Donor-substituted phosphanes – surprisingly weak Lewis donors for phosphenium cation stabilisation

Paradoxically, N- and O- donor substituted tri-arylphosphanes are shown to be weaker donors than PPh$_3$ when binding the soft Lewis acid moiety [PPh$_2$]$^+$. This arises from internal solvation and rehybridisation at phosphorus, precluding chelation and increasing steric demand, in direct contrast to coordination modes observed for metal complexes

A mixed-valent cyclodiphosphazane: Transition metal chemistry and cis/trans isomerisation

The hydrolysis of cis-{ClP(mu-N (t) Bu)(2)P(NH (t) Bu)} (1) produced a mixed P-III/P (V) derivative of cyclodiphosphazane, cis-{( (t) BuNH)P(mu-N (t) Bu)(2)P(O)H} (2). The treatment of 2 with elemental selenium resulted in the formation of the monoselenide, trans-{( (t) BuNH)P(Se)(mu-N (t) Bu)(2)P(O)H} (3) in good yield. The reactions of two equivalent of 2 with [Pd(mu-Cl)(eta (3)-C-3 H (5))](2) or [Ru(eta (6)-p-cymene)(mu-Cl)Cl](2) in dichloromethane afforded corresponding mononuclear complexes, [(eta (3)-C-3 H (5))PdCl{( (t) BuNH)P(mu-N (t) Bu)(2)P(O)H}] (4) and [((eta (6)-p-cymene)RuCl2){( (t) BuNH)P(mu-N (t) Bu)(2)P(O)H}] (5). The treatment of 2 with M(COD)Cl-2 (M = Pd and Pt) in dichloromethane at room temperature gave [MCl2{( (t) BuNH)P(mu-N (t) Bu)(2)P(O)H}(2)] (6 M = Pd; 7 M = Pt) in good yield. Owing to the cis/trans isomerisation of the cyclodiphosphazane rings, the complexes 6 and 7 exist as a mixture of two isomers. Various NMR spectroscopic techniques were employed for structural elucidation. The molecular structures of 5 and 7 were established by single crystal X-ray crystallographic studies

Iron-catalyzed aerobic oxidative aromatization of 1,3,5-trisubstituted pyrazolines

A simple and high yielding method for the synthesis of tri-substituted pyrazoles via iron(III) catalyzed aerobic oxidative aromatization of pyrazolines has been reported. The process demonstrates a variety of functional group tolerance. (C) 2013 Elsevier B.V. All rights reserved

Cyclodiphosphazane appended with pyridyl functionalities: Reactivity, transition metal chemistry and structural studies

A pyridyl functionalized cyclodiphosphazane, cis-{(mu-(NBu)-Bu-t)P(OCH2C5H4N-o)}(2) (1) was synthesized by reacting pyridine-2-methanol with cis-{(mu-(NBu)-Bu-t)PCl}(2). The reactions of cis-{(m-NtBu) P(OCH2C5H4N-o)} 2 with chalcogenides in appropriate stoichiometry afforded both mono and bis-chalcogenides. The treatment of 1 with ML2Cl2 (M = Pd or Pt; L-2 = COD, (SMe2)(2)) in 1:1 molar ratios resulted in the formation of mononuclear complexes, [MCl2{(mu-(NBu)-Bu-t) P(OCH2C5H4N-o)}(2)] (8 M = Pd; 9 M = Pt), whereas the 1:2 reactions produced binuclear complexes [(MCl2)(2){(mu-(NBu)-Bu-t)P(OCH(2)C(5)H4N-o)}(2)] (10 M = Pd; 11 M = Pt). The reaction of 1 with [Ru(eta(6)-p-cymene)(mu-Cl)Cl](2) afforded [((eta(6)-p-cymene) RuCl2)(2){(mu-(NBu)-Bu-t) P(OCH2C5H4N-o)}(2)] (13). Reaction of [Rh(mu-Cl)(COD)](2) with 1 in a 1:2 molar ratio yielded the mononuclear complex, [{(CO) RhCl}(2){(m-(NBu)-Bu-t)P(OCH2C5H4N-o)}(2)] (14), while the 1:1 reaction of [Rh(mu-Cl)(CO)(2)](2) with 1 produced a binuclear complex [((CO)RhCl{(mu-(NBu)-Bu-t)P(OCH2C5H4N-o)}(2)] (15). The treatment of 1 with AuCl(SMe2) resulted in the formation of a binuclear complex [(AuCl)(2){(mu-(NBu)-Bu-t) P(OCH2C5H4N-o)}(2)] (16). The reaction of 1 with 2 equiv of CuBr gave coordination polymer [{Cu(mu-Br)} 2{(mu-(NBu)-Bu-t) P(OCH2C5H4N-o)}(2)](n) (17). The crystal structures of 5, 8-10, 13 and 17 were established by single-crystal X-ray diffraction studies. (C) 2014 Elsevier B.V. All rights reserved

Quaternization and oxidation reactions of cyclodiphosphazane derivatives and their copper(I) and gold(I) complexes

The reactions of cyclodiphosphazane derivatives cis-{(BuN)-Bu-t(H)P(mu-(NBu)-Bu-t)(2)PN(H)Bu-t} (1), cis-{MeN(C4H8N)P( mu-(NBu)-Bu-t)(2)P(NC4H8Me)} (2) and {(Me2NCH2CH2O)P(mu-(NBu)-Bu-t)(2)P(OCH2CH2NMe2)} (3) with methyl iodide and methyl triflate and their subsequent reactions with elemental sulfur and selenium are reported. Interestingly, the reactions of 1-3 with an excess of methyl iodide resulted in quaternising only one phosphorus atom in cis-[{(BuNHP)-Bu-t(mu-(NBu)-Bu-t)(2)P(CH3)(NHBu)-Bu-t}](I) (4), two exocyclic nitrogen atoms and one of the phosphorus atoms in cis-{(Me2NC4H8N)P(mu-(NBu)-Bu-t)(2)P(CH3)(NC4H8NMe2)}](I)(3) (7) and only two exocyclic nitrogen atoms in cis-[{(Me3NCH2CH2O)P(mu-(NBu)-Bu-t)(2)P(OCH2CH2NMe3)}](I)(2) (8). The reaction of 1 with one equiv. of methyl triflate produced cis-[{(BuN)-Bu-t(H)P(mu-(NBu)-Bu-t)(2)P(CH3)N(H)Bu-t}]OTf (5), whereas the same reaction in a 1:2 molar ratio afforded cis-{(BuN)-Bu-t(H)P(CH3)(mu-(NBu)-Bu-t)(2)P(CH3)N(H)Bu-t}(OTf)(2) (6). Compounds 4 and 5 showed poor solubility in water, whereas 7 and 8 were high melting crystalline solids with moderate to good water solubility. Treatment of 4 with either elemental sulfur or selenium gave both cis- and transchalcogenide derivatives. Similar reactions of 7 and 8 produced both mono-and bischalcogenides. Reactions between 4 or 7 and CuI yielded dinuclear complexes, cis-[{Cu-2(mu-I)(3)((BuN)-Bu-t(H)P)(mu-NtBu) 2( P(CH3)N( H)Bu-t)]2}(I)] (15) and cis-[{Cu-2(mu-I)(3)[(Me2NC4H8N)P(mu-(NBu)-Bu-t)(2)P(CH3)(NC4H8NMe2)] 2}(I)(5)] (16), while the reaction of 8 with CuI produced a coordination polymer [{Cu2(mu-I)3(mu-(NBuP)-Bu-t)(2)(OCH2CH2NMe3)(2)}I](8) (17), containing triiodo-bridged [Cu-2(mu-I)(3)] linkers. The molecular structures of several of these compounds were confirmed by single crystal X-ray diffraction studies. The Cu-vertical bar...Cu-vertical bar distance of 2.55 angstrom in 15 is quite short and is the same as that found in copper metal and also in complexes containing [Cu-2(mu-I)(3)] linkers. All the metal complexes exhibit strong intra-, inter- or both intra- and inter-molecular hydrogen bonding interactions

A cyclodiphosphazane based pincer ligand, [2,6-{mu-((BuN)-Bu-t)(2)P((BuHN)-Bu-t)PO}(2)C6H3I]: Ni-II, Pd-II, Pt-II and Cu-I complexes and catalytic studies

Synthesis and late-transition metal complexes of pincer capable cyclodiphosphazane, 2,6-{mu-((BuN)-Bu-t)(2)P-((BuHN)-Bu-t)PO}(2)C6H3I (1) are described. The condensation of 2-iodoresorcinol with cis-{ClP(mu-(NBu)-Bu-t)(2)PN(H)Bu-t} produced a difunctional derivative 1 in good yield. The treatment of Ni(COD)(2), Pd-2(dba)(3)center dot CHCl3 or Pt(PPh3)(4) with 1 afforded pincer complexes [2,6-{mu-((BuN)-Bu-t)(2)P((BuHN)-Bu-t)PO}(2)C6H3MI] (2 M = Ni; 3 M = Pd and 4 M = Pt). The reaction of complex 3 with copper halides resulted in the formation of heterobimetallic complexes bridged by rhombic {Cu(mu-X)}(2) units, [{{Cu(mu-X)}(2)}{mu-((BuN)-Bu-t)(2)P((BuHN)-Bu-t)PO}(2)C6H3PdI] (5 X = I and 6 X = Br). The crystal structures of 1-3, 5 and 6 were established by single X-ray diffraction studies. The palladium complex 3 was tested for catalytic P-arylation of diphenylphosphine oxide (Ph2P(O)H) under microwave irradiation. Moderate to good catalytic activity was observed with aryl bromides

Copper and palladium complexes of 2-(diphenylphosphino)-N, N-dimethylbenzylamine and its selenide derivative

The synthesis of 2-(diphenylphosphino)-N,N-dimethylbenzylamine, {Ph2P(C6H4CH2NMe2-o)} (1) and its chalcogenide derivatives, {Ph2P(E)(C6H4CH2NMe2-o)} (E = O, 2; S, 3; Se, 4) were described. The reaction of 1 with [Pd(eta(3)-C3H5)Cl](2) affords a cationic complex [{Ph2P(C6H4CH2NMe2-o)}Pd(eta(3)-C3H5)][OTf] (5) in good yield. The treatment of 1 with copper halides in 1:1 M ratio afforded complexes of the type [{Ph2P(C6H4CH2NMe2-o)}(CuX)](2) (X = Br, 6; X = I, 7). Similar reactions between copper halides and Ph2RP(Se) (4) produced [{Ph2P(Se)(C6H4CH2NMe2-o)}(CuX)](2) (X = Br, 8; X = I, 9). The copper complex 7 upon treatment with 2,2'-bipyridine and 1,10-phenanthroline produced mixed ligand complexes [{Ph2P(C6H4CH2NMe2-o)}Cu(2,2'-bpy)]I (10) and [{Ph2P(C6H4CH2NMe2-o)}Cu(1,10-phen)]I (11), respectively. Single crystal X-ray structures of 7 and 9 are described. (c) 2013 Elsevier Ltd. All rights reserved

Allyl functionalized phosphinite and phosphonite ligands: Synthesis, transition metal chemistry and orthopalladation reactions

Allyl functionalized phosphinite PPh2(OAr) [Ar = C6H4(o-C3H5)] (1) and phosphonite PPh(OAr)(2) (2) ligands were prepared by the reactions of 2-allylphenol with PPh2Cl and PPhCl2, respectively. The ruthenium(II) complexes, [Ru(eta (6)-p-cymene)(PPh2(OAr))Cl-2] (3) and [Ru(eta (6)-p-cymene)(PPh(OAr)(2)Cl-2)] (4) were obtained by reacting 1 or 2 with [Ru(eta (6)-p-cymene)Cl-2](2) in 2:1 molar ratios, respectively. Reactions of 1 or 2 with AuCl(SMe2) gave [Au{PPh2(OAr)}Cl] (5) or [Au{PPh(OAr)(2)}Cl] (6) in good yield. The palladium complex, [Pd{PPh(OAr)(2)}(2)Cl-2] (7) was prepared by reacting Pd(COD)Cl-2 with 2 in 1:2 molar ratio. The reaction between Pd(COD)Cl-2 and 1 yielded a mixture of orthopalladated cis- and trans-[Pd(Ph2P(OAr))Cl](2) (8a and 8b). The treatment of 8 with PPh3 and Ph2PCH2PPh2 resulted in the cleavage of chloro bridge to give respectively, [Ph-2(OAr)PPd(PPh3)Cl] (9) and [Ph-2(ArO)PPd(eta (2)-dppm)]OTf (10). Single crystal X-ray structure of the ruthenium complex 3 is described

Self-Assembled Cyclophane-Type Copper(I) Complexes of 2,4,6-Tris(diphenylphosphino)-1,3,5-triazine and Their Catalytic Application

The triazine-based trisphosphine, 2,4,6-tris­(diphenyl­phosphino)-1,3,5-triazine (<b>1</b>) was prepared in improved yield by reacting cyanuric chloride with 3 equiv of trimethylsilyldiphenylphosphine. The solid-state structure of <b>1</b> showed short intermolecular P···P contacts of 3.362 Å, which is significantly shorter than the sum of the van der Waals radii of phosphorus atoms (3.6 Å). The reaction of 2,4,6-tris­(diphenyl­phosphino)-1,3,5-triazine (<b>1</b>) with copper­(I) salts in a 2:3 molar ratio yielded various cyclophane-type complexes in quantitative yield. The solid-state structures of these clusters have been found to depend on the size of the halide ions, the solvent employed, and the reaction conditions. Copper­(I) chloride formed a monomeric metallocyclophane, whereas copper­(I) bromide and copper­(I) iodide derivatives preferred dimeric and 1D-polymeric structures, respectively. The tricationic complexes derived from Cu^I ion and 2,4,6-tris­(diphenyl­phosphino)-1,3,5-triazine also adopted monomeric metallocyclophane structures. These complexes have been employed in the A³ coupling reaction under microwave irradiation. The copper­(I) iodide derivative showed excellent catalytic efficiency

Dinuclear Cu-I complexes of pyridyl-diazadiphosphetidines and aminobis(phosphonite) ligands: synthesis, structural studies and antiproliferative activity towards human cervical, colon carcinoma and breast cancer cells

The copper(I) complexes containing phosphorus donor ligands such as diazadiphosphetidine, cis-{(o-OCH2C5H4N)P(mu-(NBu)-Bu-t)}(2) (1) and aminobis(phosphonite), C6H5N{P(OC6H3(OMe-o)(C3H5-p))(2)}(2) (2, PNP), have been synthesized. Treatment of 1 with copper iodide afforded the 1D coordination polymer [{Cu(mu-I)}(2){(o-OCH2C5H4N)P(mu-(NBu)-Bu-t)}(2)](n) (3). Treatment of 3 with 2,2'-bipyridine (bpy) and 1,10-phen-anthroline (phen) produced mixed-ligand complexes [(L)(2)Cu-2{(o-OCH2C5H4N)P(mu-(NBu)-Bu-t)}(2)][I](2) (4 L = bpy; 5 L = phen) in good yields. The reaction of 2 with copper iodide yielded a rare tetranuclear copper complex [(CuI)(2)C6H5N(PR2)(2)](2) (6), which on subsequent treatment with various pyridyl ligands produced binuclear complexes [{Cu(mu-I)(py)}(2)(mu-PNP)] (7), [Cu-2(mu-I)(bpy)(2)(mu-PNP)]I (8), [Cu-2(mu-I)I(bpy)(mu-PNP)] (9), [Cu-2(phen)(bpy)(mu-PNP)](OTf)(2) (10), [Cu-2(mu-I)I(phen)(mu-PNP)] (11) and [Cu-2(mu-I(phen)(2)(mu-PNP)]I (12), in an almost quantitative yield. The new copper(I) complexes (4, 5 and 7-12) were tested for anti-cancer activity against three human tumor cell lines. Compounds 5, 10 and 12 showed in vitro antitumor activity 5-7 fold higher than cisplatin, the most used anticancer drug. These three most potent compounds (5, 10 and 12) were chosen for detailed study to understand their mechanism of action. The copper(I) compounds studied in the present investigation were found to inhibit tumor cell growth by arresting cells at the S-phase of the cell cycle. The characteristic nuclear morphology of treated cells showed signs of DNA damage. The experimental evidence clearly indicated that these compounds initiated apoptosis, which is mediated through the p53 pathway