(Di-2-pyridylamine-κ2 N,N′)[hydrotris(3,5-diphenylpyrazol-1-yl-κN 2)borato]nickel(II) bromide dichloromethane monosolvate

In the title compound, [Ni(C45H34BN6)(C10H9N3)]Br·CH2Cl2, the NiII atom is five-coordinated by the tridentate hydrotris(3,5-diphenylpyrazolyl)borate ligand and a bidentate di-2-pyridylamine ligand in a distorted square-pyramidal geometry. In the crystal, intermolecular N—H⋯Br and C—H⋯Br hydrogen bonds link the Ni complex cations and the Br− ions, forming a chain along the c axis.

In the title compound, [Ni(C 45 H 34 BN 6 )(C 10 H 9 N 3 )]BrÁCH 2 Cl 2 , the Ni II atom is five-coordinated by the tridentate hydrotris(3,5-diphenylpyrazolyl)borate ligand and a bidentate di-2pyridylamine ligand in a distorted square-pyramidal geometry. In the crystal, intermolecular N-HÁ Á ÁBr and C-HÁ Á ÁBr hydrogen bonds link the Ni complex cations and the Br À ions, forming a chain along the c axis.

Comment
Tris(pyrazolyl)borates are versatile and popular ligands in coordination chemistry with many complexes now known (Trofimenko, 1999). While neutral half-sandwich complexes are common, [Tp R NiX] (Tp R = substituted tris(pyrazolyl)borate, X = monoanionic ligand) cationic species are limited to those reported by Akita and co-workers and our research group (Uehara et al., 2002;Harding et al., 2010).
The title compound, [Tp Ph2 Ni(dpa)]Br 1 (dpa = di-2-pyridylamine), crystallizes in the triclinic, P1 space group with one molecule of dicholormethane. The structure is shown in Figure 1 while important bond lengths and angles are given in the supporting tables. The nickel metal centre is five coordinate with the Tp Ph2 ligand κ 3 -coordinated resulting in a geometry best described as square pyramidal (τ = 0.23; Addison et al., 1984) The Ni-N bond lengths are also somewhat shorter than previously reported where values are between 2.029-2.121 Å (Lu et al., 2001;Rahaman et al., 2005;Uddin et al., 1997). The dihedral angle between the two pyridine rings is 22.5° and thus the ligand adopts a boat conformation as found in other Ni-dpa compounds {21.9 and 28.1° in [Ni(dpa)  The packing in the structure principally involves an N-H···Br hydrogen bond and two C-H···Br interactions (Table 2).
These combine to form one-dimensional chains of nickel cations separated by the bromide anions (Fig. 2). Further chains are found above and below the chain shown with the direction of the chain alternating throughout the structure. Interestingly, the supramolecular motif exhibited by the dpa ligand towards the bromide anion in 1 has previously been reported in the structure of [Ni(oxalate)(dpa)] although in this instance the interactions are between the N-H and C-H groups of the dpa ligand and a coordinated oxygen atom of the oxalate ligand (Lu et al., 2001).

Experimental
TpNiBr (162 mg, 0.20 mmol;Harding et al., 2007) was dissolved in CH 2 Cl 2 (10 ml) giving a deep pink solution and then stirred for 5 min. di-2-pyridylamine (35 mg, 0.20 mmol) was added giving a green solution. The solution was stirred for 2 hrs and filtered through celite. The resulting green solution was layered with hexanes (30 ml). After two days redbrown crystals appeared. These were washed with EtOH (3 × 3 ml) and hexanes (2 × 5 ml) (157 mg, 74%). ν max (KBr)/ Hydrogen atoms were placed geometrically and refined with a riding model and with U iso constrained to be 1.2 (CH, NH or BH) or 1.5 (CH 2 ) times U eq of the carrier atom. The highest residual peak and the deepest hole in the difference Fourier map are located 0.87 and 0.81 Å, respectively, from Br1. Fig. 1. The molecular structure of the title compound, showing the atom-labelling scheme. Hydrogen atoms have been removed for clarity. Displacement ellipsoids are drawn at the 30% probability level.