The molecular structure of 9 as determined by a single crystal X-ray diffraction study. The hydrogen atoms were omitted for clarity; the thermal ellipsoids were set at the 50 % probability level. Selected bond lengths are given in Å. Selected bond angles (°): N(1)-Nb(1)-N(2) 113.10(11), N(1)-Nb(1)-N(3) 104.52(10), N(2)-Nb(1)-N(3) 96.08(10), N(1)-Nb(1)-N(5) 98.71(10), N(2)-Nb(1)-N(5) 83.60(9), N(3)-Nb(1)-N(5) 154.75(9), N(1)-Nb(1)-N(4) 104.67(9), N(2)-Nb(1)-N(4) 140.91(9), N(3)-Nb(1)-N(4) 83.55(8), N(5)-Nb(1)-N(4) 81.09(8), C(1)-N(1)-Nb(1) 165.5(2), C(5)-N(2)-Nb(1) 166.7(2).