Akerman Matthew, Akerman Kate, Jaganyi Deogratius, Reddy Desigan
School of Chemistry, University of KwaZulu-Natal, Private Bag X01, Pietermaritzburg 3209, South Africa.
Acta Crystallogr C. 2011 Sep;67(Pt 9):m290-2. doi: 10.1107/S0108270111026011. Epub 2011 Aug 6.
The reaction between [PtCl(terpy)]·2H(2)O (terpy is 2,2':6',2''-terpyridine) and pyrazole in the presence of two equivalents of AgClO(4) in nitromethane yields the title compound, Pt(C(3)H(4)N(2))(C(15)H(11)N(3))(2)·CH(3)NO(2), as a yellow crystalline solid. Single-crystal X-ray diffraction shows that the dicationic platinum(II) chelate is square planar with the terpyridine ligand occupying three sites and the pyrazole ligand occupying the fourth. The torsion angle subtended by the pyrazole ring relative to the terpyridine chelate is 62.4 (6)°. Density functional theory calculations at the LANL2DZ/PBE1PBE level of theory show that in vacuo the lowest-energy conformation has the pyrazole ligand in an orientation perpendicular to the terpyridine ligand (i.e. 90°). Seemingly, the stability gained by the formation of hydrogen bonds between the pyrazole NH group and the perchlorate anion in the solid-state structure is sufficient for the chelate to adopt a higher-energy conformation.
在硝基甲烷中，[PtCl(terpy)]·2H₂O（terpy为2,2':6',2''-三联吡啶）与吡唑在两当量高氯酸银存在下反应，生成标题化合物Pt(C₃H₄N₂)(C₁₅H₁₁N₃)₂·CH₃NO₂，为黄色结晶固体。单晶X射线衍射表明，二价铂(II)螯合物为平面正方形，三联吡啶配体占据三个位点，吡唑配体占据第四个位点。吡唑环相对于三联吡啶螯合物所张的扭转角为62.4(6)°。在LANL2DZ/PBE1PBE理论水平下的密度泛函理论计算表明，在真空中，能量最低的构象中吡唑配体的取向垂直于三联吡啶配体（即90°）。显然，固态结构中吡唑NH基团与高氯酸根阴离子之间形成氢键所获得的稳定性足以使螯合物采取能量较高的构象。
