From a Diphosphanegermylene to Nickel, Palladium, and Platinum Complexes Containing Germyl PGeP Pincer Ligands

Abstract

The PGeP pincer-type germylene Ge(NCH PtBu )C H (1) has been used to prepare a family of group 10 metal complexes, namely, [MCl{κ P,Ge,P-GeCl(NCH PtBu ) C H }] (M=Ni (2 ), Pd (2 ), Pt (2 )), featuring a chloridogermyl PGeP pincer ligand and a Cl-Ge-M-Cl bond sequence. Their reactivity is not initially centered on the metal atom but on their Ge atom. Complexes 2 and 2 easily led to the hydrolyzed products [Ni Cl {μ-(κ P,Ge,P-Ge(NCH PtBu ) C H ) O}], which features a Cl-Ni-Ge-O-Ge-Ni-Cl bond sequence, and [PdCl{κ P,Ge,P-Ge(OH)(NCH PtBu ) C H }], which contains a hydroxidogermyl PGeP pincer ligand (2 is reluctant to undergo hydrolysis). Simple chloride exchange reactions led to the methoxidogermyl, methylgermyl, and phenylgermyl derivatives [MCl{κ P,Ge,P-GeR(NCH PtBu ) C H }] (M=Pd, Pt; R=OMe, Me, Ph). Whereas the palladium complexes [PdCl{κ P,Ge,P-GeR(NCH PtBu ) C H }] (R=Me, Ph) reacted with more MeLi or PhLi to give palladium black and GeR (NCH PtBu ) C H (R=Me, Ph), similar reactions with the analogous platinum complexes afforded the transmetalation derivatives [PtR{κ P,Ge,P-GeR(NCH PtBu ) C H }] (R=Me, Ph). The short length of the CH PtBu arms of the PGeP pincer ligands forces the metal atoms of all these complexes to be in a very distorted square-planar ligand environment. The reactivity results have been rationalized with theoretical calculations.

A Germylene Supported by Two 2‐Pyrrolylphosphane Groups as Precursor to PGeP Pincer Square‐Planar Group 10 Metal(II) and T‐Shaped Gold(I) Complexes

“…Regarding metal-free PGeP pincer-type germylenes,o nly two specimens have so far been reported, namely,G e-(NCH 2 PtBu 2 ) 2 C 6 H 4 [11] and Ge(NC 6 H 4 PPh 2 ) 2 C 2 H 4 [12] (compounds A and B in Figure 1) and their transition-metal derivative chemistry has just started to be developed. [12][13][14] Both A and B are very prone to get their Ge atom inserted into MÀCl bonds to give chloridogermyld erivatives. It shouldb en oted that Figure 1.…”

Synthesis, Structure, and Reactivity of a Mononuclear η2‐(Ge–H)palladium(0) Complex Bearing a PGeP‐Pincer‐Type Germyl Ligand: Reactivity Differences between Silicon and Germanium

“…We investigated the reaction of the η 2 ‐(Ge–H)Pd 0 4 with ethylene to evaluate the activity for hydrometallation/β‐hydrogen elimination through non‐innocent behavior of the germyl ligand as seen in the Si‐analogue 1 . When the reaction of 4 with 1 atm ethylene was monitored by 1 H and 31 P NMR in [D 8 ]THF, the reaction started at –40 °C to give an ethylpalladium(II) complex 6 bearing a PGeP‐pincer type germyl ligand in 66 % yield after 20 min (Entry 1, Table ) The reaction almost completed within 20 min after the temperature was raised to –20 °C. We previously reported that the hydrometallation of the Si‐analogue 1 under the same reaction conditions occurred at –20 °C to give the ethylpalladium(II) 2 in 40 % yield after 20 min, and 1 was mostly converted to 2 at 0 °C after 30 min .…”

The Transition Metal Chemistry of PGeP and PSnP Pincer Heavier Tetrylenes

“…The reactions of germylene XXV with dichlorido complexes of group 10 metals containing easily displaceable ligands gave the isostructural complexes [MCl{κ 3 P,Ge,P ‐GeCl(NCH 2 P t Bu 2 ) 2 C 6 H 4 }] (M = Ni ( 4 ), Pd ( 5 ), Pt ( 6 ); Figure13), which feature a chloridogermyl PGeP pincer ligand and a Cl–Ge–M–Cl bond sequence . While their Ge atoms are in a tetrahedral environment, their M atoms present a very distorted square plane coordination (P–M–P angles close to 150°) owing to the strain imposed by the short length of the CH 2 P t Bu 2 arms of the pincer ligand.…”

“…Their reactivity is not initially centered on the metal atom but on their Ge atom. While the platinum complex 6 was reluctant to undergo hydrolysis, complexes 4 and 5 easily led to the hydrolyzed products [Ni 2 Cl 2 {µ‐(κ 3 P , Ge , P ‐Ge(NCH 2 P t Bu 2 ) 2 C 6 H 4 ) 2 O}] ( 9 ), which features a Cl–Ni–Ge–O–Ge–Ni–Cl bond sequence, and [PdCl{κ 3 P , Ge , P ‐Ge(OH)(NCH 2 P t Bu 2 ) 2 C 6 H 4 }] ( 10 ), which contains a hydroxidogermyl PGeP pincer ligand (Figure ) . Chloride exchange reactions (studied with compounds 5 and 6 ) led to the methoxidogermyl, methylgermyl and phenylgermyl derivatives [MCl{κ 3 P , Ge , P ‐GeR(NCH 2 P t Bu 2 ) 2 C 6 H 4 }] (M = Pd, Pt; R = OMe, Me, Ph; compounds 11 – 16 in Figure ).…”

“…It its noteworthy that they all have been described in the last three years. Our contributions (compounds XXV , XXVI , XXIX and XXX , 2017–2019) have been complemented with results produced by Goicoechea's (compounds XXVII and XXVIII , 2018) and Tobita's (compound XXXI , 2019) research groups.…”