Inverse Coordination-The Janus Face of Coordination Chemistry

Ni(I) and Ni(II) Bis(trimethylsilyl)amides Obtained in Pursuit of the Elusive Structure of Ni{N(SiMe3)2}2

“…The formation of complex 5 (Figure ) is likely due to adventitious amounts of oxygen or moisture that arose during storage of the Schlenk flask in the freezer, producing an imperfect silicone grease seal at the glass stopper. In the “inverse crown” ether (ICE) structure, the metals in the “crown” act as Lewis acids for the O 2– anion. , To date, the principal isolation routes of all ICE complexes of the first-row transition metals have been reported to involve the introduction of “adventitious” amounts of oxygen, similar to the isolation route for complex 5 . , Furthermore, the syntheses designed to isolate pure ICE complexes of the 3d metals give impure products for Mn­(II) and Co­(II), but pure ICE complexes of Zn­(II) can be isolated. − For Ni­(II), storage of three separate hexane solutions of [K]­[Ni­{N­(SiMe 3 ) 2 } 2 ] ( 2 ) in a −18 °C freezer with an imperfect silicone grease seal reliably gave colorless crystals of 5 .…”

“…In the "inverse crown" ether (ICE) structure, the metals in the "crown" act as Lewis acids for the O 2− anion. 25,26 To date, the principal isolation routes of all ICE complexes of the first-row transition metals have been reported to involve the introduction of "adventitious" amounts of oxygen, similar to the isolation route for complex 5. 27,28 Furthermore, the syntheses designed to isolate pure ICE complexes of the 3d metals give impure products for Mn(II)…”