Crystallographic and spectroscopic studies of low-symmetry nickel(II) complexes possessing long nickel-nitrogen bonds

trans-Bis(N,N-diethylethylenediamine)nickel(II) dibromide

“…Following a data collection at 100 K, structure solution and refinement of this bromide compound revealed the Ni II atom to have square-planar coordination in the crystalline state (Scheme 1, Figure 1) rather than octahedral coordination as assumed by Goodgame & Venanzi (1963 also been structurally characterized as the perchlorate salt (Ikeda et al, 1995;Narayanan & Bhadbhade, 1998;Hayami et al, 2009) and observed to have similar Ni-N bond lengths of 1.930 (3) and 1.976 (2) Å (Ikeda et al, 1995 (Senocq et al, 1999), 2.064 (3) and 2.271 (3) Å where X = OH 2 (Ihara et al, 1991), and 2.083 (2) and 2.318 (2) Å (averaged values for two independent molecules) where X = -NCS (Lever et al, 1983). The longer Ni-N bond lengths in these latter compounds are due to a triplet electronic configuration in which the d Although the Br -ions do not have a bonding interaction with the Ni II atoms in the title crystal structure, they participate in a one-dimensional ribbon of hydrogen bonds, the formation of which is undoubtedly the principal factor governing the pattern of crystal packing.…”

“…The compounds containing Ni II in octahedral coordination with axial X ligands have been structurally characterized for X = À O 2 CCF 3 (Senocq et al, 1999), À NCS (Lever et al, 1983) and H 2 O with non-coordinated Cl À counter-anions (Ihara et al, 1991). [Ni(Et 2 en) 2 ][ClO 4 ] 2 containing a square-planar centrosymmetric cation has been identified as having triclinic (Ikeda et al, 1995;Narayanan & Bhadbhade, 1998) and monoclinic (Hayami et al, 2009) polymorphs.…”

DommiMOE: An implementation of ligand field molecular mechanics in the molecular operating environment

“…The radial form of the AOM e parameters is unknown in detail but has often been assumed to follow an exponential form related to the change in the overlap integral between suitable ligand and metal orbitals. 18 However, empirical fitting of AOM parameters for nickel amines complexes suggested an approximately linear dependence of e on the NiON bond length, at least in the range of 1.95-2.30 Å, 37 and indeed a linear dependence was found to be a reasonable approximation using the Dommino program.…”

Mutual Influences of Ligands as Revealed by 2H NMR Shifts and the Angular Overlap Model Parameters: trans‐ and cis‐[CrX2(N)4]‐Type Complexes with Aliphatic Amine Ligands

“…This σ bond pathway gives more definite and clearer physical meaning to the negative correlation between the axial-basal bond length than the ligand-field parameter 10 Dq (∆) 4 ]-type complexes. [2][3][4][5][6] The change of e σ (N) associated with the variation of e σ (X) indicates the invalidity of transferring the AOM parameters from one complex to another.…”

“…n+ (X = NH 3 , CN -, Cl -, Br -) were estimated from the observed 2 H NMR shift difference (∆δ) according to Equation (3). These e σ (FX) values were compared with the average e σ (FX) value [e σ (F) + e σ (X)]/2 obtained by assuming holohedralized symmetry, as shown in Table 2.…”