The complex [Fe(phen)₂(NCS)₂] (phen 1,10-phenanthroline) shows spin cross-over behaviour CFSE and at μeff 250… · ABC26IN0111
Subject: Inorganic Chemistry · Chapter: Coordination Chemistry · Topic: Coordination Chemistry – General · Exam: CSIR NET 2015 · Marks: 2 · Difficulty: Medium
The complex $\left[\mathrm{Fe}(\text { phen })_{2}(\mathrm{NCS})_{2}\right]$ (phen 1,10-phenanthroline) shows spin cross-over behaviour CFSE and at $\mu_{\mathrm{eff}}$ 250 and 150 K, respectively are
(a)$0.4 \Delta_{0}$, 4.90 BM and $2.4 \Delta$, 0.00 BM
(b)$2.4 \Delta_{0}$, 2.90 BM and $0.4 \Delta$, 1.77 BM
(c)$2.4 \Delta_{0}$, 0.00 BM and $0.4 \Delta$, 4.90 BM
(d)$1.2 \Delta_{0}$, 4.90 BM and $2.4 \Delta$. 0.00 BM
Answer
Answer: A ✓ checked by 4AB · confidence high
Explanation
High-spin Fe(II) at 250 K: t₂g⁴e_g², CFSE −0.4Δo, 4.90 BM; low-spin at 150 K: t₂g⁶, −2.4Δo, 0 BM (a).