Novel Tailoring Reaction for Two Adjacent Coordinated Nitriles Giving Platinum 1,3,5-Triazapentadiene Complexes

Abstract

The tailoring reaction of the two adjacent nitrile ligands in cis-[PtCl(2)(RCN)(2)] (R = Me, Et, CH(2)Ph, Ph) and [Pt(tmeda)(EtCN)(2)][SO(3)CF(3)](2) (8.(OTf)(2); tmeda = N,N,N',N'-tetramethylethylenediamine) upon their interplay with N,N'-diphenylguanidine (DPG; NH=C(NHPh)(2)), in a 1:2 molar ratio gives the 1,3,5-triazapentadiene complexes [PtCl(2){NHC(R)NHC(R)=NH}] (1-4) and [Pt(tmeda){NHC(Et)NHC(Et)NH}][SO(3)CF(3)](2) (10.(OTf)(2)), respectively. In contrast to the reaction of 8.(OTf)(2) with NH=C(NHPh)(2), interaction of 8.(OTf)(2) with excess gaseous NH(3) leads to formation of the platinum(II) bis(amidine) complex cis-[Pt(tmeda){NH=C(NH(2))Et}(2)][SO(3)CF(3)](2) (9.(OTf)(2)). Treatment of trans-[PtCl(2)(RCN)(2)] (R = Et, CH(2)Ph, Ph) with 2 equiv of NH=C(NHPh)(2) in EtCN (R = Et) and CH(2)Cl(2) (R = CH(2)Ph, Ph) solutions at 20-25 degrees C leads to [PtCl{NH=C(R)NC(NHPh)=NPh}(RCN)] (11-13). When any of the trans-[PtCl(2)(RCN)(2)] (R = Et, CH(2)Ph, Ph) complexes reacts in the corresponding nitrile RCN with 4 equiv of DPG at prolonged reaction time (75 degrees C, 1-2 days), complexes containing two bidentate 1,3,5-triazapentadiene ligands, i.e. [Pt{NH=C(R)NC(NHPh)=NPh}(2)] (14-16), are formed. Complexes 14-16 exhibit strong phosphorescence in the solid state, with quantum yields (peak wavelengths) of 0.39 (530 nm), 0.61 (460 nm), and 0.74 (530 nm), respectively. The formulation of the obtained complexes was supported by satisfactory C, H, and N elemental analyses, in agreement with FAB-MS, ESI-MS, IR, and (1)H and (13)C{(1)H} NMR spectra. The structures of 1, 2, 4, 11, 13, 14, 9.(picrate)(2), and 10.(picrate)(2) were determined by single-crystal X-ray diffraction.

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

“…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 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.…”

“…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. 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 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 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.…”

“…[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.…”