Synthesis and reactivity of alkaline-earth stannanide complexes by hydride-mediated distannane metathesis and organostannane dehydrogenation. Issue 30 (21st July 2020)

• Record Type: Journal Article
• Authors: Morris, Louis J.; Rajabi, Nasir A.; Mahon, Mary F.; Manners, Ian; McMullin, Claire L.; Hill, Michael S.
• Is Part Of: Dalton transactions. Volume 49:Issue 30(2020)
• Page Start: 10523
• Page End: 10534
• Publication Date: 2020-07-21
• Subjects: Chemistry, Inorganic -- Periodicals; Chemistry, Physical and theoretical -- Periodicals; Chemistry, Inorganic -- Periodicals; 546.05
• DOI: 10.1039/d0dt02406f
• Languages: English
• ISSNs: 1477-9226

Abstract

Abstract : The synthesis of heteroleptic complexes with calcium– and magnesium–tin bonds are described. Abstract : The synthesis of heteroleptic complexes with calcium– and magnesium–tin bonds is described. The dimeric β-diketiminato calcium hydride complex, [(BDI)Ca(μ-H)]2 (I Ca ) reacts with Ph3 Sn–SnPh3 to provide the previously reported μ2 -H bridged calcium stannanide dimer, [(BDI)2 Ca2 (SnPh3 )(μ-H)] (3 ). Computational assessment of this reaction supports a mechanism involving a hypervalent stannate intermediate formed by nucleophilic attack of hydride on the distannane. Monomeric calcium stannanides, [(BDI)Ca(SnPh3 )·OPPh3 ] (8·OPPh3 ) and [(BDI)Ca(SnPh3 )·TMTHF] (8·TMTHF, TMTHF = 2, 2, 5, 5-tetramethyltetrahydrofuran) were obtained from I Ca and Ph3 Sn–SnPh3, after addition OPPh3 or TMTHF. Both complexes were also synthesised by deprotonation of Ph3 SnH by I Ca in the presence of the Lewis base. The calcium and magnesium THF adducts, [(BDI)Ca(SnPh3 )·THF2 ] (8·THF2 ) and [(BDI)Mg(SnPh3 )·THF] (9·THF ), were similarly prepared from [(BDI)Ca(μ-H)·(THF)]2 (I Ca ·THF2 ) or [(BDI)Mg(μ-H)]2 (I Mg ) and Ph3 SnH. An excess of THF or TMTHF was essential in order to obtain 8·TMTHF, 8·THF2 and 9·THF in high yields whilst avoiding redistribution of the phenyl-tin ligand. The resulting Ae–Sn complexes were used as a source of [Ph3 Sn] − in salt metathesis, to provide the known tristannane Ph3 Sn–Sn( t -Bu)2 –SnPh3 (11 ). Nucleophilic addition or insertion with N, N ′-di-iso-propylcarbodiimide provided the stannyl-amidinate complexes, [(BDI)Mg{(iPrN)2 CSnPh3 }] (12 ) and [(BDI)Ca{(iPrN)2 CSnPh3 }·L] (13·TMTHF, 13·THF, L = TMTHF, THF). The reactions and products were monitored and characterised by multinuclear NMR spectroscopy, whilst for compounds 8, 9, 12, and 13·THF, the X-ray crystal structures are presented and discussed.