Conformational and Electronic Variability of N,N’,O-Ligand Documented on its Coordination to Main Group Halides

Abstract

The coordination chemistry of non-symmetric ligand L (L = 2-(C(Me)=N(C6H3-2,6-iPr2))-6-((iPrO)2P=O)C5H3N) is explored from the point of view of its ability to modify the denticity and accommodation of different main-group elements inside the potentially tridentate ‘pocket’ defined by the phosphonate P=O and imine C=N groups together with the pyridine-nitrogen atom. For this purpose, chlorides of the Groups 13, 14 and 16 were selected, namely InCl3, GeCl2, Ph3SnCl, Ph2SnCl2, SeCl4 and TeCl4. The reaction of L with GeCl2 and InCl3 produced [GeCl(L)][GeCl3] (2) and [InCl3(L)] (5), respectively. In both compounds, L coordinates to the central metal with all donor atoms with 3-N,N,O-coordination motif. On the contrary, L coordinates Ph3SnCl and Ph2SnCl2 only by phosphonate P=O group resulting in 1-O-coordinated [Ph3SnCl(L)] (3) and [Ph2SnCl2(L)] (4). The diverse chelating ability of L was found in the reaction with TeCl4 and SeCl4 yielding 2-(C(CH=SeCl2)=N(Dipp))-6-((iPrO)2P=O)C5H3N (6) and 2-(C(CH2TeCl3)=N(Dipp)-6-((iPrO)2P=O)C5H3N (7) as a result of the C-H bond activation in Me group in C(Me)=N fragment. Due to the presence of the M-Cl bond, all compounds 2 – 7 were subjected to reduction reactions with the aim of synthesising low-valent analogues. But only the reduction of 2 with K or KC8 led to the isolation of [Ge(L)] (8). Finally, theoretical studies were carried out to better understand the formation of 6 and 7 as well as the electronic properties in 8.