Methanediide Formation via Hydrogen Elimination

Substituted bis(iminophosphoranyl)methanes are CH acidic compounds that can form 15 complexes with formally dianionic central carbon centres. The reaction of H2C(Ph2P=NDip)2 (≡ 16 H2L), Dip = 2,6-diisopropylphenyl, with one equivalent of di-n-butylmagnesium afforded the 17 methanide complex [HLMgnBu] 1. Treatment of complex 1 with phenylsilane in aromatic solvents 18 at elevated temperatures afforded the methanediide complex [(LMg)2] 2 presumably via the MgH 19 intermediate [(HLMgH)n] (n = 1 or 2). The reaction of 1 with LiAlH4 in diethyl ether yielded the 20 AlH complex [HLAlH2] 3. Alternatively, this complex was also obtained from the reaction of H2L 21 with AlH3∙NMe3. The molecular structures of [HLMgnBu] 1, [(LMg)2] 2, and [HLAlH2] 3 are 22 reported. Complex 3 shows no sign of H2 elimination to a methanediide species at elevated 23 temperatures in contrast to the facile elimination of the putative reaction intermediate [(HLMgH)n] 24 (n = 1 or 2) to form [(LMg)2] 2. The chemical properties of complex 2 were investigated and this 25 complex appears to be stable against coordination with strong donor molecules. 26