Platinum(II) Complexes of 2-(Dimethylamino)ethylselenolate − Donor−Acceptor Inter-Ligand Interactions as Evident from Experimental and TD-DFT Computational Analysis

Abstract

Several platinum(II) complexes of 2‐(dimethylamino)ethaneselenolate with the formulae, [PtCl(SeCH2CH2NMe2)(PR3)] (1), [PtPh(SeCH2CH2NMe2)(PnBu3)] (2), [Pt2Ph2(Cl)(SeCH2CH2NMe2)(PnBu3)2] (3), [Pt2Cl3(SeCH2CH2NMe2)(PR3)2] (4), [Pt(SeCH2CH2NMe2)2(P−P)] (5), [Pt2(SeCH2CH2NMe2)2(P−P)2]++ (6), and [Pt(SeCH2CH2NMe2)(PPh3)]n[PF6]n (7) have been synthesized and characterized by elemental analysis, UV/Vis and NMR (1H, 31P, 77Se, 195Pt) spectroscopy. The stereochemistry of these complexes (1−7) has been deduced from NMR spectroscopic data. A weak absorption in the UV/Vis spectrum of 1 has been assigned to a ligand (Se)‐to‐ligand (PR3) charge transfer (LLCT), supported by TD‐DFT calculations. The structures of [PtCl(SeCH2CH2NMe2)(PPh3)] and [Pt2Ph2(Cl)(SeCH2CH2NMe2)(PnBu3)2] have been established by single crystal X‐ray diffraction analysis. Each platinum atom in the latter is coordinated to four different ligands and Me2NCH2CH2Se behaves as μ2‐bridging and is also simultaneously chelated to one of the platinum atoms.

Homo- and hetero-, bi- and tri-nuclear palladium(II) and platinum(II) complexes containing single bridging chalcogenolate of a metallo-ligand, [MCl(ECH2CH2NMe2)(PR3)] (M=Pt, Pd; E=Se, Te)

“…The observed magnitude of 1 J( 195 Pt-125 Te) (331 Hz) is in conformity with platinum tellurolate complexes. The 1b and similar other binuclear single chalcogenolato bridge platinum complexes described earlier [8] are stable in solution for several hours. However homo-and hetero-binuclear palladium complexes tend to disproportionate slowly in solution to [PdCl(ECH 2 CH 2 NMe 2 )] 3 and [MCl 2 (PR 3 ) 2 ] (M = Pd (for 1a) or Pt (for 1c)).…”

“…The 31 P{ 1 H} NMR spectra displayed a single resonance with platinum satellites. The magnitude of 1 J(Pt-P) is reduced by 45-80 Hz from the values reported for mononuclear complexes [PtCl(SeCH 2 -CH 2 NMe 2 )(PR 3 )] [8]. The 2c was contaminated ($10% by integration of 31 P NMR spectra) by starting material and another unidentified species.…”

“…Similarly nucleophilicity of chalcogen atoms in [M 2 (l-E) 2 (P \ P) 2 ] (P \ P = dppm, dppe, 2PPh 3 ; E = S, Se, Te) has been exploited to construct numerous tri-and high-nuclearity complexes exhibiting several interesting properties [1,15]. Recently we have reported a variety of mononuclear complexes, [MCl(ECH 2 CH 2 NMe 2 )(PR 3 )] (M = Pd, Pt; E = S, Se, Te) [7,8,16]. Arguably, the chalcogen atom in the latter should be able to act as a potential donor offering numerous possibilities for the use of these complexes as metallo-ligands in designing a new family of complexes containing single bridging chalcogenolate 1387-7003/$ -see front matter Ó…”

“…complexes [1,2], self-assembled discrete two-and three-dimensional structures [3,4] and dendrimers [5]. However, bi-and tri-nuclear palladium and platinum complexes in which metal square planes linked only through a single point (A and B) are scarce and have been described recently by us [6][7][8] and others [9,10].…”

Interconversion of structurally characterised complexes [PdCl(Se ̂ N)] 2 and [Pd(Se ̂ N) 2 ] 6 with the hemi-labile ligand Se ̂ N=Me 2 NCH 2 CH 2 CH 2 Se −

“…Internal functionalisation through the N donor provides a way to suppress polymerisation of metal chalcogenolates [3]. While the chemistry of mercaptoalkylamines is now fairly well explored [4][5][6], the heavier analogs containing Se or Te have been investigated only recently [1,2,[7][8][9].…”