Amination of the C‐isopropyldimethylsilyl P‐chlorophosphaalkene (iPrMe2Si)2C=PCl (1) leads to the P‐aminophosphaalkenes (iPrMe2Si)2C=PN(R)R′ (R, R′ = Me (2), R = H, R′ = nPr (3), R = H, R′ = iPr (4), R = H, R′ = tBu (5), R = H, R′ = 1‐Ada (6), R = H, R′ = CPh3 (7), R = H, R′ = Ph (8), R = H, RR′ = 2,6‐iPr2Ph (= DIP) (10), R = H, R′ = 2,4,6‐Me3Ph (= Mes) (11), R = H, R′ = 2,4,6‐tBu3Ph (= Mes*)] (12), R = H, R′ = SiMe3 (13), and R, R′ = SiMe2Ph (14). 31P‐NMR spectra confirm that phosphaalkenes 2–7 and 10–14 are monomeric in solution; the structures of 7, 10, and 12 were determined by X‐ray crystallography. Freshly prepared (iPrMe2Si)2C=PN(H)Ph (8) is a monomer that dimerizes with (N→C) proton migration within several hours to the stable diazadiphosphetidine [(iPrMe2Si)2CHPNPh]2 (9). NMR‐scale reactions of deprotonated 5 and 13 with tBuiPrPCl provide by P–P bond formation the P‐phosphanyl iminophosphoranes [(iPrMe2Si)2C=](RN=)PPtBu(iPr) [R = tBu (15), R = Me3Si (17)]. Deprotonated 5 and Me3GeCl deliver by N–Ge bond formation the aminophosphaalkene (iPrMe2Si)2C=PN(tBu)GeMe3 (20), which with elemental selenium 5 undergoes (N→C) proton migration to form the alkyl(imino)(seleno)phosphorane [(iPrMe2Si)2CH](tBuN=)P=Se (21), which is a selenium‐bridged cyclic dimer in the solid state.

Deprotonation of the aminophosphanes Ph2PN(H)R 1a–1h [R = tBu (1a), 1‐adamantyl (1b), iPr (1c), CPh3 (1d), Ph (1e), 2,4,6‐Me3C6H2 (Mes) (1f), 2,4,6‐tBu3C6H2 (Mes*) (1g), 2,6‐iPr2C6H3 (DIPP) (1h)], followed by reactions of the phosphanylamide salts Li[Ph2PNR] 2a, 2b, 2g, and 2h with the P‐chlorophosphaalkene (Me3Si)2C=PCl, and of 2a–2g with (iPrMe2Si)2C=PCl, gave the isolable P‐phosphanylamino phosphaalkenes (Me3Si)2C=PN(R)PPh2 3a, 3b, 3g, and (iPrMe2Si)2C=PN(R)PPh2 4a–4g. 31P NMR spectra, supported by X‐ray structure determinations, reveal that in compounds 2a, 2b, 3a, and 3b, with bulky N‐alkyl groups the Si2C=P–N–P skeleton is non‐planar (orthogonal conformation), whereas 3g, 3h, and 4g with bulky N‐aryl groups exhibit planar conformations of the Si2C=P–N–P skeleton. Solid 3g and 4g exhibit cisoid orientation of the planar C=P–N–C units (planar I) but in solid 3h the transoid rotamer is present (planar II). From 3g, 4d, and 4g mixtures of rotamers were detected in solution by pairs of 31P NMR patterns (3h: line broadening).

Deprotonation of the aminophosphanes Ph2PN(H)R1a-1h [R = tBu (1a), 1-adamantyl (1b), iPr (1c), CPh3 (1d), Ph (1e), 2,4,6-Me3C6H2 (Mes) (1f), 2,4,6-tBu(3)C(6)H(2) (Mes*) (1g), 2,6-iPr(2)C(6)H(3) (DIPP) (1h)], followed by reactions of the phosphanylamide salts Li[Ph2PNR] 2a, 2b, 2g, and 2h with the P-chlorophosphaalkene (Me3Si)(2)C=PCl, and of 2a-2g with (iPrMe(2)Si)(2)C=PCl, gave the isolable P-phosphanylamino phosphaalkenes (Me3Si)(2)C=PN(R)PPh2 3a, 3b, 3g, and (iPrMe(2)Si)(2)C=PN(R)PPh2 4a-4g. P-31 NMR spectra, supported by X-ray structure determinations, reveal that in compounds 2a, 2b, 3a, and 3b, with bulky N-alkyl groups the Si2C=P-N-P skeleton is non-planar (orthogonal conformation), whereas 3g, 3h, and 4g with bulky N-aryl groups exhibit planar conformations of the Si2C=P-N-P skeleton. Solid 3g and 4g exhibit cisoid orientation of the planar C=P-N-C units (planar I) but in solid 3h the transoid rotamer is present (planar II). From 3g, 4d, and 4g mixtures of rotamers were detected in solution by pairs of P-31 NMR patterns (3h: line broadening).

In the RhCl chelate complexes of C-bis(trimethylsilyl)-P-alkyl(diphenylphosphanyl)aminophosphaalkenes 1 [(Me3Si)(2)-C= PN(R)PPh2; 1a: R = 1-Ada; 1b: R = tBu], the P=C double bonds are preferentially eta(2)-(P,C)-coordinated to Rh-I, as shown by the structure determination of trans-[RhCl{(Me3Si)(2)C= PN(R) PPh2}](2) (5a) and by the comparison of the P-31 NMR spectra of cis- and trans-[RhCl{(Me3Si)(2)C= PN(R)PPh2}](2) (5a,b), [RhCl(PPh3)-{( Me3Si)(2)C= PN(R) PPh2}] (6a,b), [RhCl(CO){(Me3Si)(2)C= PN(R)PPh2}] (7a, b) and [(cod) Rh(mu-Cl)(2)Rh{(Me3Si)(2)C= PN(R)PPh2}] (8a,b). With excess of [RhCl(cod)](2), the ligand (Me3Si)(2)C=PN(CH2Ph)PPh2 (1c) forms solid trinuclear complex 10 containing two Rh(Cl) cod moieties attached to the central chelate unit [Rh(Cl)(1c)]: one Rh atom is attached by (terminal) P -> Rh(Cl) cod coordination and the other one by bridging Rh(mu-Cl)(2)Rhcod. The reactions of the complex [RhCl(CO)(PPh3)(2)] with ligands 1a or 1b unexpectedly led, with elimination of bis(trimethylsilyl) ketene, to racemic Rh-III-chloro complexes [RhCl({Ph2PN(R)P}(2)C(SiMe3)(2))] (11a,b) containing the dianionic tetradentate chelating "bis-PNP" ligands (Me3Si)(2)C{P(-)N(R) PPh2}(2) (12a,b) eta(4)-coordinated to Rh-III (CN 5). The CO-induced formation of Rh-III complexes 11a and 11b also occurred when 7a and 7b were treated with another equivalent of ligand 1a or 1b, when [RhCl(CO)(2)](2) was mixed with more than 2 equiv. of 1a or 1b, and even bubbling gaseous CO into a solution containing 6a provided 11a and bis(tri-methylsilyl)ketene.

The dehydrochlorination of the dichlorophosphane (iPrMe(2)Si)(2)C(H)PCl2 (2) with 1,4-diazabicyclo[2.2.2]octane (DBO) provides the P-chlorophosphaalkene (iPrMe(2)Si)(2)C=PCl (3). Halide exchange reactions of 3 with AgBF4, with Me3SiBr, and with Me3SiI lead to the P-halogenophosphaalkenes (iPrMe(2)Si)(2)C=PX (X = F: 4; X = Br: 5; X = I: 6). From the reaction of 3 with AgCN, the sterically stabilized P-cyanophosphaalkene (iPrMe(2)Si)(2)C=P-CN (7) was isolated. The structures of the related P-fluorenylphosphaalkene 9 (from 3 with fluorenyllithium) and of the P-selenophosphaalkenes (iPrMe(2)Si)(2)C = PSe(2,4,6-tBu(3)C(6)H(2)) (10) and [(iPrMe(2)Si)(2)C=P](2)Se (11) were determined by X-ray crystallography.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

An overview is given on synthesis and structures of new bidentate phosphaalkene ligands [(RMe2Si)2CP]2E (E=O, NR, N−) and (RMe2Si)2CPN(R′)PR′′2. Exceptional properties of these ligands, extending beyond predictable properties of phosphaalkenes are: (i) the NSi bond cleavage of [(iPrMe2Si)2CP]2NSiMe3 with AuI and RhI chloro complexes under mild conditions leading to binuclear complexes of the 6π-delocalised imidobisphosphaalkene anion [(iPrMe2Si)2CP]2N−, and (ii) the chlorotropic formation of molecular 1:2 PdII and PtII metallochloroylid complexes with novel ylid-type ligands [(RMe2Si)2CP(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)2CP]2E (E=S, Se, Te, PR, P−, As−) and (RMe2Si)2CPEPR′′2 (E=S, Se, Te) are also described.

Metalation of the aminophosphaalkene (iPrMe(2)Si)(2)C=PN(H)SiMe3 (2) with lithium diisopropylamide (LDA) in THIF solution, followed by the reaction of the lithium salt 3 with the P-chlorophosphaalkenes (RMe2Si)(2)C=PCl (1a, R = Me; 1b, R = iPr; 1c, R = Ph), furnishes the first N-silylimmo-bridged bis(phosphaalkenes) [(iPrMe(2)Si)(2)C=P](2)NSiMe3 (4a) and [(iPrMe(2)Si)(2)C=P][(RMe2Si)(2)C=P]NSiMe3 (4b, R = Me; 4c, R = Ph). The N-Si bond cleavage of 4a under very mild conditions with AuCl(THT) and with [RhCl(COD)](2) provides binuclear Au-1 and Rh-1 complexes 5, 6 of the P, P'-coordinated imidobis(phosphaalkene) anion [(iPrMe(2)Si)(2)C=P](2)N-, the first case of elusive P=C-unsaturated congeners of the "classic" bis(phosphanyl)amide ligands. Solid 4a exists in a helically distorted S-shaped structure with two inequivalent P=C groups, but P-31-NMR reveals the equivalence of both P=C groups in solution at the NMR time scale. The P=C and P-N bonds distances in 4a do not indicate significant conjugation within the C=P-N-P=C moieties whereas in complexes 5 and 6 the W-shaped CPNPC heteropentadienide anion exhibits strong 5-center-6-pi conjugation according to DFT calculations and to the experimental P=C and P=N bond lengths.

Deprotonation of amino-phosphaalkenes (RMe(2)Si)(2)C=PN(H)(R') (R=Me, iPr; R'=tBu, 1-adamantyl (1-Ada), 2,4,6-tBu(3)C(6)H(2) (Mes*)) followed by reactions of the corresponding Li salts Li[(RMe(2)Si)(2)C= P(M)(R')] with one equivalent of the corresponding P-chlorophosphaalkenes (RMe(2)Si)(2)C=PCl provides bisphos-phaalkenes (2,4-diphospha-3-azapentadienes) [(RMe(2)Si)(2)C=P](2)NR'. The thermally unstable tert-butyliminobisphosphaalkene [(Me(3)Si)(2)C=P](2)NtBu (4a) undergoes isomerisation reactions by Me(3)Si-group migration that lead to mixtures of four-membered heterocyles, but in the presence of an excess amount of (Me(3)Si)(2)C=PCl, 4a furnishes an azatriphosphabicyclohexene C(3)(SiMe(3))(5)P(3)NtBu (5) that gave red single crystals. Compound 5 contains a diphosphirane ring condensed with an azatriphospholene system that exhibits an endocylic P=C double bond and an exocyclic ylidic P((+))-)C(-)(SiMe(3))(2) unit. Using the bulkier iPrMe(2)Si substituents at three-coordinated carbon leads to slightly enhanced thermal stability of 2,4-diphospha-3-azapentadienes [(iRr-Me(2)Si)(2)C=P](2)NR' (R'=tBu: 4b; R' = 1-Ada: 8). According to it low-temperature crystal-structure determination, 8 adopts a non-planar structure with two distinctly differently oriented P=C sites, but (31)P NMR spectra in solution exhibit singlet signals. (31)P NMR spectra also reveal that bulky Mes* groups (Mes*=2,4,6-tBu(3)C(6)H(2)) at the central imino function lead to mixtures of symmetric and unsymmetric rotamers, thus implying hindered rotation around the P-N bonds in persistent compounds [(RMe(2)Si)(2)C=P]NMes* (11a, 11b). DFT calculations for the parent molecule [(H(3)Si)(2)C=P](2)NCH(3) suggest that the non-planar distortion of compound 8 will have steric grounds.

Hydrolytic cleavage of the P-chlorophosphaalkenes (RMe2Si)2C=PCl (R = Me: 1a; R = iPr: 1b) in the presence of triethylamine leads to di(phosphavinyl) ethers (2,4-diphospha-3-oxapentadienes) [(RMe2Si)2C=P]2O (2a, 2b) as main products, accompanied by alkylphosphinic acids (RMe2Si)2(H)CP(H)(O)OH (3a, 3b). The hydrolysis of (PhMe2Si)2C=PCl (1c) proceeds less selectively. Reactions with metal oxides under aprotic conditions provide 2a [impure, from 1a with (nBu3Sn)2O] and 2b [from iodophosphaalkene (iPrMe2Si)2C=PI with Ag2O] as oils. 1H, 13C, 29Si and 31P NMR spectra, however, allow unambiguous characterisation of 2a and 2b. Formation mechanisms, structure, and C=P-O π stabilisation of the oxabisphosphaalkene [(H3Si)2C=P]2O (2ʹ) were studied with DFT methods. The double [2+4] cycloaddition reaction of 2a with two equivalents of cyclopentadiene leads to the phosphinous anhydride 7 as a mixture of diastereomers whereas the addition of two equivalents of tetrachloro-o-benzoquinone proceeds in a diastereoselective fashion. An X-ray crystal structure determination of the resulting oxo-bridged bis(2-phospha-2,5-dioxa-3,4-benzophospholene) derivative 8 revealed the presence of a racemic mixture of (R,R)- and (S,S)-configurated molecules. The solid state structure of a by-product, bisylphosphonic tetrachlorocatechol monoester (Me3Si)2CH-P(=O)(OH)-o-OC6Cl4OH 9, was also determined crystallographically.

Unique molecular bis-chelate complexes M[(Me3Si)(2)C=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)(2)C=PN-(1-Ada)PPh2 (1). Attachment of chloride ions to Pd-II- and Pt-II-coordinated 1 leads to the novel anionic (alkylidene)-(chlorido)(phosphanylamino)phosphanido ligand [(Me3Si)(2)C=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)(2)C=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. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

Chiral racemic 1,8-bis(tert-butylphenylphosphino)naphthalene oxide (2a) was resolved into enantiomers by fractional crystallization of its diastereomeric adducts 3a with (+)-(2S,3S)-di-O-benzoyl tartaric acid (DBTA), followed by neutralization. Racemic 1,8-bis(tert-butylphenylphosphino)naphthalene (1a) was oxidized with sulfur to two isomers of 1,8-bis(tert-butylphenyl-phosphino)naphthalene monosulfide, rac-4a and rac-4a′, or 1,8-bis(tert-butylphenylphosphino)naphthalene disulfide, rac-5a. The compounds were characterized by NMR spectroscopy (1H, 31P, 13C). Crystal structures were determined by the X-ray method for (−)-3a, rac-4a, rac-4a′ and rac-5a; this allowed the determination of the absolute configuration (S,S) for the more soluble adduct (−)-3a. It was found that rac-1a undergoes partial epimerization in boiling xylene to give the meso form.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

The reaction of 1,8-dilithionaphthalene 2, with 2 equivalents of rac-Me(C6F5)PCl, gave a 6 : 1 mixture of rac- and meso-1,8-di(methyl-pentafluorophenylphosphino)naphthalene (dmfppn, rac-3h and meso-3h), but no reaction was observed when the sterically crowded rac-tBu(C6F5)PCl was used. In P-31 NMR experiments, rac-3h and meso-3h exhibited characteristic signals (virtual quintets), which indicate that there is significant coupling through space ((3)JPF + (7)J(PF) approximate to 15 Hz). Compound rac-3h was isolated by fractional crystallisation and treated with aqueous H2O2 to yield the corresponding bis-phosphine dioxide, rac-7h. In contrast to rac-3h, there was no sign of through-space coupling in rac-7h, which again illustrates that the latter operates via the lone pairs at phosphorus.Platinum(II) complexes were prepared from the new, P-chiral chelate rac-3h, and the related ligand 1,8-di(tert-butylphenylphosphino)naphthalene (rac-dtbppn, rac-3e). All isolated new compounds were characterised by multinuclear NMR and IR spectroscopy, mass spectrometry, and elemental analysis. Single-crystal X-ray structure determinations were performed for rac-dmfppn (rac-3h). rac-[PtCl2(dtbppn)] (rac-17e), and rac-[PtCl2(dmfppn)] (ra(-17h). rac-3h displays crystallographic twofold symmetry. In rac-17h, the electron-withdrawing effect of the C6F5 groups causes a shortening of the Pt -P bond to ca. 220 pm (cf. 223 pm in rac-17e).

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

This paper describes the preparation of 1,8-bis[bis(dimethylamino)phosphino]naphthalene (2a) and the attempted preparation of its isopropyl analogue 2c, which led to the formation of 1-naphthyl-bis(diisopropylamino)phosphine (4), and to other unidentified products. The X-ray structures of 2a and 4 are discussed in comparison to those of 1,8-bis[bis(diethylamino)phosphino]naphthalene (2b) and 1-naphthyl-di-tert-butylphosphine (5), respectively. In the structures of 2a, 2b and 4 the (R2N)2P groups (R=alkyl) are eclipsed with respect to the naphthalene plane, whereas the R2P groups (R=alkyl or aryl) in 5, as in 1,8-bis(diorganophosphino)naphthalenes in general, adopt a conformation between bisecting and eclipsed. Furthermore, the reactions of 2a and 2b with BX3 ether adducts (X=F, Cl) are described, which furnished the heterocyclic [σ3P–σ4P+]-diphosphorus compounds, 1-dimethylamino-2-bis(dimethylamino)-, 1-diethylamino-2-bis(diethylamino)- and 1-chloro-2-bis(diethylamino)-1-phospha-2-phosphonium-acenaphthene (6a, 6b and 7b); the first examples of the 1,2-dihydro-1,2-diphospha-acenaphthene ring system. The X-ray structures of 6a and 7b display a relief of strain compared to the parent bis-aminophosphines 2a and 2b, quantified by negative splay angles [−7.89° (6a) and −9.40° (7b); cf. +12.16° (2a) and +12.0° (2b)] and the bonded [225.38 (6a) and 223.16 (7b) pm] compared to the non-bonded phosphorus–phosphorus distances [311.9 (2a) and 311.7 (2b) pm]. A mechanism is discussed for the formation of 6b and 7b from 2b and gaseous hydrogen chloride.

A series of naphthalenediyl-1,8-bis(phosphine oxides) 1-RR'P(:O)(C10H6)-8-P(:O)RR' (R=R'=Me (2a), Et(2b), iPr (2c), Cy (2d), Ph (2f) and R = tBu, R' = Ph (2e) was prepared by oxidation of the corresponding bis(phosphines) 1a-f with molecular oxygen or H2O2. (H2N)(2)C(:O) and characterized by NMR and IR spectroscopy, mass spectrometry, and elemental analysis (2a, 2b, 2d-f). X-ray crystal structure analyses were performed for 1,8-bis(dimethylphosphinyl)naphthalene (2a), (RR,SS)-1,8-bis-(phenyl-tert-butylphosphinyl)naphthalene (2e) and 1,8-bis(diphenylphosphinyl)naphthalene (2f). Treatment of 1,8-bis(diphenylphosphino)naphthalene (dppn, 1f) with an excess of sulfur in hot toluene afforded the bis(phosphine sulfide) 1-Ph2P(:S) (C10H6)-8-P(:S)Ph-2 (dppnS(2), 3f) the structure of which was elucidated by X-ray crystal structure analysis. The geometries of the compounds 2a, 2e, 2f, and 3f revealed an increase of strain from the corresponding bis(phosphines). In each case, the proximity of the P(:X)R-2 groups (X = O, S) led to distortion, the main feature of which was the out-of-plane displacement of the P atoms. (C) 2001 John Wiley & Sons, Inc.