Hydrazine Ligand Research Articles

Conversion of bonded cyclo-octadiene into a cyclo-octadienyl ligand and cleavage of boron–phenyl bonds of arene-bonded tetraphenylborate anions in ruthenium(II) systems: X-ray crystal and molecular structures of [Ru(η6-C6H5BL3)(1–3,5,6-η-C8H11)](L = Ph or F)

Labilisation of the hydrazine ligands in either [Ru(cod)(N2H4)4][BPh4]2(I; cod = cyclo-octa-1,5-diene) or [RuH(cod)(NH2NMe2)3][BPh4](II) in acetone produces [Ru(η6-C6H5BPh3)(1–3,5,6-η-C8H11)] which reacts with HA (A = BF4 or PF6) to give [Ru(η6-C6H5-BF3)(1–3,5,6-η-C8H11)]; a byproduct of the reaction with (II) is [Ru(cod)(C6H6)].

Reactions of hydrazine ligands. Part I. Synthesis and X-ray structure determination of a nickel(II) complex of a novel monoanionic macrocyclic ligand

Reactions of 1,3-bis(2-hydrazinophenylthio)propane (2) with formaldehyde in the presence of nickel(II) salts are reported, the first of a study of metal-ion template control of condensation reactions of aromatic hydrazines. Complexes of an unusual macrocyclic ligand result, in which the two hydrazine groups have been ‘bridged’ by the carbon atom of formaldehyde, and spontaneous aerial oxidation gives a novel monoanionic chelate ring containing four nitrogen atoms, (16,17-Dihydro-15H-dibenzo[f,m][1,11,4,5,7,8]dithiatetra-azacyclotetradecinato-N5,N9,S14,S18)-nickel(II) perchlorate (9) in an unsolvated monoclinic form, space group P21/c with a= 13.646(4), b= 9.374(3), c= 16.674(4)A, γ= 96.02(4)°, and Z= 4, allowed a more satisfactory X-ray structure determination (heavy-atom method, 2 299 diffractometer data, R 7.7%) than the triclinic methanol salvate previously examined.The complex shows planar co-ordination geometry with the conjugated anionic chelate ring lying close to this plane. The perchlorate counter ion is well separated from the nickel ion in both crystalline modifications [shortest Ni ⋯ O contacts 3.51(2) and 3.51(6)A].

Reactions of hydrazine ligands. Part 2. The X-ray structure determination of {7-(3-hydroxypropyl)-16,17-dihydro-15H-dibenzo[f,m][1,11,4,5,7,8]-dithiatetra-azacyclotetradecinato-N 6,N 9,S 14,S 18}nickel(II) perchlorate, an unexpected product for a template cyclization in tetrahydrofuran

The reactions of 1,3-bis(2,-hydrazinophenylthio)propane with a variety of ketones in tetrahydrofuran solutions of nickel(II) perchlorate have been investigated as part of a programme of study of the reactions of co-ordinated hydrazines. Many of these reactions giveacrystalline by-product in low yield, which is shown to be the perchlorate salt of the macrocyclic monocation : {7-(3-hydroxypropyl)-16,17-dihydro-15H-dibenzo[f,m][1,11,4,5,7,8]dithia-tetra-azacyclotetradecinato-N5,N9,S14,S18}nickel(II) perchlorate. Crystals are monoclinic, space group P21/c with a= 9.973(8), b= 14.44(1), c= 17.83(1)A, β= 124.3(1)°, and Z= 4. Structural refinement based on 2 180 two-circle diffractometer data converged at 0.067.

Reaction of bromotricarbonylbis(dimethylphenylphosphine)manganese(I) with anhydrous hydrazine to yield isocyanato(dicarbonyl)hydrazinebis(dimethylphenylphosphine)manganese(I)

Bromotricarbonylbis(dimethylphenylphosphine)manganese(I)(1), prepared by the photochemical reaction of bromopentacarbonylmanganese(I) with 2·2 molar equivalents of dimethylphenylphosphine, reacts with anhydrous hydrazine at room temperature in tetrahydrofuran to yield the air-sensitive isocyanato(dicarbonyl)hydrazinebis(dimethylphenylphosphine)manganese(I)(2). The hydrazine ligand is readily replaced by CO or PMe2Ph yielding the new complexes [Mn(NCO)(CO)3(PMe2Ph)2](3) and [Mn(NCO)(CO)2(PMe2Ph)3](4) respectively. The isocyanate ligand in [Mn(NCO)(CO)2(PMe2Ph)3](4) undergoes metathetical replacement with the bromo-ligand. [Mn(NCO)(CO)2(NH2·NH2)(PMe2Ph)2] decomposes in chlorinated solvents to yield a bright green solution. [Mn(NCO)(CO)2(NH2·NH2)(PMe2Ph)2] reacts with hydrogen chloride to yield a similar solution, from which [MnCl(CO)3(PMe2Ph)2](6) was isolated. The stereochemistries of these new complexes are discussed in terms of their i.r. spectra. The mass spectrum of [Mn(NCO)(CO)3(PMe2Ph)2] is presented. The 1H n.m.r. spectra of these complexes cannot be used to determine stereochemistry as the ‘J’(P–P) coupling in trans-[MnBr(CO)3-(PMe2Ph)2] is not strong enough to produce a well defined 1:2:1 triplet.

Ligand field spectra of hydrazine complexes of NiII, and the spectrochemical position of hydrazine

Solid nickel(II)-hydrazine complexes, Ni(N2H4)2X2 and Ni(N2Ht)3X2, have ligand-field spectra corresponding to those expected for [trans-NiN4X2] and [NiN6] chromophores respectively. This contrasts with solution spectra of hydrazine complexes, where hydrazine is often unidentate and is often only partially substituted in the coordination sphere. The present study thus affords a unique occasion to establish the spectrochemical properties of the hydrazine ligand. The spectrochemical position of hydrazine is practically coincident with that of other diamines, and higher than that of, say, ammonia. The axial field strength is unusually low, and the nephelauxetic ratio unusually high in the trans-disubstituted octahedral chromophores [NiN4X2]. These date imply that (in these complexes) hydrazine can acquire a conformation which is particularly favorable for the formation of stable σ bonds, and that the axial field is particularly weak, thus implying weak σ-covalent character of the axial bonds and hence poor σ-delocalization and low nephelauxetic effect.