Alloyed Tetranuclear Metal Chains of Pd_4−nPt_n (n=0–3) Scaffolded by a New Linear Tetraphosphine Containing a PNP Bridge

Abstract

An ew linear tetraphosphine containing aP NP phosphazane bridge, rac-bis[(diphenylphosphinomethyl)phenylphosphino]phenylamine (rac-dpmppan), was synthesized andu tilized to support as eries of Pd/Pt mixed metal tetranuclearc hains, [Pd 4Àn Pt n (m-racdpmppan) 2 (XylNC) 2 ](PF 6 ) 2 (XylNC = xylyl isocyanide; n = 0: Pd 4 (1), 1: PtPd 3 (2), 2: PtPd 2 Pt (3), 2: Pt 2 Pd 2 (4), 3: Pt 2 PdPt (5)), in whicht he number and positions of additional Pt atoms were successfully controlled depending on the respective synthetic procedures using transformationsf rom 1 to 3 through 2 and from 4 to 5 by redox-coupled exchange reactions. The 31 P{ 1 H} NMR and ESI mass spectra and X-ray diffractiona nalyses revealed almosti dentical tetranuclear structures, with slight contraction of metalmetal bonds according to incorporation of Pt atoms. The electronic absorption spectra of 1-5 exhibited characteristic bands at 635-510 nm with an energy propensity depending on the number and positions of Pt centres, which were assigned to HOMO (ds*ss*) to LUMO (ds*s*s*) transition by theoretical calculations.T he present results demonstrated that the electronic structures of Pd/Pt mixed-metal tetranuclear complexes are finely tuned as orbital-overlapping alloyedm etal chains by atomically precise Pt incorporation in the Pd 4 chain.[a] Prof.

Tetranuclear Pd4, PtnPd4‐n (n=1–3), and Pt4 Chains Supported by rac‐ and meso‐Ph2PCH2P(Ph)N(Ar)P(Ph)CH2PPh2 Tuned by Changing N‐Substituents, P‐Configuration, and Terminal Ligands

“…ESI-TOF mass spectra were recorded on a JEOL JMS-T100LC in a positive detection mode in the range of m/z 100-3000, equipped with an ion spray interface. [11] According to the reported procedures, a mixture of PhPCl 2 (3.00 g, 16.7 mmol) and [(diphenylphosphino)methyl]trimethylsilane (4.45 g, 16.3 mmol) was placed in a round flask under argon atmosphere and heated at 95 °C for 1 hr. The volatile products were removed under reduced pressure to give colorless oil of Ph 2 PCH 2 P(Ph)Cl quantitatively.…”

“… Preparation of [M 4 ( rac ‐dpmppan) 2 (XylNC) 2 ](PF 6 ) 2 (M 4 =Pd 4 ( 1 ), PtPd 3 ( 2 ), PtPd 2 Pt ( 3 ), Pt 2 Pd 2 ( 4 ), and Pt 2 PdPt ( 5 )) [11] …”

“…[8][9][10] Recently, a linear tetraphosphine possessing a PN(Ph)P phosphazane bridge, rac-bis[(diphenylphosphinomethyl)phenylphosphino]phenylamine (rac-dpmppan), was synthesized to tune the linear Pd 4 units (Scheme 1). [11] Reaction of racdpmppan with [Pd 2 (XylNC) 6 ](PF 6 ) 2 and [Pd(dba) 2 ] (Xyl = 2,6-xylyl, dba = dibenzalacetone) in 2 : 1 : 2 ratio afforded the Pd 4 chain with XylNC terminal ligands, [Pd 4 (rac-dpmppan) 2 (XylNC) 2 ](PF 6 ) 2 (1), that was interestingly transformed by treating with [Pt 3 (XylNC) 6 ] into [PtPd 3 (rac-dpmppan) 2 (XylNC) 2 ](PF 6 ) 2 (2) and [PtPd 2 Pt(rac-dpmppan) 2 (XylNC) 2 ](PF 6 ) 2 (3), successively. When the tetraphosphine was reacted with [Pt 2 (XylNC) 6 ](PF 6 ) 2 and [Pd(dba) 2 ], the Pt 2 Pd 2 mixed metal chain, [Pt 2 Pd 2 (racdpmppan) 2 (XylNC) 2 ](PF 6 ) 2 (4), was isolated and was further converted to [Pt 2 PdPt(rac-dpmppan) 2 (XylNC) 2 ](PF 6 ) 2 (5).…”

Nanoarchitectonics for Coordination Asymmetry and Related Chemistry

“…48 Formation of alloyed tetranuclear asymmetric metal chain, Pd4-nPtn (n = 0-3), supported by tetraphosphine containing a P-N-P phosphazane bridge, rac-bis[(diphenylphosphinomethyl)phenylphosphino]phenylamine, was demonstrated by Tanase, Nakajima, and co-workers. 49 For recognition of hydrogen phosphonate anions, Nakamura et al newly synthesized per(5-N-carboxamide-5-dehydroxylmethyl)-β-cyclodextrins. 50 Prassides and coworkers investigated asymmetric mixedvalence sesquioxide Cs4O6 for their elusive valence transition.…”

Development of Multinuclear Metal Systems Structurally Constrained by Linear Polyphosphines

“…Fig 16. Preparations of Pd 4 , PtPd 3 , PtPd 2 Pt, Pt 2 Pd 2 , and Pt 2 PdPt chains supported by rac-dpmppan 32. …”