Phosphaguanidinate yttrium carbene, carbyne and carbide complexes: three distinct C1 functionalities

Abstract

The phosphaguanidinate rare-earth-metal bis(aminobenzyl) complexes [(Ph₂P)C(NC₆H₃ⁱPr₂-2,6)₂]Ln(CH₂C₆H₄ NMe₂-o)₂ (Ln = Y(1-Y) and Lu(1-Lu)) were synthesized by the protonolysis of (Ph₂P)[C(NHR)(NR)] (R = 2,6-(ⁱPr)₂C₆H₃) with Ln(CH₂C₆H₄NMe₂-o)₃ (Ln = Y and Lu). Interestingly, the ring-opening rearrangement product [o-Me₂NC₆H₄CH₂C(NC₆H₃ⁱPr₂-2,6)₂]Lu(CH₂C₆H₄NMe₂-o)[O(CH₂)₄PPh₂] (2) was obtained when the acid–base reaction was carried out in THF solution at 60 °C for 36 h. Additionally, the trinuclear homometallic yttrium multimethyl/methylidene complex {[(Ph₂P)C(NC₆H₃ⁱPr₂-2,6)₂]Y(μ-Me)}₃(μ₃-Me)(μ₃-CH₂) (3) was synthesized by the treatment of 1-Y with AlMe₃ (2 equiv.) in toluene at ambient temperature in a good yield. However, the binuclear lutetium methyl complex {[(Ph₂P)C(NC₆H₃ⁱPr₂-2,6)₂]Lu(μ-Me)Me}₂ (4) can be generated through the same synthetic method. Likewise, the heterobimetallic Ln-Al complexes [(Ph₂P)C(NC₆H₃ⁱPr₂-2,6)₂]Ln(Me)(AlMe₄) (Ln = Y(6-Y) and Lu(6-Lu)) were afforded from the treatment of complex 1 with AlMe₃ (3 equiv.) at ambient temperature for 6 h. Interestingly, upon extending the reaction time of the treatment of 1-Y with three equivalents of AlMe₃, the phosphaguanidinate binuclear yttrium carbyne complex [(Ph₂P)C(NC₆H₃ⁱPr₂-2,6)₂]₂Y₂(μ₄-CH)(μ-Me)(AlMe₃)₂ (7) and the yttrium carbide complex [(Ph₂P)C(NC₆H₃ⁱPr₂-2,6)₂]₂Y₂(μ₅-C)(AlMe₂)(μ-Me)(AlMe₃)₂ (8) were isolated via multiple C–H bond activation reactions. Furthermore, the heterobimetallic Y-Al complex [(Ph₂P)C(NC₆H₃ⁱPr₂-2,6)₂]Y(AlMe₄)₂ (9) was also obtained from the treatment of 1-Y with four equivalents of AlMe₃.