Platinum amides from platinum nitriles: x-ray crystal structures of the unbridged dinuclear compounds bis[bis(1-imino-1-hydroxy-2,2-dimethylpropane)dichloroplatinum(II)] and bis[bis(1-imino-1-hydroxy-2,2-dimethylpropane)(1-amino-1-oxo-2,2-dimethylpropane)dichloroplatinum(II)]

Abstract

Mono-and bisnitrile platinum complexes, [PtC13(NCR)]-and cis-and trans-[PtC12(NCR)2] (R = Bu', Me and Ph), hydrolyze to amidate amide and mixed amide-nitrile complexes. The amide ligands generally adopt the enol tautomeric form and coordinate to platinum through nitrogen. The presence of two amides cis to one another plays a critical role in favoring the association of platinum units in dimers. For example, molecules of cis-[PtCl2{HN=C-(OH)Bu'jz]2, 7b, comprise two monomeric units, placed face to face, with a Pt-Pt distance of 3.165(1) A and four interplanar N-H...Cl hydrogen bonds. Although hydrogen bonding interactions would place the dimer in the eclipsed conformation, the compound adopts the staggered conformation which minimizes interligand steric interactions allowing a closer approach of the two platinum subunits. The driving force to shortening the intermetallic distance stems from a direct intermetallic bonding interaction. Addition of two extra amides to axial sites of 7b gave [PtClz{HN= C(OH)BU')~{H~NC(=O)BU']]~, 7c. The axial amides differ from the equatorial ones, in both tautomeric form (keto instead of enol) and donor atom (oxygen instead of nitrogen). In spite of a very long Pt-0 distance [3.229(5) A] the axial coordination causes a considerable lengthening of the intermetallic distance (0.23 A) and, furthermore, conversion from the staggered to the eclipsed conformation. The solution chemistry of both 7b and 7c is in accord with their dimeric structure. A fast rate of proton exchange, between the hydroxyl group of the amide ligands and water present in the solvent, was observed whenever two amide ligands are cis to one another. Such an exchange process could be favored by the hydrogen bonding interaction of the two cis amides with a molecule of water. Mixed amide nitrile complexes have also been prepared; one trans-[PtC12{HN=C(OH)Buf}(NCBu')] proved to be the complex previously formulated as a platinum(1V) dichlorobisamidate derivative having the two amidate ligands in different tautomeric forms. The structure of 7b-CzH4C12 and 7c have been solved by single-crystal X-ray diffraction. 7b crystallizes as 1 ,Zdichloroethane solvate (1:l) in the space group P i (no 2) with a = 11.292(3), b = 13.618(3), c = 14.069(4) A, a = 62.12(2), p = 83.58(2), y = 76.47(2)', V = 1859(1) A3, Z = 2. 7c crystallizes in the space group P i (no 2) with a = 10.279(1), b = 10.772(1), c = 11.099(3) A, CY = 90.66(1), fl = 89.58(1), y = 114.27(1)', V = 1120(1) A3, Z = 1.

Conversion of acetonitrile into acetamide in the co-ordination spheres of cis- and trans-M II (amine)2(M = Pt or Pd). Solution and crystal structural studies

“…In contrast, several structures of platinum compounds with terminal amides have been described. 8 Here we report on the formation, structure and hydrolysis of acetonitrile complexes of cis-[Pt(NH,),Cl,] and the related compounds cis-[Pt(NH,Me), Cl,] and [Pt(en)Cl,] (en = t Supplementary data available: see Instructions for Authors, J. Chem. ethane-l,2-diamine) as well as of the corresponding trans isomer trans-[Pt(NH,),Cl,].…”

Isomerism of Amides Coordinated to Platinum – X-ray Crystal Structure ofO-Bonded Acetamide in a Platinum(II) Complex

“…The signal is found more downfield at Ϫ80°C and more upfield at ϩ50°C. A possible expla-ies by an alternative route, that is, by hydrolysis of the corresponding nitrile complexes as already reported [11] . The Nnation for this behavior is that at low temperature there is preference for a given isomer and that, as the temperature bonded amides invariably adopt the iminol form with two downfield signals at δ ഠ 12 and 8Ϫ9 assigned to the OH is raised, a second isomer contributes to the stereochemistry of the complex causing the observed spectral changes.…”

Click‐Type PtII‐Mediated Hydroxyguanidine–Nitrile Coupling Provides Useful Catalysts for Hydrosilylation Cross‐Linking

“…Materials and Instrumentation : Solvents were obtained from commercial sources and used as received. Complexes trans ‐ and cis ‐[PtCl 2 (RCN) 2 ] (R=Et ( NC1 , NC5 ); t Bu (( NC2 , NC6 ); Ph ( NC3 , NC7 )) were synthesized in accord with the published procedures; the trans and cis ‐isomers were separated by column chromatography on silica gel (SiO 2 , 0.063–0.200 mm, Merck). For preparation and characterization (including X‐ray structure determination) of NC4 see the Supporting Information.…”