N ‐ Versus P ‐Coordination in Bis(amino)cyclodiphosph(III)azane Complexes of Aluminum

The reaction of the bis(amino)cyclodiphosph(III)azane, cis ‐{( t BuNH) 2 (PN t Bu) 2 }, with AlMe 3 , AlClMe 2 , AlCl 2 Me, and AlCl 3 is reported. The less Lewis acidic compound AlMe 3 forms the adduct cis ‐[( t BuNH) 2 (PN t Bu){P( ⋅ AlMe 3 )N t Bu}] ( 1 ), in which the aluminum atom is exclusively coordinated to one phosphorus atom. At elevated temperatures AlMe 3 undergoes migratory exchange between the two phosphorus atoms, but no methane elimination is observed. By using the more Lewis acidic compound AlClMe 2 the P ‐coordinated compound cis ‐[( t BuNH) 2 (PN t Bu){P( ⋅ AlClMe 2 )N t Bu}] ( 2 ) can be obtained at low temperatures. Compound 2 rearranges irreversibly to a product in which the AlClMe 2 group is coordinated by one exo‐cyclic nitrogen atom. A concomitant 1,2‐H shift from this nitrogen atom onto the phosphorus atom is observed. The N ‐coordinated rearrangement product slowly decomposes via a PN bond cleavage in solution. Reaction of the even more Lewis acidic compounds AlCl 2 Me and AlCl 3 finally led to stable adducts, cis ‐[( t BuNH)(PN t Bu)( t BuN ⋅ AlCl 2 Me){P(H)N t Bu}] ( 3 ), and cis ‐[( t BuNH)(PN t Bu)( t BuN ⋅ AlCl 3 ){P(H)N t Bu}] ( 4 ), in which the aluminum atoms are N ‐coordinated by a t BuNPH unit.