Large effects of ion pairing and protonic-hydridic bonding on the stereochemistry and basicity of crown-, azacrown-, and cryptand-222-potassium salts of anionic tetrahydride complexes of iridium(III).

The compounds [K(Q)][IrH(4)(PR(3))(2)] (Q = 18-crown-6, R = Ph, (i)Pr, Cy; Q = aza-18-crown-6, R = (i)Pr; Q = 1,10-diaza-18-crown-6, R = Ph, (i)Pr, Cy; Q = cryptand-222, R = (i)Pr, Cy) were formed in the reactions of IrH(5)(PR(3))(2) with KH and Q. In solution, the stereochemistry of the salts of [IrH(4)(PR(3))(2)](-) is surprisingly sensitive to the countercation: either trans as the potassium cryptand-222 salts (R = Cy, (i)Pr) or exclusively cis (R = Cy, Ph) as the crown- and azacrown-potassium salts or a mixture of cis and trans (R = (i)Pr). There is IR evidence for protonic-hydridic bonding between the NH of the aza salts and the iridium hydride in solution.

Acidic Dicationic Iron(II) Dihydrogen Complexes and Compounds Related by H(2) Substitution.

[trans-Fe(H(2))(CO)(dppe)(2)](2+) (3) (dppe = 1,2-bis(diphenylphosphino)ethane) was generated by protonation of [trans-FeH(CO)(dppe)(2)](+) in CD(2)Cl(2). [trans-Fe(H(2))(CO)(depe)(2)](2+) (6) (depe = 1,2-bis(diethylphosphino)ethane) was generated by the treatment of [trans-FeCl(CO)(depe)(2)](+) in CD(2)Cl(2) with AgSbF(6) under 1 atm of H(2). Complex 3 is more acidic than trifluoromethanesulfonic acid (HOTf) in CD(2)Cl(2), while 6 is suspected to be less acidic than [Et(2)OH](+).