Dipyrromethane‐Based PGeP Pincer Methylgermyl and Methoxidogermyl Nickel and Palladium Complexes

The dipyrromethane‐based chloridogermyl complexes [MCl{κ3P,Ge,P‐GeCl(pyrmPiPr2)2CMe2}] (1M; M=Ni, Pd; (pyrmPiPr2)2CMe2=5,5’‐dimethyl‐2,2’‐bis(di‐isopropylphosphanylmethyl)dipyrromethane‐1,1’‐diyl) reacted with one or more equivalents of LiOMe to give the monosubstituted complexes [MCl{κ3P,Ge,P‐Ge(OMe)(pyrmPiPr2)2CMe2}] (2M−OMe; M=Ni, Pd). However, analogous treatments of complexes 1M with LiMe afforded the dimethyl complexes [MMe{κ3P,Ge,P‐GeMe(pyrmPiPr2)2CMe2}] (3M−Me; M=Ni, Pd). The monomethyl complexes [MCl{κ3P,Ge,P‐GeMe(pyrmPiPr2)2CMe2}] (2M−Me; M=Ni, Pd), which were identified as intermediates in the syntheses of 3M−Me, were satisfactorily prepared by treating 3M−Me with HCl. The regioselectivities of these reactions have been rationalized with DFT calculations. While LiOMe is only able to substitute the Ge−Cl chlorido ligand of the PGeP pincer germyl complexes 1Ni and 1Pd, LiMe is able to sequentially substitute first the Ge−Cl and then the M−Cl chlorido ligands. The regioselectivity of these reactions is orbital‐controlled because the LUMO of the dichlorido complexes contains an important contribution of the Ge atom.