Abhaya Nand Sahay

Synthetic, spectral and structural aspects of some mono- and binuclear (homo/hetero) Ru(II) hydrido carbonyl complexes

Abstract Reactions of the poly-pyridyl bridging ligand 2,4,6-tris(2-pyridyl)-1,3,5-triazine; 2,3-bis(2-pyridyl)-pyrazine and 3,6-bis(2-pyridyl)-1,2,4,5-tetrazine (referred hereafter as tptz, bppz and bptz respectively) with [RuH(CO)Cl(PPh3)3] in methanol, gave highly stable cationic complexes with the formulation [RuH(CO)(PPh3)2(L)]+. Further, the mononuclear complex [RuH(CO)(PPh3)2(bppz)]PF6 reacted with K2PtCl4, [PdCl2(benzonitrile)2], [{Ru(η6-C10H14)(μ-Cl)Cl}2], [{Ru(η6-C6Me6)(μ-Cl)Cl}2], [RuCl(η5-C5H5)(PPh3)2] and [{Rh(η5-C5Me5)(μ-Cl)Cl}2] in methanol under refluxing conditions to give bppz bridged binuclear complexes with the formulation [RuH(CO)(PPh3)2(bppz)PtCl2]PF6, [RuH(CO)(PPh3)2(bppz)PdCl2]PF6, [RuH(CO)(PPh3)2(bppz)(η6-C10H14)RuCl](PF6)2, [RuH(CO)(PPh3)2(bppz)(η6-C6Me6)Cl2Ru](PF6)2, [RuH(CO)(PPh3)2(bppz)(η5-C5H5)(PPh3)Ru](PF6)2 and [RuH(CO)(PPh3)2(bppz)Rh(η5-C5Me5)Cl](PF6)2 in quantitative yield. The reaction products have been characterized by elemental analyses, IR, 1H-, 1H–1H-COSY, 13C-, 31P-NMR, ESMS, FAB mass spectroscopy, electronic spectra and cyclic voltammetry. Molecular structure of the representative mononuclear complex [RuH(CO)(PPh3)2(tptz)]BF4 has been confirmed by X-ray crystallography. Crystal structure determination revealed η2-coordination of the ligand tptz with the metal center. Crystal data: monoclinic, P21/n, a=17.810(6) A, b=22.233(9) A, c=12.156(4) A, β=90.06(3)°, Z=4, R=0.078.

Synthesis and spectroscopic properties of cationic Ru(II) arene complexes [Ru(η6-arene)(P)Cl(L)]+. (P=PPh3, PEt3, MePPri2 and L=4-cyanopyridine or 1,4-dicyanobenzene)

Abstract Reactions of [Ru(η6-arene)(P)Cl2] (P=PPh3, PEt3 or MePPri2) with organonitriles 4-cyanopyridine or 1,4-dicyanobenzene (referred hereafter as CNPy or DCB) in methanol, in the presence of NH4PF6, gives the cationic arene complexes [Ru(η6-arene)(P)Cl(L)]+ (L=CNPy or DCB). The reaction products have been characterized by physico-chemical methods viz., elemental analyses, IR, 1H-, 13C-, 31P-NMR, electronic and FAB mass spectra. The spectral data of the complexes revealed the presence of a pendant nitrile group. These could behave as potential metallo-ligands and could find wide application in the syntheses of homo- or heterobimetallic mixed valence bridged complexes.

Synthetic, spectral and structural aspects of some Rh(III) pentamethylcyclopentadiene complexes containing N,N′-donor bridging ligands

Abstract Reactions of the chloro-bridged dimeric rhodium complex [{(η5-C5Me5)Rh(μ-Cl)Cl}2] with the N,N′-donor bridging ligands pyridine-2-carbaldehyde azine (paa), p-phenylene-bis(picoline)aldamine (pbp) or p-biphenylene-bis(picoline)aldamine (bbp) in 1:1 molar ratio in methanol led in the formation of cationic binuclear complexes [(η5-C5Me5)ClRh(μ-L)RhCl(η5-C5Me5)]2+ (L=paa, pbp or bbp) in high yield. It was further observed that reactions of the chloro-bridged dimeric rhodium complex [{(η5-C5Me5)Rh(μ-Cl)Cl}2], with an excess of the above mentioned ligands also, resulted in binuclear complexes. The reaction products have been characterized by microanalyses and spectroscopic studies (IR, 1H-, 13C-NMR, ESMS/FAB mass and electronic spectra). Molecular structure of the representative binuclear complex [(η5-C5Me5)ClRh(μ-paa)RhCl(η5-C5Me5)](BF4)2 has been confirmed by single crystal X-ray analysis. Crystal data: monoclinic, P21/n, a=10.2050(7), b=15.4470(7), c=24.959(2) A, β=97.904(6)°, V=3897.1(5) A3, Z=4, R=0.0609.

Synthesis and characterization of some mono and binuclear (η3:η3-C10H16) containing ruthenium(IV) complexes. Crystal structure of [Ru(η3:η3-C10H16)Cl2(CNPy)]

Abstract Reaction of [{Ru(η3:η3-C10H16)(μ-Cl)Cl}2] with 4-cyanopyridine (referred hereafter as (CNPy) in dichloromethane in 1:2 and 1:1 molar ratio gives mononuclear complex [Ru(η3:η3-C10H16)Cl2(CNPy) (1) and binuclear complex [{Ru(η3:η3-C10H16)Cl2}2(μ-CNPy)] (2) in quantitative yield. The mononuclear complex 1 reacts further with the chloro bridged arene Ru(II) complexes [{Ru(η6-C6H6)(μ-Cl)Cl}2], [{Ru(η6-C10H14)(μ-Cl)Cl}2], [{Ru(η6-C6Me6)(μ-Cl)Cl}2] and the rhodium complex [{Rh(η5-C5Me5)(μ-Cl)Cl}2], to form Ru(IV)Ru(II) or Ru(IV)Rh(III) binuclear complexes, in which the respective metal centers are bridged by a 4-cyanopyridine ligand. The reaction products have been characterized by microanalyses and spectroscopic studies (IR, 1H-, 13C-NMR and FAB mass spectra). The structure of the complex [Ru(η3:η3-C10H16)Cl2(CNPy)] has been confirmed by single-crystal X-ray analysis.

Synthesis and characterization of some arene hydrido-complexes [Ru(η6-arene)(EPh3)2H]+ (η6-arene=benzene, p-cymene or hexamethylbenzene; E=P, As or Sb). Crystal structure of [Ru(η6-C6H6)(PPh3)2H]BF4

[{Ru( η 6 -arene)Cl 2 } 2 ] ( η 6 -arene=benzene, p-cymene or hexamethylbenzene) reacts with EPh 3 (E=P, As or Sb) in methanol to give monomeric cationic arene hydrido complexes [Ru( η 6 -arene)(EPh 3 ) 2 H] + in presence of AgBF 4 or AgPF 6 . However, reactions in presence of triphenylphosphine also yield a symmetrically bridged tris ( μ -methoxy) complex [(PPh 3 ) 3 Ru( μ -OMe) 3 Ru(PPh 3 ) 3 ] + . The crystal structure of [Ru( η 6 -C 6 H 6 )(PPh 3 ) 2 H]BF 4 has been determined. Crystal data, monolinic system, space group P2 1/n , a =14.792 (2) A; b =14.351 (1) A; c =17.661 (2) A; β =102.25 (1)° and Z =4. Crystal structure determination reveals the distortion of the Ru(PPh 3 ) 2 H + unit in the cation [Ru( η 6 -C 6 H 6 )(PPh 3 ) 2 H] + .

Synthetic and spectroscopic aspects of some maleonitrile dithiolate complexes of ruthenium(II)

Abstract Reactions of [RuH(CO)Cl(PPh3)3] with Na2S2C2(CN), (referred hereafter as Na2mnt) lead to the formation of [RuH(CO)(PPh3),{S2C2(CN)2}] which, upon treatment with [RuCp(EPh3)2Cl], yields neutral complexes with the general formulation [RuH(CO)(EPh3)2{S2C2(CN)2)RuCp(EPh3)] (E = P, As, Sb). These complexes have been characterized by various physico-chemical techniques (elemental analyses, IR, 1H, 13C and 31P NMR and electronic spectra).