Mono-, Di-, and Tricoordinated Phosphorus Attached to a N−N Unit: An Experimental and Theoretical Study

Abstract

N,N',N'-[Tris(trimethylsilyl)]hydrazino-diphenylphosphane, (TMS)2 N-(TMS)N-PPh2 (1), and N,N',N'-[tris(trimethylsilyl)]hydrazino-phenyl(chloro)phosphane, (TMS)2 N-(TMS)N-P(Cl)Ph2 (2), were obtained in the reaction of bis-[lithium-tris(trimethylsilyl)hydrazide] with Ph(n)PCl(3 - n) (n = 1, 2). The structure and bonding of both species are discussed on the basis of experimentally observed (X-ray, Raman, NMR, and MS) and theoretically obtained data (B3LYP/6-31G(d,p), NBO analysis). Oxidation with sulfur and selenium results in the formation of (TMS)2 N-(TMS)N-P(S)Ph2 (4), (TMS)2 N-(TMS)N-P(Se)Ph2 (5), (TMS)2 N-(TMS)N-P(S)Ph(Cl) (6), and (TMS)2 N-(TMS)N-P(Se)Ph(Cl) (7). Moreover, the thermal decomposition of N,N',N'-[tris(trimethylsilyl)]hydrazine-dichlorophosphane, (TMS)2 N-(TMS)N-PCl2 (3) and the reaction with magnesium have been investigated. The formation and molecular structure of the novel MgCl2(THF)2 x 2Mg[(TMS)NP(O)2 N(TMS)2](THF) (8) salt containing the hitherto unknown (TMS)NP(O)2 N(TMS)2(2-) anion are discussed. DFT calculations (B3LYP/6-311+G(3df,2p)//B3LYP/6-31G(d,p)) are used to evaluate the bonding, ground-state structures, and energy landscape for the different isomers of 3: the thermodynamics and kinetics of the successive elimination of chlorotrimethylsilane (TMS-Cl) resulting in the formation of covalent azide analogues such as TMS-PNN or TMS-NNP.

Tetrazarsoles—A New Class of Binary Arsenic–Nitrogen Heterocycles

“…Triazadiphosphole [1] was recently prepared from (Me 3 Si) 2 N À N(SiMe 3 )PCl 2 [2] and GaCl 3 under mild conditions in a formal GaCl 3 -assisted [3+2] cycloaddition. The second example of a binary azaphosphole, the tetrazaphosphole, [3] was formed in the reaction of Me 3 SiN 3 with Mes*N=PCl (Mes* = 2,4,6-tBu 3 C 6 H 2 ), again catalyzed by GaCl 3 .…”

Transition‐Metal‐Free Boron–Carbon Bond Activation: Insertion of an NNP Fragment into a Boron–Carbon Bond

“…Also, after further stirring of this reaction mixture for 5 h at -100°C no Me 3 SiCl elimination could be observed; only the starting material was isolated after removal of BF 3 [5] Me 3 SiF, and PFCl 2 could be identified amongst the decomposition products. These failures prompted us to utilize the sterically demanding fluorine-containing Lewis acid B(C 6 F 5 ) 3 . Again, no reaction was observed when 1 was added to a solution of B(C 6 F 5 ) 3 in CH 2 Cl 2 at ambient temperature.…”

“…Surprisingly, upon cooling of the above reaction mixture down to 5°C, a large amount of beautiful orange crystals of the new species was obtained (isolated yield 29 %). Single-crystal X-ray studies revealed a surprising 2,4-bis(pentafluorophenyl)-1,3-bis[N-trimethylsilyl-N-bis(pentafluorophenyl)boranyl]amino [1,3,2,4]diazadiphosphetidine (3) as the product (Scheme 2, Figure 1). …”

“…The ambivalent (Me 3 Si) 2 N-N(SiMe 3 )-PCl 2 displays both dipolarophile and/or 1,3-dipole characteristics. GaCl 3 is required to release the hidden dipolarophile and/or 1,3-dipole by decreasing the activation barrier to Me 3 SiCl elimination. In this context, we studied the influence of fluorine-containing Lewis acids such as neat BF 3 , BF 3 ·OEt 2 , and B(C 6 F 5 ) 3 on the Me 3 SiCl elimination in Scheme 2.…”

“…Herein, we detail the reactivity of these fluorine-containing Lewis acids towards (Me 3 Si) 2 -N-N(SiMe 3 )-PCl 2 , which proceeds in the case of B(C 6 F 5 ) 3 , by the first reported example of an unusual NNP fragment insertion into a boron-carbon bond (Scheme 2).…”