Supramolecular Coordination Complexes of theN-Thiophosphorylated 2,5-Dithiobiurea [NHC(S)NHP(S)(OiPr)2]2with ZnIIand CdIIIons - Cation-Induced Dinuclear Mesocate Structure versus Tetranuclear Nanoscaled Aggregate

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.

On the Stability of Cis- and Trans-2-Butene Isomers. An Insight Based on the FAMSEC, IQA, and ETS-NOCV Schemes

In the present account, the real space fragment attributed molecular system energy change (FAMSEC) approach, interacting quantum atoms energy decomposition scheme as well as molecular orbitals based the extended transition state scheme coupled with natural orbitals for chemical valence (ETS-NOCV) have been, for the first time, successfully used to delineate factors of importance for stability of the 2-butene conformers (cis-eq, cis-TS, trans-eq, trans-TS). Our results demonstrate that atoms of the controversial H-H contact in cis-eq (i) are involved in attractive interaction dominated by the exchange-correlation term, (ii) are weekly stabilized, (iii) show trends in several descriptors found in other typical H-bonds, and (iv) are part of most stabilized CH-HC fragment (loc-FAMSEC = -3.6 kcal/mol) with most favourably changed intrafragment interactions on trans-eq→cis-eq. Moreover, lower stability of cis-eq vs. trans-eq is linked with the entire HCCH (ethylenic) fragment which destabilized cis-eq (mol-FAMSEC, +3.9 kcal/mol) the most. Although the H-H contact can be linked with smaller, relative to trans-, rotational energy barrier in cis-2-butene, we have proven that to rationalize this phenomenon one must account for changes in interactions between various fragments that constitute the entire molecule. Importantly, we discovered a number of comparable trends in fundamental properties of equivalent molecular fragments on a methyl group rotation; for example, interaction between BP-free H-atoms in trans-eq (involving CH bonds of the methyl and ethylenic units) and BP-linked H-atoms in cis-eq. Clearly, rotational energy barrier cannot be entirely (i) rationalized by the properties of or (ii) attributed to the H-H contact in cis-eq. © 2016 Wiley Periodicals, Inc.

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.

Metal ion influences distortion of the ligand in the structure of [M{2-MeO(O)CC6H4NHC(S)NP(S)(OiPr)2}2] (M = Zn(II), Cd(II)) complexes: a driving force for intermolecular aggregation

Reaction of the in situ deprotonated N-thiophosphorylated thiourea 2-MeO(O)CC6H4NHC(S)NHP(S)(OiPr)2 () with MCl2 (M = Zn(II), Cd(II)) in aqueous ethanol leads to complexes of the formula . Both compounds crystallise in the triclinic space group P1[combining macron] with Z = 2 and the metal cations are found in a tetrahedral S2S coordination environment formed by the C-S and P-S sulfur atoms. The crystal structures reveal intramolecular N-HO[double bond, length as m-dash]C hydrogen bonds formed within the 2-MeO(O)CC6H4NH fragments. Both structures are further stabilised by intermolecular ππ stacking interactions, which are more efficient in . Here, a pronounced dimeric intermolecular aggregate is observed which goes along with a pronounced distortion of the chelate [(S)CNP(S)](-) backbone of the ligand upon coordination to Cd(II) as well as a significantly distorted coordination tetrahedron CdS2S. The aggregation is also reflected in the positive electrospray ionisation (ESI) mass spectrum of the Cd(II) complex, which exhibits peaks for the dimeric cations [Cd2L3](+), [Cd2L4 + H](+) and [Cd2L4 + Na](+), while for the Zn(II) analogue only monomeric species were observed. Quantum chemical ETS-NOCV (ADF) calculations confirm the higher stability of dimers in compared with . The ππ stacking interactions are prodominantly due to dispersion contributions, though the electrostatic and orbital interaction components are also important. QTAIM (ADF) type calculations additionally quantify the covalent and non-covalent interactions in the momomers.