Steric factors affecting the additions of acids to complexes of type trans-[IrCl(CO)(PButR2)2] and trans-[IrCl(CO)(PBut 2R)2](R = Me, Et, or Prn)
- 1 January 1971
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in J. Chem. Soc. A
- p. 3716-3721
- https://doi.org/10.1039/j19710003716
Abstract
New complexes of the types [IrHX2(CO)L2] and trans-[IrX(CO)L2]{X = Cl or Br, L = PButR2 or PBut 2R (R = Me, Et, or Prn)} have been prepared. With L = PButR2 or PBut 2Me the complexes [IrHCl2(CO)L2] were readily converted into trans-[IrCl(CO)L2] by treatment with sodium methoxide in methanol. The complexes [IrHCl2(CO)L2](L = PBut 2Et or PBut 2Prn) lose hydrogen chloride in ethanol to give trans-[IrCl(CO)L2]. Although trans-[IrCl(CO)(PButMe2)2] undergoes metathesis readily with sodium iodide to give trans-[Irl(CO)(PButMe2)2], other complexes of this type require much longer treatment to affect metathesis, e.g. trans-[IrCl(CO)(PBut 2Prn)2] requires 18 h in boiling acetone. Treatment of trans-[IrX(CO)L2](X = Cl or Br, L = PButPrn 2 or PBut 2Prn) with sodium isopropoxide in propan-2-ol, followed by water, gives the corresponding hydroxo-complexes, trans-[Ir(OH)(CO)L2]. These hydroxo-complexes readily undergo metathesis when treated with a variety of sodium salts, NaX, to give trans-[IrX(CO)L2](X = Cl, Br, I, N3, NCO, NCS, NO2 or NO3). Complexes of the type trans-[IrCl(CO)L2] are protonated reversibly by benzoic acid (L = PButR2) or hydrochloric acid (L = PBut 2R) and the position of equilibrium measured spectrophotometrically. The relative order of the extent of protonation is L = PMe2Ph > PButMe2 > PButEt2 > PButPrn 2 > PBut 2Me > PBut 2Prn > PBut 2Et, i.e. the bulky t-butyl group has a marked effect. The extent of addition of hydrogen chloride to trans-[IrCl(CO)(PBut 2Et)2] in ethanol–benzene solution is increased by increasing the chloride ion concentration (with lithium chloride). In contrast, nitrate ion inhibits the addition and trans-[IrCl(CO)(PBut 2Et)2] shows much less affinity for nitric acid than for hydrochloric acid. I.r. and 1H n.m.r. data are given and discussed.Keywords
This publication has 0 references indexed in Scilit: