Cu(I) catalysts for alkylation of diphenylphosphine were developed. Treatment of [Cu(NCMe)(4)][PF(6)] (1) with chelating ligands gave [CuL(NCMe)][PF(6)] (2; L = MeC(CH(2)PPh(2))(3) (triphos), 3; L = 9,9-dimethyl-4,5-bis(diphenylphosphino)xanthene (XantPhos)). These complexes catalyzed the alkylation of PHPh(2) with PhCH(2)Br in the presence of the base NaOSiMe(3) to yield PPh(2)CH(2)Ph (4). The precursors Cu(dtbp)(X) (dtbp =2,9-di-t-butylphenanthroline, X = Cl (5) or OTf (6)), CuCl, and 1 also catalyzed this reaction, but dtbp dissociated from 5 and 6 during catalysis. Both 2 and 3 also catalyzed alkylation of PHPh(2) with PhCH(2)Cl/NaOSiMe(3), but XantPhos dissociation was observed when 3 was used. When CH(2)Cl(2) was used as the solvent for alkylation of PhCH(2)Cl with precursors 2 or 3, or of PhCH(Me)Br with 2, it was competitively alkylated to yield PPh(2)CH(2)Cl (7), which was formed exclusively using 2 in the absence of a benzyl halide. Cu(triphos)-catalyzed alkylation of PhCH(Me)Br gave mostly PPh(2)CHMePh (8), along with some Ph(2)P-PPh(2) (9), which was also formed in attempted alkylation of dibromoethane with this catalyst. The phosphine complexes [Cu(triphos)(L')][PF(6)] (L' = PH(2)Ph (10), PH(2)CH(2)Fc (Fc = C(5)H(4)FeC(5)H(5), 11), PHPh(2) (12), PHEt(2) (13), PHCy(2) (Cy = cyclo-C(6)H(11), 14), PHMe(Is) (Is = 2,4,6-(i-Pr)(3)C(6)H(2), 15), PPh(2)CH(2)Ph (16), PPh(2)CH(2)Cl (17)), and [Cu(XantPhos)(L')][PF(6)] (L' = PHPh(2) (18), PPh(2)CH(2)Ph (19)) were prepared by treatment of 2 and 3 with appropriate ligands. Similarly, treatment of dtbp complexes 5 or 6 with PHPh(2) gave [Cu(dtbp)(PHPh(2))(X)] (X = OTf (20a) or Cl (20b)), and reaction of PPh(2)CH(2)Ph (4) with 1 formed [Cu(PPh(2)CH(2)Ph)(3)][PF(6)] (21). Complexes 2, 3, 11-14, 16, 17, 19, and 21 were structurally characterized by X-ray crystallography. Deprotonation of diphenylphosphine complex 12 in the presence of benzyl bromide gave diphenylbenzylphosphine complex 16, while deprotonation of 12 in CD(2)Cl(2) gave 17 containing a PPh(2)CD(2)Cl ligand. Low-temperature deprotonation of the soluble salt 12-[B(Ar(F))(4)] (Ar(F) = 3,5-(CF(3))(2)C(6)H(3)) in THF-d(8) gave the phosphido complex Cu(triphos)(PPh(2)) (22). Thermally unstable 22 was characterized by NMR spectroscopy and, in comparison to 12, by density functional theory (DFT) calculations, which showed it contained a polarized Cu-P bond. The ligand substitution step required for catalytic turnover was observed on treatment of 16 or 17 with PHPh(2) to yield equilibrium mixtures containing 12 and the tertiary phosphines 4 or 7; equilibrium constants for these reactions were 8(2) and 7(2), favoring complexation of the smaller secondary phosphine in both cases. These observations are consistent with a proposed mechanism for catalytic P-C bond formation involving deprotonation of the cationic diphenylphosphine complex [Cu(triphos)(PHPh(2))][PF(6)] (12) by NaOSiMe(3) to yield the phosphido complex Cu(triphos)(PPh(2)) (22). Nucleophilic attack on the substrate (benzyl halide or CH(2)Cl(2)) then yie...

Generating monovalent pnictogens within NCN pincers has resulted in the isolation of three distinct types of 1,2-azaheteroles, highly aromatic nitrogen analogues like pyrazole-based 5, aromatic yet fluxional P- and As-derived bell-clappers 1 and 2, and hypervalent Sb and Bi derivatives 3 and 4, which are supported by 3-center, 4-electron N–E–N bonds. Careful analysis of the solid-state structures of 1–5/[5-Me]­[OTf] in combination with NICS calculations (at the GIAO/M06/cc-pVTZ­(-PP) level) and other computational methods (NBO) suggest that simpler NC chelates may support new phosphorus- and arsenic-containing heterocycles. Indeed, reduction of ECl2 (E = P or As) derivatives supported by N-Dipp (Dipp = 2,6-diisopropylphenyl) substituted NC bidentate ligands produced 1,2-benzoazaphosphole 11 and 1,2-benzoazaarsole 12. NICS calculations revealed 11 and 12 had aromatic character on par with that of pyrazole-based 5.

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The trapping of a phosphinidene (R-P) in an NCN pincer is presented. Stabilized phosphinidene 1 was characterized by P{ H}, H, and C{ H} NMR spectroscopy, exhibiting an averaged C symmetry in solution between -60 and 60 °C. In the solid state, the phosphinidene is coordinated by one adjacent N atom featuring a formal P-N bond (1.757(2) Å) to give a five-membered ring with some aromatic character, confirmed by DFT calculations (B3LYP-D3/6-311G**++) to be the ground-state structure. Equilibration of the two N ligands occurs rapidly in solution via a "bell-clapper"-type process through an associative symmetric transition state calculated to lie 4.0 kcal mol above the ground state.

Diastereoselective coordination of racemic secondary phosphines (PHRR′) to Cu(I) precursors containing chiral bis(phosphines) (diphos*) was explored as a potential route to P-stereogenic phosphido complexes. Reaction of [Cu(NCMe) 7); two of the three expected isomers of the bis(secondary phosphine) complexes [Cu((R,R)i-Pr-DuPhos)(PhHP(CH 2 ) n PHPh)][PF 6 ] (n = 2 (8); n = 3 (9)) were formed preferentially in related reactions. Reaction of the halide-bridged dimers [Cu((R,R)-i-Pr-DuPhos)(X)] 2 or [Cu((R,R)-Me-FerroLANE)(I)] 2 with PHMe(Is) gave the labile adducts Cu((R,R)-i-Pr-DuPhos)(PHMe(Is))(X) (X = Cl (10), Br (11), I (12)) and Cu((R,R)-Me-FerroLANE)(PHMe-(Is))(I) (13). Complexes 1, 6, and 8−11 were structurally characterized by X-ray crystallography. Variable temperature NMR studies of 6 and 8 showed that the secondary phosphine ligands underwent reversible dissociation. Deprotonation of 6 or 7 generated the P-stereogenic phosphido complexes Cu(diphos*)(PMeIs) (diphos* = (R,R)-i-Pr-DuPhos ( 14) or (R,R)-Me-FerroLANE) (17)), observed by 31 P NMR spectroscopy, but decomposition also occurred. Density functional theory calculations were used to characterize the diastereomers of thermally unstable 17 and the inversion barrier in a model copperphosphido complex. These observations provided structure−property relationships which may be useful in developing catalytic asymmetric reactions involving secondary phosphines and P-stereogenic copper phosphido intermediates.

A substituted TREN has been prepared in which the aryl groups in (ArylNHCH2CH2)3N are substituted at the 3- and 5-positions with a total of six OCH2(CH2)nCH═CH2 groups (n = 1, 2, 3). Molybdenum nitride complexes, [(ArylNCH2CH2)3N]Mo(N), have been isolated as adducts that contain B(C6F5)3 bound to the nitride. Two of these [(ArylNCH2CH2)3N]Mo(NB(C6F5)3) complexes (n = 1 and 3) were crystallographically characterized. After removal of the borane from [(ArylNCH2CH2)3N]Mo(NB(C6F5)3) with PMe3, ring-closing olefin metathesis (RCM) was employed to join the aryl rings with OCH2(CH2)nCH═CH(CH2)nCH2O links (n = 1-3) between them. RCM worked best with a W(O)(CHCMe3)(Me2Pyr)(OHMT)(PMe2Ph) catalyst (OHMT = hexamethylterphenoxide, Me2Pyr = 2,5-dimethylpyrrolide) and n = 3. The macrocyclic ligand was removed from the metal through hydrolysis and isolated in 70-75% yields relative to the borane adducts. Crystallographic characterization showed that the macrocyclic TREN ligand in which n = 3 contains three cis double bonds. Hydrogenation produced a TREN in which the three links are saturated, i.e., O(CH2)10O.

Asymmetric deprotonation of PMe 2 (t-Bu)(BH 3 ) with s-BuLi/ (−)-sparteine, followed by treatment with MeSiCl 3 , gave a 2.6:1 mixture of the C 3 -and C 1 -symmetric triphosphine−boranes MeSi(CH 2 PMe(t-Bu)(BH 3 )) 3 (3). Recrystallization gave highly diastereomerically and enantiomerically enriched C 3 -3. After deprotection with morpholine, the triphosphine (R)-MeSi(CH 2 PMe(t-Bu)) 3 (4; (Me, t-Bu)-Siliphos or MT-Siliphos) was used to prepare the metal complexes [Rh(MT-Siliphos)(norbornadiene)][OTf] (5), Ru(MT-Siliphos)(DMSO)Cl 2 (6), [Ru(MT-Siliphos)(NCMe) 3 ][OTf] 2 (7), M(MT-Siliphos)(PPh 3 ) (M = Pd (8), Pt (9)), Cu(MT-Siliphos)(Cl) (10), and polymeric [Cu 2 Cl 2 (μ-(κ 2 ,κ 1 )-MT-Siliphos)] ∞ (11). The crystal structures of C 3 -3 and of complexes 5, 7, and 11 were determined, and dynamic processes in 6 and 8 were characterized by variable-temperature NMR spectroscopy.

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