Synthesis and Coordination Chemistry of a Novel Bidentate Phosphine:  6-(Diphenylphosphino)-1,3,5-triaza-7-phosphaadamantane (PTA-PPh₂)

Abstract

The upper rim of 1,3,5-triaza-7-phosphaadamantane (PTA) has been modified for the first time. Lithiation of PTA, with n-butyllithium, resulted in deprotonation of an alpha-phosphorus methylene and the formation of 1,3,5-triaza-7-phosphaadamantane-6-yllithium (PTA-Li). The chiral chelating phosphine 6-(diphenylphosphino)-1,3,5-triaza-7-phosphaadamantane (PTA-PPh2) was synthesized, in racemic form, by the reaction of PTA-Li with ClPPh2. PTA-PPh2 has been fully characterized in solution by multinuclear NMR spectroscopy and mass spectrometry and in the solid state by X-ray crystallography. The 31P NMR spectrum contains a pair of doublets at -19.8 and -100.1 ppm (d, (2)J(PP) = 65 Hz). Unlike PTA, the new bidentate phosphine, PTA-PPh2, is insoluble in aqueous solutions. Two group 6 metal carbonyl complexes, [M(CO)4(PTA-PPh2)] (M = W and Mo), were synthesized by the addition of PTA-PPh2 to cis-[M(CO)4(pip)2] and characterized by NMR spectroscopy, IR spectroscopy, and X-ray crystallography. Also reported are the solid-state structures of cis-[W(CO)4PTA2], cis-[W(CO)4(PTA)(PPh3)], and [W(CO)4DPPM] (DPPM = diphenylphosphinomethane). PTA-PPh2 appears to be sterically similar to and slightly more electron-donating than DPPM.

Water soluble diphosphine ligands based on 1,3,5-triaza-7-phosphaadamantane (PTA-PR2): Synthesis, coordination chemistry, and ruthenium catalyzed nitrile hydration

“…As expected the 31 a) in CDCl 3 ; b) in CD 2 Cl 2 ; c) see ref [18] The 13 C{ 1 H} NMR spectrum of 1 contains six separate resonances between 47 and 77 ppm for the six carbons in the PTA cage with the PCHP carbon appearing as a doublet of doublets at 57.25 ppm. The 13 C{ 1 H} NMR spectrum of 2 also contains 6 resonances for the six chemically distinct carbons in the PTA cage with the N-C-N carbons the most downfield between 69 and 76 ppm.…”

“…Our group, [10,[18][19][20] and others, [21][22][23][24][25][26][27][28][29][30] have been interested in the development of derivatives of the water-soluble and air-stable phosphine 1,3,5-triaza-7-phosphaadamantane (PTA). [31,32] A variety of lower-rim (C 3 N 3 ring) modified derivatives have been published involving opening of the cage, [21,22,23,25,27,33] expansion of the ring, [34,35] substitution of a methylene with SO 2 , [24,36] or trisubstitution of the triazacyclohexane ring.…”

“…Our initial report describing the synthesis of PTA-Li included the synthesis of 6-(diphenylphosphino)-1,3,5-triaza-7-phosphaadamantane (PTA-PPh 2 ) by addition of ClPPh 2 to PTA-Li. [18] PTA-PPh 2 is a chiral and air-stable, but unfortunately water insoluble, phosphine ligand isolated in somewhat poor yield (10%). [18] Herein we report the synthesis of two new bisphosphine ligands of the type PTA-PR 2 , and details of their coordination chemistry to tungsten carbonyl and a ruthenium(II) arene.…”

“…[18] PTA-PPh 2 is a chiral and air-stable, but unfortunately water insoluble, phosphine ligand isolated in somewhat poor yield (10%). [18] Herein we report the synthesis of two new bisphosphine ligands of the type PTA-PR 2 , and details of their coordination chemistry to tungsten carbonyl and a ruthenium(II) arene. In addition, a number of ruthenium complexes have been explored as aqueous phase catalysts for nitrile hydration.…”

Approaches to quantifying the electronic and steric properties of metallodithiolates as ligands in coordination chemistry

“…Using the Fe 0 (CO) 4 fragment as acceptor, entries 4 -9 of and bipyridine ligands, entries 12 -14 [21][22][23]. While the donor ability of ligands does not necessarily correspond to binding ability (or metal ligand distances), the donor ability has been effective to gage the ligand's ability to stabilize higher oxidation states as might be expected for intermediates in catalytic processes involving oxidative addition reactions.…”