Preparation of buta-1,3-diynyl complexes of platinum(ii) and their use in the construction of neutral molecular squares: synthesis, structural and theoretical characterisation of cyclo-{Pt(μ-C![[triple bond, length as m-dash]](https://www.rsc.org/images/entities/char_e002.gif)
CCC)(dppe)}4 and related chemistry
Abstract
Copper(I)-catalysed reactions of cis-PtCl2(L)2 (L = PEt3, L2
= dppe, dppp) with buta-1,3-diyne have given the corresponding diynyl complexes, cis-Pt(CCCCH)2(L)2 (L = PEt31, L2
= dppe 2, dppp 3) whose solid-state structures have been determined from single crystal X-ray diffraction studies. Theoretical calculations were carried out to probe the electronic structure of these diynyl complexes. Complex 2 reacts with Co2(CO)8 to give a bis-adduct 5 and with Ru3(μ-dppm)(CO)10 to give a mono-adduct 6; in both, the least hindered CC
triple bond(s) is(are) coordinated. Lithiation (LiBut) of 2 gives a dilithio derivative, which has been converted to dimethyl 7 or mono-SiMe38 or -Au(PPh3) 9 complexes. Cu(I) and Ag(I) (MI) adducts (“tweezer” complexes) have been obtained from reactions of 2 with MISCN or [MI(NCMe)4]+. An ES mass spectrometric study of the interactions of 2 with Group 1 cations and with Tl+ is also described; comparative experiments with {W(CO)3Cp}2(μ-C8), in which the four CC triple bonds do not have a “tweezer” conformation, have also been carried out.
The degree of association is determined by the competitive solvation of the Group 1 cation. Coupling of the buta-1,3-diynyl complexes with Pt(OTf)2(L′)2 gives homo- or mixed-ligand molecular squares cyclo-{(L)2Pt(μ-CCCC)2Pt(L′)2}2 (L, L′
= PEt3, L2, L′2
= dppe, dppp; not all combinations), of which the molecular structure of cyclo-{Pt(μ-CCCC)(dppe)}417 is described (as solvates containing dmso). The molecular squares form adducts with substituted ammonium triflates [NH2R2][OTf] (R = Et, Pri, Cy; NH2R2
= dbuH) and with Group 11 cations [MI(NCMe)]+.
![Graphical abstract: Preparation of buta-1,3-diynyl complexes of platinum(ii) and their use in the construction of neutral molecular squares: synthesis, structural and theoretical characterisation of cyclo-{Pt(μ-C [[triple bond, length as m-dash]] CC [[triple bond, length as m-dash]] C)(dppe)}4 and related chemistry](/en/Image/Get?imageInfo.ImageType=GA&imageInfo.ImageIdentifier.ManuscriptID=B107929H&imageInfo.ImageIdentifier.Year=2002)
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![[triple bond, length as m-dash]](https://www.rsc.org/images/entities/h2_char_e002.gif)
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