Unusual Stability despite a P-bonded Proton: Phospha and Diphospha Ureas with the TrtP(H)-Moiety

Plack, Volker; Goerlich, Jens R.; Schmutzler, Reinhard

doi:10.1002/(sici)1521-3749(199906)625:6<919::aid-zaac919>3.0.co;2-7

Cited by 12 publications

(4 citation statements)

References 6 publications

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“…For the sake of comparison, the reported diphospha-urea (Ph 3 CPH) 2 CO displays resonances at d( 31 P) ¼ 16.8 ppm, | 2 J(PP)| ¼ 127 Hz for the conformer with syn, axial lone pairs (lp) at P, and 23.6 ppm, | 2 J(PP)| ¼ 23 Hz for the anti, axial lp conformer. 92 In contrast, 5a and 6a experience a P-C bond strengthening upon complexation (Table 14). This could be interpreted in terms of roughly non-hybridized p-type atomic orbitals (AO) used by phosphorus in the P-C bond in the uncomplexed species 5a, in agreement with the result of the NBO (natural bond orbital) analysis pointing to 85.3% of p-character at P. Upon complexation the tetracovalency of the P atom requires sp 3 -hybridization, as indicated by the (just moderately) higher s-character of the involved AO at P (18.5% for 5b and 17.5% for 5c).…”

Section: Compliance Constants Of Acyclic and Cyclic Phosphoorganic Co...mentioning

confidence: 99%

Coordination of CO to low-valent phosphorus centres and other related P–C bonding situations. A theoretical case study

2013

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The multi-faceted bonding of CO in molecular phosphorus compounds is described using calculated P-C bond strengths as a criterion. Full compliance matrices at coupled cluster level of HPCO (1a), singlet oxaphosphirane-3-ylidene HP(h 2 -CO)), the dimer (HPC]O) 2 as well as P^CH, HP]CH 2 and H 2 P-CH 3 were calculated to obtain quantifiable data and enable comparison. The quest for CO coordination and activation was examined for phosphaketenes 1a-f: the P-C compliance constants (inÅ mdyn À1 ) reveal a clear trend that shows a weakening of the P-CO bond strength from 1a to mono-ligation as in [(OC) 5 W {P(CO)Me}] (1c) (0.301), in H 3 BP(CO)Me (1b) (0.322), to bis-ligation as in [{(OC) 5 W} 2 P(CO)R] (1f) (0.488)to (H 3 BP) 2 (CO)Me (1d) (0.649). Availability of p-type electron density at phosphorus drastically strengthens the P-CO bond and weakens the C-O bond via p-back-donation, bis complexes are better described as weak CO (C/P) adducts to phosphorus. In complexes [(OC) 5 W{P(CO)R}] the CO activation by phosphorus equals that of CO activation through tungsten in pentacarbonyltungsten complexes. A comparative study of various CO bonding motifs in molecular compounds indicates that acyclic (2) or cyclic diphospha-urea derivatives (2-5) or isomers (6) display P-CO bond strengths (compliance constants range 0.502-0.640) well below that of the P-C bond of H 2 P-CH 3 (0.364), thus providing insight into the bonding and the ease of CO extrusion, experimentally known for some cases. A highly unusual adduct of CO was obtained in silico through two-fold P-ligation in diphosphiren-3-ones 2a-d, the parent compound of which was found to be properly described as a side-on (P]P)/(C]O) complex, in contrast to its aza-analogue 2a N . A drastic weakening of the P-CO bond strength is observed from P 2 CO (2a) (0.502) to the C 2 -symmetrical (H 3 BP) 2 CO (2b) (0.913); the latter represents an extreme case of a weakly bound CO. Furthermore, calculated 31 P NMR shifts and scalar 1 J(P,E) couplings were correlated with P-CO and PC-O compliance constants as a tool for experimentalists.In the area of dinuclear electrophilic phosphinidene complexes and their higher homologues [{L n M} 2 PnR] (L n M ¼ 16e transition-metal complex, pnictogen (Pn), Pn ¼ P, As, Sb, Bi, R ¼ e.g. alkyl, aryl etc.) it has long been known that the central Pn atom can add Lewis bases (e.g. thf, acetone, NH 3 , NEt 3 , TMEDA, pyridine) 13,14thus representing an early landmark in the coordination-to-phosphorus chemistry. 15 In this case the mostly reversible and strongly temperature dependent adduct formation is accompanied by drastic changes in colour caused by the disturbance of the M-P-M p-system. In a recent study, the P-acetonitrile adduct [{W(CO) 5 } 2 P(N^CMe)Cp*] was deduced based on 31 P NMR spectroscopy. 16 In a broader context and although dissociation has not been reported as yet, "adducts" of N-heterocyclic carbenes to pnictinidenes, formally described by the formula NHC/PnR (Pn ¼ P, As), should be mentioned. 17 Upon borane complexation of the phospho...

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Section: Compliance Constants Of Acyclic and Cyclic Phosphoorganic Co...mentioning

confidence: 99%

Coordination of CO to low-valent phosphorus centres and other related P–C bonding situations. A theoretical case study

2013

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“…The bulkiness of the triphenylmethyl group (“trityl”) combined with its intrinsic abilities to stabilize a negative and/or positive charge, or even a radical center makes the trityl group unique and has attracted interest from various angles since the early and fundamental work of Gomberg . Schmutzler was first to demonstrate that the trityl group can be used in molecular phosphorus chemistry to great advantage and to access a wide variety of very reactive and/or unstable compounds, for example, acyclic diphospha-urea derivatives, 1,3-diphosphetane-2,4-dione, and acyl(chloro)organophosphanes, and more . Grützmacher recognized the synthetic potential for low-coordinate phosphorus compounds and reported on the synthesis and reactivity of C -tritylphosphaalkyne .…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Reactions of the First Room Temperature Stable Li/Cl Phosphinidenoid Complex

et al. 2012

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P-Trityl substituted Li/Cl phosphinidenoid tungsten(0) complex (OC)5W{Ph3CP(Li/12-crown-4)Cl} (3) was prepared via chlorine/lithium exchange in complex (OC)5W{Ph3CPCl2} (2) using (t)BuLi in the presence of 12-crown-4 in tetrahydrofuran (THF) at low temperature; complex 3 possesses significantly increased thermal stability in contrast to previously reported analogue derivatives. Terminal phosphinidene-like reactivity of 3 was used in reactions with benzaldehyde and isopropyl alcohol as oxaphosphirane complex (OC)5W{Ph3CPC(Ph)O} (5) and phosphinite complex (OC)5W{Ph3CP(H)O(i)Pr} (6) were obtained selectively. Reaction of 3 with phosgene allowed to obtain the first kinetically stabilized chloroformylphosphane complex (OC)5W{Ph3CP(Cl)C(O)Cl} (4). Density functional theory (DFT) calculations revealed remarkable differences in the degree of P-Li bond dissociation 3a-d: using a continuum model 3 displays a covalent character of P-Li bond (COSMO (THF)) (a), which becomes elongated if 12-crown-4 is coordinated to lithium (b) and is cleaved if a dimethylether unit is additionally coordinated to lithium (c). A similar result was obtained for the case of 3(thf)4 in which also a solvent-separated ion pair structure is present (d). All products were unambiguously characterized by various spectroscopic means and, in the case of 2 and 4-6, by single-crystal X-ray diffraction analysis. In all structures very long P-C bonds were determined being in the range from 1.896 to 1.955 Å.

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“…In contrast, compound 5 undergoes quantitative decarbonylation under ambient light within approximately 7 hours generating the known diphosphine t Bu 2 P−P(CH 3 ) 2 with no evidence of diphosphine scrambling. These observations are consistent with the expected photochemically induced loss of CO. Only in the case of 2 is this followed by P−P bond homolysis generating a mixture of diphosphines (Scheme ), whereas in the case of 3 and 5 the photogenerated dissymmetric diphosphines are photochemically stable.…”

Section: Figurementioning

confidence: 99%

Diphospha‐Ureas from the Phosphaketene Ph₃GePCO

Szkop

Jupp

Razumkov

et al. 2019

Chemistry A European J

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The phosphaketene Ph3GePCO is shown to react with the phosphide KP(tBu)2 to generate the anion [Ph3GePC(O)P(tBu)2]− 1. This species reacts with CH3I or ClGePh3 to give the dissymmetric diphospha‐ureas (tBu)2PC(O)P(GePh3)(CH3) 2 and (Ph3Ge)2PC(O)P(tBu)2 3 respectively. Sequential treatment of 2 with a base and CH3I affords a route to (tBu)2PC(O)P(CH3)2 5. These species are products of the first modular diphospha‐urea synthesis. The subsequent thermal and photochemical reactivity of these species was also probed and described.

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Unusual Stability despite a P-bonded Proton: Phospha and Diphospha Ureas with the TrtP(H)-Moiety

Cited by 12 publications

References 6 publications

Coordination of CO to low-valent phosphorus centres and other related P–C bonding situations. A theoretical case study

Coordination of CO to low-valent phosphorus centres and other related P–C bonding situations. A theoretical case study

Synthesis and Reactions of the First Room Temperature Stable Li/Cl Phosphinidenoid Complex

Diphospha‐Ureas from the Phosphaketene Ph₃GePCO

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Unusual Stability despite a P-bonded Proton: Phospha and Diphospha Ureas with the TrtP(H)-Moiety

Cited by 12 publications

References 6 publications

Coordination of CO to low-valent phosphorus centres and other related P–C bonding situations. A theoretical case study

Coordination of CO to low-valent phosphorus centres and other related P–C bonding situations. A theoretical case study

Synthesis and Reactions of the First Room Temperature Stable Li/Cl Phosphinidenoid Complex

Diphospha‐Ureas from the Phosphaketene Ph3GePCO

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Diphospha‐Ureas from the Phosphaketene Ph₃GePCO