The preparation of stable dimercury(I)-nitrogen donor complexes

Kepert, DL; Taylor, DK

doi:10.1071/ch9741199

Cited by 17 publications

(5 citation statements)

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“…The dynamic behavior of the encapsulated Hg 2 2+ dimer is particularly striking especially when considering the large number of known stable and inert complexes of Hg 2 2+ with similar nitrogen-containing ligands including pyridine, 2,2‘-bipyridine, and 1,10-phenanthroline . To render the phosphine environments equal in the 31 P{ 1 H} NMR spectrum (likewise, the mercury environments) requires labilization of the Hg−N bonds and subsequent rotation of the Hg 2 2+ dimeric unit about the Pd···Pd or Pt···Pt axes.…”

Section: Discussionmentioning

confidence: 99%

“…The bonding about the four-metal center is unique, and no analogous compounds with two Pd or Pt atoms coordinated “side-on” to a mercurous dimer could be found. However, there are several triangular adducts of Fe(CO) 4 to mercurous dimer complexes that possess short Fe−Hg separations (∼2.55 Å) but with much longer Hg−Hg separations (∼3.1 Å) 17b, and numerous cluster compounds that contain Hg−Pt bonds 21,23 with separations ranging 2.531(1)−3.071(3) Å. It is notable in 1 and 2 that the Hg− Hg bond (2.7362(6) and 2.6881(4) Å) is preserved and is only slightly lengthened compared to the distance of 2.508(2) Å measured in Hg 2 (NO 3 ) 2 , whereas the addition of Fe(CO) 4 to this core significantly weakens the Hg−Hg bond.…”

Section: Discussionmentioning

confidence: 99%

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Pd(0) and Pt(0) Metallocryptands Encapsulating a Spinning Mercurous Dimer

2002

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The deep-red, air-stable complexes [Pt(2)Hg(2)(P(2)phen)(3)](PF(6))(2), 1, or [Pd(2)Hg(2)(P(2)phen)(3)](PF(6))(2), 2, (P(2)phen is 2,9-bis(diphenylphosphino)-1,10-phenanthroline) are most conveniently prepared by the stoichiometric reaction of either Pt(dba)(2) or Pd(2)(dba)(3).CHCl(3) (dba is dibenzylideneacetone) with P(2)phen and a single drop of elemental mercury in refluxing dichloromethane under an atmosphere of nitrogen. The (31)P[(1)H] NMR spectrum (CD(3)CN) of 1 shows a single sharp resonance at 43.1 ppm for the phosphorus atoms of the P(2)phen ligand with both (195)Pt ((1)J(P-Pt) = 4350 Hz) and (199)Hg ((2)J(P-Hg) = 620 Hz) satellites indicating the Hg(2)(2+) unit is dynamic. Compound 2 has a similar resonance at 44.9 ppm with (199)Hg satellites ((2)J(P-Hg) = 638 Hz). The (199)Hg NMR (CD(2)Cl(2), vs Hg(OAc)(2)) spectrum of 2 shows a heptet pattern at 833 ppm while for 1 a heptet superimposed on a doublet of heptets is observed at 770.8 ppm. The (195)Pt NMR spectrum of 1 displays a quartet at -3071 ppm with (199)Hg satellites and a (1)J(Pt-Hg) value of 1602 Hz. Characterization of 1 and of 2(BF(4)(2) by single-crystal X-ray diffraction studies confirms the metallocryptand structure consisting of three phosphine-imine ligands forming a D(3) symmetric cage with a Hg(2)(2+) ion in its center coordinated to two phenanthroline rings with the Hg-Hg bond (1, 2.7362(6); 2(BF(4)(2), 2.6881(4) A) oriented perpendicular to the vector between the trigonally coordinated Pt(0) or Pd(0) atoms on each end. The Pt-Hg separations in 1 average 2.8143(6) A while in 2(BF(4)(2) the average Pd-Hg separation is 2.7698(5) A. Excitation into the low energy excitation bands of 1 (475 nm) and 2 (430 nm) produces weak emissions centered at 593 nm with shoulders at 530 and 654 nm in 1 and centered at 524 nm with a shoulder at 545 nm in 2.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Pd(0) and Pt(0) Metallocryptands Encapsulating a Spinning Mercurous Dimer

2002

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“…77 Apparently, the introduction of an acceptor substituent at position 4 of the pyridine ring leads to a decrease in the donor ability of the nitrogen atom. Some substituted low-basicity pyridines and anilines also form stable [Hg 2 L 2 ]X 2, complexes, 78 the basicity of the ligand depending on both the electronic and steric properties of the substituents. Structural study of the isolated [Hg 2 (L 1 ) 2 ](ClO 4 ) 2 compound 79 demonstrated that the (Hg 2 ) 2+ ion can be covalently coordinated to the N-donor ligands through both mercury atoms.…”

Section: Monovalent Mercury Compounds With Organic Ligandsmentioning

confidence: 99%

Crystal chemistry of compounds containing mercury in low oxidation states

Pervukhina¹,

Магарилл²,

Борисов³

et al. 1999

Russ. Chem. Rev.

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We demonstrated the precise measurement of a 20-V programmable Josephson voltage standard (PJVS) system with an accuracy of 10 À9 . A 20-V PJVS chip including 524288 NbN/TiN x /NbN Josephson junctions (JJs) was used and operated in a cryocooler. By optimizing a microwave frequency, the widest current margin of a voltage step greater than 1 mA was obtained at 15.85 GHz. The maximum voltage of 17 V was also obtained at 18.00 GHz although we could not obtain voltages exceeding 20 V due to defective JJs. We also successfully compared the PJVS system with a 10-V Zener diode with an accuracy of 10 À8 . #

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“…More basic ligands show enhanced complex stability for the mercuric ion and promote disproportionation. Complexation studies , using heterocyclic nitrogen donor ligands indicate disproportionation impedes isolation of the complexed mercurous dimer. Introduction of electron withdrawing substitutents − or steric interactions between metal ion and complexing ligand effectively decreases the basicity of the nitrogen donor atom facilitating the isolation of [L 2 Hg 2 ] 2+ complexes.…”

Section: Introductionmentioning

confidence: 99%

“…Complexation studies , using heterocyclic nitrogen donor ligands indicate disproportionation impedes isolation of the complexed mercurous dimer. Introduction of electron withdrawing substitutents − or steric interactions between metal ion and complexing ligand effectively decreases the basicity of the nitrogen donor atom facilitating the isolation of [L 2 Hg 2 ] 2+ complexes. Predictably, [L 2 Hg 2 ] 2+ complexes of oxygen donor ligands are more readily synthesized but are relatively few in number.…”

Section: Introductionmentioning

confidence: 99%

Complexation of Mercury(I) and Mercury(II) by 18-Crown-6: Hydrothermal Synthesis of the Mercuric Nitrite Complex

et al. 2009

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A dimercury(I) 18-crown-6 complex is isolated, and its possible role in the hydrothermal preparation of the mercuric nitrite complex is discussed. The reported structures are of [Hg(2)(18-crown-6)(2)(H(2)O)(2)](ClO(4))(2) (1), monoclinic, C2/c, a = 21.0345(9), b = 12.1565(5), c = 16.8010(7) A, beta = 113.2000(10) degrees , V = 3948.7(3) A(3), Z = 16, R = 0.0230; [Hg(18-crown-6)](NO(2))(2) (2), monoclinic, P2(1)/c, a = 8.027(5), b = 14.437(9), c = 7.827(5) A, beta = 95.165(11) degrees , V = 905.6(10) A(3), Z = 2, R = 0.0175. The complex cation in compound 1 consists of a mercurous dimer exhibiting a Hg-Hg bond length of 2.524(2) A. Non-bonding interactions between adjacent crown ether macrocycles across the Hg-Hg bond result in large variations in mercury to oxygen distances within equatorial coordination sites. At low pH compound 1 is proposed to be preferentially formed under hydrothermal conditions affording compound 2 upon disproportionation. Nitrite ions ligate via a unidentate nitrito (cis to metal) coordination mode as interpreted using vibrational (infrared) spectroscopy. The conformation adopted by 18-crown-6 in compounds 1 and 2 is closely related to a D(3d) conformation as evidenced by X-ray crystallography. Band splitting readily observed in vibrational spectra of the metal free crown ether, attributed to vibrational modes of oxyethylene fragments, is absent in spectra of 1 and 2 confirming a regular D(3d) macrocyclic orientation. Short Hg-O bonds observed for axially coordinated water molecules in 1 and coordinated nitrite ligands in 2, illustrate the prevalence of relativistic effects commonly observed in mercury complexes.

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The preparation of stable dimercury(I)-nitrogen donor complexes

Cited by 17 publications

References 0 publications

Pd(0) and Pt(0) Metallocryptands Encapsulating a Spinning Mercurous Dimer

Pd(0) and Pt(0) Metallocryptands Encapsulating a Spinning Mercurous Dimer

Crystal chemistry of compounds containing mercury in low oxidation states

Complexation of Mercury(I) and Mercury(II) by 18-Crown-6: Hydrothermal Synthesis of the Mercuric Nitrite Complex

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