The butterfly dimer [(tBu3SiO)Cr]2(μ-OSitBu3)2 and its oxidative cleavage to (tBu3SiO)2Cr(=N-N=CPh2)2 and (tBu3SiO)2Cr=N(2,6-Ph2-C6H3)

Treatment of CrCl2(THF)(2) with (NaOSiBu3)-Bu-t afforded the butterfly dimer [((Bu3SiO)-Bu-t)Cr](2)(mu-(OSiBu3)-Bu-t)(2) (1(2)), whose d(CrCr) of 2.658(31) angstrom and magnetism were indicative of strong antiferromagnetic coupling. A Boltzmann distribution of low-energy (1)A(1), B-3(1), (5)A(1), B-7(1), and (9)A(1) states obtained from calculations on [(HO)(2)Cr](2)(mu OH)(2) (1'(2)) were used to provide a reasonable fit of the mu(eff) vs T data. Cleavage of 1(2) with various L (L = 4-picoline, p-tolunitrile, (BuCN)-Bu-t, (BuNC)-Bu-t, Ph2CO, and PMe3) generated ((Bu3SiO)-Bu-t)(2)CrL2 (1-L-2). The dimer was oxidatively severed by Ph2CN2 to give ((Bu3SiO)-Bu-t)(2)Cr(N2CPh2)(2) (2) and by RN3 at 23 degrees C to afford (silox)(2)Cr=NR (3-R) for bulky R (adamantyl (Ad), 2,6-Pr-i(2)-C6H3, 2,4,6-Me-3-C6H2 = Mes, 2,6-Ph-2-C6H3) and ((Bu3SiO)-Bu-t)(2)Cr(=NR)(2) (4-R) for smaller substituents (R = 1-Naph, 2-Anth). X-ray structural studies were conducted on 1(2), square planar 1-(OCPh2)(2), pseudo-T-d 2 and pseudo-trigonal 3-(2,6-Ph-2-C6H3), whose S = 1 ground state was discussed on the basis of calculations of (H3SiO)(2)Cr= NPh (3 ''-Ph).