(Cyanido-κC)(2,2-diphenylacetamido-κ2 N,O)bis(η5-pentamethylcyclopentadienyl)zirconium(IV)

In the title compound, [Zr(C10H15)2(C14H12NO)(CN)], the ZrIV atom is coordinated by two pentamethylcyclopentadienyl ligands, the amidate ligand via the N and O atoms, and an additional C N ligand. The four-membered metallacycle is nearly planar (r.m.s. deviation = 0.008 Å). In the crystal, the molecules are connected into centrosymmetric dimers via pairs of N—H⋯N hydrogen bonds.

In the title compound, [Zr(C 10 H 15 ) 2 (C 14 H 12 NO)(CN)], the Zr IV atom is coordinated by two pentamethylcyclopentadienyl ligands, the amidate ligand via the N and O atoms, and an additional C N ligand. The four-membered metallacycle is nearly planar (r.m.s. deviation = 0.008 Å ). In the crystal, the molecules are connected into centrosymmetric dimers via pairs of N-HÁ Á ÁN hydrogen bonds.
We thank our technical staff, in particular Kathleen Schubert, for assistance. This work was supported by the Deutsche Forschungsgemeinschaft (RO1269/8-1).

Comment
We studied the reactions of several nitriles with metallocene precursors as Cp* 2 M(η 2 -Me 3 SiC 2 SiMe 3 ) (Cp* = η 5 -pentamethylcyclopentadienyl, M = Ti, Zr) to synthesize and characterize new strained metallacycles with heteroatoms. In the reaction with diphenylacetonitrile the complex Cp* 2 Zr(N=CH-CHPh 2 )(N=C=CPh 2 ) (Becker et al. (2013)) was formed after 4 h at 358 K. However a longer reaction time of 24 h led to the cleavage of the Ph 2 CH-CN bond upon partial oxidation thus forming the title compound. The zirconium(IV) atom is coordinated by two pentamethylcyclopentadienyl ligands in a η 5 -fashion, as well as by the N-and O-atoms of the amidate and an additional C≡N ligand. The fourmembered ring is almost planar (mean deviation from the best plane defined by Zr1, O1, C1, N1 = 0.008 Å). The bond lengths O1-C1 1.290 (3) and N1-C1 1.294 (3) Å suggest the resonance form with electronic delocalization within the OCN unit. The molecules are connected to centrosymmetric dimers via N-H···N hydrogen bonds.

Experimental
To a stirred solution of Cp* 2 Zr(η 2 -Me 3 SiC 2 SiMe 3 ) (0.266 g, 0.5 mmol) in 5 mL of toluene was added a solution of Ph 2 CH -CN (0.193 g, 1.0 mmol) in 10 mL of toluene. The solution was stirred for 2 h at room temperature and subsequently 24 h at 358 K till the color turned to orange. All volatiles were removed under vacuum and the residue was dissolved in nhexane. After filtration the solution was allowed to stand at r.

Refinement
H1 and H2 could be found from the difference Fourier map and were refined freely. All other H atoms were placed in idealized positions with d(C-H) = 0.98 (CH 3 ) and 0.95 Å (CH) and refined using a riding model with U iso (H) fixed at 1.5 U eq (C) for CH 3 and 1.2 U eq (C) for CH. In one of the both phenyl rings two distances (C5-C6 and C6-C7) were restrained to be equal (SADI).  The molecular structure of the title compound with 30% displacement ellipsoids. Hydrogen atoms (except H1 and H2) are omitted for clarity.

Crystal data
[Zr(C 10 H 15 ) 2 (C 14 H 12 NO)(CN)] M r = 597.93 Monoclinic, P2 1 /n Hall symbol: -P 2yn a = 11.8961 (3) Special details Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. 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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq N2 0.34293 (17