Platinum(iv)-mediated nucleophilic addition of 1,3-diphenylguanidine to propiononitrile

Abstract

The reaction of the trans [PtCl 4 (EtCN) 2 ] complex with diphenylguanidine (DPG) in a molar ratio of 1 : 2 proceeds via the nucleophilic addition of DPG to coordinated nitrile and the coordination of DPG to the metal center to form the [PtCl 4 {NH=C(NHPh) 2 }{NH=C(Et) N=C(NHPh) 2 }] complex with the open chain 1,3,5 triazapentadiene ligand. The latter undergoes chelation in solution (84 h, 50 °C, CDCl 3 ), and the ring closure is accompanied by the replacement of the coordinated chloride and the formation of the cationic complex [PtCl 3 {NH=C(NHPh) 2 }{NH=C(Et)NHC(NHPh)=NPh}](Cl). The reaction of the trans [PtCl 4 (EtCN) 2 ] complex with DPG in a molar ratio of 1 : 4 affords the [PtCl 3 {NH=C (NHPh) 2 }{NH=C(Et)NC(NHPh)=NPh}] complex with the chelating 1,3,5 triazapentadienate ligand.

Crystal structure of dichloro{[anilino(phenylimino)methyl]- (propanimidoyl)azanide}-[η2-(N,N′-diphenylguanidinato)]platinum(IV) – deuterochloroform (1:1), PtCl2(C13H12N3)(C16H17N4) · CDCl3

“…The N1-C7 distance (1.333(2) Å)islonger than atypical N=C double bonds in the (1,3,5-triazapentadiene)M and/or (1,3,5-triazapentadienato)M (M =Pt II or Ni II )complexes [1,3,4], due to the influence of the N(H)Ph group. However, this interatomic distance is typical (within 3s)for this type of 1,3,5-triazapentadiene-and/or 1,3,5-triazapentadienato-containing metallacycles, and is comparable with the lengths of the corresponding C=N double bonds in the monochelated and bischelated (1,3,5-triazapentadienato)Pt II complexes [1]a nd the monochelated (1,3,5-triazapentadienato)Pt IV complex [2]. The N=C double bond lengths and the N-Csingle bond lengths in the metallacycle, in contrast to complexes of the types (1,3,5-triazapentadiene)M and/or (1,3,5-triazapentadienato)M (M =Pt II or Ni II ) [1,3,4], are indicative of ahigher degree of delocalization in the metallacycle.…”

“…The Pt Iv centre is coordinated by two Natoms of the chelating triazapentadienato ligand, two Natoms of the chelating guanidinato species, and two Cl atoms. [1], and the monochelate (1,3,5- [ 2]. The N4-C14 and N4-C7 bond lengths (1.330(3) and 1.334(2) Å,r espectively) are close to the N-C bond lengths in Pt II and Pt IV complexes containing the Pt-N(H)=C(Et)NC(N(H)Ph)=NPh moiety [1,2].…”

“…The N3-C7 bond distance (1.370 (2) Å)issimilar to the length of the corresponding N-Csingle bond in Pt II and Pt IV complexes containing the analogous structural fragment, i.e. PtN(H)=C(Et)NC(N(H)Ph)=NPh [1,2]. The N5-C23 and N6-C23 bond lengths (1.352(2) and 1.327(2) Å,respectively) within the four-membered chelate ring formed by h 2 -diphenylguanidinato ligand are similar (within 3s)tothose found in related CN bonds in the (NPh) 2C-N(H)2 h 2 -N,N'-diphenylguanidinato ligand in the Mo complex [5], and (NPh) 2C-NHPh h 2 -N,N',N''-triphenylguanidinato ligand in the Pt, Pd, Ru and Mo complexes [5][6][7][8], as well as to the CN bonds found in the h 2 -(NPh) 2CNEt2 ligand in some Ti complexes [6].…”

“…[1], and the monochelate (1,3,5- [ 2]. The N4-C14 and N4-C7 bond lengths (1.330(3) and 1.334(2) Å,r espectively) are close to the N-C bond lengths in Pt II and Pt IV complexes containing the Pt-N(H)=C(Et)NC(N(H)Ph)=NPh moiety [1,2]. The N1-C7 distance (1.333(2) Å)islonger than atypical N=C double bonds in the (1,3,5-triazapentadiene)M and/or (1,3,5-triazapentadienato)M (M =Pt II or Ni II )complexes [1,3,4], due to the influence of the N(H)Ph group.…”

Phosphorescent PtII Systems Featuring Both 2,2′‐Dipyridylamine and 1,3,5‐Triazapentadiene Ligands

“…As we were interested in the extension of the tailoring reaction [9] to other (RCN) 2 Pt II complexes as a continuation of our study of the metal-mediated integration of nitrile ligands and DPG [9][10][11] and other reactants bearing amidine moieties, [3,[12][13][14][15][16] we attempted the reaction between the guanidine and another platinum(II) precursor, viz., cis-[Pt (dpa) On the other hand, dpa provides substantial activation of platinum(II) centers toward nucleophilic addition. [17] The starting nitrile complexes [2a-d](OTf) 2 were prepared by halide abstraction from [PtI 2 (dpa)] with AgOTf in a molar ratio of 1:2 in the corresponding nitrile by a slightly modified protocol.…”