Phosphaalkene Ligand Research Articles

Synthesis and coordination behavior of CuI bis(phosphaethenyl)pyridine complexes

Cu(I) complexes bearing BPEP as a PNP-pincer type phosphaalkene ligand undergo effective bonding interactions with SbF(6)(-) and PF(6)(-) as non-coordinating anions to give [Cu(SbF(6))(BPEP)] and [Cu(2)(BPEP)(2)(μ-PF(6))](+), respectively [BPEP = 2,6-bis(1-phenyl-2-phosphaethenyl)pyridine]. NMR and theoretical studies indicate a reduced anionic charge of the μ-PF(6) ligand, which is induced by the strong π-accepting ability of BPEP.

Nitrogen- and oxygen-bridged bidentate phosphaalkene ligands

Abstract An overview is given on synthesis and structures of new bidentate phosphaalkene ligands [(RMe2Si)2C P]2E (E = O, NR, N−) and (RMe2Si)2C P N(R′) PR′′2. Exceptional properties of these ligands, extending beyond predictable properties of phosphaalkenes are: (i) the N Si bond cleavage of [(iPrMe2Si)2C P]2NSiMe3 with AuI and RhI chloro complexes under mild conditions leading to binuclear complexes of the 6π-delocalised imidobisphosphaalkene anion [(iPrMe2Si)2C P]2N−, and (ii) the chlorotropic formation of molecular 1:2 PdII and PtII metallochloroylid complexes with novel ylid-type ligands [(RMe2Si)2C P(Cl) N(R) PR2]−, and the transformation of a P-platina-P-chloroylid complex into a C-platina phosphaalkene by intramolecular chlorosilane elimination. Properties of the heavier congeners [(RMe2Si)2C P]2E (E = S, Se, Te, PR, P−, As−) and (RMe2Si)2C P E PR′′2 (E = S, Se, Te) are also described.

Exceptional Coordination Mode of Unsaturated PNP Ligands (Me3Si)2C=PN(R)PPh2 with Palladium and Platinum Dichlorides: Insertion of Phosphaalkene Phosphorus Atoms into Metal–Chlorine Bonds

AbstractUnique molecular bis‐chelate complexes M[(Me3Si)2C=P(Cl)N(1‐Ada)PPh2]2 (1‐Ada = 1‐adamantyl; 3: M = Pt; 4: M = Pd) were isolated as crystalline solids from solutions that contain mixtures of products from reactions of the metal dichlorides with the P‐phosphanylaminophosphaalkene (Me3Si)2C=PN(1‐Ada)PPh2 (1). Attachment of chloride ions to PdII‐ and PtII‐coordinated 1 leads to the novel anionic (alkylidene)(chlorido)(phosphanylamino)phosphanido ligand [(Me3Si)2C=P(Cl)N(1‐Ada)PPh2]–, which contains a stereogenic phosphorus atom. With PdCl2(COD), only the centrosymmetric (R,S) isomer 4a was isolated, whereas three of the four possible isomeric platinum complexes Pt[(Me3Si)2C=P(Cl)N(1‐Ada)PPh2]2 (3a–3c) were investigated crystallographically. DFT calculations on model compounds indicate that the enhanced electrophilicity of the chelating phosphaalkene ligand 1 leads to chlorine migration from the metals to the phosphaalkene phosphorus atom.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

Design, Synthesis, and Application of Phosphaalkenes to Unique Palladium and Gold Catalysts

A 2-silyl-1,3-diphosphapropene was utilized as an asymmetrical P2 ligand of stable palladium(II) catalysts. Several phosphaalkene ligands were utilized for synthesis of novel gold(I) complexes which exhibited unique catalytic activity in 1,6-enyne cycloisomerization, indicating effects of P = C double bond, Au–Au contact, and sulfanyl group.

Neue Kupferkomplexe mit Phosphaalkenliganden. Molekülstruktur von [Cu{P(Mes*)C(NMe2)2}2]BF4 (Mes* = 2,4,6‐tBu3C6H2)

AbstractNew Copper Complexes Containing Phosphaalkene Ligands. Molecular Structure of [Cu{P(Mes*)C(NMe2)2}2]BF4 (Mes* = 2,4,6‐tBu3C6H2)Reaction of equimolar amounts of the inversely polarized phosphaalkene tBuP=C(NMe2)2 (1a) and copper(I) bromide or copper(I) iodide, respectively, affords complexes [Cu3X3{μ‐P(tBu)C(NMe2)2}3] (2) (X =Br) and (3) (X = I) as the formal result of the cyclotrimerization of a 1:1‐adduct. Treatment of 1a with [Cu(L)Cl] (L = PiPr3; SbiPr3) leads to the formation of compounds [CuCl(L){P(tBu)C(NMe2)2}] (4a) (L = PiPr3) and (4b) (L = SbiPr3), respectively. Reaction of [(MeCN)4Cu]BF4 with two equivalents of PhP=C(NMe2)2 (1b) yields complex [Cu{P(Ph)C(NMe2)2}2]BF4 (5b). Similarly, compounds [Cu{P(Aryl)C(NMe2)2}2]BF4 (5c (Aryl = Mes and 5d (Aryl = Mes*)) are obtained from ArylP=C(NMe2)2 (1c: Aryl = Mes; 1d: Mes*) and [(MeCN)4Cu]BF4 in the presence of SbiPr3. Complexes 2, 3, 4a, 4b, and 5b‐5d are characterized by means of elemental analyses and spectroscopy (1H‐, 13C{1H}‐, 31P{1H}‐NMR). The molecular structure of 5d is determined by X‐ray diffraction analysis.

Synthesis and Structure of the Decanuclear Gold(I) Cluster Cation [Au8(AuCl)2{μ3-P(tBu)}2{μ-P(tBu)=C(NMe2)2}6]4+ with Bridging Phosphaalkene and Phosphanediide Ligands

Reaction of the inversely polarized phosphaalkene HP=C(NMe2)2 (1) with [AuCl(PPh3)] (2a) in a molar ratio of 2:1 in THF led to the formation of complex [Au{HP=C(NMe2)2}2]Cl (3) as a pale yellow solid. In contrast to this, treatment of 2a with two molar equivalents of tBuP=C(NMe2)2 (4) afforded a mixture of [Au{P(tBu)=C(NMe2)2}2]+Cl− (5) and [{(Me2N)2C=(tBu)PAu}2(μ-Cl)]+Cl− (6). In CH2Cl2 solution this mixture was slowly converted into the novel decanuclear complex [Au8(AuCl)2{μ3-P(tBu)}2{μ-P(tBu)=C(NMe2)2}6]4+(Cl−)4 (7) featuring six edge-bridging phosphaalkene ligands and two μ3-tert-butylphosphanediide ligands. In solution the cluster 7 shows a high order 31P{1H} NMR spectrum of the [AB2C]2 type. According to the X-ray structural analysis the Au10 framework may be described as a slightly puckered ladder constructed of three quadrangles. The central Au4 parallelogram is capped on both faces by a pair of [tBuPAuCl] units. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)

Mono- and bi-dentate phosphaalkene ligands: structures of their copper(I) chloride complexes

While the reaction of the monophosphaalkene [(2,4,6-tri-tert-butylphenyl)phosphanediylmethyl]-benzene (L2) with copper(I) chloride led to a dimeric complex [Cu2Cl2L22(NCMe)2]1, use of the diphosphaalkene 1,3-bis[(2,4,6-tri-tert-butylphenyl)phosphanediylmethyl]benzene (L1) gave rise to a tetrameric complex [Cu4Cl4L12]·3EtOH 2. The crystal structures of the complexes have been determined and indicate that 1 is a centrosymmetric dimer with tetrahedrally co-ordinated copper(I) centres, whereas 2 adopts a ‘cubane-like’ structure with pairs of copper atoms bridged by different L1 units.

Chlormethylchlorphosphane R(Cl)PCH 2Cl - synthone für den aufbau von phosphaalkenen im metalltemplat

On reaction of the chloromethylchlorophosphines R(Cl)PCH 2Cl (R  Cl, iPr, tBu, NEt 2, N( iPr) 2, NPh 2, O-2,6- iPr 2C 6H 3; 1– 7) with diiron enneacarbonyl the iron carbonyl complexes 8– 14 are formed in good yields. Dehalogenation of the phosphine complexes 9– 14 with Fe 2(CO) 9 affords the phosphaalkene clusters [μ 3,η 2-RP CH 2]Fe 3(CO) 10 ( 15– 19). If Fe 3(CO) 12 is used instead of Fe 2(CO) 9 for the dehalogenation of 10- 13 phosphinidene phosphaalkene clusters [μ 3,η 2-RPCH 2][μ 3-PR]Fe 3(CO) 9 ( 25– 28) and binuclear complexes with bridging RPCH 2 ligands ( 21– 24) or α-metallated phosphido-phosphine bridges ( 20) (μ 2-P(R) CH 2P(R)CH 2 (R  tBu)) are obtained. The crystal structure of 18 (R  Ph 2N; space group P2 1/ n) shows the phosphaalkene ligand to be twisted about the P C bond (dihedral angle N(1)P(1)C(31)Fe(3) 177.5(1)°) the CH 2 group being pyramidalized (H(31)C (31)H(32) 104.0°). In the binuclear complex 20 (space group P2 1/ c phosphinoalkyl unit of the μ 2,η 3-P (R)CH 2P(R)CH 2 ligand spans the FeFe bond forming a distorted four-membered FePCFe ring with a short PC bond (P(2)C(12) 176.5(4) pm). The PCP donor set is coordinated to Fe(1) within a strained four-membered P 2CFe chelate ring. Then η 1,η 2-RPCH 2 ligand (R  N( iPr) 2) in 23 with a short PC bond (P(1)C(1) 173.4(4) pm) bridges two iron atoms, a distorted, almost planar Fe 2P 2 ring being formed.

Synthese von Phosphaalkenclustern durch reduktive Phosphinidenfragmentierung zweizähniger Halogenphosphane RXP— CH2 — PXR mit Fe2(CO)9 / Synthesis of Phosphaalkene Clusters by Reductive Phosphinidene Fragmentation of Bidentate Halogenphosphines RXP—CH2—PXR with Fe2(CO)9

Reaction of halogen functional methylenebisphosphines 1 XRP–CH2–PRX (X = Cl, Br) with excess Fe2(CO)9 affords μ3-phosphinidene clusters (5) containing phosphaalkene ligands R–P=CH2. The fragmentation of the P–C–P skeletons in 1 proceeds stepwise, phosphide complexes 2 and novel Fe3 clusters 3 with RP–CH2–PR bridging units being formed as intermediates of the oxidative addition reductive elimination process. The X-ray structural analysis for 5b (R = NEt2) reveals an Fe3(CO)9PR butterfly core to which the phosphaalkene ligand R–P=CH2 (P=C bond length 1.766(4) A) is coordinated in a μ3,η2-manner. In case of methylenebisphosphines 1 with bulky substituents (R = 2,4,6-iPr3C6H2) the phosphinidene fragmentation of the P–C–P skeleton is accompanied by the formation of 2,3-dihydrobenzo[b]-phosphole ligands.

Enthalogenierung und regioselektive Phosphiniden‐Fragmentierung unsymmetrisch substituierter Methylenbisphosphane RXP–CH2–PXR′ mit Fe2(CO)9

Dehalogenation and Regioselective Phosphinidene Fragmentation of Unsymmetrically Substituted Methylenebisphosphanes RXP‐CH2‐PXR′ with Fe2(CO)9Reductive dehalogenation of the unsymmetrically substituted methylenebisphosphanes RXP–CH2‐PR′X [X = Cl, Br; R = tBu, NEt2; R′ = 2,4,6‐R”3C6H2 (R” = Me, tBu), NEt2, 2,6‐iPr2C6‐H3O, 2,6,4‐tBu2MeC6H2O] with Fe2(CO)9 affords, depending on the reaction conditions employed, phosphido complexes [μ2‐(RP‐CH2‐PR′)]Fe2(CO)6 (2) or phosphaalkene clusters (μ3‐PR′)(η2,μ3‐PRCH2)Fe3(CO)9(6) or [(μ‐PR)(η2,μ3PR′CH2)]Fe3‐(CO)9 (7), respectively, by regioselective phosphinidene fragmentation of the RP–CH2‐PR′ skeletons. The unstable cluster compounds [μ3‐PR′–CH2–PR)]Fe3(CO)9 (4) are formed as intermediate products. X‐ray structural analysis of 6c (R = tBu; R′ = NEt2) reveals a flat butterfly (μ3‐PR)Fe3 structure bridged by the phosphaalkene ligand tBuP = CH2 with a short P = C distance [177.2(4) pm].

Reduktive Enthalogenierung zweizähniger Halogenphosphane RXPCH 2PXR mit Fe 2(CO) 9—ein neuer Weg zu clusterstabilisierten Phosphaalkenen mit funktionellen Gruppen

Bidentate halogenphosphines RXPCH 2PRX are dehalogenated by Fe 2(CO) 9 to give complexes of diphosphiranes R PP R or phosphido complexes Fe 2(CO) 6(RPCH 2) with strained PRCH 2PR backbones. At elevated temperatures clusters Fe 3(CO) 9(μ 3-PR)(η 2-μ 3-RPCH 2) containing phosphaalkene ligands RPCH 2 are formed by transition metal mediated cleavage of the PCP-skeletons.

η 1- and η 2-coordination in phosphaalkeneplatinum(0) complexes. High resolution solid state 31P NMR spectrum of mesityl(diphenylmethylene)phosphinebis(triphenylphosphine)platinum(0)

The high resolution solid state 31P NMR spectrum of Pt(PPh 3) 2(P(mesityl)=CPh 2) shows the expected features for an η 1-coordinated phosphaalkene ligand and is completely different from that of the η 2-complex which exists in solution.