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Premium Zinc Guanidinate Complexes and Their Application in Ring‐Opening Polymerisation Catalysis
Author(s)
Coles Martyn P.,
Hitchcock Peter B.
Publication year2004
Publication title
european journal of inorganic chemistry
Resource typeJournals
PublisherWILEY‐VCH Verlag
Abstract The insertion reaction between 1 equiv. of carbodiimide, R′N=C=NR′, and the zinc bis(amide) [Zn{N(SiMe 3 ) 2 } 2 ] affords the homoleptic zinc( II ) guanidinate compounds [Zn{(Me 3 Si) 2 NC(NR′) 2 } 2 ] ( 3 , R′ = i Pr; 4 , R′ = Cy) in preference to the monosubstituted compounds. Compound 3 also results from the protonation reaction of 1 equiv. of the neutral guanidine (Me 3 Si) 2 NC(N i Pr)(NH i Pr) ( 2 ) with [Zn{N(SiMe 3 ) 2 } 2 ] or ZnMe 2 . In contrast, the N ‐dimethylguanidine analogue Me 2 NC(N i Pr)(NH i Pr) ( 1 ) reacts cleanly with 1 equiv. of ZnMe 2 to afford the dimeric species [Zn{Me 2 NC(N i Pr) 2 }Me] 2 ( 5 ). Attempted protonation of the Zn−C bond in 5 with 2,6‐di‐ tert ‐butylphenol resulted in preferential reaction at the Zn−N bond and formation of the mixed (aryloxo)methyl complex [Zn(OAr)Me·{Me 2 NC(N i Pr)(NH i Pr)}] ( 6 ), isolated as the guanidine adduct. Heating of 6 , in an attempt to promote methane elimination, afforded a small amount of the dimetallic complex [{Zn(OAr)} 2 (μ‐{Me 2 NC(N i Pr) 2 })(μ‐NMe 2 )] ( 7 ) as a result of the extrusion of NMe 2 − from the guanidine‐based ligand. The amine‐elimination reaction between [Zn{N(SiMe 3 ) 2 } 2 ] and 1 equiv. of 1,3,4,6,7,8‐hexahydro‐2 H ‐pyrimido[1,2‐ a ]pyrimidine (hppH) proceeds smoothly to afford the mixed (guanidinate)(amide) complex [Zn(hpp){N(SiMe 3 ) 2 }] 2 ( 8 ), which forms a dimer in the solid state. Crystal structures of compounds 3 − 8 are reported and a preliminary study of the activity of 8 in the ring‐opening polymerisation of lactide is described. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004
Subject(s)adduct , amide , amine gas treating , biochemistry , catalysis , chemistry , dimer , guanidine , homoleptic , ion , ligand (biochemistry) , medicinal chemistry , metal , organic chemistry , protonation , pyrimidine , receptor , stereochemistry , zinc
Language(s)English
SCImago Journal Rank0.667
H-Index136
eISSN1099-0682
pISSN1434-1948
DOI10.1002/ejic.200400031

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