Physical and structural properties of the MMX-type halogen-bridged mixedvalence complex, Ptz(dta)4I (dta = CH~CSZ-) were investigated. This complex exhibits metallic conduction above room temperature, which is the first observation in halogenbridged 1-D transition-metal complexes. Below 300 K, the metal-semiconductor transition was observed. The mixed-valence state of this compound is discussed.

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)°.