The synthesis, isolation, and reactivity of a cationic, geometrically constrained σ 3 -P compound in the hexaphenylcarbodiphosphoranyl-based pincer-type ligand (1 + ) are reported. 1 + reacts with electron-poor fluoroarenes via an oxidative additiontype reaction of the C−F bond to the P III -center, yielding new fluorophosphorane-type species (P V ). This reactivity of 1 + was used in the catalytic hydrodefluorination of Ar−F bonds with PhSiH 3 , and in a catalytic C−N bond-forming cross-coupling reactions between fluoroarenes and aminosilanes. Importantly, 1 + in these catalytic reactions closely mimics the mode of action of the transition metal-based catalysts.
The reaction of tetraphenyldiphosphazane (Ph2P)2NH with mesityl azide 2,4,6‐Me3C6H2‐N3 affords a new [N,N′] chelating ligand, [HN(Ph2PN(2,4,6‐Me3C6H2))2] (LH). The ligand can be easily deprotonated by using nBuLi or Li[N(SiMe3)2] in Et2O to yield [{N(Ph2PN(2,4,6‐Me3C6H2))2}Li·OEt2] (1). The reaction of LH with AlMe3 and BH3·SMe2, respectively, gives the corresponding mononuclear complexes [{N(Ph2PN(2,4,6‐Me3C6H2))2}AlMe2] (2) and a rare borondihydride [{N(Ph2PN(2,4,6‐Me3C6H2))2}BH2] (3). Similarly, reaction of 1 with the trihalides, MX3, of group 13 elements afford the corresponding dihalo complexes, [{N(Ph2PN(2,4,6‐Me3C6H2))2}MX2] [M = B, X = F (4); M = Al, X = Cl (5); M = Ga, X = Cl (6); M = In, X = Br (7)]. All the complexes reported in this work have been isolated in good yields and are expected to serve as useful synthons in a number of reactions. The solid‐state structure of LH and 1–7 have been investigated by single‐crystal X‐ray structural analysis.
A geometrically constrained phosphenium cation in bis(pyrrolyl)pyridine based NNN pincer type ligand (1 + ) was synthesized, isolated and its preliminary reactivity was studied with small molecules. 1 + reacts with MeOH and Et 2 NH, activating the OÀ H and NÀ H bonds via a P-center/ligand assisted path. The reaction of 1 + with one equiv. of H 3 NBH 3 leads to its dehydrogenation producing 5. Interestingly, reaction of 1 + with an excess H 3 NBH 3 leads to phosphinidene (P I ) species coordinating to two BH 3 molecules (6). In contrast, [1 + ] [OTf] reacts with Et 3 SiH by hydride abstraction yielding 1-H and Et 3 SiOTf, while [1 + ][B(C 6 F 5 ) 4 ] reacts with Et 3 SiH via an oxidative addition type reaction of SiÀ H bond to P-center, affording a new P V compound (8). However, 8 is not stable over time and degrades to a complex mixture of compounds in matter of minutes. Despite this, the ability of [1 + ][B(C 6 F 5 ) 4 ] to activate SiÀ H bond could still be tested in catalytic hydrosilylation of benzaldehyde, where 1 + closely mimics transition metal behaviour.
Reduction of the cyclodiphosphazane [(S=)ClP(μ-NtBu)]2 (1) with sodium metal in refluxing toluene proceeds via two different pathways. One is a Wurtz-type pathway involving elimination of NaCl from 1 followed by head-to-tail cyclization to give the hexameric macrocycle [(μ-S)P(μ-NtBu)2 P(=S)]6 (2). The other pathway involves reduction of the P=S bonds of 1 to generate colorless singlet biradicaloid dianion trans-[S-P(Cl)(μ-NtBu)]2 (2-) , which is observed in the polymeric structures of three-dimensional [{(S-)ClP(μ-NtBu)2 PCl(S)}Na(Na⋅THF2 )]n (3) and two dimensional [{(S-)ClP(μ-NtBu)2 PCl(S)} (Na⋅THF)2 ]n (4).
Geometrically constrained, square pyramidal phosphoranide was synthesized, and its reactivity study showed that it is both a nucleophile and reductant.
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