Pyridine-2-selenolate complexes of palladium(II) and platinum(II): crystal structure of [(Prn3P)Cl2Pd(NC5H4Se)PdCl(PPrn3)]

Abstract

Reactions of sodium pyridine-2-selenolate with several palladium() and platinum() complexes were carried out and a variety of products isolated and characterized. Treatment of [M 2 Cl 2 (µ-Cl) 2 (PR 3 ) 2 ] with NaSeC 5 H 4 N readily afforded complexes of the type [MCl(NC 5 H 4 Se)(PR 3 )] 1 (M = Pd or Pt; PR 3 = PEt 3 , PPr n 3 , PBu n 3 , PMe 2 Ph, PMePh 2 or PPh 3 ). Some of the complexes containing trialkylphosphine existed as binuclear species,gave an unusual series of binuclear complexes, [(R 3 P)Cl 2 M(NC 5 H 4 Se)MCl(PR 3 )] 3, in which NC 5 H 4 Se acts simultaneously as a Se bridging and Se,N chelating ligand. Reactions of [PtCl 2 (cod)] or Na 2 [PdCl 4 ] with NaSeC 5 H 4 N afforded [{M(NC 5 H 4 Se) 2 } n ]. Similar reactions with [MCl 2 (L᎐L)] and [MCl 2 (PPh 3 ) 2 ] (L᎐L = dppm or dppe) gave [M(NC 5 H 4 Se) 2 (L᎐L)] and [M(NC 5 H 4 Se) 2 (PPh 3 ) 2 ], respectively. The latter complex exists in a dynamic equilibrium with [M(NC 5 H 4 Se)(NC 5 H 4 Se-N,Se)(PPh 3 ) 2 ] and PPh 3 . All the complexes were characterized by elemental analyses and NMR ( 1 H, 31 P, 77 Se, 195 Pt) spectral data. The crystal structure of [(Pr n 3 P)Cl 2 Pd(NC 5 H 4 Se)-PdCl(PPr n 3 )] revealed that NC 5 H 4 Se acts as a triply bridging ligand. One of the palladium atoms is co-ordinated to two trans chlorine atoms, one PPr n 3 , and a Se atom, while the second is bound to a chelating NC 5 H 4 Se ligand, a chlorine atom and a PPr n 3 ligand.

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

“…The magnitude of 1 J(Pt-P), (3434Ϫ3662 Hz) indicates that the phosphane ligand is trans to the nitrogen atom of the chelated [SeCH 2 CH 2 NMe 2 ] Ϫ group. [16,19,20] The 195 Pt{ 1 H} NMR spectra of these complexes displayed a doublet due to coupling with a single 31 P nucleus. The doublet appeared in a narrow range of δ ϭ Ϫ4266 to Ϫ4308.…”

“…The doublet appeared in a narrow range of δ ϭ Ϫ4266 to Ϫ4308. As is evident from [16,21,22] The appearance of a single resonance in 77 Se NMR spectra suggests that the phosphane is cis to the selenium atom as the 2 J( 77 Se-31 P) cis couplings are usually small (Ͼ 10 Hz). [22,23] However, such couplings are slightly larger for 1d and 1e (24 and 30 Hz, respectively) and could thus be resolved in the 77 Se NMR spectra.…”

“…Similar NMR spectroscopic data have been reported for [Pt 2 Cl 3 (µ-Sepy)(PR 3 ) 2 ]. [16] Although the spectra of 4b did not change with time, 4a slowly isomerised in solution to establish an equilibrium with another species 4aЈ. Thus, a CDCl 3 solution of 4a, after 2 h, displayed four resonances (δ ϭ 5.1, 3.4, 3.1, 2.4), each showing platinum satellites, the intensity of which changed with time until an equilibrium is reached after two days.…”

“…It is likely that the ''PtCl 2 (PR 3 )'' fragment of 4a isomerises from cis-''PtCl 2 '' to the trans-''PtCl 2 '' configuration, a structure observed for palladium complex, [Pd 2 Cl 3 (Sepy)(PR 3 ) 2 ]. [16] Thus, the second set of resonances (δ ϭ 3.1, 1 J(Pt-P) ϭ 3504 Hz; δ ϭ 2.4, 1 J(Pt-P) 3218 Hz) may be attributed to 4aЈ in which ''PtCl 2 '' has a trans configuration.…”

“…[11Ϫ14] The continued current interest in selenium containing inorganic materials [15] and in pursuance of our program on the design and development of molecular precursors, we explored some chemistry of internally functionalized selenolates, viz. pySe [16] and Me 2 NCH 2 CH 2 Se Ϫ . [8] Herein we now report the synthesis, spectroscopy, electrochemistry, structures, and DT-DFT calculations of platinum complexes derived from the latter ligand.…”