Self-assembled organoplatinum(II) supermolecules as crystalline, SO2 gas-triggered switches †

Abstract

Square-planar platinum() complexes containing N,C,N terdentate coordinating, anionic 'pincer' ligands reversibly bind gaseous SO 2 in the solid state by Pt-S bond formation and cleavage giving five-coordinate adducts. When the starting material is crystalline, exposure to this gas leads to quantitative adduct formation with the unique feature that the product is also crystalline, although the crystal structures of the adduct and the SO 2 free complex are significantly different from each other and are both non-porous. Remarkably, the reverse reaction, i.e. the release of SO 2 gas, modifies but does not destroy the crystalline ordering in the arylplatinum assemblies. These processes include repetitive expansion and reduction of the crystal lattice without any loss of crystallinity of the material. Variation of the ligand framework revealed that the presence of intermolecular interactions such as α-or β-type networks is not an essential prerequisite for these crystalline transformations. Consequently, this class of supermolecules provides access to sensitive crystalline switches with 'on' and 'off' positions which are a direct response to the gaseous environment.

Self-assembly of para-OH functionalized ECE-metalated pincer complexes

“…For example, NCN-pincer Pt-complexes [PtCl(NCN-Z)] with Z = OH or C"C-H form one-dimensional polymeric chains via intermolecular hydrogen bonds of the O-HÁ Á ÁCl [8] or C"C-HÁ Á ÁCl [4,29] type, respectively, in the solid-state. These materials revealed reversible binding of SO 2 in the solidstate with retention of the polymeric structure [27,30]. Here, we have extended this concept to ECE-pincer Pd-complexes which are also known to be excellent catalysts for C-C and C-X bond formation reactions [5,11,15,20,22,31].…”

“…Ample evidence has been collected now that in the protonated form, they afford self-assembled, non-covalent polymeric chains [27,30]. Moreover, via selective deprotonation followed by halide-phenoxy anion exchange, dimeric structures are accessible.…”

“…Self-assembly of functionalized pincer-metal complexes controlled by H-bonding through a H-donor (Z-substituent) and a H-acceptor site (M-X) both in the solid-state and in solution has led to the finding of interesting polymers [25] and supramolecular structures [4,8,[26][27][28][29]. For example, NCN-pincer Pt-complexes [PtCl(NCN-Z)] with Z = OH or C"C-H form one-dimensional polymeric chains via intermolecular hydrogen bonds of the O-HÁ Á ÁCl [8] or C"C-HÁ Á ÁCl [4,29] type, respectively, in the solid-state.…”

“…After stirring for 2 h at ambient temperature, the reaction mixture was concentrated to a quarter of its volume and then treated with 0.2 M HCl (12.5 mL), which caused turbidity. Stirring was continued for 1 h. The precipitate was then filtered and washed with water (25 mL) and diethyl ether (25 mL) 27,145.06,146.98,156.72 (ArC). Anal.…”

Toward a comprehensive definition of oxidation state (IUPAC Technical Report)

“…However, the attendant OS S = +3 and OS Rh = +2 in the complex would be difficult to reconcile with the diamagnetism of the compound, which is more in line with a Rh(I) (d 8 ) donating a pair of electrons to a neutral SO 2 ligand (OS S = +4). This is by no means unique, and SO 2 adducts with, for example, Pt(PR 3 ) 2 (R = cyclohexyl, tert-butyl) [317] or [PtX(C 6 H 2 {CH 2 N(CH 3 ) 2 } 2 -2,6-R-4)] (R = OH, X = Cl; R = H, X = Cl, Br, I) [318] are considered to contain respectively Pt(0) and Pt(II). Their reversible binding of SO 2 is more in accord with these OS than with ionic approximation towards Pt +2 The first structural identification of a TM → B donor-acceptor bond in the [Ru(CO)(P(C 6 H 5 ) 3 ){B(mt) 3 }] (B(mt) 3 = tris(methimazolyl)borane) metallaboratrane by Hill [321] in 1999 has rekindled interest in the field, which has seen spectacular progress in the intervening years when similar complexes of Co [322], Ni [323], and others have been synthesized.…”