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

The reactivity of the PGeP germylene 2,2'-bis(di-isopropylphosphanylmethyl)-5,5'-dimethyldipyrromethane-1,1'-diylgermanium(II), Ge(pyrmPiPr ) CMe , with late first-row transition metal (Fe-Zn) dichlorides has been investigated. All reactions led to PGeP pincer chloridogermyl complexes. The reactions with FeCl and CoCl afforded paramagnetic square planar complexes of formula [MCl{κ P,Ge,P-GeCl(pyrmPiPr ) CMe }] (M=Fe, Co). While the iron complex maintained an intermediate spin state (S ; μ =3.0 μ ) over the temperature range 50-380 K, the effective magnetic moment of the cobalt complex varied linearly with temperature from 1.9 μ at 10 K to 3.6 μ at 380 K, indicating a spin crossover behavior that involves S (predominant at T<180 K) and S (predominant at T>200 K) species. Both cobalt(II) species were detected by electron paramagnetic resonance at T<20 K. The reaction of Ge(pyrmPiPr ) CMe with [NiCl (dme)] (dme=dimethoxyethane) gave a square planar nickel(II) complex, [NiCl{κ P,Ge,P-GeCl(pyrmPiPr ) CMe }], whereas the reaction with CuCl involved a redox process that rendered a mixture of the germanium(IV) compound GeCl (pyrmPiPr ) CMe and a binuclear copper(I) complex, [Cu {μ-κ P,Ge,P-GeCl(pyrmPiPr ) CMe } ], whose metal atoms are in tetrahedral environments. The reaction of the germylene with ZnCl led to the tetrahedral derivative [ZnCl{κ P,Ge,P-GeCl(pyrmPiPr ) CMe }].