A one-dimensional platinum mixed-valence complex with bridging thiocyanate S atoms: [[Pt^II(en)₂](μ-SCN)[Pt^IV(en)₂](μ-SCN)](ClO₄)₄(en is ethane-1,2-diamine)

Abstract

A new one-dimensional platinum mixed-valence complex with nonhalogen bridging ligands, namely catena-poly[[[bis(ethane-1,2-diamine-κ(2)N,N')platinum(II)]-μ-thiocyanato-κ(2)S:S-[bis(ethane-1,2-diamine-κ(2)N,N')platinum(IV)]-μ-thiocyanato-κ(2)S:S] tetrakis(perchlorate)], {[Pt(2)(SCN)(2)(C(2)H(8)N(2))(4)](ClO(4))(4)}(n), has been isolated. The Pt(II) and Pt(IV) atoms are located on centres of inversion and are stacked alternately, linked by the S atoms of the thiocyanate ligands, forming an infinite one-dimensional chain. The Pt(IV)-S and Pt(II)···S distances are 2.3933 (10) and 3.4705 (10) Å, respectively, and the Pt(IV)-S···Pt(II) angle is 171.97 (4)°. The introduction of nonhalogen atoms as bridging ligands in this complex extends the chemical modifications possible for controlling the amplitude of the charge-density wave (CDW) state in one-dimensional mixed-valence complexes. The structure of a discrete Pt(IV) thiocyanate compound, bis(ethane-1,2-diamine-κ(2)N,N')bis(thiocyanato-κS)platinum(IV) bis(perchlorate) 1.5-hydrate, [Pt(SCN)(2)(C(4)H(8)N(2))(2)](ClO(4))(2)·1.5H(2)O, has monoclinic (C2) symmetry. Two S-bound thiocyanate ligands are located in trans positions, with an S-Pt-S angle of 177.56 (3)°.

Inducing Platinophilic Interactions in [Pt(SCN)4]2– Salts by Cation Tuning

“…Weak intermolecular Pt···S–Pt interactions (<3.70 Å) also exist between the sulfur of the thiocyanate anion and the vacant axial sites of adjacent Pt­(II) atoms. Similar intermolecular Pt···S interactions have been reported, for example, in [Pt­(CNMe) 4 ]­[Pt­(S 2 C 2 (CN) 2 ) 2 ] 2 (3.490 Å), [Pt­(en) 2 ]­[Pt­(en) 2 (μ-SCN) 2 ]­(ClO 4 ) 4 (3.571 Å), and [Pt­(CN–C 6 H 3 -2,6-Me 2 ) 2 (PMe 3 ) 2 ]­(SCN) 2 (3.373 Å). − Within the platinophilic dimer, there are intermolecular Pt···S interactions between Pt1 and S2 of 3.689(3) Å (on Pt2) that further assist the platinophilic interaction. The platinophilic dimer is capped by a third [Pt­(SCN) 4 ] 2– unit that interacts with the dimer through an additional Pt···S interaction of 3.580(3) Å between Pt2 and S5 (on Pt3).…”