Despite the well-established tradition of organomagnesium reagents, lit-tIe attention was given to the heavier congeners, until very recently. Since the 1990s, researchers have intensified their efforts in the quest for sterically demanding ligand frameworks capable of preventing classic decomposition re› actions of Ae organometallics. Sterically demanding N -donors have become increasingly popular owing to their ability (i) to provide stable metal-donor interactions and (ii) to achieve kinetic stabilisation of the complex via steric crowding around the metal centre. This has led to reports which challenge the common knowledge of the Ae metals. Group 2 complexes have also found applications as stoichiometric reagents, catalysts and as precursors for MOCVD techniques. The work here discussed is aimed at investigating the use of aminopy› ridinate, amidinate and carbazolyl ligands in the stabilisation of novel Ae coordination compounds. Several synthetic procedures have been employed: (i) precursors for metathetical reactivity with Group 2 halides have been obtained from the reaction between the preligands and KH or K[N(SiMe3)2] (13, 12-18, 31-34); (ii) metathesis reactions between potassium salts and MgI2 or CaI2 afforded homoleptic (4-7), heteroleptic (35-38) and hetero› bimetallic compounds (8 and 9); (iii) organoelimination reactions between the preligands and (nBuhMg led to the isolation of homoleptic (4 and 5, 19-24) and heteroleptic magnesium complexes (25) ; (iv) reactions be› tween amidines and MeMgI afforded heteroleptic magnesium halides (28-30) and a rare homometallic magnesium inverse crown ether complex (26); (v) aminopyridines were employed in co-complexation reactions with nBuLi and (nBuhMg, affording the magnesiate complexes lOa and lOb; (vi) the metathesis reaction between the l,l-di-Grignard complex CH2(MgBr)2 and 1 produced the rare methylene bridged magnesium derivative 11. All the compounds herein reported were characterised via analytical and spectroscopic techniques. NMR characterisations in solution of amidinate Group 1 and Group 2 derivatives highlighted the presence of rotational bar› riers for some of these compounds. Moreover, several molecular structures of potassium (14 and 15, 31 and 33), magnesium (19, 21-24, 26-30, 35-38) , calcium (7) and heterobimetallic compounds (8, lOa and lOb) were obtained.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:713701 |
| Date | January 2013 |
| Creators | Ortu, Fabrizio |
| Publisher | University of Nottingham |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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