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CHAPTER I I EXPERIMENT 2 .1 Reagent 2 .1 .1 S o lid e
A c e ty la c e to n a te s o f th e fo llo w in g m e ta ls were p urchased fro m M e rc k -S c h u c h a rd t
Chrom ium ( I I I ) C o b a lt ( I I I ) C o b a lt ( I I ) Copper ( I I ) Ir o n ( I I I ) Manganese ( I I I ) Manganese ( I I ) N ic k e l ( I I ) P a lla d iu m ( I I ) Z in c ( I I ) 2 .1 .2 . L iq u id s
The s o lv e n ts , fro m M erck and BDH w h ic h were n o t a n a la r grade were d o u b le - d is tille d and w ere d rie d w ith d ry in g a g e n ts p r io r to u s e .
2 .2 P ro c e d u re U lt r a - v io le t s p e c tra l m easurem ents
A l l s p e c tra were m easured a t ~
25 c
on a p e rk in -E lm e r M odel 12zf d oub le beam g r a tin g s p e c tro p h o to m e te r,• u s e in g 1-crn.q u a rtz c e lls and 1 .0 nm s p e c tra l s li t - w i d t h . The s o lu tio n s m easured w ere a l l ~ 10 M.
All A A !> a re r e la t iv e to is o b c ta n e .
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2 .3 A c e ty la c e to n e and i t s M e ta l Com plexes
A c e ty la c e to n e is a m ix tu re o f two fo rm s h a v in g k e to ( F ig . 2 A) and e n o l ( F ig . 2 B) s tr u c tu r e s . I t is a weak a c id (pKa 8 . 8 ) าๆ and one p ro to n can be lo s t e a s ily to g iv e th e e n o la te ; a n io n . T h is e n o la te a n io n has a fiv e -a to m IF n e t-w o rk e x te n d in g o v e r th e tw o oxygen and th re e n o n -te rm in a l carb on ato m s. S ix e le c tro n s th u s occup ied a re d e lo c a liz e d in t o a
sym m e tric s tr u c tu r e . T h is can be c o n v e n ie n tly c a lle d q u a s i
a ro m a tic fo rm ( F ig . 2 c ) .
The m e ta l com plexes w h ic h a re s tu d ie d h e re can be c la s s if ie d in t o 2 g roups ะ-
2.3. ๆ T r iv a le n t m e ta l c o m p le xe s, in c lu d e c o b a lt ( I I I ) , chrom ium ( I I I ) , i r o n ( l l l ) , and manganese ( I I I ) a c e ty la c e to n a te s .
1 2 ,1 3 T h e ir g e o m e trie s have been e s ta b lis h e d by X -ra y c ry s ta llo g ra p h y
( F ig . 2 D) and t h e ir s y m m e trie s a re i . e . a d is to r te d o c ta h e d r a l. The a c e ty la c e to n e c h e la te b e in g p la n a r and s y m m e tric a l, i . e . q u a s i-a r,o .m a tic fo rm .
2 .3 .2 D iv a le n t m e ta l com plex e s , in c lu d e p a lla d iu m ( I I ) , copper ( I I ) , n ic k e l ( i l ) , c o b a lt ( I I ) , z in c ( I I ) , and m a n g a n e s e !II) a c e ty la c e to n a te s . The (P d ) com plex has a p la n a r c o n fig u r a tio n w ith a d is to r te d o c ta h e d ra l c o - o r d in a tio n o f th e Pd atom .1 ^
Cu ( I I ) com plex has a bonded b rid g e s tr u c tu r e w ith th e c e n tr a l carb on atom a c tin g as a b rid g e betw een th e tw o n e a r ly sq uare p la n a r Cu
(Xckc)^
u n it s . ^ The re m a in in g com plexes a re o lig o m e r w ith p o ly m e r iz a tio n v ia c h e la te d oxygen b rid g e . C r y s ta llo g r a p h ic? lg . 2 [From P . H . , M .S c . T h e s is (C h u la 1 9 7 4}~j
-, 20
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e v id e n c e s fo r ,p o ly m e r iz a tio n has been d e f in it e ly e s ta b lis h e d to d a te w ith ^ N i (A c A c )^ ^ ^ (F ig * 2 ร ) , ^Co (A cA c)^ j
(F ig o 2 F ) , and ^Zn ( AcTtc^J j^ ( F ig . 2 G) ; and m o le c u la r w e ig h t s tu d y in d ic a te s p o ly m e r is a tio n a ls o f o r I Mn (A c A c )3 ^ w h ic h is b e lie v e d to have th e same s tr u c tu r e as N i ( I I ) .
P o ly m o ric 's p e c ie s in M ( I I )
C u ( I l) fo rm s d im e r and th e monomer is p la n a r, sym m etry
. N i ( l l ) and M n ( ll) a re b e lie v e d to have id e n t ic a l s tr u c tu r e s , b o th a re t r im e r ic 1 ' . In N i( I I ) th e re a re n in e p o s s ib le s tr u c tu r e s o f t r im e r ic a lo n e ]1'7 N i ( l l ) and M n ( II) monomers a re p la n a r,
sym m etry D2h*
Z n ( I I ) is a ls o t r im e r ic , b u t th e monomer is te tr a h e d r a l, sym m etry £>2(3^ C o ( ll) fo rm s te tra m e rs , th e monomer is a ls o
2d* '' te tr a h e d r a l, sym m etry D
