Cs[Yb(NPPh3)(4)] - a homoleptic phosphoraneiminato complex of ytterbium

Cesium tetrakis(phosphoraneiminato)ytterbate, short Yb-N-bond lengths betwe en 212.1 and 221.9(8)pm. Cs[Yb(NPPh3)(4)] (1) has been prepared by the reac tion of the dimeric complex [Yb(NPPh3)(312) with CsNPPh3 in thf solution. 1 crystallizes from thf solution to give colourless moisture sensitive cryst als which contain three molecules thf per asymmetric unit. According to the crystal structure determination 1 forms a dimeric ion ensemble [Cs{Yb(NPPh 3)(4)}](2) in which the Cs' ions connect the [Yb(NPPh3)(4)](-) ions via Cs . . .N bridges. The ytterbium atoms are distorted tetrahedrally coordinated by the nitrogen atoms of the phosphoraneiminato ligands (NPPh3-) with shor t Yb-N-bond lengths between 212.1 and 221.9(8) pm. The included thf molecul es are without bonding contacts with the complex. Cs{Yb(NPPh3)(4)}](2) . 6 thf: Space group P (1) over bar, Z = 2, lattice di mensions at 193 K: a = 1837.2(2), b = 2041.5(2), c = 2095.8(2) pm, alpha = 79.953(13)degrees, beta = 79.364(11)degrees, gamma = 88.239(12)degrees, R = 0.0625.