Haymore, Maatta, Wentworth zyxwvutsrq / zyxwvu C~S-MO(NC~H~)~(S~CN(C~H~)~)~ 2063 A Bisphenylnitrene Complex of Molybdenum with a Bent Nitrene Ligand. Preparation and Structure of zyxwvut cis- Mo(NC6H5)2( S2CN(C2H5)2)2 Barry L. Haymore,* Eric A. Maatta, and R. A. D. Wentworth* Contribution from the Department of Chemistry, Indiana University, Bloomington, Indiana 47405. Received July 25, 1978 Abstract: The first bisnitrene complex of molybdenum, M O ( N C ~ H ~ ) ~ ( S ~ C N ( C ~ H & ) ~ , has been prepared in high yield by al- lowing an excess of phenyl azide to react with M O ( C O ) ~ ( S ~ C N ( C ~ H ~ ) ~ ) ~ in dry methylene chloride. Red-brown, solvent-free crystals of the complex were grown from methylene chloride-hexane. The structure of the complex was determined at -130 "C using X-ray diffraction techniques. The complex is monomeric and six coordinate with a somewhat distorted octahedral geometry caused by the small bite angles of the sulfur chelates, 67.60 (5) and 69.51 (4)"; the angle between the nitrene ligands is 103.5 (2)". Of special import are the inequivalent phenylnitrene ligands. One nitrene is strongly bent at the nitrogen atom with Mo-N( I)-C( 1) = 139.4 (4)" and Mo-N( 1) = 1.789 (4) A, and the other nitrene is nearly linear and has a shorter metal- nitrogen distance with Mo-N(3)-C(17) = 169.4 (4)" and Mo-N(3) = 1.754 (4) A. Available structural evidence indicates that linear nitrene ligands exert little if any trans influence on trans ligands while the bent nitrene in the title complex has a sig- nificant trans influence. The Mo-S(4) distance of the sulfur atom trans to N( 1) is 0.15 8, longer than that which is trans to N(3), and 0.30 8, longer than that which is trans to another sulfur. The title complex crystallizes in space group P2,/n with zyx a = 17.193 (8) A, b = IO. 194 (4) A, zyxwvutsr c = 18.127 (8) zyxwvuts .i, p = 123.59 (l)", and Z = 4. zyxwv On the basis of 351 8 unique reflections with Fo2 > 3u(FO2), the structure was refined using full-matrix, least-squares methods to R(F) = 0.042 and R,(F) = 0.055. Introduction The first nitrene complexes, OsO3(NR), were reported in 1959,' and several years later Ta(NR)(NR2)3 (1962),2 ReCI3(NR)(PPhEt2)2 ( 1962),3 and ReC1(NR)(RNHh2+ ( 1965)4were reported. In comparison to the number of carbene complexes, far fewer nitrene complexes are known. Although few in number, nitrene complexes include all second- and third-row transition metals of groups 4A, 5A, 6A, IA, and 8 except Tc. Nitrene ligands are of current scientific interest owing to their potential utility as stable sources of nitrenes in organic synthetic reactions. Furthermore, the metal in a nitrene complex can act as a variable source of electrons, thus allowing the NR group to react either as a nitrene or an imidea5 The synthetic utility of nitrene complexes has not been fully ex- ploited nor appreciated in the past because many of the more stable nitrene complexes are relatively inert toward reaction at the nitrogen atom of the NR group. This inertness is prob- ably connected with the linear ligand geometry and short metal-nitrogen bond length. Recent work with certain osmium complexes has shown nucleophilic activity at the nitrene ni- trogen atom.lc It is important to realize that the nitrene ligand can have amphoteric character similar to other N-ligating li- gands such as NO, NNR, and NNR2. Simple bonding theories suggest that nitrenes can act as linear four-electron donor li- gands (I) or as bent two-electron donor ligands (11). The only R I N 111 M I R \$ II M I1 nitrene complexes which have been structurally characterized in detail are C P ~ M O ~ S ~ ( N R ) ~ ~ and the very stable rhenium complexes, ReC13(NR) (PR'3)2 and ReCl(NR) ( RNH2)42+;7 in these complexes the nitrene ligands have a linear geometry with very short metal-nitrogen distances. Incomplete struc- tural details of another molybdenum nitrene complex, MoC12(NR)(PhC(O)N=NPh)(PPhMe2), have been re- ported.8 We now report the synthesis and structural characterization at low temperature of the molybdenum nitrene complex Mo(NPh)z(Et2dtc)2, which was prepared by the action of PhN3 on Mo(CO)*(Etzdtc)2. This is the second bisnitrene complex which has been reported, and it is the first structurally characterized example of a complex containing a bent nitrene ligand. A bisnitrene complex of osmium, Os02(NR)2, was recently described,Ic and a brief report of the preparation of a bisaminonitrene complex, Mo(NNPh2)2(Me2dtc)2, has also appeared.* Experimental Section Crystal Preparation. The molybdenum complex was prepared by the method described subsequently. Crystals were grown from a so- lution of dry methylene chloride to which hexane had been added to create a nearly saturated solution at room temperature. The solution was placed in a refrigerator (-10 "C) for 12 h, and large, red-brown crystals formed. These crystals were separated from the supernatant and used in subsequent structural studies. Infrared spectra were measured in Nujol mulls using a Perkin- Elmer 283 spectrometer and were calibrated using a polystyrene film. NMR spectra were measured in CD2C12 solution at ambient tem- perature using a Varian Associates HR-220 spectrometer. Spectra were calibrated using internal tetramethylsilane. Elemental analyses were performed by Galbraith Laboratories, Inc., Knoxville, Tenn. Mo(CO)2(Etzdtc)2 was prepared according to the literature method? All reactions were performed in an inert atmosphere using dry, freshly distilled solvents. X-ray data collection was accomplished using a locally constructed diffractometer consisting of a Picker goniostat interfaced to a Texas Instruments TI980 computer. The attached low-temperature device has been described.I0 Bis(phenylnitrene)bis(diethyldithiocarbamato)molybdenum. Freshly prepared Mo(CO)z(Et2dtc)2 (0.50 g, 1.1 mmol) was allowed to react with 0.30 g of phenyl azide (2.5 mmol) in 25 mL of dry methylene chloride. After the solution was stirred at room temperature for 24 h, the volume of the solution was reduced to IO mL, and 5 mL of dry hexane was added. After several minutes, the mixture was filtered to remove a yellow byproduct, and the solution was again concentrated in vacuo to a volume of IO mL. More yellow byproduct was then re- moved by filtration. The remaining solution was allowed to stand overnight at -10 "C in order to crystallize the product from solution. The supernatant liquid was decanted and the product was washed with hexane to yield 0.32 g (50%) of deep red-brown crystals. In some in- stances, the above procedure produced an oil instead of crystals during the final crystallization step. The addition of 1-2 mL of methylene 0002-7863/79/ 150l-2063$01 .OO/O 0 1979 American Chemical Society