Hydrogen bond network structures based on sulfonated phosphine ligands: The effects of complex geometry, cation substituents and phosphine oxidation on guanidinium sulfonate sheet formation

Abstract

Interactions between guanidinium cations and the sulfonate groups on the phosphine [PPh 2C 6H 4- m-SO 3] − have been exploited to incorporate iridium(I) centres into hydrogen-bonded networks. The crystal structure of [C(NH 2) 3] 2{ trans-[IrCl(CO)(PPh 2C 6H 4- m-SO 3) 2]} ( 4) contains hexagonal guanidinium sulfonate (GS) sheets in which both of the sulfonate groups from each complex anion form hydrogen bonds within the same sheet. The crystal structures of [C(NH 2) 2(NHMe)][PPh 2C 6H 4- m-SO 3] ( 5) and [C(NH 2) 2(NHEt)][PPh 2C 6H 4- m-SO 3] ( 6) reveal that the GS sheets can tolerate the loss of one hydrogen bond donor, though twisting occurs to accommodate the alkyl group. However, the crystal structure of [C(NH 2) 2(NMe 2)][PPh 2C 6H 4- m-SO 3] ( 7) shows that ribbon structures are formed instead of sheets when two hydrogen bond donors are lost. The compound [C(NH 2) 2(NHMe)] 2{ trans-[IrCl(CO)(PPh 2C 6H 4- m-SO 3) 2]} · 3/8H 2O ( 8) contains hydrogen-bonded cylinders as opposed to sheets. This is a likely consequence of a mismatch between the intramolecular S⋯S distance present in the anion, and the closer S⋯S distance present in a twisted GS sheet such as that in 5. The crystal structures of [C(NH 2) 2(NHEt)][P(O)Ph 2C 6H 4- m-SO 3] ( 9) and [C(NH 2) 2(NMe 2)][P(O)Ph 2C 6H 4- m-SO 3] · H 2O ( 10) show that the phosphine oxide group successfully competes with the sulfonate as a hydrogen bond acceptor. The crystal structure of 9 contains hydrogen-bonded ribbons that are interlinked through the anions which act as pillars to form a layer structure. In contrast, the crystal structure of 10 contains hydrogen-bonded sheets that involve cations, sulfonate groups, phosphine oxides and the included water molecule. These sheets are linked into a three-dimensional network through the anion pillars.