Synthesis of the first hydroxomonoaryltin(IV) complexes. Crystal and molecular structure of [{Sn[C6H3(NNC6H4Me-4′)-2,Me-5]Cl2(µ-OH)}2]

Abstract

Tin(II) chloride reacts in refluxing xylene with [HgLCl][L = C₆H₃(NNC₆H₄R-4′)-2,R-5; R = Me (mpap) or MeO (mopap)] to give metallic mercury and [SnLCl₃](L = mpap 1 or mopap 2). Complex 1 reacts with Cl^–, dimethyl sulfoxide or [Hg(dmap)₂](dmap = C₆H₄CH₂NMe₂-2) to give, respectively, [Sn(mpap)Cl₄]^–3, [Sn(mpap)Cl₃(OSMe₂)]4 or [Sn(mpap)(dmap)Cl₂]5. Several types of hydrolytic process occur when 1, 2 or [Sn(mpap)Ph₂Cl] react with various ligands. Thus, [Hg(dmap)Cl] reacts with 1 or 2 as a base to give [{SnLCl₂(µ-OH)}₂](L = mpap 6 or mopap 7) and Hg(Hdmap)Cl₂. Similarly, PhCH₂NMe₂(bdma) reacts with 1(1 : 1) to give the hydrolysis product [Hdma][Sn(mpap)Cl₃(OH)]8. By treating 6 with excess of NaBr, [{Sn(mpap)Br₂(µ-OH)}₂]9 can be obtained. Acetic anhydride reacts with complex 6 to give [Sn(mpap)Cl₂(O₂CMe)]10, but not with 8. The complex [Sn(mpap)Ph₂Cl] reacts with Tl(acac)(acac = acetylacetonate), NaH or Ag₂O to give the hydrolysis product [Sn(mpap)Ph₂(OH)]11. The crystal structure of 6 was determined at –95 °C; the dimeric doubly bridged nature of the compound was confirmed. The Sn–O bridges are asymmetric, the bond lengths depending on the nature of the trans ligand. Two molecules of diethyl ether form hydrogen bonds to the bridging OH groups; another diethyl ether molecule is disordered over a symmetry centre. The structure of compound 7 was also determined; it too is dimeric with two hydroxo bridges, but the refinement was unsatisfactory, probably because of twinning effects.