Jane Browning

Coordination chemistry of [CH{P(S)Ph2}2]−: X-ray diffraction studies of S,S-chelate complexes of iridium and rhodium

Reactions of the chloro-bridged complexes, [M2Cl2(cod)2], M  Ir or Rh, with CHR(P(S)Ph2)2, R  H or Me, provide a synthetic route to the cations, [M(cod){CHR(P(S)Ph2)2-S,S}]+, which are isolated as fluoroborate or perchlorate salts. Treatment of these products with sodium hydride results in facile deprotonation to the neutral complexes, [M(cod){CR(P(S)Ph2)2-S,S}], and when R  H, the neutral complexes are also accessible via reactions of [M2Cl2(cod)2] with Li[CH{P(S)Ph2)2]. The complexes, [Ir(cod){CH(P(S)Ph2)2-S,S}], and [Rh(cod){CH(P(S)Ph2)2-S,S}], crystallize in the P1 (No. 2) space group (Z = 2) with respective unit cells: a = 11.570(4), b = 15.122(2), c = 9.919(3) A, α = 79.86(4), β = 64.87(3), γ = 97.94(4)°; and α = 11.571(16), b = 15.078(2), c = 9.869(2) A, α = 100.16(1), β = 64.97(1), γ = 82.10(1)°. Both structures consist of puckered 6-membered rings formed by coordination of the disulfide ligands via two sulfur atoms to the metal center. The rings lie in distorted boat conformations with the prows occupied by one sulfur and one phosphorus and the metal atoms in one side.

THE SYNTHESIS AND STRUCTURE OF SOME, RAC-TRANS-, MESO-TRANS- AND (S, S)-TRANS-CO(III) COMPLEXES WITH ME6-14-DIENE(5,7,7,12, 14,14-HEXAMETHYL-1,4,8,11- TETRAAZACYCLOTETRADECA-4,11-DIENE)

Abstract The reaction of cis-[Co(CO3)(Me6-[14]-diene)]ClO4 with S-(+)-mandelic acid gives first (S,S)-trans-[Co(S-mandelato)2(Me6-[14]-diene)]ClO4·2H2O (1) and then (R,S)-trans-[Co(S-mandelato)2(Me6-[14]-diene)]ClO4·H2O (2). With HCl, the cis-carbonato gives first rac–trans-[CoCl2(Me6-[14]-diene)]ClO4 (3) and then increasing amounts of meso–trans-[CoCl2(Me6-[14]-diene)]ClO4 (4). The rac–trans-perchlorate (3) can be isomerised partially to the meso-form (4) in refluxing methanol. Treatment of 1 with HCl/HClO4 gives (+)-(S,S)-trans-[CoCl2(Me6-[14]-diene)]ClO4 which racemises in methanol to give a rac-/meso-mixture. Attempts to resolve rac–trans-[CoCl2(Me6-[14]-diene)]+ directly with the antimonyl(III) tartrate anion were not successful, but work-up of the solution with HCl gave X-ray quality crystals of rac–trans-[CoCl2(Me6-[14]-diene)]2Sb2Cl8 (5) containing dimers of the seesaw shaped SbCl4− anion. trans-[CoBr2(Me6-[14]-diene)]ClO4 reacts with dilute aqueous ammonia to give trans-[Co(OH)(Me6-[14]-diene)(NH3)](ClO4)2. Acidification of this allows the isolation of synrac–trans-[Co(Me6-[14]-diene)(NH3)(OH2)](ClO4)3, which slowly isomerises in acidic solution [kisom=2.92×10−5 s−1 at 25°C] to the meso-form. Two isomers of [CoCl(Me6-[14]-dien)(NH3)]2+ have also been isolated, the synrac–trans-perchlorate and the meso–trans-tetrachlorozincate (6) and their aquation rates (chloride release) have been measured. The crystal structures of compounds 1–6 have been determined.

Coordination chemistry of [C(PPh2)P(S)Ph2)2]- : 31P NMR of rhodium, iridium and platinum complexes, and the crystal and molecular structures of [Rh(cod){C(PPh2)(P(S)Ph2)2-P,S}].CH2Cl2 and [RhI2(tBuNC)2{C(PPh2)P(S)Ph2)2-P,S}]

Complexes of the anionic ligand, [C(PPh2)(P(S)Ph2)2]−, are readily prepared under mild conditions by reactions of CH(PPh2)(P(S)Ph2)2, in the presence of base (NHEt2), with chlorobridged complexes, [M2Cl2(cod)2], M  Rh or Ir, cod = cycloocta-1,5-diene, [Pt2Cl4(PEt3)2], and [Pt2Cl2(MeOcod)2], MeOcod = 8-methoxy-cyclooct-4-ene-1-yl. The products are [M(cod){C(PPh2)(P(S)Ph2)2-P,S}], [PtCl(PEt3){C(PPh2)(P(S)Ph2)2-P,S}], and [Pt(MeOcod){C(PPh2)(P(S)Ph2)2-P,S}] respectively, and the platinum complexes are both mixtures of the two possible isomers. Subsequent reactions of [Rh(cod){C(PPh2)(P(S)Ph2)2-P,S}] with tBuNC followed by oxidative addition of I2 or benzyl bromide give [Rh(tBuNC)2{C(PPh2)(P(S)Ph2)2-P,S}], and isomeric mixtures of [RhI2(tBuNC)2{C(PPh2)(P(S)Ph2)2- P, S}] and [RhBr(Bz)(tBuNC)2{C(PPh2)(P(S)Ph2)2-P, S}]. The complexes were characterized primarily by 31P nuclear magnetic resonance (NMR) studies and by two crystal structure determinations. Complex 1a, [Rh(cod){C(PPh2)(P(S)Ph2)2-P,S}]·CH2Cl2 crystallized in the P21/c (No. 14) space group (Z = 4) with a = 12.294(3), b = 16.063(5), c = 21.384(5), A, β = 91.60(3)°. Complex 4a(i), [RhI2(tBuNC)2{C(PPh2)(P(S)Ph2)2-P,S}] crystallizes in the P421/c (No. 114) space group (Z = 8) with a = b = 30.174(3), c = 11.317(2) A. Both complexes contain bidentate P, S bonded ligands with the second PS group non-coordinated (“dangling”). In 1a, approximate square planar coordination about rhodium is completed by the two double bonds of a cod ligand, and in 4a(i), the P,S ligand and two cis iodides comprise the equatorial plane of an octahedron which is completed by two tBuNC ligands.

Formation of the novel bis(diphenylphosphino)methadane ligand by deprotonation of a coordinated bis(diphenyl- phosphino)methane. Crystal and molecular structure of chloro-triethylphosphine-bis(diphenylphosphino)methano- platinum(II)

Abstract [PtCl(PEt 3 )(Ph 2 PCHPPh 2 )], a complex containing the bis(diphenylphosphino)- methanide ligand, has been synthesized by reaction of NaH with [PtCl(PEt 3 )- (Ph 2 PCH 2 PPh 2 )] + and characterized by 31 P NMR and X-ray cystallography.

Fragmentation reactions of phosphido and sulphido bridged, trinuclear platinum and palladium clusters and formation of [M2(μ-PPh2)(μ-dppm)(PPh3)2]+, a new type of M(I) cation

Abstract Reactions of the trinuclear clusters, [M 3 (μ-X)(μ-PPh 2 ) 2 (PPh 3 ) 3 ] n + , M = Pd or Pt, X = H, Cl, S, SR, PPh 2 , n = 0 for S, n = 1 otherwise, with bis(diphenylphosphino)methane (dppm) and related ligands result in unusual cluster fragmentations to give a new type of M(I) cation, [M 2 (μ-PPh 2 )(μ-dppm)(PPh 3 ) 2 ] + , in which a metal—metal bond is supported by both dppm and phosphido bridges. The products indicate that the phosphido bridge is always the most robust of the set of bridging ligands.

Anionopentaaminecobalt(III) complexes with polyamine ligands: Part 30. The base hydrolysis kinetics and structure determination of some [CoCl(N)5]2+ complexes containing pyridine ligands

The base hydrolysis rates ( k OH , M −1 s −1 , I =0.1 M, 25°C) have been measured for cis- [CoBr(en) 2 (py)] 2+ ( k OH =3.33×10 3 ), cis- [CoBr(en) 2 (d 5 py)] 2+ (3.34×10 3 ), cis- [CoCl(en) 2 (4-NH 2 -py)] 2+ (78.2), cis- [CoCl(en) 2 (4-N(Me) 2 -py)] 2+ (77.0), cis- [CoCl(en) 2 (4-CNpy)] 2+ (326), trans- [CoCl(tn) 2 (py)] 2+ (3.87×10 3 ), pf -[CoCl(dien)(NH 3 ) 2 ] 2+ (252) and pf- [CoCl(dien)(py) 2 ] 2+ (2.77×10 4 ) using pH-stat techniques. The crystal structures of pf- [CoCl(dien)(py) 2 ](NO 3 )(ClO 4 ) and p 3 f- [CoCl(2,3-tri)(py) 2 ]ZnCl 4 have been determined. The k OH values for py complexes are significantly greater than those observed for the analogous methylamine complexes and the rate enhancement is attributed to weak π[3d(Co)]→π*[pyridine] back donation.

Coordination chemistry of [CH(PPh2)(P(S)Ph2)2]: Pd, Pt, Rh, and Ir complexes, including the crystal and molecular structures of the ligand and a tripodal iridium complex, [Ir(cod){CH(PPh2) (P(S)Ph2)2-P,S,S}]BF4 · CH2Cl2

Abstract The complex cations, [M(cod){CH(PPh2)(P(S)Ph2)2-P,S,S}]+, M = Ir or Rh, and [MCl(PEt3)(CH(PPh2) (P(S)Ph2) 2-P,S]+, M = Pt or Pd, are readily prepared as fluoroborate salts by reactions of the ligand, CH(PPh2)(P(S)Ph2)2, with the chlorobridged complexes, [M2Cl2(cod)2], M = Ir or Rh, cod = cycloocta-1,5-diene, and [M2Cl4(PEt3)2], M = Pt or Pd, under mild conditions in the presence of NaBF4. Structures are assigned on the basis of 31P NMR spectra and, in the case of M = Ir, by X-ray diffraction. The iridium and rhodium complexes contain tripodal η3-P,S,S coordinated ligands in contrast to the examples for palladium and platinum, where the ligands are bidentate η2-P,S coordinated with the second PS group non-coordinated (“dangling”). In solution at 25°C, the palladium complex exhibits fluxional behaviour with rapid exchange between the coordinated and “dangling” PS groups. Both platinum and palladium complexes consist mainly of the isomers having the coordinated PS group trans to Cl,but small quantities of the other isomer are formed for both metals. The ligand 1, CH(PPh2)(P(S)Ph2)2 crystallizes in the P21/n (No. 14) space group (Z = 4) with a = 19.867(9) A, b = 18.889(7) A, c = 8.828(4) A, β = 100.47(5) ° and complex 3a, [Ir(cod)(CH(PPh2)(P(S)Ph2)2-P,S,S]BF4 CH2Cl2, in the P 1 (No. 2) space group (Z = 2) with a = 10.899(6) A, b = 21.653(9) A, c = 11.124(5) A, α = 85.14(4)°, β = 111.59(4)°, γ = 107.93(6)°. In 3a, iridium is five-coordinate with an η3-P,S,S ligand and the two double bonds of the cod ligand in an irregular geometry. The structural parameters of the ligand, 1, are changed relatively little by coordination except for a narrowing of the PCP angles.

Synthesis and structural characterisation of tris(diphenylthiophosphinoyl)methane and tris(diphenylthiophosphinoyl)methanide complexes of rhodium and iridium; X-ray structures of [Rh(C8H12){η2-C(P(S)Ph2)3-S,S}] and [Ir(CO)2{gh2-C(P(S)Ph2)3-S,S}]

Reactions of [MCl(cod)]2, M = Rh or Ir, cod = cyclooctadiene, with CH{P(S)Ph2}3 give the complex cations, [M(cod){CH(P(S)Ph2)3}]+, which are isolated in high yield as BF4− or ClO4− salts. These are the first reported examples of CH{P(S)Ph2}3 complexes in which the methine proton is retained after coordination. The high acidity of this proton is demonstrated by easy deprotonation to corresponding [M(cod){C(P(S)Ph2)3}] complexes. The 31P NMR spectrum of [Rh(cod){CH(P(S)Ph2)3}]BF4 remains a single line to −100°C whereas that of [Rh(cod){C(P(S)Ph2)3}] is resolved into two resonances at −60°C, suggesting that the former complex is 5-coordinate with an η3 (S,S,S) ligand and the latter 4-coordinate, η2 (S,S). The 4-coordinate structure is confirmed by X-ray diffraction studies of [Rh(cod){C(P(S)Ph2)3}] and [Ir(CO)2{C(P(S)Ph2)3}] which both show approximately square planar metal centers, η2 ligands with the third sulfur non-coordinated (“dangling”), and trigonal planar geometry at the central carbon of the tris(phosphinesulfide) ligand. [Rh(cod){C(P(S)Ph2)3}] and [Ir(CO)2{C(P(S)Ph2)3}] crystallize in the Pbca space group (Z = 8) with respective unit cells: a = 20.427(4) A, b = 16.931(2) A, c = 23.138(3) A; and a = 22.140(6) A, b = 22.317(5) A, c = 14.792(3) A. Line shape analysis for a variable temperature 31P NMR study of [Rh(cod){C(P(S)Ph2)3}] gives ΔGo‡ 46 ± 2 kJ mol−1 for the dynamic exchange of coordinated and non-coordinated sulfur.

Phosphido-bridged iridium clusters: crystal and molecular structure of [Ir3(μ-PPh2)3(μ-bis(diphenylphosphino)methane)(CO)4] and correlation of IrIr distances with valence electron count

The 46 electron cluster, [Ir3(μ-PPh2)3(μ-dppm)(CO)3] (1), dppm=bis(diphenylphosphino)methane, undergoes (reversible) addition of carbon monoxide to the 48 electron derivative, [Ir3(μ-PPh2)3(μ-dppm)(CO)4] (2). This product crystallizes in the P1space group (Z=2) with two molecules in the asymmetric unit and with unit cell parameters: a=21.559(4), b=22.337(4), c=13.860(3) A, α=89.05(2), β=95.46(2), γ=108.66(1)°. The molecular structure consists of an iridium triangle with two edges bridged by roughly coplanar phosphorus atoms. The third edge is also bridged by phosphorus but approximately perpendicular to the Ir3 plane. The unique IrIr distance is 2.707(3) A and the other distances average 2.989(3) A. Comparison of the latter distance with corresponding distances in 1 and [Ir3(μ-PPh2)3(CO)5(t-BuNC)2] (3), shows a regular increase in IrIr length, 2.805(2), 2.989(3), and 3.188 A in 1–3, respectively, as the valence electron count changes from 46 to 48 to 50 electrons. 31P NMR data for the three molecules are also consistent with the changes in IrIr distances.