Structural Diversity of Sn(II) Phosphine Oxide Complexes with Weakly Coordinating Anions and Comparisons with Related Ge(II) and Pb(II) Species

A series of tin(II) triflate phosphine oxide complexes has been prepared from the reaction of Sn(OTf) 2 (OTf − = [O 3 SCF 3 ] − ) with various ratios of OPPh 3 , OPMe 3 or dppmO 2 (dppmO 2 = Ph 2 (O)PCH 2 P(O)Ph 2 ). The complexes [Sn(OPPh 3 ) n ][OTf] 2 (n = 2, 3 or 4), [Sn(OPMe 3 ) n ][OTf] 2 (n = 2 or 3) and [Sn(dppmO 2 ) n ][OTf] 2 (n = 1 or 2) have been isolated in moderate to good yields. Selected germanium(II) and lead(II) analogues have been made for comparison, namely [Ge(OPPh 3 ) n ][OTf] 2 (n = 2 or 3) and [Pb(OPR 3 ) 4 ][OTf] 2 (R = Me, Ph). The effect of changing the weakly coordinating OTf − anion for the non‐coordinating [BAr F ] − anion was investigated through anion metathesis, furnishing the complexes [Sn(OPPh 3 ) n ][BAr F ] 2 (n = 3 or 4) and [Ge(OPPh 3 ) 3 ][BAr F ] 2 . The isolated solids were characterised by 1 H, 19 F{ 1 H}, 31 P{ 1 H} and IR spectroscopy and microanalysis. Crystal structures were obtained for all complexes except [Ge(OPPh 3 ) 2 ][OTf] 2 and [Sn(OPPh 3 ) 3 ][BAr F ] 2 , allowing comparisons of the structural features of these divalent group 14 complexes down the group and as a function of coordination number, ligand sterics and electronics.