Insertion Reactions and Catalytic Hydrophosphination of Heterocumulenes using α-Metalated N,N-Dimethylbenzylamine Rare-Earth-Metal Complexes

Abstract

The reactivity of homoleptic α-metalated dimethylbenzylamine lanthanide complexes (α-Ln(DMBA)3; Ln = La, Y; DMBA = α-deprotonated dimethylbenzylamine) was probed through a series of stoichiometric insertion and catalytic hydrophosphination reactions. Both rare-earth-metal species inserted 3 equiv of various carbodiimides to form the corresponding homoleptic amidinates. α-La(DMBA)3 was also found to be a useful precatalyst for the room-temperature hydrophosphination of heterocumulenes to form phosphaguanidines, phosphaureas, and phosphathioureas in moderate to excellent isolated yields. Furthermore, through a series of stepwise stoichiometric protonation and insertion reactions, a plausible mechanism for the hydrophosphination catalysis was investigated.

Half-sandwich rare-earth metal tris(alkyl) ate complexes catalyzed phosphaguanylation reaction of phosphines with carbodiimides: an efficient synthesis of phosphaguanidines

“…Low yields were found when the reaction was carried out at room temperature (Table 1, entry 5) or under low catalyst loading (1 mol%) (Table 1, entry 6). The comparison clearly shows the significance of combining cyclopentadiene-based ligands and ate complexes (Table 1, entries 4 and [11][12][13]. The ate complex 8-Y showed better catalytic activity than the neutral yttrium complexes such as the halfsandwich constrained-geometry complex 6-Y, mono-Cp complex 10-Y, and tris(trimethylsilylmethyl) complex Y(CH 2 TMS) 3 (THF) 2 .…”

“…11 In the attempt to test the rare-earth metals, the half-sandwich lanthanum aminobenzyl complex 5-La was found by Hou et al to display the highest activity among the rare-earth metals because of its largest ionic Fig. 13 All these reported catalyst systems involved only the neutral metal amides or alkyl complexes. a Beijing National Laboratory for Molecular Sciences, MOE Key Laboratory of radius (1.032 Å for La 3+ ); however, the corresponding yttrium complexes 5-Y and 6-Y (0.900 Å for Y 3+ ) showed evidently lower activity.…”

Lanthanides and actinides: Annual survey of their organometallic chemistry covering the year 2013

“…of various carbodiimides to form the corresponding homoleptic amidinates. ␣-La(DMBA) 3 also served as a precursor for the synthesis of a homoleptic lanthanum phosphaguanidinate (Scheme 30) [20].…”

“…The homoleptic ␣-metalated dimethylbenzylamine lanthanum complex La(o-CH 2 C 6 H 4 NMe 2 ) 3 (␣-La(DMBA) 3 ) has been found to be a useful pre-catalyst for the room-temperature hydrophosphination of heterocumulenes to form phosphaguanidines, phosphaureas, and phosphathioureas in moderate to excellent isolated yields (Scheme 159) [20].…”

“…Furthermore, through a series of stepwise stoichiometric protonation and insertion reactions, a plausible mechanism for the hydrophosphination catalysis was proposed (Scheme 160) [20].…”