety i n the b i s ( a r e n e ) dichromim
55.
Francis, J . Mol. S t r u c t . , 5&(1980),
& i n and C.G. Francis, J . Macromcl. Sci. (Chem).
c,
(I),
(1981), 167.
ct.mr,lex. Tlile above s t r u c t u r e seems t o b e mre plausible than the a l t e r -
8. M.P.
naLive s y m n e t r i c a l l y bonded 24 e l e c t r o n system ( B ) , e s p e c i a l l y i n l i g h t
9.
Andrrws,
C.G. t'rwsis aria G. A.
work from tt.e i a 0 o r a t o r i e s of
Thpubli.,ned
G.A. O!in
10. Lnpuhlished worK from t h e l a b o r a t o r i e s of G . A .
11. G . A . Ozin, C.G. P r a r c i s , 11. Huoer, M.?.
aid
J. Miz,ll.
Ozin am P. M m t a n u .
AnJ:wg
J. Pner. Chem. S o c . , 103, (l98l), 21153.
i ~ .G. 4. O ~ i n ,H . Hmcr, C.G.
Francis and L. PJazar, Inor,;.
Chem.,
5,
(1981), 363;.
13. E.O. Piischer and W.
E.O. Fischer and A. 'icch
1 4 . K..J. Klaburrde and H.F. E
Tirm?, Cnen. Corm.., (19691, 1023.
'Ia, K , V a:d Cr aton
thcminl.
17. 1'. Poki, F.
?~a,&??i
wd
Y. T ' u w r . 3Li. Ch,en'. ! L c . ,-ap?n, -~
'
I
,
(1769), 5'15.
-
389
-
-
391
-
19. Note t h a t t h e sene r i n g s i n t h i s complpx a= disglaced with
SCHEME 111
pect t o tne Pd
ITS-
core so as t o produce approxirnatelg square p l m a r
coordiriatlon a-ourid eari. Pd (I) atom. G. Alleigra, G . C a s e r a n d e ,
A. Irncirzi, L. P o r r i arid C. ' j i t u l i i , J. h e r . Chem. Soc., 2,,'1970)
289.
20. L. .~oll,X. Reisc, J. Schafer and P. Klufer', J. Organorr&t. Cnen..
Received September 17, 1981 / Z 13b S /
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390
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392
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