Reactions of Late First-Row Transition Metal (Fe-Zn) Dichlorides with a PGeP Pincer Germylene.

Abstract

The reactivity of the PGeP germylene 2,2 -bis(di-isopropylphosphanylmethyl)-5,5 -dimethyldipyrromethane-1,1 -diylgermanium(II), Ge(pyrmPiPr2)2CMe2 , with late first raw transition metal (Fe-Zn) dichlorides has been investigated. All reactions led to PGeP pincer chloridogermyl complexes. The reactions with FeCl2 and CoCl2 afforded paramagnetic square planar complexes of formula [MCl{κ3P,Ge,P-GeCl(pyrmPiPr2)2CMe2}] (M = Fe, Co). While the iron complex maintains an intermediate spin state (S1; μeff=3.0 μB) over the temperature range 50-380 K, the cobalt complex presents a gradual spin crossover behavior (the magnetic moment varies linearly with temperature from 1.9 μB at 10 K to 3.6 μB at 380 K, the effective magnetic moment of the cobalt complex varies linearly with temperature from 1.9 μB at 10 K to 3.6 μB at 380 K, indicating a spin crossover behavior that involves S1/2 (predominant at T<180 K) and S3/2 (predominant at\xa0 T > 200 K). Both cobalt(II) species have been detected by EPR at T<20 K). The reaction of Ge(pyrmPiPr2)2CMe2 with [NiCl2(dme)] (dme = dimethoxyethane) gave a square planar nickel(II) complex, [NiCl{κ3P,Ge,P-GeCl(pyrmPiPr2)2CMe2}], whereas the reaction with CuCl2 involved a redox process that rendered a mixture of the germanium(IV) compound GeCl2(pyrmPiPr2)2CMe2 and a binuclear copper(I) complex, [Cu2{μ-κ3P,Ge,P-GeCl(pyrmPi Pr2)2CMe2}2 ], whose metal atoms are in tetrahedral environments. The reaction of the germylene with ZnCl 2 led to the tetrahedral derivative [ZnCl{κ3P,Ge,P-GeCl(pyrmPiPr2)2CMe2 }].