Synthesis and structural characterisation of heavy alkaline earth N, N′-bis(aryl)formamidinate complexes

Marcus L Cole, Glen Berenger Deacon, Craig Macdonald Forsyth, Kristina Konstas, Peter Courtney Junk

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Treatment of calcium or strontium with 2.0 equivalents of N, N′-bis(o-methylphenyl)formamidine (o-TolFormH), N, N′-bis(2,6-dimethylphenyl)formamidine (XylFormH) or N, N′-bis(o-phenylphenyl)formamidine (o-PhPhFormH) in the presence of 1.0 equivalent of Hg(C6F5)2 in tetrahydrofuran (thf) affords the bis(formamidinate) complexes [Ca(o-TolForm)2(thf)2] (1), [Ca(XylForm)2(thf)2] (2), [Ca(o-PhPhForm)2(thf)2]·thf (3), [Sr(o-TolForm)2(thf)3] (4), [Sr(XylForm)2(thf)3]·3thf (5) and [Sr(o-PhPhForm)2(thf)3]·2thf (6). Analogous reactions with barium were generally unsatisfactory but [Ba(o-PhPhForm)2(thf)3]·2thf (7) was successfully prepared. Compounds 1–7 have been characterised by various spectroscopic methods (1H, 13C(1H) NMR and IR), elemental analyses and, for 1, 2 and 4–6, X-ray crystallography. The calcium complexes are monomeric and six-coordinate with either transoid octahedral or trigonal prismatic geometry, whilst the larger radius of strontium accommodates an additional thf solvent donor to give seven-coordinate structures with two types of coordination polyhedra.

Original languageEnglish
Pages (from-to)3360-3367
Number of pages8
JournalDalton Transactions
Issue number27
Publication statusPublished - 4 Jul 2006

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