Crystal structures of six complexes of phosphane chalcogenides <i>R</i> ¹ <i>R</i> ² <i>R</i> ³P<i>E</i> (<i>R</i> = <i>tert</i>-butyl or isopropyl, <i>E</i> = S or Se) with the metal halides <i>MX</i> ₂ (<

The <i>L</i> ₂ <i>MX</i> ₂ complexes <b>1</b>-<b>5</b> (<b>1</b>: <i>L</i> = ^<i>t</i> BuⁱPr₂PSe, <i>M</i> = Pd, <i>X</i> = Cl; <b>2</b>: <i>L</i> = ^<i>t</i> Bu₂ ⁱPrPSe, <i>M</i> = Pd, <i>X</i> = Cl; <b>3</b>: <i>L</i> = ^<i>t</i> Bu₂ ⁱPrPSe, <i>M</i> = Pd, <i>X</i> = Br; <b>4</b>: <i>L</i> = ^<i>t</i> Bu₂ ⁱPrPS, <i>M</i> = Pd, <i>X</i> = Br; <b>5</b>: <i>L</i> = ^<i>t</i> Bu₂ ⁱPrPS, <i>M</i> = Pt, <i>X</i> = Cl) {systematic names: (<i>tert</i>-butyl-diiso-propyl-phosphine selenide-κ<i>Se</i>)di-chlorido-palladium(II), [PdCl₂(C₁₀H₂₃PSe)₂] (<b>1</b>), (di-<i>tert</i>-butyl-iso-propyl-phosphine selenide-κ<i>Se</i>)di-chloridopalladium(II), [PdCl₂(C₁₁H₂₅PSe)₂] (<b>2</b>), di-bromido-(di-<i>tert</i>-butyl-iso-propyl-phosphine selenide-κ<i>Se</i>)palladium(II), [PdBr₂(C₁₁H₂₅PSe)₂] (<b>3</b>), di-bromido-(di-<i>tert</i>-butyl-iso-propyl-phosphine sulfide-κ<i>S</i>)palladium(II), [PdBr₂(C₁₁H₂₅PS)₂] (<b>4</b>), di-chlorido-(di-<i>tert</i>-butyl-iso-propyl-phosphine sulfide-κ<i>S</i>)palladium(II), [PdCl₂(C₁₁H₂₅PS)₂] (<b>5</b>)} all display a <i>trans</i> configuration with square-planar geometry at the metal atom. Compounds <b>2</b> and <b>3</b> are isotypic. The mol-ecules of <b>1</b> and <b>4</b> display crystallographic inversion symmetry; compound <b>5</b> involves two independent mol-ecules, each with inversion symmetry but with differing orientations of the tri-alkyl-phosphane groups. Chemically equivalent bond lengths all lie in narrow ranges, whereby the values for palladium and platinum compounds scarcely differ. Compound <b>6</b>, ( ^<i>t</i> BuⁱPr₂PS)₂Pd₂Cl₄ {systematic name: di-μ-chlorido-bis-[(<i>tert</i>-butyldiiso-propyl-phosphine sulfide-κ<i>S</i>)chlorido-palladium(II)], [PdCl₂(C₁₀H₂₃PS)₂]}, is dinuclear with a central Pd₂Cl₂ ring, and displays crystallographic inversion symmetry. The bonds to the bridging are longer than those to the terminal chlorine atoms; the Pd-S bond is shorter than the <i>M</i>-S bonds in <b>4</b> and <b>5</b>, reflecting the weaker <i>trans</i> influence of (bridging) chlorine compared to sulfur. Compounds <b>7</b> and <b>8</b>, 2( ^<i>t</i> Bu₂ ⁱPrP<i>E</i>Br)⁺ [Pd₂Br₆]^2- with <i>E</i> = S for <b>7</b> and Se for <b>8</b> {systematic names: (bromo-sulfan-yl)di-<i>tert</i>-butyl-iso-propyl-phosphanium di-μ-bromido-bis-[di-bromido-palladium(II)], (C₁₁H₂₅BrPS)₂[Pd₂Br₆] (<b>7</b>) and (bromo-selan-yl)di-<i>tert</i>-butyl-iso-propyl-phosphanium di-μ-bromido-bis-[di-bromido-palladium(II)], (C₁₁H₂₅BrPS₂)₂[Pd₂Br₆], (<b>8</b>)}, were obtained by oxidizing the appropriate Pd^II precursors with elemental bromine; they are not isotypic. The ions are connected by very short halogen bonds Br⋯Br. For both compounds, two <i>E</i>⋯Br contacts further link the cations and anions to form ribbons. Compound <b>9</b> {systematic name: bis-[dimeth-yl(sulfanyl-idene)phosphin-ito-κ<i>Se</i>]bis-(hy-droxy-diiso-propyl-phosphine selenide-κ<i>Se</i>)palladium(II), [Pd(C₆H₁₄OP)₂(C₆H₁₅OP)₂], {(ⁱPr₂PSeO)₂H}₂Pd, is a hydrolysis product with inversion symmetry and contains an intra-molecular P-O⋯H-O-P group with a disordered hydrogen atom. Compounds <b>1</b>-<b>6</b> and <b>9</b> show few, if any, short inter-molecular contacts, although some H⋯<i>M</i> contacts are observed. A problem with atom-type assignment for structure refinement is discussed.