(Butane-1,4-diyl)(trimethylphosphane-κP)[tris(3,5-dimethylpyrazol-1-yl-κN 2)hydroborato]iridium(III)

In the mononuclear title iridium(III) complex, [Ir(C4H8)(C15H22BN6)(C3H9P)], which is based on the [tris(3,5-dimethylpyrazol-1-yl)hydroborato]iridium moiety, Ir[TpMe2], the IrIII atom is coordinated by a chelating butane-1,4-diyl fragment and a trimethylphosphane ligand in a modestly distorted octahedral coordination environment formed by three facial N, two C and one P atom. The iridium–butane-1,4-diyl ring has an envelope conformation. This ring is disordered because alternately the second or the third C atom of the butane-1,4-diyl fragment function as an envelope flap atom (the occupancy ratio is 1:1). In the crystal, molecules are organized into densely packed columns extending along [101]. Coherence between the molecules is essentially based on van der Waals interactions.

In the mononuclear title iridium(III) complex, [Ir(C 4 H 8 )-(C 15 H 22 BN 6 )(C 3 H 9 P)], which is based on the [tris(3,5dimethylpyrazol-1-yl)hydroborato]iridium moiety, Ir [Tp Me2 ], the Ir III atom is coordinated by a chelating butane-1,4-diyl fragment and a trimethylphosphane ligand in a modestly distorted octahedral coordination environment formed by three facial N, two C and one P atom. The iridium-butane-1,4diyl ring has an envelope conformation. This ring is disordered because alternately the second or the third C atom of the butane-1,4-diyl fragment function as an envelope flap atom (the occupancy ratio is 1:1). In the crystal, molecules are organized into densely packed columns extending along [101]. Coherence between the molecules is essentially based on van der Waals interactions.

Related literature
For general aspects of hydrogen trispyrazolylborate ligands, see: Pettinari & Trofimenko (2008). For general information on mechanistic aspects of organometallic reactions, involving oxidative addition and reductive elimination, see: Crabtree (2005). For information on -CAM mechanisms, see: Perutz & Sabo-Etienne (2007). For general information on the chemistry and potential of Ir [Tp Me2 ] complexes, see: Conejero et al. (2010). For selected aspects of the synthesis and the crystal structure of the precursor of the title compound, see: Paneque et al. (2000). For aspects of the chemistry of a CO-instead of PMe 3 -containing analogue to the precursor of the title compound, see: Gó mez et al. (2007). For a description of the Cambridge Structural Database, see: Allen (2002).

Experimental
Crystal data [Ir(C 4 Trofimenko, 2008) and containing carbon bearing co-ligands possess a rich chemistry (Conejero et al., 2010) and are capable of a broad range of bond activation and coupling reactions either via oxidative addition and reductive elimination (Crabtree, 2005) or via σ-CAM mechanisms (Perutz & Sabo-Etienne, 2007). When the conveniently accessible Ir(I) complex [(Tp Me2 )Ir(η 4 -CH 2 ═CH-CH═CH 2 )] containing a π-bonded butadiene is treated with a Lewis base like PMe 3 it transforms cleanly into the Ir(III) complex [(Tp Me2 )Ir(κ 2 -CH 2 -CH═CH-CH 2 )(PMe 3 )] in a process which implies the transformation of the butadiene ligand into a but-2-ene-1,4-diyl one (Paneque et al., 2000). This complex is inert to substitution of the phosphine ligand so the metallacyclic structure can experience some cyclopentene-like reactivity without rupturing the Ir-C bonds. The analogous product with a CO ligand instead of PMe 3 behaves similarly and experiences for instance a series of reactions (subsequent hydroboration-oxidation of double bond, alcohol oxidation to ketone and α-formylation of ketone) leading to the formation a new α-formyl-3-iridacyclopentanone (Gómez et al., 2007). The catalytic hydrogenation of the PMe 3 derivative under slightly harsher conditions leads to the formation of the title compound [(Tp Me2 )Ir(κ 2 -CH 2 -CH 2 -CH 2 -CH 2 )(PMe 3 )], (I). A view of the complex is shown in Fig. 1. Iridium has a modestly distorted octahedral coordination with bond lengths given in Table 1. Bond angles about Ir are in the ranges 82.12 (8)-96.06 (7)° and 172.64 (7)-175.42 (4)° with the smallest angle (C-Ir-C = 82.12 (8)°) for the Ir butane-1,4diyl ring. This ring has an envelope conformation but is disordered because either the 2 nd or the 3 rd carbon atom of the butane fragment is the flap atom in 1:1 ratio (cf. Fig. 1). In the first case Ir1, C16A, C18A, and C19A are flat within 0.053 Å mean deviation from planarity and C17A is the flap atom that deviates by 0.569 (6) Å from the mean plane of the four.
In the second case Ir1, C16B, C17B, and C19B are flat (0.028 Å mean deviation) and C18B is the flap atom which deviates by 0.537 (7)

(Butane-1,4-diyl)(trimethylphosphane-κP)[tris(3,5-dimethylpyrazol-1-yl-κN 2 )hydroborato]iridium(III)
Crystal data Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.