TY - JOUR
T1 - Vanadium(II) alkyls. Synthesis and X-ray crystal structures of trans-VMe2(dmpe)2 and cis-V(CH2SiMe3) 2(dmpe)2
AU - Morris, Robert J.
AU - Wilson, Scott R.
AU - Girolami, Gregory S.
N1 - Funding Information:
We thank the National Science Foundation (Grant CHE 89-17586) for support of this research and Quantum Chemicals and Lubrizol for fellowships to R.J.M. We also thank Charlotte Stern of the University of Illinois X-ray Diffraction Laboratory for assistance with the X-ray crystal structure determination and Dr. James Jensen for help in the early stages of the synthetic work. G.S.G. is the recipient of an A.P. Sloan Foundation Research Fellowship (1988-1990) and a Henry and Camille Dreyfus Teacher-Scholar Award (1988-1993).
PY - 1994/10/18
Y1 - 1994/10/18
N2 - Treatment of the vanadium(II) tetrahydroborate complex trans-V(η1-BH4)2(dmpe)2 with (trimethylsilyl) methyllithium gives the new vanadium(II) alkyl cis-V(CH2SiMe3)2(dmpe)2, where dmpe is the chelating diphosphine 1,2-bis(dimethylphosphino)ethane. Interestingly, this complex could not be prepared from the chloride starting material VCl2(dmpe)2. The CH2SiMe3 complex has a magnetic moment of 3.8 μB, and has been characterized by 1H NMR and EPR spectroscopy. The cis geometry of the CH2SiMe3 complex is somewhat unexpected, but in fact the structure can be rationalized on steric grounds. The X-ray crystal structure of cis-V(CH2SiMe3)2(dmpe)2 is described along with that of the related vanadium(II) alkyl complex trans-VMe2(dmpe)2. Comparisons of the bond distances and angles for VMe2(dmpe) 2, VC = 2.310(5) Å, VP = 2.455(5) Å, and PVP = 83.5(2)° with those of V(CH2SiMe3)2(dmpe)2, VC = 2.253(3) Å, VP = 2.551(1) Å, and P VP = 79.37(3)° show differences due to the differing trans influences of alkyl and phosphine ligands, and due to steric crowding in latter molecule. The VP bond distances also suggest that metal-phosphorus π-back bonding is important in these early transition metal systems. Crystal data for VMe2(dmpe)2 at 25°C: space group P21/n, with a = 9.041(1) Å, b = 12.815(2) Å, c = 9.905(2) Å, β = 93.20(1)°, V = 1145.8(5) Å3, Z = 2, RF = 0.106, and RwF =0.127 for 74 variables and 728 data for which I ≫ 2.58 σ(I); crystal data for V(CH2SiMe3)2(dmpe)2 at -75°C: space group C2/c, with a = 9.652(4) Å, b = 17.958(5) Å, c = 18.524(4) Å, β = 102.07(3)°, V= 3140(3) Å3, Z = 4, RF = 0.033, and RwF = 0.032 for 231 variables and 1946 data for which I ≫ 2.58 σ(I).
AB - Treatment of the vanadium(II) tetrahydroborate complex trans-V(η1-BH4)2(dmpe)2 with (trimethylsilyl) methyllithium gives the new vanadium(II) alkyl cis-V(CH2SiMe3)2(dmpe)2, where dmpe is the chelating diphosphine 1,2-bis(dimethylphosphino)ethane. Interestingly, this complex could not be prepared from the chloride starting material VCl2(dmpe)2. The CH2SiMe3 complex has a magnetic moment of 3.8 μB, and has been characterized by 1H NMR and EPR spectroscopy. The cis geometry of the CH2SiMe3 complex is somewhat unexpected, but in fact the structure can be rationalized on steric grounds. The X-ray crystal structure of cis-V(CH2SiMe3)2(dmpe)2 is described along with that of the related vanadium(II) alkyl complex trans-VMe2(dmpe)2. Comparisons of the bond distances and angles for VMe2(dmpe) 2, VC = 2.310(5) Å, VP = 2.455(5) Å, and PVP = 83.5(2)° with those of V(CH2SiMe3)2(dmpe)2, VC = 2.253(3) Å, VP = 2.551(1) Å, and P VP = 79.37(3)° show differences due to the differing trans influences of alkyl and phosphine ligands, and due to steric crowding in latter molecule. The VP bond distances also suggest that metal-phosphorus π-back bonding is important in these early transition metal systems. Crystal data for VMe2(dmpe)2 at 25°C: space group P21/n, with a = 9.041(1) Å, b = 12.815(2) Å, c = 9.905(2) Å, β = 93.20(1)°, V = 1145.8(5) Å3, Z = 2, RF = 0.106, and RwF =0.127 for 74 variables and 728 data for which I ≫ 2.58 σ(I); crystal data for V(CH2SiMe3)2(dmpe)2 at -75°C: space group C2/c, with a = 9.652(4) Å, b = 17.958(5) Å, c = 18.524(4) Å, β = 102.07(3)°, V= 3140(3) Å3, Z = 4, RF = 0.033, and RwF = 0.032 for 231 variables and 1946 data for which I ≫ 2.58 σ(I).
KW - Alkyls
KW - Catalysis
KW - Electron spin resonance
KW - Phosphine
KW - Vanadium
KW - X-ray diffraction
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U2 - 10.1016/0022-328X(94)87095-0
DO - 10.1016/0022-328X(94)87095-0
M3 - Article
AN - SCOPUS:0002410170
SN - 0022-328X
VL - 480
SP - 1
EP - 9
JO - Journal of Organometallic Chemistry
JF - Journal of Organometallic Chemistry
IS - 1-2
ER -