Stephen M. Aucott

An alternative strategy to an electron rich phosphine based carbonylation catalystThis paper is dedicated to the memory of Prof. Noel McAuliffe in recognition of his contribution to phosphine chemistry and friendship.

The complexes [Rh(CO)Cl(2-Ph2PC6H4COOMe)], 1, and trans-[Rh(CO)Cl(2-Ph2PC6H4COOMe)2], 2, have been synthesized by the reaction of the dimer [Rh(CO)2Cl]2 with 2 and 4 molar equivalents of 2-(diphenylphosphino)methyl benzoate. The complexes 1 and 2 show terminal ν(CO) bands at 1979 and 1949 cm−1 respectively indicating high electron density at the metal centre. The molecular structure of the complex 2 has been determined by single crystal X-ray diffraction. The rhodium atom is in a square planar coordination environment with the two phosphorus atoms trans to each other; the ester carbonyl oxygen atom of the two phosphine ligands points towards the rhodium centre above and below the vacant axial sites of the planar complex. The rhodium–oxygen distances (Rh⋯O(49) 3.18 A; Rh⋯O(19) 3.08 A) and the angle O(19)⋯Rh⋯O(49) 179° indicate long range intramolecular secondary Rh⋯O interactions leading to a pseudo-hexacoordinated complex. The complexes 1 and 2 undergo oxidative addition (OA) reactions with CH3I to produce acyl complexes [Rh(COCH3)ClI(2-Ph2PC6H4COOMe)], 4, and trans-[Rh(COCH3)ClI(2-Ph2PC6H4COO-Me)(2-Ph2PC6H4COOMe)], 5, and the kinetics of the reactions reveal that the complex 1 undergoes faster OA reaction than that of the complex 2. The catalytic activity of the complexes 1 and 2 in the carbonylation of methanol were higher than that of the well known species [Rh(CO)2I2]− and the complex 1 shows higher activity than 2.

Preparation and organometallic complexes of the new unsymmetrical Ligand: Ph2PNHC6H4PPh2

Deprotonation of (2-diphenylphosphino)benzeneamine with BuLi followed by reaction with ClPPh 2 in THF gave Ph 2 PNHC 6 H 4 PPh 2 in good yields. The new unsymmetrical ligand has been incorporated into a number of complexes [[Rh{Ph 2 PNHC 6 H 4 PPh 2 }(cod)][ClO 4 ] 2 , RhCl 2 (η 5 -C 5 Me 5 ){Ph 2 PNHC 6 H 4 PPh 2 -P ( N ) } 3 , [RhCl(η 5 -C 5 Me 5 ){Ph 2 PNHC 6 H 4 PPh 2 - P ( N ), P }][Cl] 4 , IrCl 2 (η 5 -C 5 Me 5 ){Ph 2 PNHC 6 H 4 PPh 2 -P { N } } 5 , RuCl 2 (η 6 -MeC 6 H 4 i Pr){Ph 2 PNHC 6 H 4 PPh 2 -P ( N ) } 6 , [RuCl(η 6 -MeC 6 H 4 i Pr){Ph 2 PNHC 6 H 4 PPh 2 - P ( N ), P }][BF 4 ] 7 , RuCl 2 (η 6 -C 6 Me 6 ){Ph 2 PNHC 6 H 4 PPh 2 -P ( N ) } 8 , [RuCl(η 6 -C 6 Me 6 ){Ph 2 PNHC 6 H 4 PPh 2 - P ( N ), P }][BF 4 ] 9 , RuCl 2 (η 3 :η 3 -C 10 H 16 ){Ph 2 PNHC 6 H 4 PPh 2 - P ( N ) } 10 , OsCl 2 (η 6 -MeC 6 H 4 i Pr){Ph 2 NHPC 6 H 4 PPh 2 -P ( N ) } 11 ] to demonstrate its coordination behaviour as a monodentate or as a chelate ligand. The X-ray structures of for 5 , 9 and 10 are reported.

Synthesis and Coordination Chemistry of the New Unsymmetrical Ligand Ph2PCH2NHC6H4PPh2

Condensation of Ph2PCH2OH with 2-(diphenylphosphanyl)aniline in toluene gave the new unsymmetrical ligand Ph2PCH2NHC6H4PPh2 (1) in good yield. Oxidation of 1 with H2O2 or elemental sulfur led to the oxidised products Ph2P(O)CH2NHC6H4P(O)Ph2 (2) and Ph2P(S)CH2NHC6H4P(S)Ph2 (3). The new ligand 1 demonstrates three distinct modes of coordination. Reaction of compound 1 with [MX2(cod)] (M = Pd, Pt; X = Cl, Br, Me) or [Mo(CO)4(pip)2] gave the chelate complexes [PdCl2(Ph2PCH2NHC6H4PPh2-PX,PA)] (4), [PdBr2(Ph2PCH2NHC6H4PPh2-PX,PA)] (5), [PtCl2(Ph2PCH2NHC6H4PPh2-PX,PA)] (6), [PtMe2(Ph2PCH2NHC6H4PPh2-PX,PA)] (7) and [Mo(CO)4(Ph2PCH2NHC6H4PPh2-PX,PA)] (8). Coordination of 1 with [{RuCl(μ-Cl)(η3:η3-C10H16)}2] or [{RhCl(μ-Cl)(η5-C5Me5)}2] gave the monodentate complexes [RuCl2(η3:η3-C10H16)(Ph2PCH2NHC6H4PPh2-PX)] (9) and [RhCl2(η5-C5Me5)(Ph2PCH2NHC6H4PPh2-PX)] (10). Reaction of 1 with [{IrCl(μ-Cl)(η5-C5Me5)}2] led to a mixture from which the monodentate complex [IrCl2(η5-C5Me5)(Ph2PCH2NHC6H4PPh2-PX)] (11) and the chelate cationic complex [IrCl(η5-C5Me5)(Ph2PCH2NHC6H4PPh2-PX,PA)][Cl] (12) were separated. Abstraction of the chloride ligands from complexes 9 and 10 with AgClO4 gave the cationic chelate complexes [RuCl(η3:η3-C10H16)(Ph2PCH2NHC6H4PPh2-PX,PA)][ClO4] (13) and [RhCl(η5-C5Me5)(Ph2PCH2NHC6H4PPh2-PX,PA][ClO4] (14). Compound 1 also functions as a bridging ligand when reacted with two molar equivalents of [AuCl(tht)] or one molar equivalent of [{RhCl(μ-Cl)(η5-C5Me5)}2] to give the bimetallic complexes [Ph2P{AuCl}CH2NHC6H4PPh2{AuCl}] (15) and [{RhCl2(η5-C5Me5)}2(Ph2PCH2NHC6H4PPh2)] (16). The dioxidised compounds 2 and 3 and several typical complexes 8, 9, 11 and 14 were structurally characterised by X-ray diffraction. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)

Coordination chemistry of o-Ph2PNHC6H4P(S)Ph2 a P,S-donor ligand: synthesis of new Ru, Rh and Ir complexes

Abstract The late transition metal complexes [(Ar)RuCl2(PS)] (Ar=C6H6, o-MeC6H4(iPr) and C6Me6), [RuCl2(η3:η3-C10H16)(PS)], [RhCl(cod)(PS)] (cod=1,5-cyclooctadiene) and [(Cp*)MCl2(PS)] (Cp*=pentamethylcyclopentadienyl, M=Rh or Ir) (where PS=Ph2PNHC6H4P(S)Ph2) have been synthesised by the reaction of Ph2PNHC6H4P(S)Ph2 with the appropriate chloride bridged transition metal dimers. In all of these complexes the ligand is monodentate P-bound. Chloride abstraction from representative complexes, using Ag[ClO4], gave the cationic compounds [(o-MeC6H4{iPr})RuCl(PS)][ClO4], [Rh(cod)(PS)][ClO4] and [(Cp*)RhCl(PS)][ClO4] in which the ligand is k2-P,S bound. All new compounds were characterised by a combination of 31P{1H} and 1H NMR spectroscopy, microanalysis, FAB mass spectrometry and IR spectroscopy. The molecular structures of five complexes have been determined by single-crystal X-ray diffraction—both monodentate and chelate coordination has been characterised. The P-monodentate compounds all display intramolecular NH⋯S hydrogen bonding.

The co-ordination chemistry of 2-(diphenylphosphinoamino)pyridine

2-(Diphenylphosphinoamino)pyridine, dppap [Ph2PNHpy], and over 40 illustrative examples of its complexes have been prepared. Monodentate, bidentate and bridging co-ordination of the neutral (and bidentate deprotonated ligand) has been demonstrated in a range of palladium, platinum and gold complexes. Ten demonstrative examples have been characterised by single crystal X-ray diffraction. Ph2PNHpy exists as hydrogen-bonded dimer pairs; cis-[PtCl(Ph2PNHpy-P,N){Ph2PNHpy-P}]Cl packs in hydrogen-bonded infinite chains; cis-[Pt(Ph2PNpy-P,N)2] and cis-[Pd(Ph2PNpy-P,N)2] are isomorphous. The structures of cis-[Pd(Ph2PNHpy-P,N)2][BF4]2, [AuCl(Ph2PNHpy-P)], [Pt(C8H12OMe)(Ph2PNpy-P,N)]·H2O illustrating hydrogen-bonding, cis-[PtCl(Ph2PNHpy-P,N)(PMe3)]Cl, cis-[PtCl(Ph2PNpy-P,N)(PMe3)] and cis-[PtCl(Ph2PNHpy-P,N)(P(OPh)3)]Cl are also reported.

Synthesis and Late Transition Metal Complexes of the Heterofunctional Phosphaneo-Ph2PNHC6H4P(S)Ph2

The difunctional ligand o-Ph2PNHC6H4P(S)Ph2 (PS) has been prepared by treatment of the lithium amide salt of 2-(diphenylthiophosphanyl)aniline {2-[Ph2P(S)]C6H4NH2} with Ph2PCl. The new ligand was oxidised to give the mixed chalcogen species Ph2P(E)NHC6H4P(S)Ph2, by treatment with H2O2 (where E = O) or aerial oxidation by recrystallisation from MeOH, and by reaction with Se8 (where E = Se) in warm toluene. The complexes [MCl(η3-C3H5)(PS)] (M = Pt or Pd), cis-[PtCl2(PS)(PMe2Ph)], [(AuCl)(PS)], cis-[MCl2(PS)2] (M = Pt or Pd), cis-[PtMe2(PS)2] and trans-[PtMeCl(PS)2] have been synthesised by reaction of either [Pt(μ-Cl)(μ-η2:η1-C3H5)]4, [Pd(μ-Cl)(η3-C3H5)]2, [{PtCl(μ-Cl)(PMe2Ph)}2], [AuCl(tht)] (tht = tetrahydrothiophene), [PdCl2(cod)] or [PtX2(cod)] (X = Me or Cl; cod = cycloocta-1,5-diene) with (PS). In all these complexes the ligand (PS) is monodentate P-bound. Chloride abstraction from [MCl(η3-C3H5)(PS)] (M = Pt or Pd), cis-[PtCl2(PS)(PMe2Ph)], cis-[PtCl2(PS)2] and trans-[PtMeCl(PS)2], using Ag[ClO4], gave the monocationic [M(η3-C3H5)(PS)][ClO4] (M = Pt or Pd), cis-[PtCl(PS)(PMe2Ph)][ClO4], trans-[PtMe(PS)2][ClO4] or dicationic [Pt(PS)2][ClO4]2 compounds in which the ligand (PS) is κ2-P,S-bound. All compounds described here have been characterised by a combination of 31P{1H} and 1H NMR spectroscopy, microanalyses, FAB mass spectrometry and IR spectroscopy. The molecular structures of [AuCl(Ph2PNHC6H4P(S)Ph2-P)] in which there is an intramolecular hydrogen-bonding interaction between the amine proton and the sulfur atom of the thiophosphoryl group and trans-[Pt(Ph2PNHC6H4P(S)Ph2-κ2-P,S)2][ClO4]2·CH2Cl2·2H2O in which the perchlorate counterions are associated by hydrogen-bonding interactions to the amine protons of the κ2-P,S ligands have been determined by single-crystal X-ray diffraction. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)

N-Metallation of MS2N2 rings. X-ray crystal structures of [(η5-C5Me5)Ir(S2N2)Au(PPh3)][ClO4], [{(η5-C5Me5)Ir(S2N2)Au}2(μ2-dppm)][ClO4]2 and [Au(dppeS-P)Cl]2

Bimetallic complexes [(η5-C5R5)M(S2N2)Au(PPh3)][ClO4] and tetrametallic species [{(η5-C5R5)M(S2N2)Au}2(μ2-P^P)][ClO4]2 (R=H, M=Co; R=Me, M=Ir; P^P=dppm or dppe) can be prepared by treatment of [(η5-C5R5)M(S2N2)] with gold(I) electrophiles generated by chloride abstraction from [AuCl(PPh3)] or [(AuCl)2(μ2-P^P)]. X-Ray crystallography of [(η5-C5Me5)Ir(S2N2)Au(PPh3)][ClO4] and [{(η5-C5Me5)Ir(S2N2)Au}2(μ2-dppm)][ClO4]2 confirms auration of the metal-bound nitrogen atom of the MS2N2 ring. π-Stacking of theMS2N2 rings occurs within both structures.

Reactions of mono- and bis-N-bromosulfimides with thio-ether crowns, phosphines and selenides

The brominated sulfimide Ph2SNBr reacts with diphosphines 1,2-(PPh2)2C2H4 and 1,4-(Ph2P)2(C6H4) to give the bis-N-phosphoniosulfimidium cations [1,2-(Ph2PNSPh2)2C2H4]2+ and [1,4-(Ph2PNSPh2)2(C6H4)]2+, respectively. Treatment of the bis-sulfimide 1,4-[PhSNH]2C6H4 with N-bromosuccinimide results in 1,4-[PhSNBr]2C6H4, which in turn reacts with triphenylphosphine to generate [1,4-(PhS{NSPPh3})2C6H4]Br2. Both Ph2SNBr and 1,4-[PhSNBr]2C6H4 react with the thio-ether crown [9-ane]S3, giving [9[ane]S3NSPh2]Br and [1,4-{[9-ane]S2S(NSPh)2C6H4]Br2, respectively. The first examples of seleniosulfimidium salts have been isolated from the reactions of Ph2SNBr and 1,4(PhS{NBr})2C6H4 with Ph2Se and the structures of the [Ph2SNSePh2]+ and [1,4-(PhSNSePh2)2C6H4]2+ cations confirmed by X-ray crystallography. Reaction of 1,2-PhS(NH)C6H4SPh with one equivalent of N-bromosuccinimide followed by addition of Na[BPh4] results in [1,2-(PhS)2(μ-N)C6H4][BPh4] in which a CCSNS ring is observed; two forms of this material may be isolated upon crystallisation—X-ray crystallography reveals them to differ by the relative orientations of the phenyl rings.

Roesky’s ketone: a spectroscopic study

We present a joint experimental-theoretical spectroscopic study of 5-oxo-1,3,2,4-dithiadiazole, also known as Roesky’s ketone. The theoretical results of a vibrational analysis, calculated at the DFT/B3LYP/6-311+G* level of theory, of the title compound have been compared with experimental data, consisting of Raman and IR frequencies in different phases, and the bands have been assigned to the normal vibrations of the molecule. Additionally, an analysis of the origin of the high intensity of the band assigned to the CO stretching mode was performed based on calculated stockholder charges and atomic dipoles. The results of theoretical calculations of the 13C and 14N NMR chemical shifts are compared to experimentally obtained shifts.

Synthesis and characterisation of cyanodithioimidocarbonate [C2N2S2]2− complexes

[PPh4]2[M(C2N2S2)2](M = Pt, Pd) and [Pt(C2N2S2)(PR3)2](PR3= PMe2Ph, PPh3) and [Pt(C2N2S2)(PP)](PP = dppe, dppm, dppf) were all obtained by the reaction of the appropriate metal halide containing complex with potassium cyanodithioimidocarbonate. The dimeric cyanodithioimidocarbonate complexes [[Pt(C2N2S2)(PR3)]2](PR3 = PMe2Ph), [M[(C2N2S2)(eta5-C5Me5)]2](M = Rh, Ir)and [[Ru(C2N2S2)(eta6-p-MeC6H4iPr)]2] have been synthesised from the appropriate transition metal dimer starting material. The cyanodithioimidocarbonate ligand is S,S and bidentate in the monomeric complexes with the terminal CN group being approximately coplanar with the CS2 group and trigonal at nitrogen thus reducing the planar symmetry of the ligand. In the dimeric compound one of the sulfur atoms bridges two metal atoms with the core exhibiting a cubane-like geometry.