Supramolecular structures of NiII and CuII with the sterically demanding Schiff base dyes driven by cooperative action of preagostic and other non-covalent interactions

This work reports on synthesis and extensive experimental and theoretical investigations on photophysical, structural and thermal properties of the NiII and CuII discrete mononuclear homoleptic complexes [Ni(L I,II)2] and [Cu(L I,II)2] fabricated from the Schiff base dyes o-HOC6H4-CH=N-cyclo-C6H11 (HL I) and o-HOC10H6-CH=N-cyclo-C6H11 (HL II), containing the sterically crowding cyclo-hexyl units. The six-membered metallocycles adopt a clearly defined envelope conformation in [Ni(L II)2], while they are much more planar in the structures of [Ni(L I)2] and [Cu(L I,II)2]. It has been demonstrated by in-depth bonding analyses based on the ETS-NOCV and Interacting Quantum Atoms energy-decomposition schemes that application of the bulky substituents, containing several C-H groups, has led to the formation of a set of classical and unintuitive intra- and inter-molecular interactions. All together they are responsible for the high stability of [Ni(L I,II)2] and [Cu(L I,II)2]. More specifically, London dispersion dominated intramolecular C-H⋯O, C-H⋯N and C-H⋯H-C hydrogen bonds are recognized and, importantly, the attractive, chiefly the Coulomb driven, preagostic (not repulsive anagostic) C-H⋯Ni/Cu interactions have been discovered despite their relatively long distances (∼2.8-3.1 Å). All the complexes are further stabilized by the extremely efficient intermolecular C-H⋯π(benzene) and C-H⋯π(chelate) interactions, where both the charge-delocalization and London dispersion constituents appear to be crucial for the crystal packing of the obtained complexes. All the complexes were found to be photoluminescent in CH2Cl2, with [Cu(L II)2] exhibiting the most pronounced emission - the time-dependent density-functional-theory computations revealed that it is mostly caused by metal-to-ligand charge-transfer transitions.

Conformational flexibility in amidophosphoesters: a CSD analysis completed with two new crystal structures of (C6H5O)2P(O)X [X = NHC7H13 and N(CH2C6H5)2]

The crystal structures of diphenyl (cycloheptylamido)phosphate, C19H24NO3P or (C6H5O)2P(O)(NHC7H13), (I), and diphenyl (dibenzylamido)phosphate, C26H24NO3P or (C6H5O)2P(O)[N(CH2C6H5)2], (II), are reported. The NHC7H13 group in (I) provides two significant hydrogen-donor sites in N—H...O and C—H...O hydrogen bonds, needed for a one-dimensional hydrogen-bond pattern along [100] in the crystal, while (II), with a (C6H5CH2)2N moiety, lacks these hydrogen bonds, but its three-dimensional supramolecular structure is mediated by C—H...π interactions. The conformational behaviour of the phenyl rings in (I), (II) and analogous structures from the Cambridge Structural Database (CSD) were studied in terms of flexibility, volume of the other group attached to phosphorus and packing forces. From this study, synclinal (±sc), anticlinal (±ac) and antiperiplanar (±ap) conformations were found to occur. In the structure of (II), there is an intramolecular C ortho —H...O interaction that imposes a +sc conformation for the phenyl ring involved. For the structures from the CSD, the +sc and ±ap conformations appear to be mainly imposed by similar C ortho —H...O intramolecular interactions. The large contribution of the C...H/H...C contacts (32.3%) in the two-dimensional fingerprint plots of (II) is a result of the C—H...π interactions. The differential scanning calorimetry (DSC) analyses exhibit peak temperatures (T m) at 109 and 81 °C for (I) and (II), respectively, which agree with the strengths of the intermolecular contacts and the melting points.

Dicyclohexylammonium O,O’-Diphenyl Phosphate, [(C6H11)2NH2][(C6H5O)2P(O)(O)]: Spectroscopic Study, Crystal Structure, and Hirshfeld Surface Analysis

The title salt, [(C6H11)2NH2][(C6H5O)2P(O)(O)], crystallizes in the chiral space group P212121, composed of achiral cation and anion components. The strong charge-assisted N–H…O hydrogen bonds build a linear assembly along the a axis, including a non-centrosymmetric C22(6) chain graph-set motif. The intra and intermolecular C–H…O interactions as well as the C–H…π-electron ring interactions also exist in the crystal structure. Fingerprint plots are used for a detailed investigation of intermolecular interactions participating in the crystal packing. The spectroscopic features (IR, 1H NMR, 13C{1H} NMR, 31P{1H} NMR, and mass) are studied.

Detailed studies of the interaction of 3-chloroaniline with O,O′-diphenylphosphorylisothiocyanate

The reaction of neat 3-chloroaniline with neat SCN–P(O)(OPh)₂ leads to 1. The same reaction in non-dried CH₂Cl₂ or C₆H₆ or Me₂CO leads to 2, 3·0.5C6H6 and 4, respectively.

An intermolecular pyrene excimer in the pyrene-labeled N-thiophosphorylated thiourea and its nickel(ii) complex

(1-pyrene)NHC(S)NHP(S)(OiPr)₂ (HL) and its Ni^II complex ([NiL2]) have been synthesized. Both HL and [NiL2] were found to be emissive in solution of CH₂Cl₂, which is due to the concentration dependent emission of the pyrene monomer and excimer.

N-Salicylidene aniline derivatives based on the N′-thiophosphorylated thiourea scaffold

A new family of thermochromic N′-thiophosphorylated thiourea-containing N-salicylidene aniline derivatives (anils) of the common formula 6-{(2-OH-aryl)–CHN}-Py-2-NHC(S)NHP(S)(OiPr)₂ has been synthesized by the condensation of N-thiophosphorylated thiourea 6-NH₂-Py-2-NHC(S)NHP(S)(OiPr)₂ with the corresponding salicylaldehyde.

From a mononuclear Ni(II) precursor to antiferromagnetically coupled trinuclear double-stranded helicates

Reaction of the mononuclear Ni(II) complex [Ni{2-Py(6-NH2)NHC(S)NP(S)(OiPr)2}2] with different salicylaldehydes leads to new antiferromagnetically coupled trinuclear double-stranded helicates , where Ni(II) metal ions are coordinated by two bis-anionic thiourea ligands and two deprotonated molecules of the corresponding aldehyde.